[Federal Register Volume 59, Number 138 (Wednesday, July 20, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17576]


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[Federal Register: July 20, 1994]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AB88

 

Endangered and Threatened Wildlife and Plants; Final Rule To List 
the Rio Grande Silvery Minnow as an Endangered Species

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: The U.S. Fish and Wildlife Service (Service) determines the 
Rio Grande silvery minnow (Hybognathus amarus) to be an endangered 
species under the Endangered Species Act of 1973 (Act), as amended. 
This fish occurs only in the middle Rio Grande from Cochiti Dam 
downstream to the headwaters of Elephant Butte Reservoir, New Mexico. 
Threats to the species include dewatering, channelization and 
regulation of river flow to provide water for irrigation; diminished 
water quality caused by municipal, industrial, and agricultural 
discharges; and competition or predation by introduced non-native fish 
species. Currently, the species occupies about five percent of its 
known historic range. This action will implement Federal protection 
provided by the Act for the Rio Grande silvery minnow. The Service 
further determines that finalization of proposed critical habitat will 
not occur at this time, as critical habitat is not now determinable 
because the required economic analysis has not been completed. Pursuant 
to section 4(b)(6)(C)(ii) of the Act, a final determination on critical 
habitat may be delayed up to 1 year beyond the normal deadline.

EFFECTIVE DATE: August 19, 1994.

ADDRESSES: The complete file for this rule is available for inspection, 
by appointment, during normal business hours at the U.S. Fish and 
Wildlife Service, New Mexico Ecological Services State Office, 3530 Pan 
American Highway NE., Suite D, Albuquerque, New Mexico 87107.

FOR FURTHER INFORMATION CONTACT: Jennifer Fowler-Propst, State 
Supervisor, at the above address (505/883-7877).

SUPPLEMENTARY INFORMATION:

Background

    The Rio Grande silvery minnow is one of seven species in the genus 
Hybognathus found in the United States (Pflieger 1980). The species was 
first described by Girard (1856) from specimens taken from the Rio 
Grande near Fort Brown, Cameron County, Texas. It is a stout silvery 
minnow with moderately small eyes and a small, slightly oblique mouth 
(Pflieger 1975). Adults may reach 90 mm (3.5 in) in total length 
(Sublette et al. 1990). Its dorsal fin is distinctly pointed with the 
front located slightly closer to the tip of the snout than to the base 
of the tail (Pflieger 1975). Life color is silver with emerald 
reflections. Its belly is silvery white, fins are plain, and barbels 
are absent (Pflieger 1975, Sublette et al. 1990).
    This species was historically one of the most abundant and 
widespread fishes in the Rio Grande basin, occurring from Espanola, New 
Mexico, to the Gulf of Mexico (Bestgen and Platania 1991). It was also 
found in the Pecos River, a major tributary of the Rio Grande, from 
Santa Rosa, New Mexico, downstream to its confluence with the Rio 
Grande in south Texas (Pflieger 1980). Collection data indicate the 
species presently occupies about five percent of its historic range 
(Platania 1993). It has been completely extirpated from the Pecos River 
and from the Rio Grande downstream of Elephant Butte Reservoir. 
Currently, it is found only in a 275 km (170 mi) reach of the middle 
Rio Grande, New Mexico, from Cochiti Dam, Sandoval County, to the 
headwaters of Elephant Butte Reservoir, Socorro County (Bestgen and 
Platania 1991). Throughout much of its historic range, decline of H. 
amarus may be attributed to modification of stream discharge patterns 
and channel desiccation by impoundments, water diversion for 
agriculture, and stream channelization (Bestgen and Platania 1991, Cook 
et al. 1992).
    The Rio Grande silvery minnow no longer exists in the Pecos River 
where it was replaced by a congener, the introduced plains minnow (H. 
placitus) (Hatch et al. 1985, Bestgen et al. 1989, Cook et al. 1992). 
It is believed that the plains minnow was introduced into the Pecos 
drainage during 1968, probably the result of the release of ``bait 
minnows'' that were collected from the Arkansas River drainage. The 
replacement that ensued was complete in less than one decade (Cowley 
1979). The plains minnow may be more tolerant of modified habitats and 
therefore able to replace H. amarus in the modified reaches of the 
Pecos River where it was introduced. It is also believed the two 
species hybridized (Cook et al. 1992). Habitat alteration and resulting 
flow modification could have also contributed to extirpation of the Rio 
Grande silvery minnow in the Pecos River.
    Decline of the species in the Rio Grande probably began in 1916 
when the gates at Elephant Butte Dam were closed. Elephant Butte was 
the first of five major mainstream dams constructed within the Rio 
Grande silvery minnow's habitat (Shupe and Williams 1988). These dams 
allowed the flow of the river to be manipulated and diverted for the 
benefit of agriculture. Often this manipulation resulted in the 
desiccation of some river reaches and elimination of all fish. 
Concurrent with construction of the mainstream dams was an increase in 
the abundance of non-native and exotic fish species, as these species 
were stocked into the reservoirs created by the dams (Sublette et al. 
1990). Once established, these species often completely replaced the 
native fish fauna (Propst et al. 1987). Development of agriculture and 
the growth of cities within the historic range of H. amarus resulted in 
a decrease in the quality of water in the river that may have adversely 
affected the range and distribution of the species.
    Most land bordering the river where the species currently exists is 
owned by the Middle Rio Grande Conservancy District, which is a quasi-
public agency of the State of New Mexico. Other landowners include six 
Native American Pueblos, the U.S. Bureau of Reclamation, the Service, 
the U.S. Bureau of Land Management, New Mexico State Parks, New Mexico 
Department of Game and Fish, New Mexico State Lands Department, and the 
U.S. Army Corps of Engineers (Corps).
    Water flow in the middle Rio Grande is controlled by the Rio Grande 
Compact Commission. Established in 1929 for the purpose of permanently 
and equitably apportioning the flows of the Rio Grande, the Commission 
is composed of a Federal chairperson appointed by the President of the 
United States and three voting members--a representative designated by 
the Texas Governor and the State Engineers of New Mexico and Colorado. 
The Commission meets annually to review compliance with the compact 
over the preceding year, to hear reports from Federal water management 
agencies, and to consider water management decisions that have 
interstate implications. Federal agencies that also determine timing 
and amount of flow in the river include the International Boundary and 
Water Commission, the Bureau of Reclamation, and the Corps.

Previous Service Actions

    The Rio Grande silvery minnow was listed on the Service's Animal 
Notice of Review (56 FR 58804; November 21, 1991) as a category 1 
species. A category 1 species is one for which the Service has on file 
substantial information on biological vulnerability and threat(s) to 
support a proposal to list it as an endangered or threatened species. A 
proposed rule to list the Rio Grande silvery minnow as endangered with 
critical habitat was published in the Federal Register on March 1, 1993 
(58 FR 11821).

Summary of Comments and Recommendations

    In the March 1, 1993, proposed rule and associated notifications, 
all interested parties were requested to submit factual reports or 
information that might contribute to the development of a final rule. 
The comment period originally scheduled to close on April 30, 1993, was 
extended until August 25, 1993, (58 FR 19220; April 13, 1993) to 
conduct public hearings and allow submission of additional comments. 
Appropriate Tribal governments, State agencies, county governments, 
Federal agencies, scientific organizations, and other interested 
parties were contacted and requested to comment. Newspaper notices 
inviting public comment were published in New Mexico in the Albuquerque 
Journal on May 2, 1993; Las Cruces Sun News on April 30, 1993; Socorro 
Defensor Chieftain on April 28, 1993; Santa Fe New Mexican on April 20, 
1993; and in Texas in the El Paso Times on March 20, 1993.
    Because of anticipated widespread public interest, the Service held 
two public hearings that were announced in an April 13, 1993, Federal 
Register notice. Interested parties were contacted and notified of the 
hearings. Thirty-seven people attended the hearing in Albuquerque, New 
Mexico, and 58 attended the hearing in Socorro, New Mexico. Oral or 
written comments were received from 25 parties at the hearings; none 
directly supported the proposed listing. Transcripts of these hearings 
are available for inspection (see ADDRESSES). Briefing sessions were 
also held for tribal leaders on May 18, 1993, in Albuquerque, New 
Mexico; and for a number of northern pueblos at Santo Domingo Pueblo, 
New Mexico, on September 9, 1993.
    A total of 40 written comments were received at the Service's 
Ecological Services State Office in Albuquerque, New Mexico: 13 
supported the proposed listing; 14 opposed the proposed listing; and 13 
commented on information in the proposed rule but expressed neither 
support nor opposition.
    Oral or written comments were received from 7 Federal and 5 state 
agencies, 14 local officials, and 36 private organizations, companies, 
and individuals. Written comments and oral statements presented at the 
public hearings and received during the comment periods are covered in 
the following summary. Comments of a similar nature or point are 
grouped into a number of general issues. These issues, and the 
Service's response to each, are discussed below.
    Issue 1: The Service has come to the conclusion that only instream 
flow will assure the species' existence. Will the Service propose a 
program for the purchase of water rights in order to provide water for 
the species?
    Response: The Service has not reached this conclusion. Possible 
instream flow requirements of the species are among several factors 
that need to be considered in the recovery planning process. If, during 
the recovery planning process, the Service determines that the purchase 
of water rights will enhance recovery of the species, the Service would 
explore with other State and Federal entities the possible purchase of 
water rights from willing sellers.
    Issue 2: The United States, under the terms of the Convention of 
1906, has the obligation to deliver 60,000 acre-feet of water annually 
to the Republic of Mexico. The U.S. International Boundary and Water 
Commission (IBWC) is responsible for ensuring that the U.S. government 
meets those obligations. The IBWC is concerned that the listing may 
interfere with their ability to meet these treaty requirements.
    Response: The Service recognizes the treaty obligation of the 
United States to provide to the Republic of Mexico 60,000 acre-feet of 
water annually from the Rio Grande. Measures taken to protect and 
recover the Rio Grande silvery minnow will take into consideration this 
treaty obligation and IBWC's ability to meet treaty requirements.
    Issue 3: Completion of the dams above Elephant Butte Dam has had 
the effect of extending stream flow. Flood control and conservation 
storage operations do not, cannot, and have not been used to create or 
extend reaches of no flow in the riverbed.
    Response: The Service agrees with the statement. Availability of 
flow is likely not the only factor affecting decline of the silvery 
minnow. These operations change the natural flow regime of the river 
and thus may affect survival of the Rio Grande silvery minnow. The 
final rule recognizes these other factors in the ``Summary of Factors 
Affecting the Species.''
    Issue 4: Reservoirs do not, as implied, store all spring runoff and 
summer inflows. Water is normally released during summer, not winter 
months. Diversion dams and canals have limited capacities to divert 
flows. They cannot ``completely divert all flows . . . into irrigation 
ditches'' under flood conditions.
    Response: The Service agrees with the statement that reservoirs do 
not store all spring runoff and summer inflow. While most water is 
released during the spring and summer, a fall and winter release does 
occur in the Middle Rio Grande Valley when conditions permit (Beal and 
Gold 1988, Borland and Gold 1989). Under flood conditions, the 
irrigation diversions do not have the capacity to divert all flows. 
Under non-flood flows they do have the capacity to divert all flows. 
United States Geological Survey (USGS) records substantiate the 
occurrence of no-flow periods downstream of the various irrigation 
diversion dams.
    Issue 5: The proposed regulation is unsupported by any hydrological 
study as to the statements that irrigation uses have depleted the water 
flow. Not a single source of information is cited for comments 
regarding hydrology of the river. Depletions of water in the system may 
be the result of the construction of wildlife watering impoundments by 
the Forest Service and Bureau of Land Management.
    Response: It can be readily documented by examining USGS flow gage 
records that river flows decrease when the irrigation season starts. In 
addition, the Service reviewed Bullard and Wells (1992), which provides 
information on the hydrology of the middle Rio Grande. This reduction 
in flow is most noticeable in mid-summer after the spring to early 
summer peak flow has passed. Wildlife impoundments are often very small 
(less than one acre in size) and are considered to be insignificant in 
the amount of water they deplete from the drainage.
    Issue 6: Economic considerations should be given more weight when 
communities may be affected.
    Response: Section 4(a)(1) of the Act identifies five factors that 
are considered in making a determination of whether a species should be 
listed as threatened or endangered. Section 4(b)(1)(A) of the Act 
requires that listing determinations be based solely on the best 
available scientific and commercial data, and prohibits the Service 
from considering economic factors (50 CFR 424.11(b)). However, because 
economics are considered in the designation of critical habitat, the 
Service will conduct an economic analysis in the process of evaluating 
proposed critical habitat for the Rio Grande silvery minnow.
    Issue 7: The Service needs to ensure public input before listing 
the Rio Grande silvery minnow. The Service is required to notify 
counties and other affected parties to solicit their input prior to 
listing a species under the Act. The Service failed to meet this 
obligation.
    Response: On February 19, 1991, about 80 pre-proposal letters of 
inquiry were mailed to various governmental agencies, knowledgeable 
individuals, and the New Mexico Congressional delegation. On March 20, 
1992, the Service held a meeting in Albuquerque, New Mexico, with 
various interested governmental and private entities to explore 
existing or potential flexibility in water delivery schedules that 
might avoid dewatering of the Rio Grande within the range of the Rio 
Grande silvery minnow. The Service also published notices of the 
proposal in 5 local newspapers and mailed copies of the proposed rule 
to 148 different government agencies, private organizations, and 
interested individuals, including all counties having lands that border 
the area being proposed for critical habitat designation. Two public 
hearings were also held. The Service has fully met or surpassed the 
requirements of the Endangered Species Act for public notification.
    Issue 8: The Service held public hearings only to fulfill a legal 
obligation and will not pay attention to any public comment. The 
Service should have held public hearings in El Paso and Las Cruces.
    Response: The Service disagrees. All comments are carefully 
evaluated before the Service makes a determination on whether to 
proceed with a final rule. Numerous notifications of the proposed rule 
and extension of the comment period were distributed, and Service 
biologists traveled to several areas, including El Paso and Las Cruces, 
to present briefings on the proposed rule and accept comments.
    Issue 9: The Service should establish a coordinating committee 
composed of interests below Elephant Butte Reservoir whose task would 
be to develop a full-scale report on the existing data available on the 
Rio Grande silvery minnow and how the river could be managed for the 
benefit of all, including the Rio Grande silvery minnow.
    Response: After the species is listed the Service will consider, 
through the recovery planning process, establishing a coordinating 
committee to develop a report on the Rio Grande silvery minnow and how 
the river could be managed for the benefit of all, including the Rio 
Grande silvery minnow.
    Issue 10: During periods of dewatering of the river, the ditches 
provide habitat for the species. The Service should consider exploring 
with the Middle Rio Grande Conservancy District, the counties, and 
other agencies the multiple use of riverside drains for the species and 
the preservation of bosque habitat.
    Response: The Service agrees that during periods of drought, which 
result in the dewatering of the mainstream Rio Grande, the various 
irrigation ditches and drains may provide a temporary place of refuge 
for the Rio Grande silvery minnow. However, these areas do not contain 
suitable habitat for long-term use by the species. Few Rio Grande 
silvery minnows are found in the ditches and drains. Those that are 
found are believed to represent Rio Grande silvery minnows that became 
entrapped due to the diversion of irrigation water from the mainstream. 
The Service intends to investigate, with all interests, the potential 
use of the riverside drains for recovery of the species.
    Issue 11: Few data exist on the abundance of the species on Pueblo 
lands or whether it can survive in the mud and sand when the river bed 
is dry.
    Response: The Service used all available biological information in 
making the determination to list the Rio Grande silvery minnow as an 
endangered species. Recent census data from Pueblo lands are reported 
by Bestgen and Platania (1991), Platania and Bestgen (1988), Platania 
and Clemmer (1984), and the U.S. Bureau of Reclamation (1992). As 
additional information becomes available, including information from 
Pueblo waters, the Service will use that information in the recovery 
planning process. The Service hopes that, through initiation of 
recovery efforts for the species, and in cooperation with the Pueblos, 
additional information can be obtained on the status of the species on 
Pueblo lands. The Service has no scientific data indicating that the 
species survives in the mud and sand during periods when the river is 
dry.
    Issue 12: Competition between H. amarus and its congener H. 
placitus could have also contributed to extirpation of the species from 
the Pecos River. Studies should be conducted to determine if predation 
or competition by non-native fishes impacts the species. The studies 
should not just determine if it is a problem, they should also 
determine where and to what extent it is a problem.
    Response: The Service has no data to substantiate any reasons for 
extirpation of the Rio Grande silvery minnow from the Pecos River and 
replacement by its congener H. placitus. Competition may have been a 
factor in its extirpation; however, it is more likely that 
hybridization between the two species was the primary factor. Studies 
designed to determine if predation or competition by non-native fishes 
impacts the survival of the Rio Grande silvery minnow will be conducted 
as part of recovery efforts for the species.
    Issue 13: Recent biological studies have been conducted during a 
period of high flow; therefore, the results of those studies do not 
accurately reflect the distribution of the species under normal 
conditions.
    Response: It is true that, other than 1989, recent data have been 
collected during a period of higher than normal flow. However, even 
these data show that the species is not as abundant as it was during 
other periods of above-normal flow. This leads to a conclusion that 
factors other than flow may be impacting the species and its habitat.
    Issue 14: It seems a fair conclusion that the Cochiti downstream 
reach is no longer favorable habitat because of lowered water 
temperatures and degradation of favored H. amarus substrate. This 
further limits the area in which the species has to survive.
    Response: Although the reach immediately downstream of Cochiti Dam 
may not be favorable habitat for the Rio Grande silvery minnow, it is 
not known how far downstream these conditions persist. As part of 
recovery efforts for the species, studies will be conducted on this 
question, and attempts may be made to correct the unfavorable 
conditions.
    Issue 15: Since little is known of feeding habits or reproduction, 
the claim that channel modification would adversely affect the Rio 
Grande silvery minnow is not supported by the best scientific evidence. 
Changes in food supply, not water supply, may be a factor affecting the 
species in the Rio Grande. Also, the effects of non-native plants upon 
the habitat need to be investigated.
    Response: Recent data have shown that spawning activity occurs 
during peak spring and early-summer flows. The fertilized eggs drift 
with the current for about 24 hours and then hatch. The larval fish 
continue to drift downstream until they are swept into calm backwater 
and edge areas where food is abundant and they can continue to grow. 
Because of this spawning behavior, any modifications to the channel 
that result in changes that sweep the eggs and larval fish into less 
favorable habitats would adversely affect the species. There are no 
data presently available to support the contention that a reason for 
decline of the species was a decrease in the species' food supply or 
the invasion of non-native plants. As part of recovery efforts, the 
impacts of all habitat modifications will be investigated to determine 
if and how they impact the species.
    Issue 16: Very little information was presented at the public 
hearing or in the Federal Register to show a cause-and-effect 
relationship between water quality and decline of the species.
    Response: Limited information exists on the relationship between 
water quality and the decline of the species. A better understanding of 
this relationship will be developed as a result of recovery efforts.
    Issue 17: The proposed listing of the Rio Grande silvery minnow is 
just a part of a much larger problem--the modification of the 
floodplain. Are activities at Bosque del Apache National Wildlife 
Refuge (NWR) affecting the species?
    Response: The Service agrees. Listing the species will invoke 
protective provisions of the Act, such as those contained in section 7. 
The Service has no information that indicates activities at Bosque del 
Apache NWR impact the species. The Service will work with Federal 
agencies, including Bosque del Apache NWR, to ensure that their actions 
do not jeopardize the species through adverse effects on the 
floodplain. In addition, the Service is involved in several cooperative 
efforts with Federal, State, and private entities to protect the Rio 
Grande Bosque and associated floodplain.
    Issue 18: The facts presented in the status report do not support 
the conclusion that ``anticipated additional modifications'' would 
limit prospects of survival for the species in the middle Rio Grande.
    Response: The facts presented in the status report do support the 
conclusion that ``anticipated additional modifications'' would limit 
prospects of survival for the species in the middle Rio Grande. 
According to the authors of the status report, ``Conservation measures 
are necessary as continued habitat and flow modifications, 
introductions of non-native species, and lack of refugia threaten 
survival of H. amarus.'' The present status of the species is such that 
any activity that could negatively impact the species may limit 
prospects for its survival.
    Issue 19: Only two facts support listing; that the species is 
presently found in only 5 percent of its historic range, and that other 
fish native to the middle Rio Grande (Rio Grande bluntnose shiner, 
phantom shiner, Rio Grande shiner, and speckled chub) have been 
extirpated from the river. The Service does not have adequate data to 
support the conclusion that the Rio Grande silvery minnow is endangered 
and should be listed under the Act.
    Response: The Service agrees that the above two facts support 
listing. However, other facts that support listing include the species' 
decrease in abundance within the area it presently occupies, and its 
extirpation from the Pecos River after the introduction of the plains 
minnow into that system. The Service concludes, as detailed in the 
``Summary of Factors'' section, that there is sufficient evidence to 
support listing the species as endangered under the Act. The Service 
reviewed the best scientific and commercial data available to make this 
determination.
    Issue 20: The Rio Grande silvery minnow is not a distinct species. 
It is just a local population of the Mississippi silvery minnow. The 
Service should consider conducting studies for two years on the 
species' taxonomy.
    Response: The Service has taxonomic information that verifies the 
Rio Grande silvery minnow as a distinct species. The Rio Grande silvery 
minnow is recognized by the American Fisheries Society, which is 
considered the scientific authority for the names of fishes, as a full 
species (American Fisheries Society 1991). Cook et al. (1992), using 
starch gel electrophoretic methods, found that phenetic and 
phylogenetic analyses corroborated the hypothesis that H. amarus is 
distinct at the species level from H. nuchalis and H. placitus, with 
which it was previously grouped.
    Issue 21: The Service has not conducted in-depth studies to 
determine the number of silvery minnows that exist in the Middle Rio 
Grande Valley and associated drainage ditches. The species may be doing 
well without protection of the Federal government.
    Response: Since 1987, studies have been conducted to document the 
population of Rio Grande silvery minnows in both the Middle Rio Grande 
Valley and its associated irrigation and drainage ditches from Velarde 
to Elephant Butte Reservoir, New Mexico. These studies have shown that 
very few Rio Grande silvery minnows survive in the drainage ditches. 
The listing is based, in part, upon the extirpation of the species from 
about 95 percent of its historic range. The species was once thought to 
be one of the most numerous fish in the Rio Grande. In 50 fish 
collections made between Bernalillo and Elephant Butte Reservoir 
between 1987 and 1988, the Rio Grande silvery minnow was the second 
most abundant species, comprising 18 percent of the total fish 
collected. From 1989 to 1992, 56 collections were made in the same area 
and only 3 Rio Grande silvery minnows were collected. During that 
period, the Rio Grande silvery minnow went from being the second most 
abundant native fish species to the least abundant native species 
(Platania 1993). The Service believes that without the protection 
afforded through Federal listing, the species is likely to become 
extinct. Two native Rio Grande fish species have already become 
extinct.
    Issue 22: The fish exist in stretches of the river that have been 
subject to drying for at least 50 years, but have disappeared from 
areas where there has been instream flow for the past 50 years.
    Response: The Service agrees that the species has persisted in 
reaches of the river that have experienced seasonal drying during the 
past 50 years and has been extirpated from reaches where there has been 
continual flow during the last 50 years. In the past, during periods of 
extremely low flow, the species survived in areas where irrigation 
water returned to the river, in seepage and leakage pools located 
downstream of irrigation diversion dams, and, prior to construction of 
Cochiti Dam, in the canyon reach of the Rio Grande upstream of Cochiti. 
Prior to the construction of irrigation and flood control dams in the 
southwest, it was not unusual for portions of major rivers to become 
dry during periods of drought. During these drought periods, native 
fishes would retreat to canyon reaches where permanent water existed. 
After the drought ended, they would re-inhabit the reaches of river 
that had formerly been dry. There was a constant expansion and 
contraction of fish populations. Construction of mainstream dams 
prevented this movement and may have contributed to the extitirpation 
of downstream populations of native fishes.
    The reasons for the extirpation of the species from continual flow 
reaches of the river are not known but probably relate to factors other 
than flow. Changes in species composition, flow regimes, and water 
quality could all have been causative factors in the decline of the Rio 
Grande silvery minnow from these areas. Even in those areas where the 
species presently persists, its abundance has been substantially 
reduced (Platania 1993).
    Issue 23: Listing is not necessary because of existing protection 
that is afforded the species by the requirements of the Coordination 
Act, National Environmental Policy Act, and other habitat protection 
regulations, such as section 404 of the Clean Water Act. Any activity 
that could affect the habitat of the species would have to undergo 
these reviews, including the Middle Rio Grande Conservancy District's 
work on its structures. Such work could not be done with impunity. 
Protection is also provided to the species because of its listing as 
endangered by the State of New Mexico.
    Response: To date, the species has declined even with these 
regulations in place. These regulations do not ensure that habitat for 
the Rio Grande silvery minnow will be protected. Listing of the species 
by the State of New Mexico only regulates collecting of the species. It 
does not provide protection for its habitat or for its recovery. The 
Service believes the protective mechanisms of the Act are necessary to 
prevent the species' extinction.

Summary of Factors Affecting the Species

    After a thorough review and consideration of all information 
available, the Service has determined that the Rio Grande silvery 
minnow should be classified as an endangered species. Procedures found 
at section 4(a)(1) of the Act (16 U.S.C. 1531 et seq.), and regulations 
(50 CFR Part 424) promulgated to implement the listing provisions of 
the Act were followed. A species may be determined to be an endangered 
or threatened species due to one or more of the five factors described 
in section 4(a)(1). These factors and their application to the Rio 
Grande silvery minnow (Hybognathus amarus) are as follows:

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    The only existing population of H. amarus continues to be 
threatened by annual dewatering of a large percentage of its habitat. 
This dewatering is primarily the result of diversion of river flow for 
agriculture within the Middle Rio Grande Valley of New Mexico. During a 
year when an average or above-average amount of water is available, the 
impacts of the diversions are not severe. During a below-average water 
year, the river channel may be dry from Isleta Diversion Dam downstream 
about 179 km (111 mi) to the headwaters of Elephant Butte Reservoir for 
two months or more. When two below-average flow years occur 
consecutively, a short-lived species such as H. amarus can be severely 
affected, if not completely eliminated from the dry reaches of river. 
During the 94 years for which flow records have been maintained for the 
middle Rio Grande, it has not been unusual for the 245 km (153 mi) 
reach of the Rio Grande from the Angostura Diversion Dam downstream to 
Elephant Butte Reservoir to experience periods of no flow. Even before 
construction of mainstream dams, the middle Rio Grande frequently 
experienced periods of no flow. During such periods, it is suspected H. 
amarus survived in areas where irrigation return flows re-entered the 
river, in the pools formed by water leaking through the gates of the 
diversion dams, in the irrigation ditches and drains, and in the 
reaches of stream above the diversions from which their offspring could 
repopulate downstream reaches when conditions permitted. It is not 
known why these same factors do not provide sufficient habitat to 
support H. amarus under current conditions. Other factors, such as an 
increase in non-native and exotic fish species, or an increase in 
contamination may be exacerbating the stress placed upon the species 
during low-flow periods.
    Mainstream dams permit the artificial regulation of flow, prevent 
flooding, trap nutrients, alter sediment transport, prolong flows, and 
create reservoirs that favor non-native fish species. These changes may 
affect the Rio Grande silvery minnow by reducing its food supply, 
altering its preferred habitat, preventing dispersal, and providing a 
continual supply of non-native fishes that may compete with or prey 
upon the species. Altering flow regimes may also improve conditions for 
other native fish species that occupy the same habitat as the Rio 
Grande silvery minnow and may thereby cause their populations to expand 
at the expense of the Rio Grande silvery minnow.
    Since completion of Elephant Butte Dam in 1916, four additional 
mainstream dams have been constructed on the middle Rio Grande, and two 
dams have been constructed on one of its major tributaries, the Rio 
Chama (Shupe and Williams 1988). Construction and operation of these 
dams, which are either irrigation diversion dams such as Angostura, 
Isleta, and San Acacia; or flood control and water storage dams such as 
Elephant Butte, Cochiti, Abiquiu, and El Vado, have modified the 
natural flow of the river. The dams make it possible during a low-flow 
year to completely divert all of the flow from the river channel into 
irrigation ditches. The species does not persist in the irrigation 
ditches or the low-flow conveyance channel. Platania (1993) collected 
fish samples from 11 locations along the low-flow conveyance channel 
between 1987-1989 and failed to locate any Rio Grande silvery minnows. 
The dams also store spring runoff and summer inflow, which would 
normally cause flooding, and release this water back into the river 
channel over a prolonged period of time. This release is often made 
during the winter months when low flows would normally occur. 
Artificially-controlled flows depart significantly from natural 
conditions. Reduced flows may limit the amount of preferred habitat 
available to the species and may limit dispersal of the species. 
Although the mechanisms of how the decline of the species occurred are 
not fully understood, manipulation of flow may be one of the primary 
reasons H. amarus has been extirpated from portions of its historic 
range.
    Channelization of the middle Rio Grande has resulted primarily from 
the placement of Kellner jetty fields, or jacks, along the river. They 
are designed to protect the levees by retarding flood flows, trapping 
sediment, and promoting the establishment of vegetation. Since 1951, 
the Bureau of Reclamation and Corps have installed in excess of 100,000 
individual jetties occupying more than 2,000 ha (5,000 ac) (Bullard and 
Wells 1992).
    From Elephant Butte Dam downstream about 325 km (200 mi) to its 
confluence with the Rio Conchos, the Rio Grande is fully controlled by 
reservoir releases and irrigation return flows. Meanders, oxbows and 
other components of historic aquatic habitat have been eliminated in 
order to pass water as efficiently as possible for agricultural 
irrigation and downstream deliveries. These changes affected the Rio 
Grande silvery minnow by altering its habitat to the extent that its 
survival was not possible. The sandy substrate, which it prefers, has 
been replaced by gravel and cobble, and no backwater areas exist where 
the young can develop. Winter flows released from Caballo Dam often 
equal .06 cubic meters per second (2 cubic feet per second), which is 
not enough flow to maintain habitat for fishes.
    In 1958, in an effort to meet Rio Grande Compact water delivery 
requirements, the Bureau of Reclamation initiated operation of a 97 km 
(60 mi) long conveyance channel from San Acacia to Elephant Butte 
Reservoir. The purpose of the conveyance channel is to divert all flow 
less than 63 cubic meters per second (2000 cubic feet per second) in 
order to prevent loss of the Rio Grande flow to seepage and evaporation 
from the aggraded riverbed. Prior to 1985, the conveyance channel had 
been operated to its full capacity for about 28 years. Since 1985, it 
has not been operated at full capacity. If, however, the channel were 
to be operated at full capacity, the natural stream bed downstream of 
San Acacia would be dry more frequently and for longer periods of time. 
Both the Corps and the Bureau of Reclamation are drafting plans to 
rehabilitate and protect the conveyance channel in order to bring it 
into full operation. Should the conveyance channel be placed in full 
operation, the portion of the Rio Grande silvery minnow's habitat 
downstream of San Acacia dam would be desiccated when river flows at 
the dam became less than 63 cubic meters per second (2000 cubic feet 
per second), resulting in death or displacement of individuals.
    Water diversions also occur above the Middle Rio Grande Valley in 
both Colorado and New Mexico. These diversions, which provide 
irrigation for about 248,000 ha (620,000 ac) in Colorado and about 
24,400 ha (61,000 ac) in New Mexico, have a significant effect on flows 
(Cruz et al. 1993). In addition to these upstream diversions, about 
94,000 acre-feet of water are diverted annually from the San Juan River 
basin and transported via a tunnel into the Rio Grande basin. This 
diversion may benefit the species since it is used to supplement flows 
during periods of low flow.
    Growth of agriculture and cities along the Rio Grande during the 
last century may have adversely affected the quality of the river's 
water. During low-flow periods, a large percentage of the river's flow 
consists of municipal and agricultural discharge and less water is 
available to dilute pollutants. This degradation of water quality may 
affect H. amarus survival. Poor water quality in the Rio Grande near 
Albuquerque, especially during low flows, may be a problem, as low 
numbers of H. amarus and an overall reduced fish community are found 
there (Bestgen and Platania 1991).

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    It is not presently known if the species is being overutilized for 
commercial, recreational, scientific, or educational purposes. New 
Mexico Department of Game and Fish controls scientific taking of the 
species through a permit process. Licensed commercial bait dealers may 
sell bait minnows only within the drainage where they have been 
collected. They are also restricted from selling any State-listed fish 
species. However, it has been demonstrated on the Pecos River, New 
Mexico, that often the dealers and retailers cannot identify listed 
fish species. Utilization of the species for recreational purposes 
could occur should an individual unknowingly collect the species while 
gathering bait minnows for personal use.

C. Disease or Predation

    When fish are forced into confined habitats due to low flow, they 
are more susceptible to both disease and predation. Predation takes 
place when non-native species, including northern pike (Esox lucius), 
walleye (Stizostedion vitreum), white crappie (Pomoxis annularis), 
white bass (Morone chrysops), black and brown bullheads (Ameiurus 
melas, A. nebulosus), smallmouth bass (Micropterus dolomieui), and 
largemouth bass (Micropterus salmoides) are confined, during low flow 
or no flow, in limited habitat with H. amarus and other native species. 
These species have been introduced primarily by State and Federal fish 
and wildlife management agencies in efforts to develop sport fisheries 
in reservoirs created by the mainstream dams. The species have not 
remained confined to the reservoirs and have become established in the 
river both upstream from the impoundments and downstream of the dams 
where it is suspected they may compete with H. amarus for space and 
food in addition to preying upon them. Native predatory fish species, 
including the Rio Grande chub (Gila pandora) and bluegill (Lepomis 
macrochirus), may also prey upon subadult H. amarus under these 
circumstances. Avian and mammalian predation probably increases when H. 
amarus become confined in small clear-water pools.
    Confining fish to pools causes stress that can often result in 
outbreaks of parasitic disease. Most notable is parasitism by the 
protozoan Ichthyophthirius multifilis, which can be promoted by stress. 
External parasites, such as the copepod Lernaea, are more common among 
fish in confined conditions. No studies have been conducted on the 
impact of disease and parasites upon H. amarus; therefore, the 
significance of these threats for existing populations of the species 
is not known. However, stress-induced outbreaks may be exacerbated when 
high levels of pollutants or other stresses are present.

D. The Inadequacy of Existing Regulatory Mechanisms

    The State of New Mexico lists H. amarus as an endangered species, 
Group 2 (New Mexico Department of Game and Fish 1993), which includes 
those species ``. . . whose prospects of survival or recruitment within 
the State are likely to be in jeopardy within the foreseeable future.'' 
This listing provides the protection of the New Mexico Wildlife 
Conservation Act (Section 17-2-37 through 17-2-46 NMSA 1978) and 
prohibits taking of such species except under the issuance of a 
scientific collecting permit. The protection afforded to the species by 
the State does not provide protection to the habitat upon which the 
species depends.
    New Mexico water law does not include provisions for acquisition of 
instream water rights for protection of fish and wildlife and their 
habitats. This has been a major factor affecting the survival of 
species dependent upon the presence of instream flow. Agencies 
responsible for administering water rights have been unable to 
administer the rights in a manner that protects, maintains, and 
recovers the Rio Grande silvery minnow. Under the existing water rights 
administration, two native fish species in the Rio Grande have become 
extinct, and two others have been extirpated.
    State Game and Fish regulations in New Mexico allow the use of live 
minnows, including those brought into the State from other drainages, 
for sport fishing. This practice has encouraged the spread of these 
species, one of which, the plains minnow, has completely replaced and/
or hybridized with H. amarus in the Pecos River.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    In 1979, Cowley discovered the introduction of plains minnow (H. 
placitus) into the Pecos River drainage, New Mexico, from collections 
made as early as 1968, and also recognized the disappearance of native 
H. amarus. The last known collections of H. amarus from the Pecos River 
took place in 1968 near Roswell, New Mexico. These same collections 
verified the first specimens of H. placitus from the river. It is 
suspected, because of the widespread use of H. placitus as a commercial 
bait species, that its introduction into the Pecos River was the result 
of release of bait fish by anglers.
    The Service has carefully assessed the best scientific and 
commercial information available regarding the past, present, and 
future threats faced by this species in determining to make this rule 
final. Based on this evaluation, the preferred action is to list the 
Rio Grande silvery minnow (Hybognathus amarus) as endangered throughout 
its historic range. A decision to take no action would constitute 
failure to properly classify this species pursuant to the Endangered 
Species Act and would exclude it from protection of the Act. The 
Service believes threatened status is not the proper classification for 
the species because of the extremely limited habitat the species 
presently occupies and the threats it faces. Endangered status is 
appropriate because of the significantly reduced range and declining 
abundance of the species, and because of the remaining threats to this 
fish and its habitat. Without Federal protection, the Rio Grande 
silvery minnow can be expected to become extinct in the foreseeable 
future.

Critical Habitat

    Section 4(a)(3) of the Act requires, to the maximum extent prudent 
and determinable, that the Secretary designate critical habitat at the 
time a species is determined to be endangered or threatened. Section 
4(b)(6)(C) states that a concurrent critical habitat designation is not 
required, and that the final decision on designation may be postponed 
for 1 year from the date of publication of the final rule to list the 
species. Section 4(b)(6)(C)(ii) allows the Service to delay critical 
habitat designation if it is not then determinable. The Service's 
regulations (50 CFR 424.12(a)(2)) state that critical habitat is not 
determinable if information sufficient to perform required analyses of 
the impacts of the designation is lacking or if the biological needs of 
the species are not sufficiently well known to permit identification of 
an area as critical habitat. Section 4(b)(2) of the Act requires the 
Service to consider economic and other impacts of designating a 
particular area as critical habitat. The Service is in the process of 
evaluating the information obtained during the comment period on the 
economic impacts of designating critical habitat, and has started the 
process of having an economic analysis prepared on the proposed 
critical habitat designation. The complexities and extent of the 
activities that must be assessed preclude completion of the economic 
analysis within the 1-year deadline for listing the species. The 
completed draft economic analysis will be made available for public 
review and comment. The final decision on designation of critical 
habitat for the Rio Grande silvery minnow must be made by March 1, 
1995, pursuant to section 4(b)(6)(C)(ii) of the Act.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Endangered Species Act include recognition, 
recovery actions, requirements for Federal protection, and prohibitions 
against certain practices. Recognition through listing encourages and 
results in conservation actions by Federal, State, and private 
agencies, groups, and individuals. The Endangered Species Act provides 
for possible land acquisition and cooperation with the States and 
authorizes recovery plans for all listed species. The protection 
required of Federal agencies and the prohibitions against taking and 
harm are discussed, in part, below.
    Section 7(a) of the Act, as amended, requires Federal agencies to 
evaluate their actions with respect to any species that is proposed or 
listed as endangered or threatened and with respect to its critical 
habitat if any is proposed or designated. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part 402. Section 7(a)(2) requires Federal agencies to ensure that 
activities they authorize, fund, or carry out are not likely to 
jeopardize the continued existence of a listed species or to destroy or 
adversely modify its critical habitat. If a Federal action may affect a 
listed species or its critical habitat, the responsible Federal agency 
must enter into formal consultation with the Service.
    Federal actions that are expected to occur that may affect the 
survival of H. amarus include the operation and maintenance of dams and 
other structures that regulate the flow of water in the Rio Grande. 
Federal agencies that serve as water managers and decision-makers who 
determine timing and amount of flow in the river include the 
International Boundary and Water Commission, which ensures delivery of 
water to Mexico under international treaties; the Bureau of 
Reclamation, which has played an important role in water development in 
the middle Rio Grande and has been actively involved in the major water 
supply networks of the basin; and the Corps, which is responsible for 
controlling any dredging or filling within navigable waterways and 
associated wetlands under section 404 of the Clean Water Act. The Corps 
also has constructed and operates Abiquiu, Cochiti, Galisteo, and Jemez 
dams to control flood waters and sediment in the Rio Grande. The 
Environmental Protection Agency oversees water quality issues that may 
affect the river. In addition, actions on the northern pueblos that are 
funded, authorized, or carried out by the Bureau of Indian Affairs may 
affect the Rio Grande silvery minnow.
    The Act and implementing regulations found at 50 CFR 17.21 set 
forth a series of general prohibitions and exceptions that apply to all 
endangered wildlife. These prohibitions, in part, make it illegal for 
any person subject to the jurisdiction of the United States to take 
(includes harass, harm, pursue, hunt, shoot, wound, kill, trap, or 
collect, or to attempt any of these), import or export, ship in 
interstate commerce in the course of a commercial activity, or sell or 
offer for sale in interstate or foreign commerce any listed wildlife 
species. It also is illegal to possess, sell, deliver, carry, 
transport, or ship any such wildlife that has been taken illegally. 
Certain exceptions apply to agents of the Service and State 
conservation agencies.
    Permits may be issued to carry out otherwise prohibited activities 
involving endangered wildlife species under certain circumstances. 
Regulations governing permits are at 50 CFR 17.22 and 17.23. Such 
permits are available for scientific purposes, to enhance the 
propagation or survival of the species, and/or for incidental take in 
connection with otherwise lawful activities. In some instances, permits 
may be issued for a specified time to relieve undue economic hardship 
that would be suffered if such relief were not available. This species 
is not in trade, and such permit requests are not expected.

National Environmental Policy Act

    The Fish and Wildlife Service has determined that an Environmental 
Assessment, as defined under the authority of the National 
Environmental Policy Act of 1969, need not be prepared in connection 
with regulations adopted pursuant to Section 4(a) of the Endangered 
Species Act of 1973, as amended. A notice outlining the Service's 
reasons for this determination was published in the Federal Register on 
October 25, 1983 (48 FR 49244).

References Cited

    A complete list of all references cited herein, as well as 
others, is available upon request from the State Supervisor, New 
Mexico Ecological Services State Office (see ADDRESSES section).

    Author: The primary author of this final rule is Gerald L. 
Burton (see ADDRESSES section).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, and Transportation.

Regulation Promulgation

PART 17--[AMENDED]

    Accordingly, part 17, subchapter B of chapter I, title 50 of the 
Code of Federal Regulations, is amended as set forth below:
    1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Public Law 99-625, 100 Stat. 3500; unless otherwise 
noted.

    2. Amend Sec. 17.11(h) by adding the following, in alphabetical 
order under ``FISHES'', to the List of Endangered and Threatened 
Wildlife:


Sec. 17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                  Common name                                    Vertebrate population                                                  
         Species          --------------------------      Historic range          where endangered or      Status    When listed    Critical    Special 
                                Scientific name                                       threatened                                    habitat      rules  
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
                                                                      * * * * * * *                                                                     
          Fishes                                                                                                                                        
                                                                                                                                                        
                                                                      * * * * * * *                                                                     
Minnow, Rio Grande         Hybognathus amarus......  U.S.A. (NM, TX), Mexico.  Entire..................  E                   541           NA         NA
 silvery.                                                                                                                                               
                                                                                                                                                        
                                                                      * * * * * * *                                                                     
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dated: June 30, 1994.
Mollie H. Beattie
Director, Fish and Wildlife Service.
[FR Doc. 94-17576 Filed 7-19-94; 8:45 am]
BILLING CODE 4310-55-P