The dependence of commercial fishing success on strong yearclasses of striped bass is demonstrated, using four years of catch records from a small group of cooperating gill-net fishermen. Age analysis of these Rappahannock River catches during 1969 and 1970 revealed that an approximate tripling of landings in 1970 was a result of selection for the dominant 1966 year-class.https://scholarworks.wm.edu/vimsbooks/1108/thumbnail.jp

Burrell, Victor G., Jr.

Grant, George C.

Kriete, William H.

English

College of William & Mary: W&M Publish

W&M ScholarWorks VIMS Books and Book Chapters Virginia Institute of Marine Science 1971 Age Composition and Magnitude of Striped Bass Winter Gill-net Catches in the Rappahannock River, 1967-1970 George C. Grant Virginia Institute of Marine Science Victor G. Burrell Jr. Virginia Institute of Marine Science William H. Kriete Virginia Institute of Marine Science Follow this and additional works at: https://scholarworks.wm.edu/vimsbooks  Part of the Aquaculture and Fisheries Commons Recommended Citation Grant, George C.; Burrell, Victor G. Jr.; and Kriete, William H., "Age Composition and Magnitude of Striped Bass Winter Gill-net Catches in the Rappahannock River, 1967-1970" (1971). VIMS Books and Book Chapters. 109. https://scholarworks.wm.edu/vimsbooks/109 This Book Chapter is brought to you for free and open access by the Virginia Institute of Marine Science at W&M ScholarWorks. It has been accepted for inclusion in VIMS Books and Book Chapters by an authorized administrator of W&M ScholarWorks. For more information, please contact scholarworks@wm.edu. PROCEEDINGSOF THETWENTY-FOURTH ANNUAL CONFERENCESOUTHEASTERN ASSOCIATIONOF GAME AND FISH COMMISSIONERSSeptember 27-30, 1970ATLANTA, GEORGIAOFFICERSBILLY JOE CROSS, PresidentMississippi Game and Fish CommissionGEORGE T. BAGBY, Vice-PresidentGeorgia Game and Fish CommissionJAMES W. WEBB, Secretary-TreasurerSouth Carolina Wildlife Resources DepartmentMEMBER STATESAlabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Maryland,Mississippi, Missouri, North Carolina, Oklahoma, South Carolina,Tennessee, Texas, Virginia, West VirginiaEdited by JAMES W. WEBBPrinted at Columbia, S. C.1971AGE COMPOSITION AND MAGNITUDE OFSTRIPED BASS WINTER GILL-NET CATCHES INTHE RAPPAHANNOCK RIVER, 1967-1970 1 2byGeorge C. Grant, Victor G. Burrell, Jr., and William H. Kriete, Jr.Virginia Institute of Marine ScienceGloucester Point. Virginia 23062ABSTRACTThe dependence of commercial fishing success on strong yearclasses ofstriped bass is demonstrated, using four years of catch records from a smallgroup of cooperating gill-net fishermen. Age analysis of these RappahannockRiver catches during 1969 and 1970 revealed that an approximate tripling oflandings in 1970 was a result of selection for the dominant 1966 year-class.INTRODUCTIONThe occasional appearance of unusually successful, or "dominant", year-classes of certain fish species has been well-documented by fishery biologists.One such species is the striped bass, Marone saxatilis (Walbaum), an anad-romous species of considerable commercial and recreational importance alongthe Atlantic coast. In recent history, the best known strong year-classes ofstriped bass were those of 1934 and 1958, both of which resulted in waves ofheavy landings proceeding northward along the coast from Chesapeake Bay(Merriman, 1941; Raney, 1952; Shearer, Ritchie, and Frisbie, 1962; Schaefer,1968).The impact ofdominant year-classes is clearly reflected in increased commer-ciaI landings. Koo (1970) has shown an apparent six-year cycle of abundancefor the Chesapeake-spawned population from analysis of the 1930-1966 catchrecords. Heavy landings were attributed to the periodic appearances of dom-inant year-classes. A longer-term increase in abundance is also evident, withlandings increasing nine-fold from 1934 to 1966.The direct effect of strong year-classes of striped bass on the fortunes of in-dividual fishermen or segments of the fishery is less well-known than is theireffect on total landings. Vladykov and Wallace (1952) provided a detailedanalysis of the catches of two pound-netters from 1930 to 1937. Compared with1935 catches, landings tripled and quadrupled in 1936 and 1937, respectively.These increases were attributed to the dominant 1934 year-class. Similarly, adoubling of pound net catches in Maryland from 1941 to 1942 was caused by thedominant 1940 year-class (Tiller, 1950). Murphy (1960) found that haul seinecatches doubled in the summer of 1959, coincident with a slight reduction ineffort, and consisted largely of 1956 and 1957 year-classes. Continuance of thatstudy for an additional year or two would have been interesting in view of theknown abundance of the 1958 year-class.This paper will examine the effect of a strong year-class of striped bass on thelandings recorded by four gill-net fishermen on the Rappahannock River, Vir-ginia. Their cooperation in providing confidential records and allowing sam-pling of their catches is gratefully acknowledged.IVirginia Institute of Marine Science Contrihution No. 399.ZThis research was funded in part with Anadromous Fish Act (P. L. 89-304) funds. administered by the Bureau ofSport Fisheries and Wildlife.659METHODS AND MATERIALSCatch Data and Fishery DescriptionData for landings utilized in this paper were obtained from log-books main-tained by four stake gill-netters from March 1967 to April 1970. Daily entries, inpounds by species, were made by each fisherman.Catch data have not been converted to a per-unit-effort base, because totaleffort within this segment of the fishery has remained essentially constant overthe period being considered. The location of nets have also remained the same,extending along seven nautical miles of the Rappahannock River where theaverage river width is 1.6 nautical miles.This fishery employs, for the most part, two different classes of gill-nets: I) a"perch" net (3 W'-3\;2" stretch mesh) used early in the season, December- Feb-ruary, primarily for white perch, Morone americanus, but catching significantnumbers of striped bass, and 2) so-called "shad nets" (4"-5" mesh) that are sub-stituted beginning in late February or early March, in anticipation of the springrun of American shad, Alosa sapidissima. The constant location of nets elim-inates most of the bias indicated by Craig (1930) who found that catches of shadwere inversely correlated with catches of striped bass, because California fisher-men changed their location and habits of fishing when shad were abundant.Catch SamplingCatches from this gill-net fishery were sampled semi-monthly while netswere in operation during the winters of 1969 and 1970. Samples of approx-imately 50 striped bass were measured. Age was determined from scales re-moved from the region above the lateral line and below the gap between thetwo dorsal fins (Merriman, 1941).RESULTSLandings. 1967-1970Striped bass landings for the selected Rappahannock River fishery are sum-marized in Table I. Differences between catches of individual fishermen withinmonths are largely due to the number of nets fished, so that relative success frommonth to month is quite consistent. Records were not obtained before March1967, therefore data for winter 1967 are incomplete. Because ice frequently pre-vents fishing during January and February, the best months for consistentfishing and for comparison of striped bass abundance are March and April.Total landings for these two months in the years of record were as follows:1967-14,434 Ibs., 1968-29,432 Ibs., 1969-17,508 Ibs., and 1970-66,543 Ibs. Re-duced catches in March and April 1969 followed large landings early in theseason. Total catches in winter 1970 were approximately triple those of theprevious two fishing seasons.Age and Size Composition, 1969-1970Sampling of this fishery was initiated in January 1969. Figure I shows themagnitude of catches during the two seasons of sampling and the age compo-sition of the catch within semi-monthly sampling periods. The 1966 year-classcontributed over 80% of the total number of striped bass during the period ofmaximum landings (March 1970), as it did throughout the last half of the pre-ceding fishing season.Younger year-classes (primarily the 1967 year-class) contributed most tocatches during the first half of the 1970 season, when small-mesh "perch nets"were in use. Replacement of these nets with "shad nets" coincided with theheavy catches of 1966 year-class striped bass. The final sample, conversely, con-tained a large percentage of fish from the year-classes 1965 and older (oldest1957), resulting from an experimental employment of two large-mesh gill-nets(8" and 9" stretch mesh).660Size selection by the various nets employed is evident from the change in meanlength of striped bass caught through the season (Table 2). In 1969, the meanlength increased from about 350 mm to nearly 430 mm when shad nets (4"-5")were substituted for perch nets (3 W'-3W'), and in 1970 from 390 mm to 476mm. A similarjump in mean length of the 1966 year-class component of catchesoccurred in 1969. These lengths increased from about 360 mm to 420 mm.Shad nets caught faster-growing members of the 1966 year-class than didsmaller-mesh nets, as is evidenced by the mean back-ealculated lengths at Age I.This effect, however, was not as evident in the 1970 season after a further year'sgrowth by the 1966 year-class. "Perch nets" simply caught fewer of these nowlarger striped bass.Estimated Contribution by Weight of the 1966 Year-class to Total LandingsSince landings are reported only in pounds and our age and size data are innumbers of individuals, some conversion from numbers to weight is necessarybefore attributing change in total landings to abundance of any particular year-class. Table 3 lists the mean lengths of striped bass within year-classes through-out the sampling period and their calculated mean weights. The length-weightrelationship of male striped bass published by Mansueti (1961) for Maryland-caught fish has been used for these fish of unknown sex, since his equation forfemales and striped bass of unknown sex somewhat overestimates weights ofstriped bass (unknown sex) in Virginia waters. Length-weight relationshipsfor Virginia populations have not yet been published.During the winter 1969 season, including only those semi-monthly periods inwhich samples were taken, the 1966 year-class accounted for an estimated22,446 pounds, or over 70% of the total landings of 31 ,326 pounds reported dur-ing those periods. Landings of the 1966 year-class more than doubled in thefollowing season. An estimated 49,834 pounds, or nearly 60% of a total 85,351pounds, was landed in the periods sampled.DISCUSSIONStrong year-classes of striped bass increase the catch of selective-gear fisher-ies, as they have been shown to do for landings as a whole (Koo, 1970) and fornon-selective gear, such as pound nets (Tiller, 1950; Vladykov and Wallace,1952) and haul seines (M urphy, 1960). The 1966 year-class contributed over 80%by numbers and by weight to peak catches in March 1970 by four gill-net fisher-men in the Rappahannock River. Contribution of the 1966 year-class to land-ings in winter 1970, when landing were nearly triple those of the previousyear, was nearly 60% by weight.Gill-net fishermen are in the best position to maximize catches of such dom-inant year-classes, providing they have knowledge of year-class abundance,average length at different ages, expected growth from one year to the next, andthe relation between gill-net mesh size and mean length of striped bass caught.Trent and Hassler (1968) have shown a linear relationship between gill-netmesh size and length of male striped bass. Mean lengths expected to be caughtin the nets commonly employed in the Rappahannock fishery are as follows:3\4"-338 mm, 4"-403 mm, 5"-490 mm. Comparison of these expected lengthswith mean lengths of our samples in Table 2 shows close agreement. Further-more, it is apparent that peak catches occurred when the 1966 year-class ap-proached a mean length close to that expected to be optimally caught in 5"-meshnets. A further year's growth will reduce catches of 1966 year-class striped bassif 5" gill-nets are again employed in 1971. Assuming a significant return of the1966 year-class in the winter of 1971 and growth to a mean fork length ofapproximately 550 mm, catches would be maximized by use of gill-nets with5%" stretch mesh.661TABLE ILOG-BOOK RECORDS OF LANDINGS BY MONTHS FORINDIVIDUAL GILL-NET FISHERMEN, RAPPAHANNOCKRIVER, 1967-1970. STRIPED BASS CATCHES IN POUNDS.Month Fishermanand Year A B C D TotalsMar 1967 2,340 2,391 2,691 1,925 9,275Apr 1,383 1,234 1,549 993 5,15914,434*Jan 1968 1,294 1,625 2,919Feb 935 935Mar 2,316 6,776 7,291 7,518 23,901Apr 780 1,378 1,656 1,717 5,53133,286Jan 1969 2,442 2,458 5,263 2,952 13,115Feb 654 522 647 1,823Mar 771 3,286 3,010 4,943 12,010Apr 1,179 739 1,621 1,959 5,49832,446Dec 1969 2,287 1,997 4,284Jan 1970 530 1,003 2,003 1,478 5,014Feb 5,927 8,307 6,237 20,471Mar 5,344 11,009 12,475 15,853 44,681Apr 1,713 5,887 6,960 7,302 21,86296,312*incomplcte - no records for carly winter months.66228 A - TOTAL LANDINGS20~ 24z::>oa..u..o 16enoz<[en::>o:I:~1284SESA01967 + 1968 YEAR CLASSFJ- ml966 YEAR CLASS·ALL OLDER YEAR CLASI [ • I I I [ IMAD J F M1------ 1969 ------- 1970--:I: 100 B AGE COMPOSITION(,)~ 80(,)~ 60w~ 40z~ 20a::wa.. 0FIGURE I. Total landings (A) and age composition (B) of striped bass inthe sampled gill-net fishery, Rappahannock River, Virginia,during the winters of 1969 and 1970.663TABLE 2MEAN FORK LENGTHS (IN MILLIMETERS) OF ENTIRESAMPLES AND THEIR 1966 YEAR-CLASS COMPONENT, WITHBACK-CALCULATED LENGTHS AT AGE I FOR THE 1966YEAR-CLASSSample Entire Sample 1966 Year ClassDate At capture At Age IN x (t.05)S. E. N x 1. 05(S. E.) - t.05(S. E.)x3 Jan 69 50 339.8 ± 8.8 30 355.9 ± 10.0 118.7 ± 8.717 Jan 69 50 322.9 :!: 8.9 23 340.9 :!: 12.8 106.2 :!:. 9.6II Feb 69 50 373.6 ± 14.2 37 381.8 ± 11.4 130.4 .± 12.121 Feb 69 49 356.0 ± 11.0 41 357.7 ± 8.0 118.3 ± 7.96 Mar 69 49 429.6 :!: 11.8 42 420.4 :!: 10.3 151.9 ± 9.119 Mar 69 49 421.2 ± 12.0 44 412.6 ± 10.2 148.9 ± 9.62Apr 69 50 429.1 :!: 15.4 42 416.9 :!: 11.3 136.8 :!: 8.98 Dec 69 50 358.7 ± 14.4 7 434.0 ± 40.2 110.3 :!: 28.017 Dec 69 50 390.3 :!: 19.2 12 487.0 :!: 15.2 130.0 :!: 14.716 Feb 70 50 390.0 ± 13.9 13 442.3 ± 22.3 122.2 ± 14.04 Mar 70 50 476.6 :!: 15.8 41 477.7 ± 10.1 135.1 ± 8.116 Mar 70 50 463.3 :!: 11.0 41 470.5 ± 11.6 123.0 :!:. 7.610 Apr 70 50 544.4 :!: 48.2 24 484.5 :!: 13.1 134.9 ± 11.9664TABLE3CONVERSIONOFAGEFREQUENCYANDMEANLENGTHSTOWEIGHTWITHINSEMI-MONTHLYPERIODSOFSAMPLI"IGEstimatedTotalPercentContributionSampleYearMeanL.Calc.MeanSampleWI.TotalinPoundstoPeriodClassNmmm.WI.inPounds'inPoundsSampleWI.TotalLndgs.(1969)Jan1-15196630355.91.25237.5668.823841196720315.60.85117.0231.181740Total50------54.58100.005581.Jan16-311965I375.01.4921.493.25245196623340.91.08925.0554.664118196726305.00.74219.2942.093171Total50------45.83100.007534Feb.1-1519653482.73.34910.0513.1943196637381.81.57058.0976.222480-,196710310.70.8078.0710.59340-, '""Total50------76.21100.00325Feb16-2819652457.52.8185.649.02135196641357.71.27052.0783.26124719676310.50.8054.837.72116Total49------62.54100.001498Mar1-1519642482.53.3496.705.8833319655485.63.41917.1015.00849196642420.42.14890.2279.134476Total49------114.02100.015658Mar16-311964I505.03.8813.883.6223019654495.03.63814.5513.57862196644412.62.01888.7982.815261Total49------107.22100.006353Apr1-1519621588.06.3506.355.3823519644511.84.05416.2213.7560219652476.03.2066.415.43238196642416.92.08987.7474.36325519671358.01.2761.281.0847Total50------118.00100.004377TABLE3(Continued)EstimatedTotalPercentContributionSampleYearMeanL.Calc.MeanSampleWI.TotalinPoundstoPeriodClassNinmm.WI.inPounds'inPoundsSampleWI.TotalLndgs.(1969)Dec1-1519667434.02.38216.6724.74507196715387.71.65124.7636.74753196828324.40.92725.9638.52790Total50------67.39100.002050Dec.16-31196612487.03.45141.4145.051007196720387.81.65533.1036.01804196818328.70.96817.4218.95423Total50------91.93100.012234(1970)Feb16-281965I443.02.5402.542.92514196613442.32.52932.8837.756643196726384.41.60641.7647.948436196810331.30.9939.9311.402006Total50-----87.11100.0117,5990\Mar1-151964I765.014.8914.898.9015570\0\196641477.73.242132.9279.4513,90319677446.32.60618.2410.9019081968I355.01.2441.240.74130Total50----167.2999.9917,498Mar16-31196641470.53.089126.6585.9223,35619679430.12.30620.7514.083827Total50----147.40100.0027,183Apr1-151957I947.029.6429.648.56160819582940.028.9657.9216.7231411960I912.026.2926.297.591426196.13885.723.8771.6120.6738821963I840.020.1320.135.81109219642659.09.18118.365.3099619652541.04.8519.702.80526196624484.53.39581.4823.524418196713429.12.29029.778.5916131968I380.01.5481.550.4585Total50-----346.45100.0118,787·usingI-v.relationshiphyMansucti(J96J).Sectext.LITERATURE CITEDCraig, J. A. 1930. An analysis of the catch statistics of the striped bass (Roccuslineatus) fishery of California. Calif Div. Fish & Game. Fish Bulletin No.24,43 pp.Koo, T. S. Y. 1970. The striped bass fishery in the Atlantic states. ChesapeakeSci. 11:73-93.Mansueti, R. J. 1961. Age, growth, and movements of the striped bass, Roccussaxatilis, taken in size selective fishing gear in Maryland. Chesapeake Sci.2:9-36.Merriman, D. 1941. Studies on the striped bass (Roccus saxatilis) of the Atlan-tic coast. U. S. Fish & Wilel/. Serv., Fish. Bull. 50 (35) :1-77.Murphy, G. J. 1960. Availability of striped bass during summers of 1958 and1959 as reflected in commercial haul seine catch. Chesapeake Sci. 1:74-75.Raney, E. C. 1952. The life history of the striped bass, Roce'us saxatilis(Walbaum). Bull. Bingham Oceanogr. Coil. 14(1):5-97.Scheafer, R. H. 1968. Size, age composition and migration of striped bass fromthe surf waters of Long Island. N. Y. Fish and Game Jour. 15: 1-5 I.Shearer, L. W., D. E. Ritchie, Jr., and C. M. Frisbie. 1962. Sport fishing surveyin 1960 of the lower Patuxent estuary and the 1958 year class of stripedbass. Chesapeake Sci. 3:1-17.Tiller, R. E. 1950. A five-year study of the striped bass fishery of Maryland,based on analyses of the scales. Chesapeake BioI. Lab., Publ. No. 85, 30pp.Trent, L. and W. W. Hassler, 1968. Gill net selection, migration, size and agecomposition, sex ratio, harvest efficiency, and management of striped bassin the Roanoke River, North Carolina. Chesapeake Sci. 9:217-232.Vladykov, V. D. and D. H. Wallace. 1952. Studies of the striped bass, Roccussaxatilis (Walbaum), with special reference to the Chesapeake Bay regionduring 1936-1938. Bull. Bingham Oceangr. Call. 14:132-177.667

Age Composition and Magnitude of Striped Bass Winter Gill-net Catches in the Rappahannock River, 1967-1970

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Age Composition and Magnitude of Striped Bass Winter Gill-net Catches in the Rappahannock River, 1967-1970

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