Environmental guidelines for site selection, operations and monitoring of offshore agriculture in Mississippi coastal waters

[From the U.S. Government Printing Office, www.gpo.gov]

-1,:3 / <-,- z

ENVIRONMENTAL GUIDELINES FOR SITE SELECTION,

OPERATIONS AND MONITORING OF OFFSHORE AQUACULTURE IN

MISSISSIPPI COASTAL WATERS

Prepared for

Mississippi Department of Wildlife, Fisheries and Parks
Bureau of Marine Resources

FINAL REPORT

Grant No. CZM817/7.3

Jurij Homziak
Coastal Research and Extension Center
Mississippi Agricultural and Forestry Experiment Station
Mississippi State University
2710 Beach Blvd., Suite 1-E
Biloxi, MS 39531

35
SH

.M7
H6
1991

ENVIRONMENTAL GUIDELINES FOR SITE SELECTION,

OPERATIONS AND MONITORING OF OFFSHORE AQUACULTURE IN

MISSISSIPPI COASTAL WATERS

Prepared for

Mississippi Department of Wildlife, Fisheries and Parks
Bureau of Marine Resources

FINAL REPORT

Grant No. CZM817/7.3

U . S - DEPARTMENT OF COMMERCE NOAA
COASTAL SERVICES CENTER
2234 SOUTH HOBSON AVENUE
CHARLESTON , SC 29405-24 13

Jurij Homziak
Coastal Research and Extension Center
Mississippi Agricultural and Forestry Experiment Station
Mississippi State University
2710 Beach Blvd., Suite 1-E
Biloxi, MS 39531

Abstract

The major potential impacts of offshore aquaculture and

actions to quantify, regulate and minimize these impacts have

been identified in a variety of state and national studies. The

main findings of these studies are:

1. Solid wastes from both net pen and shellfish aquaculture

operations will settle to the bottom and affect the benthic

community immediately beneath the site. Selecting sites deep

enough and with sufficient currents to disperse these wastes will

minimize the impact.

2. Important marine habitats, fisheries resources, public

lands and endangered or threatened species can be affected by

aquaculture operations. Determining appropriate separation

distances and selecting sites away from sensitive or important

habitats and public lands will minimize this impact. Impacts on

piscivorous birds can be fu rther minimized by use of predator

control netting and other non-lethal control measures. Control

of avian predators must conform with existing federal guidelines.

3. Nutrients released from net pens, especially nitrogen,

can contribute to phytoplankton production in stratified,

nutrient poor waters. Siting to avoid areas where nutrient

depletion occurs and placing limits on total fish production in

such areas can prevent adverse environmental effects.

4. Fish culture in warm water conditions can place heavy

demands on available dissolved oxygen levels. Selecting sites

deep enough and with adequate current speeds to allow for

adequate dispersion of wastes, setting appropriate limits on

total fish production and following low waste feeding practices

(dry, floating feeds, high digestibility, no fines) will minimize

adverse impacts. The use of automatic feeders should be closely

watched. The proportion of wasted feed is significantly greater

with automatic feeders (overfeeding, fines) than with other

feeding methods (Weston 1991a).

5. The effect of aquaculture operations on water movement,

quality and on the benthic environment are not detectable within

tens of meters of the culture site. Major effects on benthic

biota, reduction in dissolved oxygen and increased dissolved

nutrient concentrations are limited to within a few meters of the

culture site.

6. There is no good evidence for net pens having an adverse

impact on fish and other nektonic species, transmitting diseases

to wild fish, contaminating resident fauna with antibiotics or in

contributing to the development of antibiotic resistant microbial

populations threatening to human health.

7. The environmental effects of on- and off- bottom

shellfish culture are generally limited to those associated with

sediment deposition.

Proper siting of net pens can assure the dispersion of both

solid and dissolved wastes and the protection of sensitive areas.

The severity of the environmental effects of net pen and

shellfish raft culture are related to the size of the operation.

Site characterization surveys and operations and monitoring

guidelines must be related to the size/production level of the

facilities, with increasingly extensive requirements for larger

facilities.

Because long term data on currents and water quality

conditions in the shallow, near shore waters of the northern Gulf

of Mexico are so poor, permit requests for offshore aquaculture

must be reviewed and evaluated on a case by case basis. Should a

permit request be denied because the proposed operation does not

satisfy recommended site selection, evaluation, operations and

monitoring guidelines presented here, the burden of proof that

there will be no significant environmental effect associated with

the operation should fall on the applicant.

I. INTRODUCTION

Many of the fish and shellfish species upon which the Gulf

seafood industry depends, such as redfish and oysters, have shown

dramatic declines in abundance. Similar declines in other areas

have affected the harvest of valuable species such as the striped

bass. As catches have declined, demand and prices have risen.

New techniques for farming fish and shellfish have been developed

to meet growing demand. Cultured fish and shellfish have

experienced rapid growth in Mississippi, in other parts of the

U.S. and in other countries.

Aside from pond culture, one of the most successful

approaches to fin fish farming has been net pen culture, where

fish are grown in pens or cages moored in open water. oyster

culture in mesh bags on the bottom or suspended from floating

long lines has also met with success.

The development of these techniques and the apparent

profitability of commercial net pen and suspended shellfish

aquaculture elsewhere has created a growing interest in the

establishment of such facilities in Gulf of Mexico waters.

Interest has also been spurred by some local developments. An

on-bottom bag culture system for oysters was developed and tested

in the Florida panhandle; a local aquaculturist is evaluating the

feasibility of such a system in Mississippi waters. A net pen

system moored to an offshore oil platform in 200 feet of water is

being evaluated for fin fish culture off the Texas coast.

The rapid growth of offshore aquaculture industries (defined

as fin fish net pen culture and the cultivation of mollusks in

floati ng or on-bottom structures) in other regions has brought

attention-to the potential environmental effects of open water

aquaculture. Regulatory agencies in these areas have examined

these issues an d have developed siting, operations and monitoring

guidelines to measure and limit the potential negative

environmental effects of open water aquaculture. Through an

analysis of these regulations, associated reports and the related

scientific literature, this report attempts to identify the

potential environmental effects of off shore aquaculture, to

evaluate the importance of these effects in the northern Gulf of

Mexico, and to provide guidelines for the siting, operation and

monitoring of such operations. These guidelines are intended to

aid both the industry, by identifying criteria for selecting

appropriate sites and scales of operation, and the regulatory

agencies, by creating a framework for the permit review process.

II. OPERATIONS

Commercial net pen culture of fin fish in the marine/coastal

waters of North America focuses on various species of salmon or

steelhead trout culture. Other fin fish species are also

cultured in cages, such as yellowtail in Japan and red sea bream

in Taiwan and the Mediterranean region. Research is underway in

Europe exploring the feasibility of raising cod, turbot and other

species in cages.

Because of recent advances in production technology, the

most likely fin fish candidates for warm water marine net pen

aquaculture in the U.S. are redfish and hybrid striped bass.

This review will focus on conditions associated with the

potential cultivation of these two species in Gulf waters.

Net pen culture

A brief description of commercial salmon operations (from

Weston 1986a) will serve to introduce the technology used in net

pen operations. In Washington, fish are held in net enclosures

with 10 - 30 mm mesh, depending on the size of the fish. The

dimensions of the enclosure vary among facilities. A small net

pen may be only a few meters on a side, while larger net pens may

measure 12 x 12 m. Net pens usually extend 2 - 4 in below the

surface. At most facilities, net pens are moored together to

form a single large farm unit, with individual pens separated by

walkways (Fig. 1). Buildings for shelter, equipment and feed

storage and/or processing may be incorporated as well.

Fingerlings are stocked into the pens in the spring of each

year, but usually spread over several months to insure a steady

supply of product. Stocking density of salmon depends on several
factors but is usually 15 kg/m3. "Pan-sized" fish (0.3 kg) are

held for 6 - 11 months while market fish are held for 18 - 24

months, until they reach 2 - 5 kg size.

Salmon can be fed a variety of diets, including dry, moist

and wet (minced fish) feeds. U.S. growers use dry feeds almost

exclusively. Feed may be delivered by hand, by demand feeders or

by automatic feeders. Salmon are usually fed 2% of body weight

per day. This varies greatly with fish size, water temperature

and other factors. Feed conversion ratios of 1.5 - 2:1

(feed:fish weight) are commonly achieved.

Proper husbandry practices (esp. stocking density),

vaccination or addition of medicated feeds minimized loss to

stress and disease mortality. Use of overhead netting,

especially over pens holding smaller fish, excludes bird

predators. Predation by fish and aquatic animals is prevented by

use of a large mesh outer net around the facility. Nonlethal

fish and marine mammal deterrents (e.g. acoustic devices) are

also used.

Shellfish culture

Two approaches are used to grow oysters in containers (Field

and Drinnan 1988). "Off bottom" culture refers to methods used

to grow oysters by suspending them from surface floats. In "on

bottom" culture, oysters are grown in or on structures placed

directly on the bottom. In both approaches, seed oysters from

wild or hatchery sources are used.

The distinguishing feature of off-bottom culture is the

floatation system. Two basic types are used (see Magoon and

Vining 1981, Nosho 1989): long lines and rafts. A long line

consists of a 50 - 300 m long, 12 - 25 mm thick rope which is

buoyed at 10 m intervals or less along its length, and well

anchored at both ends. Strings or structures holding the oysters

(usually nets or mesh bags) are suspended from the long line.

Because of their inherent flexibility, long lines are more suited

to open water situations. Rafts, on the other hand, have a rigid

structure and are more suitable for sheltered locations. The

most common raft type is of beams and crossbars bolted together

and mounted on-a series of floats. Rafts are used for tray

culture, where the oysters are held in mesh trays suspended from

the rafts.

The most common on-bottom systems use either mesh bags,

linked into belts, or rigid stacks of cages, both of which are

anchored to the bottom (Magoon and Vining 1981, Nosho 1989). The

"flexible belt" method (Cresswell et al 1990) appears to be the

more economically promising approach in Gulf waters. Regardless

of the approach, seed oysters are initially placed into small

mesh trays or bags. The oysters are periodically moved to larger

mesh containers as they grow, and the containers are regularly

cleaned of fouling organisms.

III. POTENTIAL ENVIRONMENTAL EFFECTS

1. Water Circulation Effects

a) Water Circulation Effects Within the Structure

Empirical studies of net pens on water circulation indicate

substantial reduction of current velocities inside net pens

(Inoue 1972). For pens 3 x 3 x 3 m with 2.4 cm mesh no fouling

and no fish, it was estimated that current velocities would be

reduced to 70 - 80t of initial velocity after passage through the

first pen, and to 10 - 25% of initial velocity of after passage

through 3 pens. Stocking density of fish, mesh size, pen volume,

fouling and other variables can dramatically increase the

resistance of the net pen to water flow (Weston 1986a). Water

flow within shellfish rafts was measured at 12 - 14% of outside

current velocity (Arakawa et al 1971). At a depth of 1 m below

the culture strings no consistent current effects were evident.

b) Water Circulation Effects Outside the Structure

While any object placed within a current will alter water

circulation,'there have been no measurements of the effects of

net pens or mollusk culture structures on water circulation.

Based on the estimated effects of solid structures on water flow,

Weston (1986a) estimated porous-structures such as net pens or

shellfish rafts will reduce current velocity upstream for a

distance about equal to the dimension of the net pen

perpendicular to the current flow. Current velocity at the sides

of the structure was estimated to be 95% of the free stream value

at a distance of about two structure diameters. Downstream

current velocity was estimated to return to 95% of the free

stream value within 20 structure diameters.

While Weston (1986a) provided no estimate on the vertical

extent of current velocity reduction by floating aquaculture

structures, the effect should be detectable at least to a depth

of two structure heights. Where cages are moored in water just

exceeding this depth, additional turbulence and boundary effects

of the bottom on current flow will have to be considered in

estimating reductions in current velocity and potential

sedimentation effects.

These figures are only order-of-magnitude approximations

since variables such as mesh size, extent of fouling and current

variation will affect the calculations significantly. Fouling of

the net mesh or use of smaller diameter mesh will significantly

increase the distances where currents are reduced.

c) Sedimentation

The reduction of current velocity in the vicinity of the

aquaculture structures will cause suspended particles to settle

out, increasing sediment deposition below net pens or rafts. As

discussed here, sedimentation is distinct from sedimentation of

waste material from the culture operation. This effect may

especially significant for on-bottom shellfish culture

structures, and for floating net pens or shellfish rafts moored

in shallow water. If such structures are located close enough to

the bottom to restrict water flow, deposition of the suspended

sediments and trapping of solid wastes from the net pens will

probably occur. The problem may be magnified in areas of high

suspended sediment loads.

d) Circulation and water quality

The reduction of current velocity within and outside the

culture units may affect water quality by preventing an adequate

supply of oxygenated water on inhibiting the removal of waste

material. For shellfish culture, reduced current velocities

within the structures may also reduce the quantity of food

reaching interior or downstream shellfish, causing poor growth or

mortality (Incze and Lutz 1980).

Inoue (1972) estimated that current velocity in net pens

will be one-half of the upstream velocity. To estimate current

velocity through pens on a model salmon farm, Weston (1986a)

incorporated the tidal variation in current velocity with net pen

effects to derive an estimated average current flow into net pens

of 20 - 40% of the peak ebb current velocity.

Operations located in areas of low current velocity (less

than 5 cm/sec) will have to take measures to minimize the effects

of the structure on water circulation. Multiple net pens should

be arranged perpendicular to current flow with an optimal spacing

between pens or rafts of two diameters or more. This arrangement

will minimize the effect of each unit on water circulation and

water quality. Water depth below the lowest point of the

structure should exceed two times pen height.

2. Water Quality

a) Waste Inputs

Waste inputs from net pen aquaculture are unutilized feed

and the metabolic products of food breakdown (Weston 1986a,

1986b, 1991a, 1991b, Weston and Gowan 1988). The inputs are:

Ammonia - the principal nitrogenous excretory product of fish and

shellfish. Can be present in ionized (NH4+) or unionized (NH3)

form. At the temperature range (15 - 30 OC) and Ph (about 8.0)of

Mississippi coastal waters, the percent of toxic unionized

ammonia will be 1.5 - 4.0%.

Nitrate and Nitrite - produced by the microbial degradation of

other nitrogenous compounds; elevated concentrations may be

expected in the vicinity of net pen aquaculture due to bacterial

oxidation of ammonia.

Organic Nitrogen - urea is the principal component, produced as

an end product of protein metabolism.

Phosphate - excreted in urine and leached from waste food and

feces.

Oxygen - respiration by the cultured organisms and the

consumption of oxygen by decomposition of waste material (the

biochemical oxygen demand on BOD) lower dissolved oxygen (DO)

levels.

b) Waste Loading

Little information is available on nutrient or BOD loading

from marine net pen culture. Most of the information has been

developed from studies of salmonid culture in cool, freshwater

systems. Reviews of published data for intensive raceway systems

(and marine net-pen systems (Weston 1986a) suggest that loadings

are extremely variable depending on type of feed, quantity and

frequency of feeding, temperature, fish size and proportion of

suspended solids in the effluent stream. As a result, loading

values from any one aquaculture operation cannot be used to

accurately predict loading values from another.

Waste loads for net pen aquaculture are difficult to

estimate for warm water marine systems. Several values are

commonly cited. Estimated loadings per kg of fish produced per

day (g/kg fish/day), based on salmonid data from Ackefors and

Enell (1990), are a BOD of 0.90 g, 0.23 g total nitrogen and 0.03

g total phosphorus. Weston (1991a) used these values to estimate

warm water net pen aquaculture waste loads in Chesapeake Bay.

Approximations of waste loads generated by net pen salmon farming

in Puget Sound, valued on a g/kg fish/day basis, are: ammonia -

0.3, nitrate 0.1, organic nitrogen - 0.04, total nitrogen - 0.6,

phosphate -0.1, total phosphorus -0.1, BOD - 3.0 (Weston 1986a).

Huguenin and Colt's (1989) estimated waste load values for cool

and warm sea water systems closely match the values derived from

fresh water and cool water culture systems.

These estimates of waste loads include both dissolved

nutrients that enter the water directly and nutrients which reach

the bottom as waste feed or feces. Most of the nitrogenous waste

will be released in dissolved form, while in marine waters most

of the phosphorous will be part of the particulate material

(Weston 1991a, 1991b). Most of the BOD is associated with the

particulate material.

Waste loading from shellfish culture is based not on inputs

of external feed but on concentration of phytoplankton from the

water column (Incze and Lutz 1980). There is no addition of new

nutrients into the system. Generalizing from studies of cultured

mussels, about 40% of the nutrients removed by shellfish are

released directly back into the water column, 30% falls to the

bottom as particulate material and 30t are removed in the harvest

(Ackefors and S6dergren 1985).

A frequent comparison contrasts waste loads from net

pen operations with other nutrient discharges (e.g. Weston 1986a,

1991a). These comparisons are misleading. The relatively high

BOD associated with net pen culture reflects the efficiency of

sludge treatment at sewage plants, not an inherently greater BOD

of fish wastes in comparison to domestic sewage (Weston 1991a).

Similarly, while BOD and nutrient loadings from net pen

operations appear to be comparable to industrial or domestic

effluents, the concentrations of these wastes are far lower

(Weston 1986a). Inputs of nutrients from farm and urban and

sewage treatment effluent runoff, channeled by river flow into

Mississippi coastal waters, is a much greater source of

enrichment.

c) Dissolved Oxygen

Fish and shellfish culture can be expected to reduce the

dissolved oxygen content of the water by two mechanisms:

respiration of the organisms and the biochemical oxygen demand of

the waste feed, feces and urine. Because oxygen consumption of

fish will depend upon fish species, size, water temperature,

swimming speed and other factors, it is impossible to determine

the oxygen needs of a net pen operation with any degree of

precision. This assessment is complicated further by the fact

that existing oxygen consumption data for hybrid striped bass and

redfish is very limited. The same limitations hold true for

shellfish culture.

Oxygen consumption rates of juvenile hybrid striped bass (20
- 100 g) at 24 OC were estimated to be 200 - 260 mg 02/kg fish/hr

at a swimming speed of 1 cm/sec, and 320 - 400 mg 02/kg f ish/hr
at a swimming speed of 10 cm/sec (Kruger andbrocksen 1978).

Respiration data for hybrid striped bass at higher temperatures

are not available. Rosati (1990) suggests a rule of thumb

approximation: a fish consumes 1/4 pound of oxygen for each

pound of f eed (about 114 9 02/kg f eed). Colt and Tchobanogious

(1981) provide a range of respiration rates, 6 - 40 kg 02/1000 kg

fish/d, for various species of freshwater fish. While their

synthesis does not provide any information on swimming speeds,

they report 100 g rainbow trout held in 150C water consumed about

312 Mg 02/kg fish/hr while 100 g channel catfish consumed nearly

three times as much oxygen, 812 mg 02/kg f ish/hr. Hybrid striped

bass hold in 300C water would have an oxygen requirement close to

the upper end of this range which no oxygen consumption data for

redfish are available, limited observations of redfish juveniles

indicates that their critical oxygen concentrations are unusually

high for warm water fishes, suggesting an elevated oxygen

consumption rate (Neill 1987).

These dissolved oxygen consumption rates may effectively

limit the size of net pen operations in Mississippi waters of the

northern Gulf of Mexico. The solubility of oxygen at 25 ppt

salinity and 28 OC is 6.8 mg/l, 7.3 mg/l at 24 OC (Colt 1980).

Assuming the water exits the net pen at a dissolved oxygen
concentration of 5 Mg 02/1 (the minimum culture requirement),
this leaves 1.8 and 7.3 Mg 02/1 for fish respiration at 25 0 and

24 *C, respectively.

A load of 250, 000 kg of f ish, consuming 600 mg 02/kg/m, in a

3 cm/sec current inside the cage would use about 0.6 mg 02/1 Of

flow. Halving the current flow will double the oxygen

consumption. As noted earlier, current velocities within cages

are 20 - 40% of maximum ebb current velocities.

Field investigations around net pens have reported decreases

in dissolved oxygen. Dissolved oxygen concentrations 0.2 - 2.5

Mg 02/1 less than ambient were observed around yellowtail and sea

bream cages in Japan. There was no evident oxygen depletion

beyond the immediate boundaries of the farm. This is an extreme

case where circulation was limited and a large quantity of fish

(400 mt) were being held. In most cool water conditions, net pen

aquaculture operations did not have any measurable effects on

dissolved oxygen content.

- Similarly, no evidence of dissolved oxygen depletion was

noted around commercial scale suspended mussel operations in

Sweden or New Zealand (see references in Weston 1986a).

Suspended shellfish culture operations in the northern Gulf of

Mexico are not expected to have significant effects on dissolved

oxygen concentrations or on other water quality parameters.

Oxygen consumption can be estimated for planned shellfish

culture operations in the northern Gulf of Mexico. Average

oxygen consumption rates for oysters have been reported to be 303

Ml 02/kg of wt tissue/hr (Hammen 1969). The rate of oxygen

consumption, however, increases as salinities decrease. Shumway

(1982) describes this function. At 28 ppt salinity and a water

temperature of 30 OC, the oxygen consumption rate is 200 ml 02/kg

wet tissue/hr or 39 ml/kg/hr for whole oysters. Long line

culture of mussels supports an additional 15% biomass of fouling

organisms (Weston 1986a). While fouling biomass for Gulf oyster

culture is not known, biomass estimates for oxygen consumption

calculations should be adjusted upwards by at least this amount.

d) Nitrogen and Phosphorus

Because feed is not added, shellfish culture does not add

new" nitrogen and phosphorous to the environment. Shellfish do,

however, increase the rate at which these nutrients are recycled.

By ingesting phytoplankton and excreting a large part of their

constituent nutrients, shellfish make dissolved nutrients more

readily available for use by other organisms. The potential for

this increased nutrient cycling to stimulate phytoplankton blooms

has been noted (Tenore and Gonzales 1975) but field studies have

failed to find any effect of shellfish culture on phytoplankton

productivity (Weston 1986a, 1986b).

Feeds are the main source of waste nutrients in net.pen

culture. Ammonia and, to a lesser extent, urea, are the

principal nitrogenous wastes associated with net pen culture.

Ammonia can be present as the non-toxic ammonium ion (NH4* or as

the toxic unionized form (NH3). At the temperatures and pH of

marine waters in the northern Gulf of Mexico, 0.2 - 5% of ammonia

will be in the toxic form (Huguenin and Colt 1989). At these

levels ammonia toxicity is not likely to be a problem.

Phosphorus is also introduced with feeds. In marine systems

only limited amounts enter into the environment through urine.

Leaching from waste feed and feces is an important source of

dissolved phosphorous.

The form of nitrogen and phosphorus input and their

potential impacts are very different. Nitrogen is released

largely in the soluble form, while phosphorus in sea water is

associated primarily with feed and feces. The phosphorus

initially deposited in the sediments can later be released into

the water column, particularly under anaerobic conditions (Weston

1991a, 1991b).

Localized increases in nutrient concentrations have been

reported in the immediate vicinity of net pen culture sites.

Such observations are common and should be expected. The extent

of measurable enrichment will depend upon hydrographic factors,

but dilution is generally very rapid and nutrient increases have

been limited to within tens of meters of the net pens.

The primary concern associated with dissolved nutrient input

is the effect it may have on phytoplankton production. Tagaki et

al. (1980) and Arakawa et al (1973, cited in Weston 1986a)

related phytoplankton blooms to oyster culture and Nishimura

(1982, cited in Weston 1986a) to fin fish culture in Japan. This

may be of particular importance where potentially toxic

phytoplankton species are involved. The neurotoxin-producing

diatom, Nitzschia pungens f. multiseries, has been identified

from the northern Gulf (Fryxell et al 1991). A related form has

been implicated in shellfish poisoning in Canada. Other toxic

algal blooms involving Ptychodiscus brevis and Gonyaulax monilata

have been reported from the Florida and Texas (Snider 1987).

It is important to remember that while nutrient discharges

have been implicated as potentially contributing factors in

phytoplankton blooms, this input alone will not cause a bloom.

Many environmental factors must interact to provide the

conditions suitable for rapid phytoplankton growth.

Phytoplankton population.also require several days to increase to

bloom proportions, while dilution and water movement mix the

nutrient rich effluent with the surrounding water on a scale of

meters and hours. Only in static systems have studies shown a

measurable effect of net pen culture on productivity (see

references in Weston 1986a).

It is only in areas with reduced nitrogen concentrations

that the additional input of nutrients may have a measurable

effect on productivity. Areas with a high degree of vertical

stratification because of fresh water inflow or minimal tidal

mixing would be particularly susceptible to nitrogen depletion in

surface waters. Japanese researchers have suggested nitrogen

concentrations of 0.35 mg/l (Takagi et al 1980), and 0.1 mg/l

(Iwasaki 1976, cited in Tagaki et al 1980), the limit proposed by

Weston (1986a, 1986b), to identify nitrogen depleted areas

susceptible to phytoplankton blooms. Stratification of the

waters south of the Mississippi barrier islands is frequent

(Kjerfve and Sneed 1984), and surface waters depleted of nitrogen

are common under these conditions. Studies by USEPA (19901 in

the area have revealed total nitrogen concentrations below 0.1

mg/l.

In areas where nutrients are limiting to phytoplankton

growth, any input would, by definition, stimulate production.

However, in most areas dilution by a current action and surface

mixing would minimize any potential localized effects on

productivity. Siting culture operations away from nutrient

depleted, stratified waters, following correct feeding
procedures, feeding only dry pellets, eliminating fines, reducing

waste and using highly digestible feeds will all contribute to

reducing waste impacts on water quality.

3. Benthic effects.

a) Solid Waste Production

Excess feed, fecal material and debris from structures are

the main solid wastes associated wit h offshore aquaculture.

The amount of wasted feed (that which passes through the

cages) is highly variable, depending upon culture practices such

as feed type used (dry, moist, wet), feeding methods (hand,

automatic, demand) and frequency of feeding. Estimates of waste

feed for net pen operations in Maine (Maine Department of Marine

Resources 1991) and Washington (Weston 1986a) are about 5%, but

can be as high as 20%.

Fecal production is the second major source of solid waste,

While fecal production rates for net pen culture are not

available, trout fed dry pelleted feed under laboratory.

conditions lost 25 - 38% as feces on a dry weight basis (Butz and

Vens-Capell 1982). Weston (1986a) assumed about one-third of the

feed ingested was lost as feces in commercial net pen culture in

Washington.

Assuming a dry feed is used and a feed conversion ratio of

2:1, the production of 1 kg of fish will result in an estimated

production of 0.7 kg (dry weight) of solid waste, using Weston's

(1986a) assumption. Of the two kg of feed fed, approximately 5%

(0.1 kg) is wasted. The remainder, 1.9 kg, is ingested by the

fish. About one-third or 0.6 kg is lost as feces. This is a

best case situation with a minimal amount (5%) of feed wastage.

Using these assumptions, a large facility producing 250 metric

tons of fish per year is estimated to produce about 175 metric

tons of solid waste per year (Weston 1986a).

In warm water areas, such as the Gulf of Mexico, the

sloughing off of fouling organism from net pen and shellfish

culture structures may also be a significant solid waste input.

The contribution of fouling organisms to the solid waste stream

is not known but is expected to be significant in warm water

,ituations where fouling may be severe.

The Institute of Aquaculture (1988, cited in Weston 1991a)

estimated solid waste production of 520 kg per metric ton of

fish, assuming 20% feed wastage and 30% feces loss. This may be

a more accurate estimate of solid wastes.

Solid waste production rates are very sensitive to changes

in feed conversion ratios (FCR) and feed wastage. Reducing FCR

from 2:1 to 1.5:1 would reduce sediment production by about 25%.

Shellfish culture also produces solid waste in the form of

feces and pseudofeces, shells lost from the structure and fouling

organisms sloughed off during cleaning. Arakawa et al (1971) and

Kusuki (1977) estimated that a single raft holding 350,000 -
630,000 oysters can produce 16 metric tons (dry weight) of feces

and pseudofeces and an additional 4.5 tons of feces from fouling

organisms in a nine month growing season.

b) Sedimentation

Sedimentation rates have been estimated for a variety of

culture situations using net pens and floating rafts (see review

in Weston 1986a). Much of the data, based on sediment trap

results, is of questionable value because of re-suspension and

artifacts related to trap size and shape. The data are useful,

however, in obtaining estimates of sedimentation beneath net

pens/rafts relative to a reference area with a similar current

regime. Sedimentation rates beneath net pens have been found to

be 2 - 10 times greater than in reference areas (Pease 1977,

Weston and Gowan 1988).

Rates of deposition beneath mussel long lines have been

reported to be 2 - 4 times greater than surrounding areas

(DahlbAck and Gunnarsson 1981). Arakawa et al (1971) reported

that approximately 20 - 30t of the 20 tons of solid waste were

generated by an oyster raft and deposited in the vicinity of the

raft.

Placement of net pens or rafts in shallow water will

significantly increase rates of sediment deposition by lowering

current velocity beneath the structures. Water depth beneath the

bottom of the net pens should be at least two structure heights-

to eliminate the effects of current reduction. Results from an

analysis by Weston (1986a, 1986b) suggest that sediment

accumulation is likely if net pens are located where water depths

under the pens are less than 15 m. Braaten et al (1983) suggests

a clearance of at least 10 m beneath net pens and further

suggests sites with strong currents. Washington State has

adopted the recommendations of Weston (1986a), using the size of

an operation to determine minimum acceptable water depths and

current speeds for siting a net pen operation (Washington

Department of Fisheries 1990). British Columbia requires a

minimum of 6 m of water depth below the bottom of net pens, New

Zealand 7.5 m (see references in Weston 1991a, 1991b). While

Maine has no rigid depth requirements for sites, they consider

the Washington guidelines and local site conditions in previewing

permit applications (Maine Department of Marine Resources 1991).

c) Effects on Sediment Chemistry

Under hydrological conditions typical of the northern Gulf

of Mexico, much of the fecal matter, waste feed and debris will

settle in the immediate vicinity of the net pens or shellfish

rafts. The area receiving solid wastes from fish culture net

pens will be visibly affected and are described in a number of

sources (e.g4 Weston 1986a, 1986b, 1991a, Washington Department

of Fisheries 1990) Aside from the presence of food pellets, the

area beneath shellfish culture rafts are similar in appearance

(Dahlb9ck and Gunnarsson 1981). Food pellets will be readily

detectible and the feces may form a flocculent deposit 5 cm or

more in thickness. Sediment color changes to anoxic black in

highly enriched conditions, or to shades of red or orange if only

moderately enriched. A common indicator of enrichment is the

presence of the filamentous, sulphide-reducing bacteria,

Begglatoa, found in dense whitish mats on the sediment surface.

The area affected by solid waste from the aquaculture

facility has been reported to be relatively small. Visible

accumulations of solid waste from net pen facilities have

generally been reported to be within 30 m of the culture facility

(Weston 1986b), while significant changes in sediment chemistry

have generally been written 15 m (Pamatmat et al 1973, Weston

1986b, 1991a, 1991b). Arakawa et al (1971) and others (Dahlback

and Gunnarsson 1981, Mattsson and Linden 1983) report that the

area affected by sedimentation from shellfish culture does not

extend more than about 20 m.

The fate of solid wastes produced by a culture facility

depends, in part, on the current velocity, water depth and

sinking speed of the particles. Dispersion of waste particles

increased with increasing depth and current velocity and with

decreased sinking speeds.

Solid wastes provide a source of labile carbon and nitrogen.

It is the re-mineralization of carbon that produces the changes

in sediment geochemistry typical of organic enrichment Weston

1986a, 1991b). Sediment organic carbon inputs are an important

measure of the impacts of fish farms on the marine environment.

These can be measured by changes in benthic oxygen consumption,

reduction-oxidation (redox) potential, total organic carbon,

total volatile solids, sulfide concentrations and levels of

nitrogenous and phosphorus compounds.

In general, only about 20% of the carbon supplied to the

farmed fish in feed is removed with the harvest. The 80%

remaining is lost, with a seasonally variable amount (30 - 70%)

accumulating in the sediments in the short term (Hall et al

1990). Over the long term, the sediment serves as a sink for

about 18% of the total carbon input (Weston 1991a).

Re-mineralization of carbon rich sediments consumes

substantial amounts of oxygen. The biochemical oxygen demand

(BOD) of fish feces and other metabolic wastes may consume 1.5 -

3 times as much oxygen as respiration (Liao and Mayo 1974).

Rosati (1990) provides a rule of thumb estimate of 750 g of BOD

oxygen consumption for each kg feed used. Since most of the BOD

is associated with solid waste, most of the oxygen required to

meet this demand will be provided by bottom waters and sediment

pore waters. Dahlbdck and Gunnarsson (1981) measured sediment

oxygen demand beneath a mussel culture operation to be 1.4 1
02/M2/day (at 15 OC and a sedimentation rate of 2.4-3.3 g organic
C/m2/day).

Rates of biochemical oxygen consumption beneath net pens

were found to be between 2 - 3 times and six times greater than

reference values in two Washington state studies (Pease 1977,

Pamatmat et al 1973). Even higher rates have been reported

elsewhere (Weston 1991a). Because organic enrichment was limited

to the vicinity of both fish and shellfish culture operations,

elevated oxygen consumption rates were not detectable away form

the site (Pamatmat et al 1973).

The depletion of pore water oxygen in the sediments results

in a shallowing of the aerobic portion of the sediment column,

measurable by both sediment color changes and more negative

reduction - oxidation (redox) potentials in the sediment

(DahlbAck and Gunnarsson 1981, Weston and Gowen 1988, Weston

1991b). In fine sediments, the aerobic layer may be very shallow

and the addition of organically enriched sediments may increase

oxygen demand to the point where bottom water dissolved oxygen is

depleted. This may well be the case in Mississippi coastal

waters where large areas of silty sediments occur.

An important chemical effect of reduced sediment oxygen

levels is the production of toxic hydrogen sulfide (DahlbAck and

Gunnarsson 1981, Weston and Gowen 1988, Weston 1991b). In the

absence of oxygen, the microbial degradation of organic matter in

seawater is accompanied by the reduction of sulfate to hydrogen

sulfide. Hydrogen sulfide production has been associated with

both net pen (e.g. Weston and Gowen 1988, Weston 1991b). and

suspended shellfish culture operations (Dahlbdck and Gunnarsson

1981). Because hydrogen sulfide is toxic, it can be harmful to

both the culture organisms and to resident farms. Fish farms in

Japan and Europe, located in shallow, enclosed waters, have been

forced to relocate because of hydrogen sulfide toxicity from

accumulated wastes (Weston 1986a, 1991a).

The redox potential measures sediment oxygen content,

defining the depth of the boundary (redox potential discontinuity

or RPD) between aerobic and anaerobic sediments. This gives a

measure of relative enrichment of the sediments, and is the

recommended method to measure enrichment impacts beneath fish

farms. It is effective, relatively inexpensive and can be used

in field conditions (Weston and Gowen 1988). The drawback is

that in fine sediments, the RPD is so close to the surface that

it may not be readily measurable. Measurement of total organic

carbon (TOC) and total volatile solids (TVS) can also be used to

document organic enrichment beneath aquaculture facilities.

d) Biological chan2es due to organic enrichment

Azoic zones (zones devoid of any animals) are reported under

most fish farms and under shellfish rafts. The affected areas

are limited to those immediately below the farm (DahlbAck and

Gunnarsson, Weston 1986a, 1991a, 1991b). Stewart (1984) and

others (e.g. Weston and Gowen 1988) observed these conditions to

extend to about 3 m (10 ft) from the farm perimeter. This zone is

usually demarcated by a "halo" of dense Begglatoa mats, which

covers and stabilizes the underlying sediments. in areas of poor

water circulation, the water immediately above the substrate may

become anoxic, precluding Beggiatoa growth. No live animals are

present in this zone, gas bubbles (methane) are evident a nd redox

potentials are severely depressed.

Pearson and Rosenberg (1978) related general changes in the

benthic communities as the result of increasing organic

enrichment. Benthic communities are altered along a gradient of

organic enrichment from the background community of unaffected

environments in towards the fish or shellfish farm. It must be

noted that the transitions from one zone to another occur along a

continuum with no clear boundaries. Depending upon the amount of

organic material deposited and the existing benthic community,

the more affected zones may or may not be present under any

specific operation. Major alterations to benthic communities are

generally limited to the area immediately beneath culture

facilities and for short (<30m) distances away from the site.

These are, re spectively, the "footprint" and "shadow" impact

areas.

A stable, diverse benthic community is comprised of filter

and sediment feeding organisms and predators exists in

undisturbed sediments. Many of these animals are large and live

in the sediment. As organic matter is introduced into an

undisturbed environment, it provides an additional source of

nutrition for the benthic organisms. This additional organic

matter benefits the existing filter and deposit feeders, and

encourages colonization by additional species. Thus, both

species diversity and biomass (total weight) of the benthic

organisms increase, and the benthic community is enhanced.

Pearson and Rosenberg (1978) refer to this as the "transition

zone".

As the level of organic input increases, the normal

community changes as many species, especially filter feeders, are

displaced. The sediments become progressively dominated by

various opportunistic deposit feeders, which flourish under these

conditions. The most notable deposit feeder is the small, common

polychaete worm Capitella capItata, indicative of organic

enrichment. Under these conditions, the abundance of these

opportunistic species can reach very high densities, to the

exclusion of other species. Elimination of the larger, deeper

borrowing animals further reduces the ability of oxygen to

penetrate the sediments. Thus, while the number of organisms

increases dramatically, the diversity of species declines.

At higher rates of sedimentation, even the opportunists

cannot survive. At this point, the anoxic layer reaches the

sediment surface, depriving the animals of oxygen and exposing

them to toxic H2S' In these sediments, the surface is black and

devoid of any animals (azoic). Methane and toxic H2S are

produced and escape as bubbles into the water. Gowen et al

(1988) estimated that input of organic matter at rates greater
than about 8 g carbon/M2 /day resulted in the production of

methane and azoic conditions. This rate of input has been

associated with large scale intensive fish (see reviews in Weston

1986a, 1991a) and shellfish culture (Cabanas et al 1979, cited in

Dahlb9ck and Gunnarsson 1981).

Accumulation of organic material may cause the mortality of

non-mobile macro-fauna. The area affected would be limited to

the zone of organic enrichment in the immediate vicinity of the

aquaculture site. Significant effects on fish or mobile

microfauna are to be expected. Only where limited flushing leads

to waste accumulation and hypoxia of the near bottom water or

other deleterious changes in water quality. Where water quality

is maintained, fish and mobile macrofauna are attracted to

aquaculture sites (Weston 1986a), even to those where azoic zones

have been created. At low concentrations, H2S can affect fish

health through gill damage and at higher concentrations be toxic

to fish or shellfish in the farm above the sediments (Braaten et

al 1983). Such effects have only been reported in stagnant areas

with little water circulation.

The extent of the effects of net pens or other aquaculture

structures depends on the extent of alterations in sediment

chemistry, itself a function of the degree of waste dispersal by

water movements and depth, as well as culture practices (Weston

1991a, 1991b). As the potential for waste dispersal increases

with increasing depth and current speed, the possibility of

significant impacts on the benthos decreases. Recovery of

affected benthic communities may take months or years. However,

the benthic sediment chemistry appears to'recover to normal

levels relatively rapidly. In Puget Sound, Pamatmat et al (1973)

observed normal benthic oxygen consumption 2 months after pen

removal. Dixon (1986, cited in Washington Department of

Fisheries 1990) noted that bottom sediments appeared normal at

two pen sites in the Shetland Islands, 12 months after removal of

the farm.

Biological recovery may take longer depending on the

successional colonization of the area by different species and

normal recruitment cycles (Pearson and Rosenberg 1978). Species

abundance will recover more quickly than biomass due to the

growth rates of the larger animals. Gowan et al (1988) observed

virtually no faunal recovery 8 months after cessation of net pen

operations. Mattsson and Linden (1983) found only limited

recovery of the macrofaunal community 18 months after the removal

of mussel long-lines.

While the chemical and biological impacts of aquaculture

operations on the benthos are readily described, they are not as

readily predictable. Weston (1986a, 1991a, 1991b) concluded that

the primary factors responsible for patterns of sediment

enrichment were current velocity, water depth and loading (weight

of fish held). Depth and current conditions in Mississippi

waters are not be sufficient to completely avoid the effects of

organic enrichment of offshore aquaculture on the benthic

community. Recognizing this limitation, it is important that

operations be located and designed so as to minimize the

accumulation of solid wastes.

Gowen et al (1988) and Weston and Gowan (1988) present a

conceptually simple model of sediment deposition from a fish

farm. The model has proven a good predictor of general sediment

impacts at farm sites, despite inherent limitations. The model

has the added ability to evaluate the effects of different pen

sizes and configurations under different siting conditions,

making it valuable for selecting suitable sites and designing

farm capacity and layout.

Minimizing feed wastage is especially important in reducing

environmental impacts, reducing potential threats to the crop and

improving operation economics. Gowan et al (1988) estimated that

reducing feed wastage from 30% to 5% would reduce the organic
load to the benthos from 5.5 to 3.5 g carbon/M2 /d.

Rotation of sites is sometimes practiced. This will not

reduce benthic impacts significantly Weston 1991a, 1991b). The

response of benthic communities to enrichment is rapid (weeks to

months) while recovery is much slower (months to years). Unless

the rotation is timed to allow complete recovery (an unlikely

situation) it is not a useful means of minimizing environmental

impact. Rotation and dredging to remove accumulated waste from

beneath net pens may, however, provide some benefit to the

cultured animals.

4. Chemical usage.

Fouling control and the treatment of diseases are essential

for the maintenance of suitable culture conditions in net pen

aquaculture. Chemicals used for these purposes pose a threat to

the marine environment only when their potential for

environmental damage is not fully known or the substances are

misused.

a) Anti-fouling compounds

The best example of an anti-fouling chemical adversely

affecting the marine environment is tributyltin (TBT). Treatment

of boat hulls and nets with TBT has proven to be toxic to marine

life in the parts per trillion range. The compound has been

banned from use in many areas.

The use of anti-foulant chemicals is probably unavoidable,

given the rapid rate of fouling development in warm waters. Any

restriction of water movement through the nets by fouling could

have profound effects on water quality within the net pens,

potentially threatening the health of the crop. At the same

time, the cost of labor involved in frequent cleaning and

changing of nets would be prohibitive.

Copper-based anti-foulants, in widespread use in Mississippi

and Gulf waters, should be used. Newly developed anti-fouling

waxes for nets would also be appropriate. In any event, the

intent to use anti-foulants should be reported and reviewed by

BMR in advance. The use of anti-fouling compounds with a known

adverse effect on (non-target) marine life or human health should

be restricted.

b) Pharmaceuticals

Fish culturists in the United States have extremely limited

che motherapeutic options (G. Jensen, National Program Leader,

USDA Aquaculture Extension, Washington, DC, personal

communication). Only one topical treatment and three feed

additive antibiotics are currently licensed by the Food and Drug

Administration for food fish culture in the United States. One

antibiotic, sulfamerizine, is no longer marketed. Romet 30, a

potentiated sulphonamide approved for use in catfish and

salmonids has not been approved for either redfish or hybrid

striped bass culture. The work on the remaining antibiotic,

oxytetracycline, and formalin, the topical anti-ectoparasite, on

striped bass/hybrids has been completed and has been sent to the

FDA for review (op. cit.).

Formalin treatment has been approved for a variety of fish

species and will probably gain approval for use on hybrid striped

bass in the near future. Because formalin is generally applied

as a bath to fish held in tanks for treatment (Federal Register

1986a) and is not applied to open water net pens, there is'no

expected environmental effect so long as the treatment waste is

disposed of in an approved manner.

Oxytetracycline (OTC) is a broad spectrum antibiotic useful

in the treatment of many fish diseases (Weston 1986a, 1991a). It

shows great potential for use in warm water marine fin fish

culture and, when approved for use on hybrid striped bass, is

likely to become the drug of choice for net pen culture in the

Gulf. Oxytetracycline is administered as a food additive at a

rate of 2.5 - 3.75 g per 45 kg (100 lbs.) of fish per day over a

10 - d treatment period (Federal Register 1986b). A 21 day

holding period is required before fish treated with

oxytetracycline can be harvested for human consumption.

The heavy use of antibiotics in the fish farming industry of

some countries has prompted concern about the quantity of

antibiotics released into the marine environment and the

potential effects of these releases. There are four major areas

of concern (Weston 1991a): 1) antibiotic accumulation in marine

biota, 2) persistence of antibiotic residues in marine

sediments, 3) development of antibiotic resistant bacterial

strains (and the potential transmission of this resistance to

human pathogens), and 4) alteration of sediment microbial

community structure. Data on these environmental effects is

severely limited.

This discussion (based on Washington Department of Fisheries

1990, Weston 1986a, 1991a) will focus on how these effects relate

to oxytetracycline use because of pending FDA approval for use of

this drug in striped/hybrid bass culture and because the scanty

research on the environmental effects of antibiotic usage have

concentrated on this drug.

OTC is widely used as a human medicine. It is also used as

a routine feed supplement in the diets of chickens, pigs and

cattle. However, unlike its use in humans or fish culture,

where it is only used for periodic disease treatment, it is given

to livestock on a continuous basis. Despite extensive use of OTC

in treatment of fish diseases in the U.S. and elsewhere, there

has been no demonstration of significant environmental effects

(Weston 1986a, 1991a). Many investigators and others have raised

the issue of potential adverse effects of antibiotic use in net

pen aquaculture, but, with few exceptions, the discussion has

remained speculative. There has been no evidence of any

detrimental effect and little or no data to argue against an

effect (see reviews in Weston 1986a, 1991a).

a. Antibiotic accumulation. A large proportion of the

oxytetracycline supplied to fish-through medicated feed will be

released into the environment through waste feed and, because of

the limited digestive absorption of the drug in fish (Cravedi et

al 1987), through feces. This has been cited as a potential

threat to oysters, shrimp, crabs, and fish living close to

culture sites. However, the probability of this presenting a

problem is remote. The concentrations of antibiotics outside the

immediate vicinity of the fish farm are regarded by most

investigators as too low to have any adverse effects (Washington

Department of Fisheries 1990).

Austin (1985) reviewed the effects of antimicrobial

compounds escaping into the marine environment from fish farms.

While data on the quantities of these materials entering the

environment are not available, research-results provide estimates

of probable concentrations for freshwater situations. As a worst

case scenario, Austin (1985) estimated the dilution of OTC to be

1:50,000,000, leading to the conclusion that only minute

quantities of the drug reach the environment. Weston (1986a)

calculated a concentration level of 3 ppb OTC in a parcel of

water passing through a net pen receiving medicated feed.

Field and laboratory research have demonstrated that OTC

does not bioaccumulate (Bureau of Veterinary Medicine 1983, cited

in Weston 1991a). Katz (1984, cited in Washington department of

Ecology, 1989) concluded that there should be no bioaccumulation

of OTC in treated lobsters. Oysters suspended near net pens

containing fish fed medicated feed were free of OTC residues

(Tibbs et al 1988, cited in Weston 1991a). There are, however,

some reports of OTC residues in wild fish and shellfish in

Scandinavian studies (see Weston 1991a). These results suggest

that additional information on the environmental persistence of

OTC under varying conditions is needed. However, there appears

to be no threat of antibiotic accumulation in resident marine

fauna in the vicinity of aquaculture operations because of

dilution and dispersion of OTC bearing waste (Maine Department of

Marine Resources 1991, Washington Department of Ecology 1989,

Washington Department of Fisheries 1990, Weston 1986a, 1991a).

b. Persistence of antibiotics in sediments. OTC appears to

persist in marine sediments, especially under the anoxic

conditions common under most net pen fish farms (Weston 1986a,

1991a). Laboratory studies and field observations indicate a

half-life of OTC in-sediments of at least 10 weeks. (Jacobsen

and Bergind 1988). Because there has been no demonstrated

detrimental effect of sediment antibiotics on resident macrofauna

on the microbial community (Weston 1991a), the significance of

this is open to speculation.

C. Antibiotic resistance. Austin (1985) noted that the use

of antibiotics in fish culture could lead to increased antibiotic

resistance among the resident bacteria in the facility effluent.

Oxytetracycline resistance has been noted in two common catfish

pathogens, Edwardsiella (Sinderman 1990) and Aeronomas (MacMillan

1985), and resistance may persist for long periods in bacterial

populations (Levy and Novick 1986), until diluted with non-

resistant strains.

While the development and persistence of antibiotic

resistance among opportunistic fish pathogens is of obvious

concern to the fish culturist, other potential consequences are

unclear. As will be discussed in a subsequent section, wild fish

are less susceptible to disease than stressed, closely held

cultured fish. Infection of wild fish has not been viewed as a

concern (Maine Department of Marine Resources 1991, Washington

Department of Ecology 1989, Washington Department of Fisheries

1990, Weston 1986a, 1991a).

There has been speculation that antibiotic resistance can

potentially be transferred to bacteria of human health

significance. This is not a concern. Fish pathogens possibly

developing antibiotic resistance are not pathogens of humans

(MacMillan 1985,, Sinderman 1990). Transfers of antibiotic

resistance among species of bacteria appear to be laboratory

phenomena that require highly controlled conditions While local

water temperatures (25'C/77*F) meet one of the requirements for

drug resistance transfer (Toranzo et al 1984), such an event is

highly unlikely. There is no evidence of such a transference

occurring in Japan, where conditions are suitable, a wide range

of antibiotics are extensively used and human pathogens are

present in the culture water (Washington Department of Fisheries

1990, Weston 1991a). Sewage effluent and runoff from livestock

growing areas are greater sources of antibiotics in coastal

waters than the aquaculture industry could be in the near future

(Weston 1991a).

d. Impacts on microbial community structure and function.

The levels of OTC expected to reach the sediments under worst-

case conditions (Weston 1986a, 1991a) are not expected to have an

inhibitory effect on non-pathogenic bacteria (see review in

Washington Department of Fisheries 1990). Samuelson et al (1988)

and others (see Weston 1986a, 1991a, 1991b) have reported

decreases in sediment microbial density associated with

antibiotic treatment. However, the significance of these

findings is questionable. Effects were not consistent and were

often associated with antibiotic types and dosage rates

prohibited in the U.S. There is no indication that application

of OTC or other FDA approved antibiotics, following established

FDA and industry guidelines, would significantly alter the

structure or function of the sediment microbial community.

e. Mitigation of antibiotic effects. Mitigation of

antibiotic effects follows two approaches. Only antibiotics

approved by the FDA should be used, in approved doses and

following approved treatment methods. Second, the culturist

should follow good husbandry practices. The frequency of

antibiotic use is a function, in part, of fish husbandry

practices. Many of the bacteria of concern to aquaculturists are

facultative pathogens, becoming a problem only when the fish are

stressed. The frequency of infection and the resulting need for

antibiotics can be reduced by keeping stocking density and waste

loads within the capacity of the site, maintaining clean nets to

maximize water flow and removing dead fish promptly. Critical to

good husbandry practices are a thorough understanding of site

water quality characteristics, their variation and the carrying

capacity (maximum loads of fish and feed).

f. Other pharmaceuticals. Two points should also be

considered in planning and regulating future use of

pharmaceuticals in net pen aquaculture.

Vaccines have been developed for salmonids and other fish

species. Vaccines reduce the probability of infection among

immunized fish, leading to less antibiotic use. While

vaccination will never replace antibiotic treatment (immunity

does not last the life of the fish and stress can reduce immunity

as well), it can significantly reduce the quantity of antibiotic

used per unit of production. Development and use of vaccines for

warm water fish in Mississippi coastal waters should be

encouraged.

Hormones are commonly used for gender control or to induce

ovulation. While little is known of the potential environmental

effects of the'se hormones, the quantities used are so small that

.no adverse impact is anticipated. No human health concerns are

associated with hormone use in fish culture (Weston 1991a)

because they are either administered to juveniles long before

human consumption or to broodstock that would not be marketed.

5. Interactions With Resident Species.

a) Genetic impacts. The escape of cultured fish from

offshore net pen operations is inevitable. This has raised

concerns in other regions about possible detrimental impacts on

local fish populations (Maine Department of Marine Resources

1991, Washington Department of Ecology 1989, Washington

Department of Fisheries 1990, Weston 1986a, 1991a). This concern

does not appear to have merit for Mississippi or northern Gulf

waters.

Genetic impacts may be important where native species or

distinct stocks of fish may be threatened. Because net pen

culture in coastal Mississippi waters in the near future would

probably be limited to species already present in Mississippi

waters (e.g. redfish or hybrid striped bass), no genetic threat

is evident.

Redfish will not be genetically affected. It has not been

clearly established whether Gulf redfish can be separated into

identifiable sub-populations associated with specific areas (Gulf

of Mexico Fishery Management Council 1984). "Exotic" redfish

will not be introduced. Seed stock for redfish culture are

produced from primarily Gulf coast brood stock. Cultured redfish

have been repeatedly released in all of the Gulf states' waters.

Gulf and Atlantic race striped bass as well as hybrid

striped bass have been stocked in northern Gulf waters since the

1960's (Lukens 1988). There is no evidence of discrete sub-

population of striped bass or hybrids (Weston 1991a). Hatchery-

produced fish, which from the basis of the Mississippi

striped/hybrid bass population, are derived from parental stock

taken from a variety of areas. These observations suggest that

there is no threat of detrimental genetic effects associated with

escaped fish.

b) Introduction of exotic species. The introduction of

non-native species and associated pathogens probably represents

the greatest environmental threat of aquaculture. If offshore

aquaculture is limited to species from the Gulf and Atlantic

waters, the probability of an accidental introduction of either

is low. Broodstock, reproductive products and fingerlings of

redfish, striped/hybrid bass and oysters have a long history of

movement between Gulf and Atlantic waters. There do not appear

to be any diseases within the ranges of these species that could

potentially be introduced by future transfer of seedstock.

Similarly, there do not appear to be any macrofaunal pest species

that could be transferred from Atlantic waters with seedstock.

Purposeful introductions of non-native marine species are

controlled under the provisions of the Mississippi Aquaculture

Act.

c) Transmission of disease from cultured to wild fish.

Concern has been expressed that cultured fish could act as

reservoirs of disease infecting wild fish populations. Despite

the proliferation of cage culture world wide, such an occurrence

has never been documented (Washington Department of Fisheries

1990). In fact, there are several examples of diseases that have

had adequate opportunities to infect wild fish but have failed to

do so (Weston 1986a). Viral hemorrhagic septicemia and whirling

disease, both thought to be endemic to Europe, are serious

diseases of rainbow trout imported to Europe and held in cage

culture. Wild fish have failed to show symptoms of the disease,

even after experimental infection.

Diseases observed in the culture of striped/hybrid bass and

redfish are non-exotic. They exist naturally in the marine

environment. In a farm environment, these diseases may originate

from wild fish, infecting cultured stock. Vibriosis is a disease

of many fish species caused by the bacteria Vibrio species.

Vibrio spp. are a natural component of marine microbial

communities world wide and commonly present on wild and cultured

fish. Vibrio spp. are not pathogenic unless the host fish is

stressed, as is often the case under culture conditions of

density and water quality. Other common diseases are also caused

by facultative pathogenic bacteria.

While there are many examples of wild fish transmitting

diseases to cultured fish (see review in Weston 1986a, Washington

Department of Fisheries 1990), there are no known examples of a

culture operation providing a reservoir for infection of the wild

fish population (Weston 1991a). A review of the technical

literature suggests that the risk of transmission of disease from

farmed to wild stock is minimal. Existing regulations will

prevent the importation of exotic pathogens that could

potentially pose a threat to native fish. Control of potential

disease vectors at the facility, such as removal of dead fish,

will prevent the spread of any potential infectious agent.

At least one author has speculated that shellfish can be

reservoirs for fish pathogens such as viruses (Meyers 1984).

Although viruses pathogenic for freshwater fish have been

isolated from oyster stocks, there is no evidence to suggest that

there is a mechanism for disease transmission from shellfish

stocks to wild fish (Washington Department of Fisheries 1990).

Vibriosis has also been reported to affect oysters,

especially larval stages (Elston 1984). The problem, however,

appears only under intensive hatchery culture conditions and is

controlled by improved husbandry practices. There is no evidence

that vibriosis is important in limiting natural populations of

oyster larvae (Washington Department of Fisheries 1990). There

does not appear to be any potential for disease transmission from

cultured fish or oysters to natural fish or shellfish

populations.

d) Interactions with protected species. Thirty three

species of cetaceans (six endangered) have been reported from the

Gulf of Mexico (Minerals Management Service 1991). Existing

regulations provide adequate protection, and offshore aquaculture

is not expected to significantly affect these species.

Five species of marine turtles are found in the Gulf of

Mexico (Minerals Management Service 1991). The loggerhead has

been reported to nest on the Mississippi barrier islands, and the

green turtle may occasionally nest in the northern Gulf as well.

Offshore Mississippi waters are areas of significant use by sea

turtles. Because they feed chiefly on marine invertebrates,

offshore fin fish or oyster aquaculture should not attract sea

turtles as predators. However, the potential for interaction

among sea turtles and off shore aquaculture remains unknown.

Concerns have been raised, however, that lights on offshore

structures may affect the behavior of nesting and hatchling sea

turtles. The recommended separation distances should be adequate

to avoid having activity on the structures or on-board lights

disturb sea turtles nesting on the barrier islands. A proportion

of hatchling sea turtles have been reported to be disoriented and

drawn towards lights immediately after emerging from the nest.

This orientation towards light is known to affect hatchlings in

their passage between the nest and the sea. Information on the

effect of surface lights on swimming hatchlings is incomplete.

Recommended separation distances between potential nesting sites

and offshore aquaculture structures should be adequate to protect

hatchlings from disturbance or disorientation. Because there is

no evidence to support or refute the suggestion that hatchlings

will be drawn towards and congregate around aquaculture

structures, a subjective determination of adequate separation

distance between lighted offshore aquaculture facilities and

nesting beaches will have to be made by the Bureau of Marine

Resources and the relevant federal agencies on a case by case

basis.

Coastal and marine birds are abundant in the northern Gulf

(see Minerals Management Service 1991 for a review). Piscivorous

species that may be attracted to net pens include waterfowl such

as mergansers, shorebirds (e.g. gulls, terns, cormorants), waders
and raptors. Bird predation on cultured fish stocks, especially
juveniles, is of concern to aquaculture operations while the

effects of predator control measures is of concern to regulatory

agencies. Of particular concern are endangered and threatened

bird species which may prey on cultured fish. These include bald

eagles (which nest on the barrier islands) and brown pelicans.

Control of bird predation must follow established federal

guidelines for such activities and conform to the requirements of

the various regulations in place to protect threatened,

endangered and migratory birds. Proposed control plans should be

coordinated with the responsible agencies through the Bureau of

Marine Resources.

Setting appropriate separation distances away from nesting

areas or important habitats will minimize impacts on these

species. Based on reviews of regulations in other states and

provinces with commercial net pen aquaculture industries (see

summary in Owen 1988, and Maine Department of Marine Resources

1991, Washington Department of Fisheries 1990), a 1/4 to 1/3 mile

separation between bird habitats and culture sites has been

generally agreed upon as adequate. Impacts on piscivorous birds

can be further minimized by use of predator control netting,

especially over pens holding small fish, and other non-lethal

control measures.

Recommended Guidelines

A synthesis of the available studies on the environmental

impacts of net pens draws two important conclusions. First, the

proper siting of net-pens can assure the dispersion of both solid

and dissolved wastes and the pro tection of sensitive areas.

Second, environmental effects of net pen culture are reversible.

Sediment chemistry can recover on a scale of months, biological

recovery will follow on a scale of months to years.

The major potential impacts of offshore aquaculture and

actions to quantify, regulate and minimize these impacts have

been identified in a variety of state and national studies. The

main findings of these studies are:

1. Solid wastes from both net pen and shellfish aquaculture

operations will settle to the bottom and affect the benthic

community immediately beneath the site. Selecting sites deep

enough and with sufficient currents to disperse these wastes will

minimize the impact.

2. Important marine habitats, fisheries resources, public

lands and endangered or threatened species can be affected by

aquaculture operations. Determining appropriate separation

distances and selecting sites away from sensitive or important

habitats and public lands, in cooperation with the Bureau of

Marine Resources, will minimize this impact.

3. Impacts on piscivorous birds can be further minimized by

use of predator control netting and other non-lethal control

measures. Control of avian predators must conform with existing

federal guidelines, and control plans should be developed and

coordinated with the responsible agencies through the Bureau of

Marine Resources. In view of the potential impact of bird

predation on fish culture operations and the effect of control

measures on the birds themselves, it is recommended that the

applicant identify potential bird predation problems (e.g.

identify bird concentration points and anticipated foraging

behavior of potential bird predators) and develop an approved

predation control plan early in the permit application process.

Minimum separation distances should consider both existing bird

concentration points and their anticipated foraging behavior.

4. Nutrients released from net pens, especially nitrogen,

can contribute to phytoplankton production in stratified,

nutrient poor waters. Siting to avoid areas where nutrient

depletion occurs and placing limits on total fish production in

such areas can prevent adverse environmental effects.

5. Fish culture in warm water conditions can place heavy

demands on available dissolved oxygen levels. Selecting sites

deep enough and with adequate current speeds to allow for

adequate dispersion of wastes, setting appropriate limits on

total fish production and following low waste feeding practices

(dry, floating feeds, high digestibility, no fines) will minimize

adverse impacts. The use of automatic feeders should be closely

watched. The proportion of wasted feed is significantly greater

with automatic feeders (overfeeding, fines) than with other

feeding methods (Weston 1991a).

. 6. The effect of aquaculture operations on water movement,

quality and on the benthic environment are not detectable within

tens of meters of the culture site. Major effects on benthic

biota, reduction in dissolved oxygen and increased dissolved

nutrient concentrations are limited to within a few meters of the

culture site.

7. There is no good evidence for net pens having an adverse

impact on fish and other nektonic species, transmitting diseases

to wild fish, contaminating resident fauna with antibiotics or in

contributing to the development of antibiotic resistant microbial

populations threatening to human health.

8. The environmental effects of on- and off- bottom

shellfish culture are generally limited to those associated with

sediment deposition.

Siting Guidelines

1. Operation size.

Because the rate of accumulation of feed, feces and organic

debris under net pens are related to farm size, regulatory

programs to detect and control potentially deleterious

environmental effects should be linked to the size of the

operation. The recommended degree of monitoring required

increases with farm size. The following classifications are

presented as a model. Either may be readily used for northern

Gulf conditions. While it is recommended that site evaluation

and monitoring requirements be geared to farm size/production

level, the number of farm classes is subjective.

There-are two established methods of classifying net pen

operations by size. Weston (1986a) and Washington Department of

Fisheries (1990) use annual fish production to divide net pen

operations into three size classes: Class I, less than 20,000

lb/yr (10,000 kg/yr), Class 11 20,000 - 100,000 lb/yr (10,000

45,000 kg/yr), and Class III, over 100,000 lb/yr (45,000 kg/yr).

The Province of British Columbia (Ministry of Environment 1988)

uses annual feed consumption, calculated on a dry weight basis

(see Appendix D), to classify fish farms: Class A operations use

less than 120 mt of feed (dry wt) per year, Class B 120 - 630 mt

and Class C over 630 mt annually.

2. Depth and Current Speed

Site current and depth characteristics are matched with

production level or feed usage rates to determine the extent of

environmental impact. However, because of the relatively shallow

depths and low current speeds in Mississippi waters and in the

northern Gulf, it may be more appropriate to evaluate permits on

a site specific basis. This will require a thorough survey of

pre-operations site conditions, and estimates of potential waste

loads, DO and BOD demands, sedimentation and nutrient-inputs

based on net pen design, array, loading and feed use. This would

be most effective if the survey and monitoring requirements were

geared to farm size..

A precedent for this approach exists. Maine does not adhere

to rigid farm size definitions but considers each permit request

on a site specific basis. This approach requires that

hydrographic and benthic data be collected in advance of

construction to adequately characterize the site. Because the

state assumes the responsibility for the collection and analysis

of this data in Maine, farm size is less of an issue. Where the

permit applicants are required to collect this data, the

requirements are geared to farm size.

Regardless of size, minimum recommended water depth (MLW)

beneath the bottom of net pens should be at least two times the

height of the side facing the prevailing current. Maintaining

this depth will insure that current velocities beneath the pen

are not reduced by the structure.

The main functions of currents are to supply dissolved

oxygen, to dilute dissolved nutrients and to disperse solid

wastes. Current speeds and direction in coastal Mississippi

waters are seasonally variable and generally weak. Surface and

bottom currents in the area often differ in speed and direction

as well.

Low current velocities have several implications. The

arrangement of the net pens will be affected. the velocity of

currents passing through net pens is appreciably reduced. In

weak current areas, below 5 cm/sec velocity, passage through even

a single cage will reduce velocity to near zero. In such areas,

net pens must be arranged in a single row perpendicular to the

prevailing current.

Depending on the site, the direction and velocity.of the

surface currents may change on several time scales (daily to

seasonal). Major seasonal changes may require periodic

relocation of the net pens.

Spacing between net pens should be at least 2 structure

diameters. Rows should be at least 20 structure diameters apart.

Based on experiences in other states, distances between farms

should be no closer than 600 m (2000 ft).

The availability of dissolved oxygen for respiration and BOD

will be limited by low current velocities. Oxygen consumption

rates of the fish species targeted for net pen culture in the

Gulf are not well known. In warm water conditions, oxygen

consumption levels of redfish will be "high" (Neill 1987), and

hybrid striped bass will consume up to 800 mg/l (Kruger and

Brocksen 1978). Summer DO saturation levels are expected to be

relatively low (say, 6.8 mg/l at 280C and 25 ppt). Under these

circumstances, low current velocities within the net pens may

seriously affect fish culture operations.

Assuming that current velocities within cages are reduced to

40% of upcurrent velocities and that most sites in Mississippi

coastal waters will have surface currents less than 8 cm/sec,

both loading rate (fish/M3 ) and total farm size will be limited

by current velocity and available dissolved oxygen.

Prevailing current velocities in coastal Mississippi will be

insufficient to appreciably disperse solid wastes from beneath

the net pens. Because the BOD of the solid waste can be up to

three-times the respiratory oxygen demand of the fish, oxygen

depletion of bottom waters is a very real concern. Farm size and

loading rates will have to be limited by current speed and

seasonally variable dissolved oxygen levels available for both

respiration and BOD. Because of anticipated high BOD and low

summer DO levels, minimum depth below the net pen must be

determined by the anticipated maximum waste load. While the

determination of current speeds within net pens and the

calculation of waste loads, sedimentation rate and dispersion,

and respiration and biochemical oxygen demands are imperfect, the

suggested methods should serve as a basis for the evaluation of

potential environmental impacts of aquaculture.

3. Areas With Chronic Water Quality Problems.

Net pens should not be located in areas subject to nutrient

depletion in surface waters (total nitrogen less than 0.1 mg/1)

or in areas subject to vertical stratification of the water.

A stratified water column tends to be depleted of nutrients,

while bottom waters are prone to reduced dissolved oxygen

conditions.

Large areas of the northern Gulf, in Louisiana coastal

waters are subject to periodic anoxia resulting from

stratification. Mississippi coastal waters are often partially

stratified in the spring and summer months (Kjerfve and Sneed

1984, Minerals Management Service 1991, USEPA 1990).

Nutrient inputs to nitrogen-poor surface waters may

contribute to unwanted phytoplankton productivity. Solid waste

inputs may compound near bottom dissolved oxygen problems in

stratified water bodies. These effects will be magnified in

areas with fine sediments, where BOD is already high.

To minimize the likelihood that aquaculture operations will

adversely affect water quality or contribute to phytoplankton

productivity, limits may be placed on fish production within

Mississippi coastal waters, pending the collection of essential

current and water quality data to allow an evaluation of the

site. On a qualitative basis, production levels will be limited

in stratified waters, nutrient depleted waters and, assuming a

standard pen height of 4 m, in waters less than 12 m deep.

4. Habitats of Special'Significance.

Habitats and species of special significance to be protected

from adverse environmental effects have been identified in all

regions. Selecting sites away from sensitive or important

habitats and public lands will minimize impact from offshore

aquaculture. Maine requires a minimum of 1/4 mile separation

between aquaculture sites and p4rks, wilderness areas, critical

habitats for endangered/threatened species and sensitive

fisheries related habitat. Washington defines a variety of

minimum separation distances from 300 feet to 1,500 feet.

British Columbia and New Brunswick require 1000 m. However,

external activities that impact park values and resources, even

those falling outside park jurisdictional areas, may require

greater separation distances based on site specific conditions.

Because of reduced current velocities in Mississippi waters,

the effects of aquaculture operations would be spatially limited.

While it appears that only minimum distances (150 - 300 ft.)

would be required to avoid impacts on seagrass beds, oyster

reefs, artificial reefs, spawning areas and other fishery

resources, actual separation distances will have to be determined

on a case by case basis. As with other separation distance

guidelines, permits should identify that separation distances may

be increased to reduce any potential impacts on these habitats.

Following recommended depth guidelines will minimize the

potential for locating aquaculture operations in close proximity

to sea grass beds.

Prudence dictates avoiding net pen locations in areas with

large concentrations of piscivorous birds (e.g. pelicans, terns),

their nesting sites or near nests of fish eating raptors

(ospreys, eagles). In view of the potential impact of bird

predation on fish culture operations and the effect of control

measures on the birds themselves, it is recommended that minimum
separation distance's should consider both existing bird

concentration points and their anticipated foraging behavior.

Based on federal and state guidelines of aquaculture in other

regions a minimum of 1/4 mile separation between bird

concentration areas and the net pens is recommended.

Net pens located closer than a certain minimum distance from

bird nesting or concentration areas (1/4 mile in northern

regions) may serve as an "attractive nuisance", drawing birds to

the site. Based on limited observations, however, birds appear

to visit sites located beyond this minimum distance (but within

the normal foraging range) with about equal frequency. It is

critical to identify and establish this minimum distance (buffer

zone) for all bird species that may be affected by the operation.

The permit should specify that the separation distance

requirement may be increased if it is determined that the number

of bird visits exceeds an accepted frequency.

A minimum of 1/4 mile should separate aquaculture operations

from any park, wilderness area, beach or areas used or frequented

by protected animal or bird species. This would include sea

turtle nesting grounds. No sensitive areas for marine mammals

have been identified in Mississippi coastal waters. However, any

permit granted to a aquaculture facility should specify that if

any critical habitats or sensitive areas are identified and are

affected by the operation, the permit may be altered. An

alteration of permit conditions may also be required should

aquaculture operations affect threatened or endangered species.

5. Dredged material disposal areas, maintained waterways and

other areas of concern.

While not technically an environmental concern or habitat of

special significance, navigation channels, open water disposal

areas and other sites permitted for specified uses are not

suitable for siting aquaculture operations. Because of the

potential conflict arising between dredging and disposal and

aquaculture operations, net pens and shellfish culture operations

should not be located in close proximity to these activities.

On-bottom shellfish structures should not be within 1500 feet of

either a dredged channel or a disposal area. Because most

suspended sediment effects of dredging are confined to bottom

waters, net pens in water over 12 m deep should be located no
closer than 5'00 ft. of a navigation channel. At least 1500-ft.

should separate shallow (<12 m) net pen operations from

maintained navigation channels and separate all net pen

facilities from designated open water disposal sites. Seasonally

variable current direction and velocity negate any possibility of

closer siting "up current" of dredging or disposal operations.

These distances should be reviewed and established on a case by

case basis.

While these guidelines do not specifically address esthetics

issues, it is important to note that these considerations will be

taken into account in reviewing permits. Specifically, the

presence of wilderness areas, marine sanctuaries, recreational

areas and national seashores in the northern Gulf of Mexico will

affect the siting, operations and monitoring requirements for

aquaculture operations. No attempt has been made in this report

to address other important concerns such as conflicts with other

users, social impacts and related issues.

Pre-operations requirements

These guidelines are not intended to be all-inclusive.

Rather, they identify some of the important pre-operations

requirements that bear directly on operational and monitoring

guidelines.

1. Permit applicant must document'financial resources for

the proposed project, demonstrating the capability to perform as

specified in the permit conditions.

2. The permit applicant must provide information regarding

the professional expertise of the on-site operations staff. This

must be sufficient to demonstrate an ability to accomplish the

proposed project.

3. Permit applicant may be required to post a performance

bond to ensure compliance with operations and monitoring

conditions. An additional bond may be required to ensure cleanup

in the event of a fish kill or other pollutant discharge, or to

allow for the and cleanup of the site after destruction or

abandonment.

4. Working with the Bureau, the permit applicant must

identify shellfish beds, submerged vegetation beds and essential

habitats/endangered or threatened species found in the

surrounding area.

5. Should a permit request be denied because the proposed

operation does not satisfy recommended site selection,

evaluation, operations and monitoring guidelines presented here,

the burden of proof that there will be no significant

environmental effect associated with the operation should fall on

the applicant.

Site Characterization Survey.

Because of the large number of areas in Mississippi waters

where potential water quality problems and adverse environmental

impacts may occur, it is essential that all sites considered for

aquaculture operations be surveyed and characterized. This

survey must be completed before the permit application and should

include: a) a bathymetric survey, b) hydrographic survey and c)

a diver survey to visually assess the area and its biological

resources. Applicants for permits should be strongly encouraged

to consult with the Bureau of Marine Resources officials prior to

completing a permit application and designing the site

characterization survey. Appendix B provides an outline of a

baseline survey.

An overview of the information needed to coordinate the

survey is provided in Appendix A, including site location,

development plan and operations plan. These will be combined

with survey data to determine the suitability of the site for the

described operation, any potential adverse environmental impacts

and any proposed mitigation approaches.

Operations Guidelines

1. A baseline survey should be completed for large (>630 mt

of feed used, dry weight, per year; in excess of 100,000 lbs.

fish annually) operations after construction but before

operations commence. Recommended guidelines for the baseline

survey are shown in Appendix B.

2. All waste discharge permits should have the condition

that discharges meet state water quality standards (State of

Mississippi 1991) for dissolved oxygen, temperature, Ph,

turbidity, toxic or deleterious materials and fecal coliforms

(temperature and Ph effects are not expected to occur).

3. The receiving water mixing zone will be defined by the

State and water quality standards will not apply in the mixing

zone adjacent to or surrounding the site. The area/volume of the

mixing zone should be limited so as to minimize mortality of

important fish or shellfish. A suggested mixing zone of 100 ft.

around the perimeter of the facility should be sufficient to

mitigate discharge and turbidity effects of both normal culture

and cleaning operations.

4. Discharges of any fish carcasses, fish processing waste,

sewage or other waste beyond feed, fish feces and debris from

fouling organisms should be prohibited.

5. To minimize nutrient inputs, only dry pelleted feed

should be used. Floating pellets, preferably formulated

specifically for the cultured fish species to maximize

digestibility, should be used. Fines should be removed prior to

feeding and automatic feeders should be discouraged.

6. Operations should use non-lethal methods of predator

control and all methods must comply with state and federal

requirements.

7. Toxic and deleterious substances

a) Net fouling control chemicals. The discharge of

antifoulants which may affect water use or adversely affect

aquatic biota or human health should be prohibited. The intended

use of antifouling agents should be reported and reviewed by

state environmental management agencies.

b) Only antibiotics licensed by the FDA for use on the

target fish species should be allowed for use. Oxytetracycline

and formalin are expected to receive approval soon for use in

hybrid striped bass culture. Only two other theraputants, Romet-

30 (a combination of sulfadimethoxine and ormetoprim) and

sulfamerazine (not presently marketed), and an anaesthetic, MS

222 or Finquel, have FDA approval for use on fish.

Antibiotics should be used strictly on a short term basis

for disease treatment or prevention. Long-term prophylactic use

should be prohibited. The Bureau should be notified of all

antibiotic use at the time of treatment and notified of the

disease condition treated and type of dosage of antibiotic used.

Concern about the environmental risks by disease prevention

medications appears to be minimal. Although it is expected that

antibiotic use in fish culture will be relatively frequent, given

the warm water temperatures and other potentially stressful

conditions in this region, there does not appear to be a risk of

the development of antibiotic resistant bacteria or accumulation

of antibiotics in marine organisms. Similarly, there does not

appear to be a risk of disease transmission from farmed fish to

wild stocks.

Should the frequency of antibiotic use at a fish farm

increase markedly, measures to reduce the frequency of infection

and the need for antibiotics should be employed. These include

reducing stocking density, more frequent net cleaning, prompt

removal of dead fish and other measures to improve water quality.

Permits should specify that these actions may be required.

Vaccinations are likely to become important in warm water

fish culture disease control in the near future. Provisions

should be made to encourage the use of vaccinated fish to reduce

antibiotic use.

c) Hormones (especially methyltestosterone) have been used

in aquaculture. Little is known of their potential environmental

impact. While there is no indication that hormones will be used

in net pen fish culture in Gulf of Mexico waters, the quantities

used are so small and so early in the life of the fish that no

major effect is anticipated. Hormone treatment for sex reversal

should not be prohibited.

8. All importation, transfer and possession of live fish or

their reproductive products must comply with state and federal

regulations.

Monitoring Guidelines

Monitoring programs should be geared to the size of the

operation. Washington State guidelines recommend annual

monitoring surveys for net pen operations over 20,000 lb annual

fish production (Appendix C). These include a benthic survey and

a diver survey for operations producing between 20,000 100,000

lbs. annually. Large operations (>100,000 lb/yr) are required to

complete a more comprehensive survey, including sediment

chemistry, benthic infauna, water quality sampling and current

information in addition to diver and benthic surveys.

The British Columbia government has developed a model annual

monitoring program (Appendix D). With modifications, this is a

useful model for Mississippi waters. This system divides farms

into three size categories by the quantity of feed used and

prescribes increasingly complex monitoring requirements with

increasing quantity of feed used. Data forms and standard

methods for use in the annual monitoring program have been

developed as well and are attached as Appendices F and G.

REFERENCES

Ackefors, H., and M. Enell. 1990. Discharge of nutrients from
Swedish fish farming to adjacent sea areas. Ambio 19(l):
28-35.

Ackefors, H., and A. S6dergren. 1985. Swedish experiences of
the impact of mussel culture on the environment.
International Council for the Exploration of the Sea. C.M.
1985/E:40.

Alabaster, J.S. 1982. Report on the EIFAC workshop on fish farm
effluents, Silkeborg, Denmark, 26-28 May 1981. EIFAC
Technical Paper No. 41. FAO, Rome, Italy.

Arakawa, K.Y., Y. Kusuki and M. Kamigaki. 1971. Studies on
biodeposition in oyster beds. (I) Economic density for
oyster culture. Venus 30(3):113-128 (in Japanese).

Austin, B. 1985. Antibiotic pollution from fish farms: effects
on aquatic microflora. Microbiological science 2(4):113-
117.

Braaten, B., J. Aure, A. Ervik and E. Boge. 1983. Pollution
problems in Norwegian fish farming. International Council
for the Exploration of the Sea, C.M. 1983/Fizg.

Butz, I., and B. Vons - Cappell. 1982. Organic load from
metabolic products of rainbow trout fed with dry food. In
J.S. Alabaster, editor, Report of the EIFAC workshop on fish
farm effluents. Silkeborg, Denmark, 26-28 May, 1981, pp.
73-82. EIFAC Technical Paper No. 41, FAO, Rome, Italy.

Colt, J.E., and G. Tchobanoglous. 1981. Design of aeration
systems for aquaculture. In Bioengineering symposium for
fish culture. Fish Culture Section Publication No. 1, pp.
138-148. American Fisheries Society, Bethesda, MD.

Colt, J. 1980. Dissolved oxygen. Department of Civil
Engineering, University of California, Davis, CA.

Cravedi, J.P., G. Choubert and G. Delous. 1987. Digestibility
of chloramphenicol, oxolinic acid and oxytetracycline in
rainbow trout and influence of these antibiotics on lipid
digestibility. Aquaculture 60:133-141.

Cresswell, L., J. Holt and D. Vaughn. 1990. Subtidal
cultivation of the American oyster, Crassostrea virginica,
using a flexible belt. Proceedings of the Gulf and
Caribbean Fisheries Institute 12: (in press).

Dahlback, B., and L.A.H. Gunnakson. 1981. Sedimentation and
sulfate reduction under a mussel culture. Marine Biology
63:269-275.

Elston, R.A. 1984. Prevention and management of infectious
diseases in intensive/mollusc husbandry. Journal of the
World Mariculture Society 15:283-293.

Federal Register. 1986a. Volume 51, No. 64. CFR Part 529.1030.
Certain other dosage form new animal drugs not subject to
certification; formalin.

Federal Register. 1986b. 21CFR Part 558.450 oxytetracycline.

Field, J., and R.W. Drinnan. 1988. Off-bottom oyster culture in
British Columbia: culture methods, harvesting, processing
and industry costs. Aquaculture Information Bulletin No.
21, Ministry of Agriculture and Fisheries, Victoria, BC.

Fryxell, G.A., M.E. Reap, D.L. Roelke, L.A. Cifuentes and D.L.
Valencic. 1991. Confirmed presence of neurotoxin-producing
diatom around Galveston, Texas. In F.S. Shipley and R.W.
Kiesling, editors, Proceedings of the Galveston Bay
characterization workshop, February 21-23, 1991. Galveston,
Bay National Estuary Program, Publication GBNEP-G, pp. 153-
154. Galveston, TX.

Gowen, R.J., J.R. Brown, N.B. Bradbury and D.S. McLusky. 1988.
Investigations into benthic enrichment, hypernutrification
and eutrophication associated with mariculture in Scottish
coastal waters (1984-1988). Department of Biological
Sciences, University of Stirling, Stirling, Scotland.

Gulf of Mexico Fishery Management Council. 1984. Fishery
profile of red drum. Tampa, FL.

Hall, P.O., L,G. Anderson, 0. Holby, S. Kollberg and M.A.
Samuelsson. 1990. Chemical fluxes and mass balance in a
marine fish cage farm. 1. Carbon Marine Ecology Progress
Series 61:61-73.

Hammen, C.S. 1969. Metabolism of the oyster Crassostrea
virginica. American Zoologist 9:309-318.

Huguenin, J.E., and J. Colt. 1989. Design and operating guide
for aquaculture seawater systems. Developments in
Aquaculture and Fisheries Science, 20. Elsevier, Amsterdam.

Incze, L.S., and R.A. Lutz. 1980. Mussel culture an east coast
perspective. In R.A. Lutz, editor, Mussel culture and
harvest: a No-rth American perspective, pp. 99-140.
Developments in Aquaculture and Fisheries Science, 7, pp. 99
- 139. Elsevier, Amsterdam.

Inoue, H. 1972. on water exchange in a net cage stocked with
the fish, hamachi. Bulletin of the Japanese Society of
Scientific Fisheries. 38(2): 167 - 176 (in Japanese)

Jacobsen, P., and L. Berglind. 1988. Persistence of
oxytetracycline in sediments from fish feces. Aquaculture
70:365-370.

Kjerfve, B., and J.E. Sneed. 1984. Analysis and synthesis of
oceanographic conditions in the Mississippi Sound offshore
region. Final report, Contract No. DACW01-83-R-0014. U.S.
Army Corps of Engineers, Mobile District, Mobile, AL.

Kruger, R.L., and R.W. Brocksen. 1978. Respiratory metabolism
of striped bass, Morone saxatilis (Walbauar), in relation to
temperature. Journal of Experimental Marine Biology and
Ecology 31: 55-66.

Kusuki, Y. 1977. Fundamental studies on the deterioration of
oyster growing grounds - I. Production of fecal materials.
Bulletin of the Japanese Society of Scientific Fisheries.
43(2): 167 - 171.

Levy, S.B., and R.P. Novick. 1986. Antibiotic resistance genes:
ecology, transfer and expression. Banbury Report 24, Cold
Spring Harbor Laboratory, NY.

Liao, P.B., and R.D. Mayo. 1974. Intensified fish culture
combining water reconditioning with pollution abatement.
Aquaculture 3:61-85.

Lukens, R. 1988. Habitat criteria for striped bass stocked in
rivers in the northern Gulf of Mexico. Gulf States Marine
Fisheries Commission, Ocean Springs, MS.

MacMillan, J.R. 1985. Infectious diseases.- In C. S. Tucker,
editor, channel catfish culture. Elserier, NY.

Magoon, C., and R. Vining. 1981. Introduction to shellfish
aquaculture in the Puget Sound region. Division of Marine
Land Management, Department of Natural Resources, Olympia,
WA.

Maine Department of Marine Resources. 1991. Joint State/Federal
Guidelines for Aquaculture Projects. MDMR, Augusta, ME.

Mattison, J., and 0. Linden. Benthic macrofauna succession under
mussels, Mytilus edulis L. (Bivalvra), cultured on hanging
long -lines. Sarsia 68:97-102.

Meyers, T.R. 1984. Marine Bivalve molluscs as reservoirs of
viral pathogens: significance to marine and anadromous
finfish aquaculture. Marine Fisheries Review 46(3): 14-17.

Minerals Management Service. 1991. Final Environmental Impact
Statement, Gulf of Mexico Sales 139 and 141, Central and
Western planning areas. Publication No. OCS EIS/EA MMS 91-
0054. Minerals Management Service, New Orleans, LA.

Ministry of Environment. 1988. Environmental monitoring program
for marine fish farms. Waste Management Branch, Ministry of
Environment, Province of British Columbia, Victoria, BC.

Neill, W.H. 1987. Environmental requirements of red drum. In
G.W. Chamberlain, R.J. Miget and M.G. Haby, editors, Manual
on red drum aquaculture, pp. IV-1 to IV-8. Texas
Agricultural Extension Service publication, Corpus Christi,
TX.

Nosho, T. 1989. Small-scale oyster farming for pleasure and
profit. Washington Sea Grant Publication WSG-AS 89-1.
Seattle, WA.

Owen, S. 1988. Aquaculture and the administration of coastal
resources in British Columbia. Public Report No. 15,
Ombudsman, Legislative Assembly, Province of British
Columbia, Victoria, BC.

Pamatmat, M.M., R.S. Jones, H. Sanborn and A. Bhaqwat. 1973.
Oxidation of organic matter in sediments. EPA 660/3-73-005.
U.S. Environmental Protection Agency, Washington, DC.

Pearson, T.H., and R. Rosenberg. 1978. Macrobenthic succession
in relation to organic enrichment and pollution in the
marine environment. Oceanography and Marine Biology Annual
Review 16:229-311.

Pease, B.C. 1977. The effects of organic enrichment from a
salmon mariculture facility on the water quality and benthic
community of Henderson Inlet, Washington. Ph.D
dissertation, University of Washington, Seattle, WA.

Rosati, R. 1990. Commercial fish culture using water
recirculating systems. In D.L. Swann, editor, Regional
workshop on commercial fl-sh culture using water reuse
systems, November 2-3, Normal, IL, pp. 13-27. Illinois-
Indiana Sea Grant publication IL-IN-SG-E-90-7.

67-

Samuelson, 0., V. Torsvik, P.K. Hansen, K. Pittman and A.Ervik.
1988. Organic waste and antibodies from aquaculture.
International Council for the Exploration of the Sea. C.M.
1988/F:14.

Shumway, S.E. 1982. Oxygen consumption in oysters: an overview.
Marine Biology Letters 3:1-23.

Sinderman, C.J. 1990. Principal diseases of marine fish and
shellfish Volume I. Academic Press, San Diego, CA.

Snider, R. 1987. Red tide in Texas. An explanation of the
phenomenon. Texas A & M Sea Grant College Program
publication TAMU-SG-87-502. College Station, TX.

State of Mississippi. 1991. Water quality criteria for
intrastate, interstate and coastal waters. Mississippi
Department of Environmental Quality, Jackson, MS.

Stewart, K.I. 1984. A study of the environmental impact of fish
cage culture in an enclosed sea loch. M.Sc. thesis,
University of Stirling, Stirling, Scotland.

Tagaki, M. H. Kamada and A. Tazaki. 1980. A consideration on
the occurrence of 'Protogonyanlax sp. at the scallop ground
in Funka Bay. Bulletin of the Faculty of Fisheries of
Hokkaido University 31(2):215-221 (in Japanese).

Tenore, K. R., and N. Gonzalez. 1975. Food chain patterns in
the Ria de Arosa, Spain: an area of intense mussel culture.
Tenth European Symposium on Marine Biology. Ostend,
Belgium, Sept. 17-23, 1975. Vol. 2:601-619.

Torzano, A.E., J.L. Baria, R.R. Colwell, F.M. Hetrick and J.H.
Crosa. 1983. Characterization of plasmido in bacterial
fish pathogens. Infection and Immunology 39:184-192.

USEPA. 1990. Draft environmental impact statement for the
designation of an ocean dredged material disposal site
located offshore Pascagoula, MS. U.S. Environmental
Protection Agency, Region IV, Atlanta, GA.

Washington Department of Ecology. 1989. Draft marine net-pen
discharge permits. Washington Department of Ecology,
Olympia, UA.

Washington Department of Fisheries. 1990. Fish culture in
floating net pens. Final Programmatic Environmental Impact
Statement. Olympia, WA.

Weston, D.P. 1986a. The environmental effects of floating
mariculture in Puget Sound. School of Oceanography,
University of Washington, for the Washington Departments of
Fisheries and Ecology.

Weston, D.P. 1986b. Recommended interim guidelines for the
management of salmon net-pen culture in Puget Sound.
Prepared by Science Applications International Corporation
for the Washington Department of Ecology. Olympia, WA.

Weston, D.P., and R.J. Gowen. 1988. Assessment and prediction
of the effects of salmon net-pen culture on the benthic
environment. In fish culture in floating net pens, Appendix
A. Final Pro4-rammatic Environmental Impact Statement,
Washington Department of Fisheries (1990), Olympia, WA.

Weston, D.P. 1991. An environmental evaluation of finfish net-
cage culture in Chesapeake Bay prepared by the University of
Maryland J.

Appendix A. Environmental Surveys.

The effect of development on the marine environment is a major
consideration, so certain site-specific information is required
for permit review. In order to assess the suitability of a site
for net-pen or on/off bottom shellfish culture and to evaluate
the extent of environmental effects after the start of culture
operations, several environmental surveys are required. These
include a site characterization survey, a baseline survey, and
annual monitoring. The components of each of these surveys are
summarized in Table Al and discussed in the following sections.

< add table Al here>

A. Site Characterization Survey . A site characterization survey
is required prior to permit application. This survey serves two
principal functions. The primary purpose is to provide state and
local governments with the information necessary to evaluate the
potential extent of environmental effects. The site
characterization survey also provides the applicant with
information on determining the suitability of a site for culture.
A site characterization survey is composed of four principal
elements: (1) initial consultation with state and local
government; (2) a bathymetric survey; (3) a hydrographic survey;
and (4) a diver survey.

1. Consultation with state government. After selecting a
potential culture site, but prior to performing the site
characterization field survey, the-prospective applicant should
contact state resource management agencies (Departments of
Wildlife, Fisheries and Parks - Bureau of Marine Resources,
Environmental Quality, Agriculture). Initial contact should be
made with the MDWFP Bureau of Marine Resources (BMR). This
agency will then facilitate consultations with all other
appropriate state and federal agencies.

While these consultations cannot be required of the applicant,
they are highly recommended. They provide state and federal
local officials with an opportunity to comment on the potential
site at an early stage in the planning process. They also ensure
that the required evaluation surveys will be designed to meet
established requirements. Resource management agencies may be
able to identify nearby habitats of special significance or
existing conditions that would make the site unacceptable for
development. Other government agencies may also need to be
contacted if the potential site-is likely to affect land or
resources under their jurisdiction.

One of the principal purposes of these consultations is to
determine the proximity of the potential site to habitats of
special significance. BMR staff may be aware of nearby critical
habitats or major shellfish beds. BMR may also be able to

Table Al

RECOMMENDED ENVIRONMENTAL SURVEYS FOR
MISSISSIPPI NET-PEN CULTURP

Site Characterization Baseline Annual
Survey Survey Monitoring

Class 1 9 Recommended consultation with e None None
Facilities state and local authorities

e Bathymetric survey
* Hydrographic survey
- Current velocity and
direction

9 Diver survey

Class II * Recommended consultation with 9 None Benthic survey
Facilities state and local authorities - Diver survey
* Bathymetric survey

9 Hydrographic survey
- Current velocity and
direction

9 Diver survey

Class III e Recommended consultation with 9 Sediment chemistry o Benthic survey
Facilities staLe and local authorities sampling - Diver survey
9 Bathymetric survey 9 Benthic infauna - Sediment chemistry
* Hydrographic survey sampling - Benthic infauna
- Current velocity and e Water quality sampling
direction
- Drogue tracking * Current velocity and direction
- Vertical hydrographic
profiling

a Diver survev

identify bird nesting sites and colonies, wilderness areas,
public beaches and parks and other areas of significance. BMR
can obtain information on endangered, threatened, and protected
species that may occur in the vicinity of the proposed site.

State and local government officials should be given an
opportunity to comment on the proposed field surveys (i.e.,
bathymetric, hydrographic and diver surveys). The survey content
should be determined in consultation with BMR and those agencies
having permit authority. The survey protocol described below is
intended to provide the information necessary for a standardized
and cost-effective permit review * This should be adequate in
most instances, but there may be certain site-specific concerns
that would require minor modifications. For example, the diver
survey may be modified to devote particular attention to areas of
special concern. Departure from this protocol should be allowed
only with strong justification, and modifications should
generally result in the collection of more, rather than less,
data.

2. Bathymetric survey. A bathymetric survey should be performed
in order to determine depth and to identify the presence of any
bathymetric features which might affect bottom accumulation of
excess feed and fecal material. All permit applicants will be
required to perform a bathymetric survey. The area of concern is
the seabed directly under the floating or on-bottom structures
and within 300 feet of the perimeter of such structures.
Multiple fathometer transects should be established with a
density and spacing so as to adequately characterize the
bathymetry under and around the pens. The position of the
transects will depend upon the intended configuration of the
planned structures. Figure Al provides a recommended survey
design given a rectangular configuration. The bathymetric survey
report should note the period during the tidal cycle when the
survey was made, and it should relate the measured depths to
MLLW (mean lower low water).

3. Hydrographic survey. Information on current velocities and
directions is necessary to determine if current velocities will
be adequate for dilution and dispersion of excess feed and wastes
from net pen culture. Current information will also be needed
for floating shellfish facilities to estimate the potential
dispersion of wastes. These data are important for operations
planning, providing essential information on the supply of
dissolved oxygen supplied by the water flow.

The hydrographic survey includes three components: (a) current
velocity and direction; (b) drogue tracking; and (c) vertical
profiles of temperature, salinity and dissolved oxygen. Class I
and II net pen facilities, as defined in Table A2 (AppendixC)

will not be required to perform the drogue tracking studies
because of their small size and reduced potential for water
quality degradation. Floating shellfish culture facilities will
only be required to describe current velocity and direction.
Only vertical temperature, salinity and oxygen profiles only will
be required for on-bottom shellfish culture.

3a. Current velocity and direction should be monitored at
the center of the proposed site. Both near-surface and mid-depth
measurements should be made. The near surface measurements
should be taken at a depth of 6 feet or at one-half the depth of
the structure. The mid-depth measurements should be taken
mid-way between the maximum depth of the proposed net-pens and
the sea floor. At both depths current velocity and direction
should be monitored throughout one complete tidal cycle (one
flood tide, one ebb tide). Collect a 15-minute sample at each of
the three depths. A minimum of ten measurements evenly spaced
throughout the tidal cycle should be made at each depth. "Mean
current" is to be determined by an arithmetic average of these
ten or more measurements. The measurements should be made during
a period of "average" tides, and should not be representative of
either extreme neap or extreme spring tides. Subsurface current
meters are preferred. However, flow meters may be used, but
surface direction must be estimated. Please provide the current
data in a tabular format and include the date and tide
predictions for that day. The report of results should note any
conditions (e.g., weather, wind speed and direction, tidal gauge
data for that day) that might make the data unrepresentative of
"typical" conditions. If there is reason to believe the data do
not reflect "typical" tidal currents and direction, resampling
may be required, but all data collected may be used in
determining a mean velocity.

3b. Drogue tracking is needed to estimate the potential
fate of particulate material and the potential for eddy
circulation (i.e., the same parcel of water is repeatedly cycled
through the area of the net-pen). Two drogues should be released
from the center of the potential net-pen site. One should be set
at a depth of 6 feet. The second drogue should be set at a depth
mid-way between the bottom of the potential net-pens and the sea
floor. The trajectory of these drogues should be followed for as
long as daylight permits, and not less than 8 hours. The drogues
may be reset at the original release site during this 8-hour
period if they are transported beyond a practical tracking range.

3c. Vertical profiles of salinity, temperature and
dissolved oxygen may be used to evaluate the intensity of water
column stratification, a factor important both from the
standpoints of environmental protection and the health of the
cultured fish. Prospective applicants should provide any
existing hydrographic information on the site. Site-specific
studies have been completed in the northern Gulf of Mexico by the

300 ft
POTENTIAL NET-PEN SITE

300 ft
Ll Ej F1 D F-I

BATHYMETRIC TRANSECTS 300 ft

I C SITIVI"), ],'OR qfTE CHARACTERIZATFON

Environmental Protection Agency, Corps of Engineers (Mobile
District), Minerals Management Service and researchers working
out of the Gulf Coast Research Laboratory.

Measurements of temperature, salinity and dissolved oxygen should
be taken throughout the water column at the center of the
potential site during the summer months, June through September.
Measurements should be made at depths of 1, 10, 20, 30 feet, and
at 30 foot intervals thereafter. The deepest measurement should
be made 3 feet above the sea floor. Water samples may be
collected or an electronic membrane probe may be used. The
sampling schedule should include one sample taken within one hour
of slack low water.

Although the preferred method is the ''Winkler Titration''
(Azide modification), described in Standard Methods, the use of
the membrane electrode is acceptable if the zero and standard
calibration methods described in the instrument manufacturer's
instructions are followed. If the membrane probe is used, the
first and last reading of each run must be verified with a
Winkler Titration of a water sample collected just prior to the
instrument readings. The verification samples must be fixed when
collected and titrated in the laboratory as soon as possible
after collection. The verification samples should be reported
next to the same readings performed by the probe.

4. Diver survey. The diver survey is primarily intended to
determine if habitats of special significance are present in the
vicinity. Because much of the biological activity in offshore
Mississippi waters occurs spring through fall, the diver survey
should be performed April through November. The requirements for
a diver survey during site characterization depend on the water
depths in the vicinity of the site. A diver survey is required
if water depth (MLLW) at the site or within a 300 foot radius of
the potential location is less than or equal to 75 feet. If any
portion of this area is in depths of 75 feet or less, it may be
subject to accumulation of feed and fecal material.

The design of the diver survey should be formulated in
consultation with BMR, who will take the lead role for the state
in design of this survey. The dive should be conducted along the
axis of the prevailing current. The number and spacing of the
transects will depend on the particular site and will be
established during these consultations. As a general guide, 3 to
5 transects, each 200 feet long, should be surveyed per acre of
pen/raft surface. A larger complex would require additional
transects. A diver should follow marked transects making
observations of substrate type, bottom features (noting erosional
or depositional areas), presence/absence of Beggiatoa mats, and
relative abundance of flora/fauna. Abundance may be
characterized approximately as follows: a) abundant: always
present within the diver's view; b) common: seen occasionally

throughout the dive, may be patchy; rare: only seen once or in a
few places throughout the dive. If eelgrass is present, counts
of turion density in 0.25 m 2 quadrats will be required. Where
oysters are present, density (per M2 ) and average size should be
provided.

5. Report. The results of the bathymetric, hydrographic and
diver surveys should be assembled in a site characterization
report to be submitted to the BMR. The report should be a
summary, analysis and interpretation of the data. The diver
survey should be described in narrative form with quantitative
data provided when required or available.The report should also
include identification of habitats of special significance in the
vicinity as determined in consultation with the BMR and the
applicant's own surveys.

The BMR may require that the diver survey shall be documented
with a video camera or photographs. One copy of the video tape
on standard VHS tape format should accompany the application.
While video format is preferred, photographs taken at 30 foot
intervals may be submitted if video is not available. A brief
narrative with the tape or photos describing reference points
should be provided. All documentation must include the dates on
which it was taken.

Information to be provided in the report should include:

-A. Vicinity Map. Use a NOAA chart or USGS Topographic
map to show the waters and shorelands within the general vicinity
of the lease area. Any aerial photos must have been taken during
the twelve month period prior to the filing of the application
and the date on which it was taken must be noted.

B. Plan View. Exact location of lease tract(s) described
as follows:

a. Mark each tract and entire lease boundary. Mark true
north with arrow. Include scale used.

b. Show depth contours and indicate mean low water and
mean high water on all land adjace nt or nearest site.

C. Show primary ebb and flood directions.

d. A figure of the drogue trajectories should be also be
included.

e. The position of the diver transects.

f. Label the location of Federal projects, navigational
channels, any structures, weirs, existing leases,
parks, etc. within 1 mile. An enlargement of a NOAA

chart or USGS topographic map is suggested to provide
this information. Also provide:

9- The latitude, longitude and LORAN coordinates for
each corner of the entire lease.

h. The metes and bounds of each 5 acre tract.

C. Site development. This section is intended to provide
accurate plans depicting the physical structures of the proposed
operation. The site characterization report should include a
figure of the proposed net-pen site in plan view at a scale of
200 feet or less to the inch.

a. Single pen/raft schematic. Provide top view, cross
section, identify dimensions, materials, labels, etc.

b. Pen system schematic. Provide top view and cross
section, identify dimensions, mooring connections,
labels, etc.

C. On-site support structures. Describe structures such
as barges, sheds, feed sheds, etc., to be located
on-site. Provide dimensions, drawings, materials, etc.

Describe the storage and use of oil, gasoline or
other hazardous material on this facility.

Describe the type and location of any sanitary
facility.

d. Mooring plan.

Cross section. Provide a schematic and
description of materials of the mooring system in place
on the sea-floor. Include depths from the bottom of
the structure to sea-floor relative to MLW and MHW.

Mooring system adequacy. Provide a schematic of
the mooring array for a pen system and a description of
its ability to withstand severe storms, surge,
equipment break-up, etc. Include dimensions and
materials, etc.

e. Pen system and mooring array schematic. Provide a
schematic of the maximum area to be utilized by pen
systems and moorings on the proposed lease.

f. Upland facilities. Describe shoreside facilities or
holdings to be used for various activities including
feed transport, processing, etc.

D. Operations.

a. List and describe your activities including boat
traffic, feed schedule, feed techniques, monitoring
schedule, transport schedule, predator control methods,
net cleaning and maintenance (methods, frequency and
location), antibiotic usage, harvest schedule, harvest
technique, processing methods.

b. Describe the start-up and projected maximum production
on a 12 month basis per pen and pen system. Also state
the maximum stocking density, in pounds per cubic foot
for fish and per square foot of structure for
shellfish.

C. Estimate the monthly pounds of feed per pen system over
12 months at start-up and maximum production.

E. Area resources.

a. Habitats of special significance/endangered species.
Oyster beds, submerged vegetation beds and other marine
resources. Provide a description of any oyster beds, sea
grass beds and other marine resources in the surrounding
area. Provide a map showing the location of these resources
if within a mile of the proposed site.

Projects cannot be located within one mile of any habitat of
special significance, such as wilderness areas, critical
habitats for endangered/threatened species, sensitive
fisheries habitat, grass beds, bird concentration points,
etc. Applicants will be required to provide a signed
statement to confirm the proposed lease either does not fall
within one mile of such habitats.

b. Surrounding area use.

Provide a tax map, chart, or topographic map showing the
locations of any adjacent or nearby lease tract(s) or
riparian/littoral property located within 1000 feet of the
lease tract(s) Property lines must be clearly marked. List
the names and addresses of every lease holder or owner of
riparian rights shown on the map. Identify any fish or
shellfish culture leases. The map and list of owners must
be certified by the tax collector or clerk of the
municipality in which the lease tract is located as being an
accurate copy of this information as maintained by the
municipality.

List all other aquaculture leases held by the applicant or
in which the applicant has a financial interest. Describe
the navigational or other uses (ocean disposal, cable, etc.)

within one mile of the area. Describe the degree of
exclusive use required by the proposed lease.

c. Point source discharge. Describe the location and
proximity of the proposed lease to any point source
discharges or facilities (sewage treatment plants, seafood
processing plants, power plants, industrial facilities,
stormwater drains, etc.).

F. Technical capability. Provide information regarding
professional expertise such as a resume and documentation of
technical expertise and practical experience necessary to
accomplish the proposed project.

G. Financial capability. Provide documentation to prove
the applicant has the necessary financial resources for the
proposed project. Provide documentation of accurate and complete
cost estimates of the proposed aquaculture activities. The
applicant must post a performance bond, the amount of which will
be determined by the nature of the aquaculture activities
proposed and set by the BMR.

Appendix B. Baseline Survey.

The baseline survey is intended to characterize bottom conditions
at the site, before they could potentially be altered by culture
activities. and benthic infauna sampling. The baseline survey
is required for Class III net-pen operations only and will not be
required of Class I and II operations or for shellfish culture.
The baseline survey is to be completed after emplacement of
net-pens but before stocking.

The Baseline Field Survey may include components for diver
observation, hydrography and water quality, but focuses primarily
on benthic analyses, sediment analyses and sediment chemistry,
The sediment sampling plan must include the number and location
of sediment samples to be collected for grain size, chemical and
biological analysis. The proposed plan should be coordinated
with BMR to insure that the quality of the sediment analysis and
infaunal data will be acceptable. Stations should be established
along a transect on the "downcurrent" side of the pens as
determined by the prevailing currents (as measured at the
mid-depth station in the site characterization survey). Stations
should be established along this transect beginning directly
under the perimeter of the net-pens and extending away from the
net-pens at distances of 20, 50, 100, and 200 feet in the
direction of prevailing currents. Each site should be sampled by
three replicate diver cores or three replicate grab or box corer
samples from which sub-cores are removed.

Cores should be collected for analysis of total organic carbon,
total Kjeldahl nitrogen and grain size distribution (median phi,
percent gravel, sand, silt/clay). Cores should be inserted to a
depth of four inches in the sediment. Care should be taken to
insure that the core is representative of the undisturbed
sediment column. Transparent cores should be used so that the
redox potential discontinuity (RPD) depth can be noted and
recorded. The position of the ]@PD is reflected by change in
sediment color form brown to black. Each core should be
homogenized for analysis, but the replicates should be treated as
distinct samples and not pooled prior to analysis.

Benthic infauna samples may be collected either by a diver using
a core sampler having an area of at least 0.01 M2 or by a grab or
box corer having an area of at least 0.1 M2 . The same stations
sampled for sediment chemistry (0, 20, 50, 100 and 200 feet from
the net-pens) should be sampled for benthic infauna. Three
replicate samples should be collected at each site. The same
grab/box corer samples used for sediment chemistry should be used
for benthic infaunal analysis provided no more than one-quarter
of the surface of each sample has been removed for sediment
chemisrty sampling. Each benthic infauna sample should be sieved
on a 0.5 mm screen or nested 1.0 and 0.5 mm screens. All

macrofaunal organisms retained on the screen(s) should be
identified to the lowest practical taxonomic level, generally
species.

The results of the baseline benthic survey should be assembled in
a report consistent with the report guidelines provided for the
site characterization survey and the annual monitoring. The
baseline report should be submitted to BMR, who will take
responsibility for distribution to other agencies for comment and
action.

Appendix C. Annual Monitoring.

Upon issuance of a state lease and State and Federal permits a
monitoring program will be required. The annual monitoring
program is designed to serve two purposes. First, it is intended
to monitor potential changes in water and sediment quality
resulting from culture activities. Secondly, it provides data
with which to review the current environmental requirements for
possible future modifications. As additional data are obtained
on the environmental effects of net-pen or'on- or off-bottom
shellfish culture, the annual monitoring protocol may be
substantially revised. It is also possible that monitoring at
some culture sites may be curtailed or eliminated entirely if
little or no measurable effect on environmental quality is found
after several years of operation. The determination to curtail
or eliminate monitoring at any site will be made after BMR review
of survey results.

The annual monitoring program consists of three principal
elements:

(1) a benthic survey, including diver observations and
sampling of sediments and benthic infauna;
(2) water quality sampling; and
(3) a hydrographic survey.

Class I facilities should be exempted from annual monitoring.
Class II net-pen fish culture facilities and on- and off-bottom
shellfish culture facilities should be required to conduct only a
diver survey.

The potential for water quality impacts related to net pen fish
culture will be directly related to the amount of feed used on
the farm. The annual monitoring requirements have been designed
to require more extensive monitoring for farms using larger
quantities of feed.

FEED USE CATEGORIES.

Three categories of monitoring have been established based on
annual feed usage. As each category has different monitoring
requirements, the first step is to identify the correct
monitoring schedule for each level of operation. Each permit
holding facility is considered to be a separate farm and must be
reported independently.

Estimate the total dry weight of fish feed to be used in the
ensuing calendar year on the farm site. Although this feed will
normally be in the form of wet feed (or silage), moist feed, or
dry feed, total feed should be calculated in terms of dry weight

only. Note that the amount of dry feed is not equivalent to dry
weight. Dry weight of feed can usually be determined by
referring to the feed manufacturer's product specifications.
These specifications should include the moisture content of the
feed. This content can then be subtracted from the total weight
of the feed to yield total dry weight. If moisture content
specifications are not provided by the feed supplier or
manufacturer, it is the responsibility of the farmer to make this
determination. Percent moisture is defined as the percent loss
in weight of feed when dried to a constant weight at a
temperature of 105 degrees Celsius.

For example, if annual feed requirements for a net pen fish farm
are:
_ 500 metric tons dry feed with 10% moisture content
- 80 metric tons moist feed with 35% moisture content
- and 50 tons wet feed with 70% moisture content,
then the total feed usage in terms of dry weight will be:
= (500 - 10%) + (80 35%) + (50 - 70t)
= (500 - 50) + (80 28) + (50 - 35)
= 450 + 52 + 15
= 517 metric tons dry weight

If the total dry weight of feed is less than 120 metric tons (mt,
1 metric ton = 2200 lbs), only a minimum of record keeping
information is required. If the total dry weight of feed is
between 120 mt and 630 mt inclusive, additional requirements for
basic oceanographic data and a diver survey of bottom sediments
will be needed. Farms using in excess of 630 mt dry weight of
feed annually are subject to the most intensive monitoring.
Table A2 shows the farm category associated with each feed use
category.

TABLE A2. Farm Categories.

Dry Weight of Feed Farm Category
(metric tons)

< 120 1

120 - 630

> 630

BENTHIC SURVEY

The benthic survey is intended to assess the extent of solids
accumulation on the bottom in the vicinity of the culture

operation and the biological effect of this accumulation. The
survey consists of diver observations and sampling of sediment
chemistry and benthic infauna. Diver observations are required
if any portion of the sea bottom within 300 feet of the site is
at a water depth of 75 feet or less. Documenting the diver
survey with either continuous video footage or with photographs
taken at 20-foot intervals may be required. A brief narrative
with the tape or photos describing reference points should also
be included. All documentation must include the dates on which
it was taken.

Four transects, each at least 20'0 feet in length, should be
established as illustrated in Figure A2. The transects should be
extended if feed or feces accumulation is visible 200 feet from
the pens. Additional transects may be required to survey
habitats or resources of special concern. Divers will not be
required to operate in depths greater than 75 feet.

A diver survey shall be conducted twice a year, between January
and February and again between August and September. One of the
principal objectives of the diver survey is to document the depth
and lateral extent of solids accumulation. The diver should
estimate the depth of feed and feces accumulation at 20-foot
intervals along each transect, and should note the greatest
distance from the net-pens that visible accumulation is present.
The diver should also note the presence/absence of Beggiatoa mats
and estimate densities of demersal fish, crabs and other
invertebrates.

The annual monitoring benthic survey for Class III operations
will also include collection of sediment and benthic infauna
samples. The station location and sampling protocol should be
exactly as described in the baseline benthic survey (Appendix B).
Benthic monitoring will be required during the first period of
peak feeding. This will generally coincide with the first
harvest at the end of the growing season. After this monitoring
will occur at the peak feeding period every year, except for
semi-annual diver surveys.

a. Sediments. Sediment cores are to be analyzed for sediment
grain size (% gravel, sand, silt, clay); the- depth of the redox
discontinuity layer, the depth of the unconsolidated organic
layer and TOC. Plexiglas type corer is to be used. Single core
samples collected according to the approved sampling plan must be
inserted to 4 inches. The depth of the discontinuity layer and
the depth of the unconsolidate&organic layer are to be measured
from the surface.

Grain size analyses should be performed using the Wet Seiving
method. The standard sieve sizes for gravel, sand, silt and clay
are to be used. Full analyses of the silt-clay fractions may be
calculated as the difference in'dry weight between the original

mmmm=MM==

200 ft

(1, more

NET-PEN SITE

200 If

ormore

TRANSECTS

Figure A2
DIVER TRANsi.,crS DURING THE ANNIJAI, MONITORING SURVEY

sample and the sum of the sieve fractions down to the 0.062 mm.
sieve (very fine sand). The fraction in each sieve should be
reported in grams (dry weight) and percent of total (dry weight)
including the total dry weight of the initial sample. The
unconsolidated material and the top 2 cm of inorganic sediments
shall be collected for the analysis of TOC. The applicant must
insure that a minimum of 30 grams are collected for analysis.
Multiple cores (which include the top 2 cm of inorganic material)
if warranted, will be required. Total Organic Carbon should be
analyzed using established methods.

b. Infauna. Benthic infauna samples may be collected either by
a diver using a core sampler having an area of at least 0.01m2
2
or by a grab or box corer having an area of at least 0. 1 m . The
same stations sampled for sediment chemistry (0, 20, 50, 100 and
200 feet from the net-pens) should be sampled for benthic
infauna. Cores should be taken during the season of maximum
feeding. Three replicate samples should be collected at each
site. The same grab/box corer samples used for sediment
chemistry should be used for benthic infaunal analysis provided
no more than one-quarter of the surface of each sample has been
removed for sediment chemistry sampling. Each benthic infauna
sample should be sieved on a 0.5 mm screen or nested 1.0 and 0.5
mm. screens. All macrofaunal organisms retained on the screen(s)
should be identified to the lowest practical taxonomic level,
generally species.

WATER QUALITY SURVEY

Water quality sampling is intended to document the effect of
culture activity on dissolved oxygen and nutrients in the water
passing through the culture structure. The survey should be
conducted every two weeks from June to September, inclusive, of
each year that the facility is in operation. Sampling during the
summer and early fall months is recommended since it is during
this period that dissolved oxygen reductions or nutrient
enrichment are of greatest concern. Three stations should be
sampled: 100 feet upcurrent of the net-pens; 20 feet downcurrent;
and 100 feet downcurrent. The precise location of the stations
will depend on net-pen configuration, but they should be located
so as to monitor the water passing through the greatest possible
number of net-pens. Sampling should be conducted within one hour
of slack tide. Three replicates should be taken at each station
at a depth mid-way between the water surface and the bottom of
the net-pens. Samples should be analyzed for the following
parameters: dissolved oxygen; temperature; salinity; pH; ammonia;
and nitrite/nitrate (either separate or combined). The
concentration of unionized ammonia should also be calculated.

Also, during the peak feeding period a one-time detailed analysis
of dissolved oxygen, temperature and salinity will be prepared

for each station, consisting of 10 equally-spaced samples over
the entire vertical depth of the station.

Water samples may be collected or an electronic membrane probe
may be used to measure the concentrations. Temperature and
salinity measurements should be used to determine percent
saturation of dissolved oxygen and stratification. Although the
preferred method is the "Winkler Titration" (Azide modification),
described in Standard Methods , the use of the membrane electrode
method is acceptable, provided recommended procedures are
followed. If the membrane probe method is used, appropriate
verification procedures (described in Appendix A) must be used.

HYDROGRAPHIC SURVEY

Current velocity and direction should be measured at the depth at
which the water quality samples are taken. A single measurement
should be made 20 feet downcurrent of the net-pens concurrently
with-collection of the water quality sample from this station.
Loading estimates (g/kg fish/day) should be calculated for
ammonia and nitrite/nitrate based on:

(1) the net increase in concentration between the upcurrent
station and the 20 foot downcurrent station;
(2) the current velocity 20 feet downcurrent;
(3) the cross-sectional area of the net-pen complex; and
(4) the weight of fish on hand at the time of the water
quality survey.

REPORT PREPARATION

The comments made regarding the site characterization report
apply here as well. Specifically, analysis and interpretation of
the data should be provided, not merely presentation of the raw
data. However, the raw data should be provided in appendices so
as to permit independent assessment of conclusions.

In addition to a description of methods and data analysis and
interpretation, the annual monitoring report should also include
information on operational practices over the past year. This
information should include:

1) General description of facility (species cultured, size
at which fish will be marketed, etc.).

2) Size, number and configuration of net-pens at time of
sampling.

3) Significant changes in size, number and configuration of
net-pens over the previous year.

4) Annual production (live weight, pounds) cumulative to
the end of the reporting period.

5) Estimated weight of fish on hand during survey (pounds).
6) Stocking density (average and range, lbs/ ft3).

7) Type of feed used, percent moisture, quantity used of
each type and feeding method employed.

8) Types of antibiotics used, amount, date, form
administered over the past year.

9) Interactions with birds and marine mammals and a summary
of types and frequency of predator control measures
used.

10) Types of antifoulants employed and frequency of net
treatment, net cleaning. List all materials directly
or indirectly released to the water (anesthetics,
cleaners, pigments, hormone treated feed etc.), date,
amount and how they were applied.

11) Waste disposal. Indicate methods used to dispose of
dead fish and any processing wastes generated on site.
Give dates, quantities involved and names of any
contractors used.

12) Provide an estimate of projected feed usage for the
upcoming year, based on production plans.

The annual monitoring report should be submitted to BMR within 30
days of the end of the reporting period set by the agency. The
BMR take responsibility for distribution to other appropriate
authorities.

i
Appendix D. Monitoring Program, British Columbia I
I
I
I
I
I
I
I
-1
I
I
I
I
I
I
1

86
I
I

I . I
I
I
I
I
I
DATE DUE I
I
I
I
I

I I
- GAYLORDINO. 2333 1 PRINTED IN U,S.A.- I
I
I
I
I
I
- I
::ll 111111111111111111111 @11 1111 1
1 3 6668 14107 6051
1