FISHERY BULLETIN: VOL. 82, NO. 3 



from pair and otter trawl fisheries in Delaware 

 Bay (n = 285). 



At each NMFS station, weakfish catches were 



FIGURE 1. — Sampling locations for weakfish, Cynoscion regalis, 

 in the New York Bight and North Carolina site of Merriner 

 (1976). 



stratified into 10 cm size intervals and 10-15 fish 

 sampled per interval. Total length to the nearest 

 centimeter, sex, and maturity stage were recorded. 

 Weakfish from Gardiners Bay were randomly 

 sampled, total length measured to the nearest mil- 

 limeter, sex, and maturity stage recorded, and 

 gonads removed and weighed to the nearest 0.1 g. 

 Sandy Hook and Delaware Bay samples were col- 

 lected by random selection of 50-lb (22.5 kg) boxes 

 in each market category available from the catch, 

 and total length to the nearest millimeter and 

 weight (whole and gutted) to the nearest gram 

 recorded. Gonads and livers were also removed 

 and weighed to the nearest 0.1 g. Gonads were 

 preserved in modified Gilson's solution (Bagenal 

 and Braum 1971) for several weeks, then removed, 

 washed with distilled water and stored in 95% 

 isopropyl alcohol. 



Maturity and Fecundity Methods 



The maturity stage of each sample was catego- 

 rized as immature, developing, ripe (spawning), 

 spent, or recovering as modified from Nikolsky 

 (1963). The maturity stages were further sub- 

 divided as mature or immature for calculation of 

 length at 50% maturity using probit analysis 

 (Finney 1971). 



Seasonality of reproduction was determined 

 from changes in the gonad condition. A gonosoma- 

 tic index (GSI) was calculated to show changes in 

 gonad weight relative to somatic weight (gutted 

 body weight). The index was computed as 



GSI = (gonad weight/somatic weight) x 100. 



To examine physiological changes associated 

 with spawning, liver condition was assessed using 

 a hepatosomatic index (HSI) computed by sub- 

 stituting liver weight for gonad weight in the 

 above relationship (Htun-Han 1978). The differ- 

 ences in monthly mean HSI between sexes were 

 analyzed statistically using a Wilcoxon test (Patz- 

 ner and Adam 1981). 



The number of spawnings in the season were 

 investigated by analyzing the seasonal frequency 

 distribution of oocyte diameters (Hickling and 

 Rutenberg 1936). In each of 15 samples collected 

 between 5 May and 22 July 1980-81 in Delaware 

 and Gardiners Bays, three subsamples were taken 

 per ovary and about 500 oocyte diameters were 

 randomly measured using an ocular micrometer. 



Fecundity estimates were determined from 28 

 fish macroscopically classified as developing, 



502 



