Wilk et al : GSI annual cycles as indicators of finfish spawning in the New York Bight 



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Table 1 



Observations relative to peak spawning activity for 14 finfish species, including mean and range of bottom temperature and depth 

 for the month, or months, of highest gonad-somatic indices (GSI) at stations where ripe females occurred during a trawl survey of 

 the New York Bight, June 1974-June 1975. Alewife and winter flounder data include only estuarine observations; bimodal spawners 

 are indicated with an asterisk (*) with observations given for both peaks; in some cases months were combined when sample sizes 

 were small. 



Species 



Alewife 

 Offshore hake 

 Silver hake 

 Red hake 

 Spotted hake* 

 Spotted hake* 

 Black sea bass 

 Butte rfish 

 Northern searobin 

 Striped searobin 

 Summer flounder 

 Fourspot flounder 

 Windowpane* 

 Windowpane* 

 Yellowtail flounder 

 Winter flounder 



Month 



Apr 75 

 May/Jun 75 

 Aug 74 

 Jun 75 

 Sep 74 

 Mar/Apr 75 

 Jul 74 



Jun 74 & 75 

 Jul 74 



Jun 74 & 75 

 Oct 74 

 Jun 75 

 Sep 74 

 May 75 

 Mar 75 

 Jan 75 



No. of Occurrence/total no. 



fish of stations 



18 



17 



5 



68 



42 



10 



16 



189 



21 



12 



51 



32 



150 



159 



45 



5 



Bottom temperature 

 (°C) 



Mean 



Range 



7/14 



4/156 



4/58 



23/72 



7/56 



4/109 



3/59 



45/130 



8/59 



8/130 



22/60 



15/72 



23/56 



44/84 



15/46 



3/9 



5.4 



10.2 



9.8 



8.0 



14.8 



10.5 



14.9 



11.8 



15.1 



10.9 



13.7 



7.3 



15.7 



7.9 



5.7 



5.7 



4.5-6.0 



9.0-11.4 



8.4-13.4 



5.7-12.5 



11.0-17.3 



7.4-12.3 



13.8-15.9 



5.4-20.4 



13.8-16.5 



8.4-14.1 



10.5-14.7 



5.6-11.2 



10.3-19.4 



5.6-13.2 



4.4-7.5 



4.8-6.5 



Depth 

 (m) 



Mean 



6 

 270 

 80 

 60 

 30 

 113 

 19 

 40 

 20 

 16 

 35 

 57 

 26 

 23 

 36 

 5 



Range 



5-11 

 222-348 

 54-127 

 12-264 

 12-86 

 75-139 

 16-22 



3-145 

 15-27 



9-21 

 11-97 

 17-127 

 10-65 



4-51 



9-68 



3-7 



total catch of ripe female alewife and winter flounder, 

 5 and 21%, respectively, were collected in the estuarine 

 study area. This was expected since these species are 

 known to inhabit the lower reaches of estuaries before 

 moving upriver to spawn. Ripe female butterfish and 

 windowpane were also collected in the estuarine study 

 area, but made up < 5% of the catch of all ripe females 

 of those species. Eggs and larvae of these four species 

 are known to occur in both Raritan Bay (Croker 1965) 

 and the New York Bight (Clark et al."l969: Smith et 

 al. 1975, 1980). Silver hake, red hake, and summer 

 flounder were also caught in the estuarine study area 

 during some months; however, no ovarian development 

 beyond the resting stage was observed. All data were 

 pooled since there were no clear differences in time of 

 spawning between bay and ocean samples of any 

 species captured during the study. Detailed results and 

 discussion for each species are given in the following 

 sections. 



Alewife Alosa pseudoharengus 



Mean GSI was highest in April, with ripe females, 

 145-345 mm, collected throughout the survey area 

 from February through May (Fig. 2). These observa- 

 tions are similar to published spawning times for ale- 

 wife in Connecticut inshore waters (Kissil 1969) and 

 the Delaware River (Smith 1971). Farther north in 



Canadian waters the species spawns primarily in May 

 (Leim and Scott 1966). 



Alewives are common in coastal waters from New- 

 foundland, Canada to North Carolina as they migrate 

 to and from their riverine spawning grounds (Hilde- 

 brand and Schroeder 1928, Bigelow and Schroeder 

 1953, Leim and Scott 1966). The average temperature 

 in the estuarine survey area during the April spawn- 

 ing peak was 5.4°C (Table 1). 



Offshore hake Merluccius albidus 



Mean GSI was highest during July 1974 and again in 

 June 1975, with ripe females, 230-575 mm, collected 

 in ocean waters during most months sampled (Fig. 3). 

 The highest percentages of ripe ovaries were observed 

 in spring and summer. In a review of historic ichthyo- 

 plankton surveys, Colton et al. (1979) stated that off- 

 shore hake larvae were present in the Middle Atlantic 

 from June through September. Smith et al. (1980) col- 

 lected eggs and larvae south of New England from 

 April through June during 1977-79 ichthyoplankton 

 surveys. They also collected eggs in late February- 

 early March 1979 from stations south of Long Island, 

 New York. Marak (1967) found eggs and larvae off 

 Martha's Vineyard, Massachusetts, in April through 

 July. Offshore hake, based on this as well as the afore- 

 mentioned studies, has either a long or irregular spawn- 



