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AN INVESTIGATION OF SIZE, AGE, AND SEX OF NORTH CAROLINA STRIPED BASS by Sara E. Winslow and Robert C. Harriss, Jr. North Carolina Department of Natural Resources and Community Development Division of Marine Fisheries Morehead City, NC 28557 Completion Report, Project AFC-25 March 1986 Research presented in this report was funded, in part, by the U.S. Department of Commerce, NOAA, National Marine Fisheries Service as part of the Emergency Striped Bass Study under the Anadromous Fish Conservation Act (PL 89-304, Section 7, as amended). QL638 .P358158 1985 CONTENTS Page ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INTRODUCTION . . . . . . . 0 . *. . . . . . . . 0 . . . . . . . . . . . STUDY AREA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 METHODS . . . . . . . . . . . . . . . . ... 0 . . . . . . . . . . . . 3 RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . 6 ALBEMARLE SOUND POPULATION . . . . . . . . . . . . . . . . . . . . . . 6 YEAR CLASS COMPOSITION OF THE COMMERCIAL HARVEST . . . . . . . . . . . 11 ROANOKE RIVER SPAWNING POPULATION . . . . . . . . . . . . . . . . . . 11 CONCLUSIONS . . ... . . . . . . . . . . . . . . . . . . . . . . . 17 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . 21 C,0 C'm gg D@V=tmmt of Comerce MGM Coastal Services Center Library 2234 South Hobson Avenue Chw1eston, SC 29405-2413 LQ (& ABSTRACT During October 1984-December 1985, a total of 813 striped bass were examined in order to determine the size, age and sex composition of fish taken in two major fisheries for striped bass in North Carolina. No striped bass samples were obtained from the ocean during,1985. This fishery was closed in response to interstate management actions along the Atlantic Coast. Those fish taken in Roanoke River during their Spring spawning run comprised the sexually mature segment of the Albemarle Sound stock and, possibly, a few of the Atlantic Ocean migratory stock native to Roanoke River. Spawning males were mostly ages 11 and III, while females were principally two to five years old. The Albemarle Sound fishery harvested from a declining population, composed mostly of fish one to three years of age. INTRODUCTION Striped bass, (Morone saxatilis) have supported significant fisheries in coastal North Carolina since Colonial times. The northern portion of the coast has historically had the most active commercial and recreational fisheries, supporting year-round fisheries in Albemarle Sound and seasonal fisheries elsewhere. Those commercial gears described by Street and Johnson (1977) continue to be the principal types of fishing gear. The Albemarle Sound-Roanoke River area supports one of the Atlantic Coast's principal spawning populations of striped bass. The oceanic area from Chesapeake Bay entrance to Ocracoke Inlet has been shown to be the principal wintering area for migratory striped bass (Holland and Yelverton 1973). Considerable work has been done on various aspects of striped bass life history throughout the coastal area of North Carolina since the late 1960s. However, only two studies (Trent and Hassler 1968; Harriss et al. 1985) have correlated age and growth with sex. Because of differential growth and age at maturity between sexes, size and age data must be collected by sex in order to be useful in estimating mortality rates, yield-per-recruit, and other population parameters. In the past decade striped bass populations have declined along the entire Atlantic Coast (Atlantic States Marine Fisheries Commission 1981). Striped bass landings in North Carolina have declined, with the recent catches being the lowest since the 1930s (Table 1). Despite the decline in landings, the pressures on this resource have increased because of its high market value. The recent year classes of striped bass produced in Albemarle Sound area are the poorest on record (Hassler et al. 1981, Hassler and Taylor 1984, Hassler 1984). The Albemarle-Roanoke stock is below its historic limits and may be in biological danger. This population is probably contributing very little at present to the migratory population, because of the relatively low stock level. The information obtained in this study is critical for the development and implementation of coordinated management actions for striped bass, both in North Carolina and along the Atlantic Coast. Due to closure of the Atlantic Ocean to the harvest of striped bass by the North Carolina Marine Fisheries Commission (MFC) in response to interstate management needs along the Atlantic Coast, no striped bass samples were obtained from the offshore fishery during the winter of 1984-85. Al 2 Table 1. North Carolina striped bass landings (pounds) 1975-1985.* Albemarle Roanoke Atlantic Other Year Sound area River Ocean areas Total 1975 565,538 69,962 585,000 82,700 1,303,200 1976 651,454 25,046 332,400 29,400 1,038,300 1977 432,880 36,620 90,700 11,200 571,400 1978 468,214 56,886 164,600 8,400 698,100 1979 292,807 34,293 240,100 47,100 614,300 1980 368,499 8,001 21,800 74,200 472,500 1981 333,132 1,468 52,000 30,400 417,000 1982 210,588 17,369 92,873 17,480 338,310 1983 279,911 8,861 52,796 19,707 361,275 1984 473-,937 1,703 14,501 22,755 512,896 1985 267,103 6,200 18-3 4,908 278,394 Data are from the following sources: Roanoke River (1975-81): Hassler, et al. 1981; (1982-84) Hassler and Taylor 1984; (1985) Hassler, pers. comm. All others are from the North Carolina/NMFS cooperative statistics program. Data for 1978-1985 are preliminary and subject to revision. 3 STUDY AREA The study areas have been previously described by Street et al. (1975). Project activities were conducted in northeastern North Carolina from the Weldon area on Roanoke River to the Outer Banks (Figure 1). METHODS Under this project, a target figure of 900 striped bass was to be sampled annually to obtain size and age data from the Albemarle Sound fishery. Approximately 25 fish were to be sampled monthly at each of three commercial- fish houses (Figure 2). By regulation of the North Carolina Marine Fisheries Commission (MFC), it was unlawful to take, sell or offer for sale striped bass between 1 June-30 September 1985. Also, with the recent striped bass size limit increase (from 12 to 14 in TL) and season adopted by the MFC, it became unlawful to take striped bass by commercial gear, except during the open season (15 November-31 March). These regulations became effective I August 1985. Due to these regulations, no striped bass samples were obtained during June-October 19-85. The sizes of fish sampled was in approximate proportion to.the sizes of fish present in the fish house. Individual fish were measured (mm, fork length (FL) and weighed (nearest .01 kg), and scales were taken for age determination. Sex was determined for each fish sampled by the Sykes (1958) method. Scales were read and annuli measured as described by Harriss et al. (1985). Age and year class were assigned according to conventions developed by the Atlantic States Marine Fisheries Commission's Striped Bass Scientific and Statistical Committee. In North Carolina, the time of annulus formation is considered to be January. Age and year class are then assigned in consideration of the date of capture relative to the January birthdate. Thus, fish from a given year class could be assigned two different ages depending on date of capture. Each striped bass from the Albemarle Sound commercial harvest, for which age, sex, and weight data were available was placed in the appropriate year class for each month sampled during October 1984-December 1985. The number of individuals of each year class was followed monthly through the sampling 4 urrituck Chowan r Beach el don Roano River COASTAL NORTH CAROLIN lbemarle Sound 34 Willi st 4z) Tar r 0 Pamlico Sound Ne iver co ive Hatteras Inlet Cape Hatteras Ocracoke 34 ?V\Inlet Northeast ape Fear River White River 0 New er Cape Lookout Cape River SCAU .34 40 once 34 3-0 % Cape Fear Figure 1. Map of eastern North Carolina showing project study area. 0100TH CAROLINA SHOWING LOCATION OF ALONNAPILI SOUND PA OTANK 0 C. RIV a Ivan N"TH is. Ivan AT LITTLE Wan PaPaUWAHI COLINA N RIVEN CHO A" TROPIN "Ivan of a ALBEMARLE SOUND Ai"It RIVEN *cup RHO" RIVER PLYMOUTH ALLIOATOR ROA110 A 1.01 RIVEN W LIAM$? Sample Locations Figure 2.' Commercial sampling locations for striped bass, Albemarle Sound area, 6 period. Striped bass were separated by sex, and monthly mean weight (kg) by year class were calculated. The total striped bass harvest (kg) for each month was multiplied by the percent weight (kg) of a year class during that month and divided by the mean weight (kg) of individuals of each sex of that year class, resulting in the number of individuals from each year class. Throughout the Roanoke River area, project personnel obtained size, age, and sex data from striped bass sampled from the commercial and recreational fisheries (a target of 300 fish annually). Procedures were the same as for Albemarle Sound samples. When necessary, fish were purchased and records maintained. This work was conducted during April and May, 1985. RESULTS AND DISCUSSION ALBEMARLE SOUND POPULATION A total of 670 striped bass were sampled from up to three fish dealers monthly in the Albemarle Sound area during October 1984-December 1985. During the legal harvest periods for striped bass, samples of up to .30 fish were taken monthly from each location. As described in the Methods, the MFC @modified its regulations on the minimum size and striped bass commercial fishing season. Of the 670 striped bass sampled, 370 were males and 300 females. All fish were aged to derive the year class composition of the sample. The sex ratio for the total sample was 1.23:1, male to female. This ratio was similar to those reported by Harriss et al. (1985). Table 2 summarizes the age and size data for striped bass, by sex, from Albemarle Sound during October 1984-December 1985. The 1982, 1983, and 1984 year classes (ages I-III) contributed 96.1% (sexes combined) of the total sample, with the 1983 year class (age 11) accounting ior 63.3%. Only 3.9% of the fish sampled were four years old or greater. Table 3 shows the percentage contribution of each year class from sampling during 1972-1985. During July 1980-July 1984, lower percentages of one to three year old fish (70-90%) and significantly higher percentages of age IV fish or older (11-31%) were reported from the commercial harvest (Table 3) (Harris et al. 1985). The present age data and that reported by Harriss et al. (1985) (sexes combined) differ significantly from that reported by Street et al. (1975) and Johnson et al. (1977) for 1972-1976 (Table 3). The number of year classes making Table 2. Striped bass number, percent, mean length, mean weight and standard deviation at age, (by sex) from the Albemarle Sound, N,C. commercial catch, October 1984-December 1985. Percent Percent of sexes Fork length (mm) -Weight (kg) Year Number total by sex combined Mean SD Mean SO class Age F M F M F M F M F M F 1984 1 32 29 8.6 9.7 9.1 362 370 22.9 37.2 .71 0.77 0.194 0.269 1983 If 254 170 68.7 56.7 63.3 357 354 33.9 32.6 .65 0.62 0.254 0.220 1982 111 80 79 21.6 26.3 23.7 434 453 47.1 43.9 1.16 1.26 0.396 0.402 1981 IV 2 10 0.5 3.3 1.8 437 514 51.6 62.9 1.26 1.87 0.509 0.751 1980 V 0 6 - 2.0 1.0 588 - 53.3 - 3.05 - 0.861 1979 VI 1 3 0.3 1.0 0.6 675 624 47.1 5.00 3.87 0.808 1978 Vil 1 2 0.3 0.7 0.4 640 658 124.0 3.81 4.67 2.70 1977 Vill 0 1 - 0.3 0.1 - 768 - - 4.54 - Total 370 300 670 Table 3. Percentage contribution of each year class of striped bass (sexes combined) from sampling the Albemarle Sound, N.C. area commercial harvest 1972-1985. FISHING YEAR Year class 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1961 0.2 0.2 1962 0.1 0.2 1963 0.2 0.2 0.3 1964 0.7 0.4 1.6 0.3 1965 1.8 0.6 1.0 - 0.3 1966 2.8 2.4 1.0 0.6 0.1 0.7 1967 11.5 4.1 - 1.7 0.1 1.0 1968 22.5 7.7 0.3 2.9 1.5 2.0 1969 28.2 19.9 7.8 5.2 1.9 3.0 1970 32.0 40.5 25.0 25.2 9.4 3.5 1971 23.8 48.4 25.5 23.7 4.0 1972 14.6 21.2 16.0 4.5 1.3 0.7 1973 17.4 43.2 10.0 8.3 5.0 0.6 0.3 0.3 0.3 1974 4.1 50.0 25.1 13.4 2.7 0.3 - 0.3 - 1975 21.0 36.2 15.1 3.8 2.3 0.3 1.1 0.6 1976 29.1 37.1 5.9 4.0 1.8 2.3 - ?977 28.7 7.4 3.7 4.9 3.1 1.5 0.1 1978 31.4 9.4 9.5 5.6 1.8 0.4 1979 48.2 45.1 34.9 16.4 11.8 0.6 1980 35.2 48.3 36.1 15.0 1.0 1981 32.8 3.8 1.8 1982 65.2 23.7 1983 63.3 1984 9.1 00 9 significant contributions to the annual harvest has changed from four or five during the 1972-1979 period to two or three in recent years. It is evident from examining the data in Table 3 that fewer and fewer striped bass are in or remain in the population long enough to reach sexual maturity. This situation results from poor reproduction, probably due to degraded water quality. Very heavy fishing pressure applied to one to three year old fish has probably also contributed to stock reduction, especially in recent years of environmental stress. Male striped bass ranged in age from one to seven years old during this project. The 1982-84 year classes (age 1-111) accounted for 98.9% of the sample. During this sampling period, only 1.1% of the males sampled were four years old or more (Table 2). This is significantly lower than that found by Harriss et al. (1985) for 1980-1984 (8.1-13.4%). Since virtually all male striped bass in the Albemarle Sound area are sexually mature by age III (Trent and Hassler 1968), the majority of these fish probably.contributed only once to the spawning population. During this project, female striped bass were found to range in age from one to eight years old. The 1980-1984 year classes (ages I-V) comprised 98% of the females sampled. As with the males, 1983 year class (age I1)_ females accounted for the majority of the sample (56.7%) (Table 2).. The percentage of one to five year old females was higher than that reported by Harriss et al. (1985). Trent and Hassler (1968) reported that almost all female striped bass were sexually mature by age five. The 1984-1985 data show a decrease of five year old females, compared to that found by Harriss et al.(1985). The length-frequency distributions for mi1e and female striped bass are presented in Figure 3. During this project, male striped bass ranged in length from 295 mm to 615 mm FL, and in weight from 0.33 kg to 5.0 kg. Females ranged in length from 304 mm to 768 mm FL, and in weight from 0.32 kg to 6.58 kg. The length-frequency distribution for males is somewhat similar to that reported by Harriss et al. (1985) for 1980-1984. That is, male striped bass dominated the 300-350, 351-400 mm size groups, while females dominated the larger size groups. The frequency of larger fish, both male and female, continued to decline from that shown by Harriss et al. (1985). 10 160 140 A-,.A A- Male 370 I Female 300 120 - 100- ce 80 60 40 20 0 r 200 300 400 500 600 700 800 900 FORK LENGTH (mm) Figure 3. Length-frequency distributions for striped bass in 50 mm size groups, captured by commercial fishermen in Albemarle Sound, N.C., October-1984-December 1985. YEAR CLASS COMPOSITION OF THE COMMERCIAL HARVEST The Albemarle Sound striped bass age data for October 1984-December 1985 were used to estimate the number of individuals in the commercial harvest from each year class by month. The estimated contribution of each year class to the striped bass harvest from the Albemarle Sound area fishery by sex and month are shown in Table 4. These data show that the 1983 and 1982 year classes (ages 11 and III) dominated the striped bass harvest, contributing 88.1% of the total. The 1981 and older year classes contributed very little to the commercial harvest (Table 5). The percentages found from the estimation of individuals by year-class to the commercial harvest are very similar to those found by year class from aging data. This method should be continued in the future so that better comparisons may be made. ROANOKE RIVER SPAWNING POPULATION During April-May 1985, a total of 143 striped bass were examined for determination of sex, size and age composition of the Roanoke River spawning population. All fish were-aged. All of the fish sampled came from commercial pound nets set in the mouth of Roanoke and Cashie rivers, below the N.C. Highway 45 bridge. (North Carolina State University personnel did not conduct tagging studies as in previous years, resulting in no samples from the upper river). Of these fish, 79 were males and 64 were females for a sex ratio of 1.23:1 (males to females). This ratio generally agrees with that for 1982 and 1983, when males outnumbered females. However, these ratios continue to disagree sharply with previous work on striped bass in Roanoke River. Trent and Hassler (1968) found that males comprised from 69.7% to 85.1% of the samples during 1963-1965. Table 6 presents data from the 1985 spawning run. The 1981-1983 year classes (ages II-IV) accounted for all of the male samples. Pound net data from previous years, 1981-1984, (Table 7) show that some males (5.4-12.0%), except for 1981, have exceeded four years of age each year. All of the pound net data in 1981 were obtained in mid-March, probably biasing the data because young male striped bass enter the river early in the season. During the other years the samples were spread out over the spawning season. 12 Table 4. Esimated contribution of each year class to the striped bass harvest from the Albemarle Sound N.C. commercial fishery by sex, by month, October 1984- December 1985. Year Male Female Tot and Year Num5-e -r-o-r Number o:F number of month class Percent individuals Percent individuals individuals 1984 Tc-tober 1983 64.7 40,366 51.8 30,871 71,237 1982 35.3 21,931 48.2 28,299 50,230 November 1983 72.7 60,352 57.1 39,767 100,119 1982 27.3 22,697 42.9 29,666 52,363 December 1983 71.4 18,834 68.0 19,734 38,568 1982 25.7 6,820 38.0 8,155 14,975 1981 0 0 4.0 1,164 1,164 1978 2.9 756 0 0 756 1985 January 1983 72.7 26,758 63.2 19,181 45,939 1982 27.3 9,902 31.6 9,639 19,541 1981 0 0 5.2 1,603 1,603 .February 1983 82.2 13,675 75.6 10,791 24,466 1982 17.8 2,927 24.4 3,495 6,422 March 1983 80.9 15,968 72.7 12,363 28,331 1982 19.1 3,721 20.4 3,469 7,190 1981 0 0 4.6 771 771 1980 0 0 2.3 388 388 April 1983 83.3 15,306 38.9 3,255 18,561 1982 11.1 2,029 25.0 2,074 4,103 1981 3.7 680 5.6 461 1,141 1980 0 0 13.9 1,154 1,154 1979 1.9 340 8.3 689 1,029 1978 0 0 5.6 460 460 1977 0 0 2.7 227 227 May 1983 70.4 8,697 64.5 7,310 16,007 1982 29.6 3,651 22.6 2,555 6,206 1981 0 0 12.9 1,467 1,467 June - October 1985 Fishery closed, no samples taken November 1984 66.7 8,137 83.3 10,790 18,927 1983 8.3 1,020 11.1 1,440 2,460 1982 25.0 3,055 5.6 719 3,774 13 Table 4. (continued) Year Male Female TotaT- and Year Number of Number oT number of month class Percent individuals Percent individuals individuals December 1984 61.5 19,447 70.0 23,506 42.953 1983 33.3 10,554 25.0 8.373 18,927 1982 5.1 1,614 5.0 1,678 3,292 TOTAL -31-9-@M 285,517 MF,7-51 14 Table 5. Estimated contribution of each year class to the striped bass harvest from the.Albemarle Sound N.C. commercial fishery, by sex, October 1984-December 1985. Year Number of Number of Total Percent class males females number of total 1984 27,584 34,296 61,880 10.23 1983 211,530 153,085 364,615 60.29 1982 78,347 89,749 168,096 27.80 1981 680 5,466 6,146 1.02 1980 0 1,542 1,542 0.25 1979 340 689 1,029 0.17 1978 756 460 1,216 0.20 1977 0 227 227 0.04 TOTAL 319,227 285,514 604,751 Tabl e 6. Number, percent, mean length, mean weight, and standard deviation at age, by so;, for striped bass sampled from the Roanoke River spawning run during April and May 1985. Percent Percent of sexes Fork length (mm) Weight (kq) Year Number total by sex combined Mean SD Mean SD class Age M F M F M F M F M F M F 1983 fI 58 18 73.4 28.1 53.1 368 368 16.1 0.106 0.62 0.59 0.092 23.8 1982 111 20 27 25.3 42.2 32.9 442 462 0.267 0.219 1.06 1.24 29.3 20.8 1981 IV 1 4 1.3 6.3 3.5 450 525 - 0.598 1.04 1.82 - 59.6 1980 V 0 12 - 18.6 8.4 - 603 0.610 - 2.91 35.9 1979 VI 0 0 - - - - - - 1978 VII 0 3 4.8 2.1 724 1.67 4.80 64.8 TOTAL 79 143 64 Table 7. Striped bass number, percent, and age (by sex) sampled from the pound nets in lower Roanoke River during the spawning run 1981-1985. 1981 1982 1983 1984 1985 Percent Percent Percent Percent Percent Percent Percent Percent Percent Percent Age of total sexes of total sexes of total sexes of total sexes of total sexes -Number by sex . combined Number by sex combined Number by sex combined Number by sex combined Number by sex combined M F M F M F M F M F M F M F M F M F M F I - 3.4 - 1.4 - - - - - - - - - - - - - - - - - - - - 11 26 2 89.8 4.8 39.5 73 11 40.1 12.9 31.5 7 1 6.4 1.2 4.8 40 7 71.4 19.0 50.5 58 18 73.4 28.1 53.1 III I - 3.4 - 1.4 59 2 32.4 2.3 22.8 45 3 54.2 3.5 28.6 3 1 5.3 2.7 4.3 20 27 25.3 42.2 32.9 IV 1 10 3.4 23.8 15.5 38 10 20.9 11.8 17.9 21 16 25.3 18.8 22.0' 10 6 17.9 16.2 17.2 1 4 1.3 6.3 3.5 V - 11 - 26.2 15.5 9 20 5.0 23.5 10.9 8 27 9.7 31.8 20.8 3 11 5.4 29.7 15.0 0 12 - 18.6 8.4 VI - 9 - 21.4 12.7 2 29 1.1 34.1 11.6 1 17 1.2 20.0 10.7 - 6 - 16.2 6.5 0 0 - - - V11 - 2 4.8 2.8 1 7 0.5 8.2 3.0 1 13 1.2 15.3 8.3 - 2 - 5.4 2.2 0 3 - 4.8 2.1 Vill - 3 - 7.1 4.2 - 5 - 5.9 1.9 - 5 - 5.9 3.0 - 3 - 8.1 3.2 - - - - - ix - 3 - 7.1 4.2 - I - 1.2 0.4 - - - - - - I - 2.7 1.1 X - 2 - 4.8 2.8 - - 2 - 2.3 1.2 - - - - - X1 - - - - - - - I - 1.2 0.6 - - - - - Total 29 42 182 85 83 85 56 37 79 64 71 267 168 99 143 ON 17 Female striped bass sampled from the pound nets ranged from two to seven years old. The 1980-1983 year classes (ages II-V), comprised 95.2% of the females sampled (Table 6). The percentage of two to five year olds in 1985 is significantly higher than that for 1981-1984 (50.6-67.6%) (Table 7). Only 4.8% of the females in 1985 were more than five years old, much lower than in previous years (32-49%, Table 7). Trent and Hassler (1968) found males exceeding four years of age and a much higher proportion of females older than five years. The 1981-1984 Roanoke River spawning run data, as reported by Harriss et al. (1985) for the entire river, are shown in Table 8. This information agrees with that found for the Albemarle Sound commercial fishery (Table 3); there is a continuing decline of older fish in the striped bass population. In 1985, male striped bass ranged in length from 318 mm to 501 mm (FL), and in weight from 0.38 kg to 1.76 kg. The mean length was 387 mm FL, and the mean weight was-0.74 kg. Female striped bass ranged in length from 327 mm to 797 mm FL, and the weight range was 0.42 kg to 6.71 kg. Mean length for females was 478 mm FL, and mean weight was 1.57 kg. The mean lengths and weight for males and females in 1984 was considerably higher (Harris et al. 1985). The length-frequency distributions for male and female striped bass, in 50 mm size groups, are presented in Figure 4 for the Roanoke River spawning run in 1985. Male striped bass showed a peak at the 400-450 mm size interval , while female fish showed a peak at the 450-500 mm size interval. The male length frequency distribution peaks during 1981 and 1984 were similar to that found in 1985, while the female peaks during 1981-1984 were at a larger size interval (Harriss et al. 1985). CONCLUSIONS The Albemarle Sound striped bass population has shown a continued decline since the 1970s. It is probable that deteriorating water quality, poor year class production, and heavy fishing pressure applied on immature fish have taken their toll on the population. The current Phase II striped bass stocking program may help sustain a population during these low levels of abundance, but probably cannot be used to restore the population to Table B. Striped bass number, percent, and age, (by sex) sampled from the Roanoke River during the spawning run 1981-1984. 1981 1982 1983 1984 Percent Percent Percent Per6ent Percent Percent Percent Percent Age of total sexes of total sexes of total sexes of total sexes Number by sex combined Number by sex combined Number by sex, combined Number by sex combined M F M M F M F M F M F M F M F 1 1 0 0.9 0.4 - - - - - - - - - - - - - 11 72 3 63.2 2.0 28.7 106 15 37.2 12.7 30.0 10 1 5.4 0.6 3.2 53 6 53.6 4.0 23.8 111 31 0 27.2 - 12.0 100 4 35.1 3.4 25.8 100 4 53.8 2.6 30.4 11 2 11.1 1.3 5.2 IV 9 37 7.8 25.2 17.6 60 16 21.0 13.6 18.9 59 45 31.7 28.8 30.4 24 45 24.2 30.2 27.9 V 0 45 - 30.6 17.2 15 33 5.3 28.0 11.9 12 52 6.4 33.3 18.7 9 64 9.1 43.1 29.4 VI 1 32 0.9 21.8 12.6 3 37 1.1 31.3 10.0 4 29 2.2 18.7 9.6 1 14 1.0 9.4 6.1 Vil 0 11 - 7.5 4.2 1 7 0.3 6.0 2.0 1 17 0.5 11.0 5.3 1 9 1.0 6.0 4.0 Vill 0 9 - 6.1 3.4 0 5 - 4.2 1.2 0 5 - 3.2 1.5 0 6 - 4.0 2.4 IX 0 7 - 4.8 2.8 0 1 - 0.8 0.2 0 1 - 0.6 0.3 0 2 - 1.3 0.8 X 0 3 - 2.0 1.1 - - - - - 0 1 - 0.6 0.3 0 1 - 0.7 0.4 X - - - - - - - - 0 1 - 0.6 0.3 - - - - - Total, 114 147 285 118 186 156 99 149 761 342 74U CO IT 110 100 90 - -Ar- - Male (N=79) 80 - Female (N=64) 70 - 60 - cc LU 50 - 40 - 30 - 20 - 10 - 0 300 400 500 600 700 800 900 1000 Fork Length (mm) Figure 4. Length-frequency distributions for male and female striped bass in 50 mm size groups, captured in Roanoke River, N.C. during the 1985 spring spawning run. 20 self-sustaining levels, especially when heavy fishing pressure continues on these fish prior to sexual maturity. The recent regulations adopted by the MFC, an increase in the minimum size limit and a shorter commercial fishing season, will probably allow more fish to reach sexual maturity and contribute to the spawning population, at least once. If the striped bass population continues to decline even further, stricter regulations may be inevitable. 21 LITERATURE CITED Atlantic States Marine Fisheries Commission (ASMFC). 1981. Interstate fisheries management plan for the striped bass. Fish. Mgmt. Rep. No. 1, ASMFC, Washington, D.C. Harriss, Robert C., Jr., Beth L. Burns, Harrel B. Johnson, and Roger Rulifson. 1985. An investigation of size, age, and sex of North Carolina striped bass., Compl. Rep., Proj. AFC-18, N.C. Dept. Nat. Res. & Community Develop., Div. Mar. Fish., 136 p. Hassler, W. W. 1984. The status and abundance of striped bass, Morone saxatilis, in the Roanoke River and Albemarle Sound, North Carolina-113777-1-9917- ".. Dept. Nat. Res. & Community Develop., Div. Mar. Fish., Compl. Rep., Proi. AFS-14, 40 p. Hassler, William W., Norman L. Hill, and James T. Brown. 1981. The status and abundance of striped bass, Morone saxatilis, in the Roanoke River and Albemarle Sound, North Carolina, 1956-7980. N.C. Dept. Nat. Res. & Community Develop., Div. Mar. Fish., Spec. Sci. Rep. No. 38, 156 p. Hassler, W. W. and S. D. Taylor. 1984. The status, abundance, and exploitation of striped bass in the Roanoke River and Albemarle Sound, North Carolina, 1982, 1983. Compl. Rep., Proj. AFC-19, N.C. Dept. Nat. Res. & Community Develop.., Div. Mar. .Fish., 67 p. + App. Holland, B. F. Jr., and George F. Yelverton. 1973. Distribution and biological studies of anadromous fishes offshore North Carolina. N.C. Dept. Nat. & Econ. Res., Div. Comm. and Sports Fish. Spec. Sci. Rep. No. 24., 132 p. Johnson, Harrel B. and William W. Hassler. 1980. Cooperative management for Albemarle Sound-Roanoke River striped bass. Progress Rep., Project AFS-14-3., N.C. Dept. Nat. Res. & Community Develop., Div. Mar. Fish., 21 p. Johnson, H. B., B. F. Holland, Jr., and S. G. Keefe. 1977. Anadromous fisheries research program, northern coastal area. Completion.rep., Project AFCS-11, N.C. Dept. Nat. and Econ. Res., Div. Mar. Fish. 97 + 40 p. Johnson, Harrel B., Henry W. Stevens, and William W. Hassler. 1979. Cooperative management program for Albemarle Sound-Roanoke River striped bass. N.C. Dept. Nat. Res. & Community Develop., Div. Mar. Fish., Ann. Rep., Proj. AFS-14-2, 63 p. Keefe, S. G. and W. W. Hassler. 1981. Cooperative management program for Albemarle Sound-Roanoke River striped bass. N.C. Dept. Nat. Res. and Community Develop., Div. Mar. Fish., Ann. Rep., Proj. AFS 14-4, 28 p. 22 Street, M. W. , P. P. Pate, Jr. , B. F. Hol I and, Jr. , and A. B. Powel 1 . 1974. Anadromous fisheries research program, northern coastal region. Completion rep., Project AFCS-8. N.C. Dept. Nat. and Econ. Res., Div. Mar. Fish., 193 + 62 p. + App. Street, M. W. and H. B. Johnson. 1977. Striped bass in North Carolina. Unpub. rep., N.C. Dept. Nat. Res. and Community Develop., Div. Mar. Fish., 12 p. Sykes, J. F. 1958. A method of determining the sex of the striped bass (Roccus saxatilis) (Walbaum). Trans. Am. Fish., Soc. 87:104-107. Trent, Lee and William W. Hassler. 1968. Gill net selection, migration, size and age composition, sex ratio, harvest efficiency, and management of striped bass in the Roanoke River, North Carolina. Chesapeake Sci. 9(4):217-232. I ,@- A i @ iiiiimiiiiliiiiiiiio 1 3 6668 00003 8267