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



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Yellowtall Flounder 



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J J A S O N D 

 1974 



Figure 14 



Annual cycle of gonad-somatic indices for yellowtall {\ounder Li man- 

 da feniiffiyiea collected in the New York Bight, June 1974-June 1975, 

 including monthly means, ranges, 95% confidence intervals, and 

 number examined. In addition, percent ripe females per month is 

 given on the upper axis. 



Figure 1 5 



Annual cycle of gonad-somatic indices for winter flounder Pseudo- 

 pleuroiiectes americanus collected in the New York Bight, June 

 1974-June 1975, including monthly means, ranges, 95% confidence 

 intervals, and number examined. In addition, percent ripe females 

 per month is given on the upper axis. 



Yellowtail flounder commonly occur from Nova Sco- 

 tia, Canada to Delaware Bay (Bigelow and Schroeder 

 1953, Leim and Scott 1966). Smith et al. (1975) con- 

 sidered the population center to be on Georges Bank, 

 with migration along the southern New England shelf 

 eastward in spring and westward in fall (Lux 1963). 

 In the New York Bight, few were caught in summer. 

 In March of this survey, the period of greatest gonad 

 development, they were collected on the inner shelf at 

 9-68 m and 4.4-7.5°C (Table 1). 



Winter flounder 

 Pseudopleuronectes americanus 



Highest mean GSI occurred during January in the 

 estuarine sui'vey area and during Febiiiary in the ocean 

 survey area (Fig. 15). Ripe females, 169-432 mm, were 

 collected from September through April wdth 21% oc- 

 curring in Raritan Bay. GSI declined rapidly after 

 February; however, spawners were likely upriver 

 beyond the range of this survey. Smith et al. (1975) cap- 

 tured larvae at inshore stations between the offing of 

 Delaware Bay and Block Island Sound, Rhode Island 

 from April through June, with spawning beginning in 

 the south and progressing northward. Perlmutter 

 (1947) reported spawning from December through May 

 and concluded that the peak time varied with temper- 

 ature. Pearcy (1962) found evidence of spawning from 

 mid-February through April in the Mystic River estu- 

 ary, Connecticut. Croker (1965) found winter flounder 



larvae in plankton collections in Sandy Hook Bay, New 

 Jersey from April to June. 



Although the water temperature at actual spawning 

 sites is unknown, the average bottom temperature in 

 Raritan Bay during January, the month of highest 

 mean GSI, was 5.7°C. Of all the species encountered 

 during this survey, winter flounder were collected in 

 the coldest water. 



Discussion 



According to Braum (1978), most temperate zone fishes 

 spawn in one of three generic seasonal patterns: spring, 

 summer, or fall-winter. Based on the current study, 

 alewife and yellowtail flounder are spring spawners; 

 silver and red hake, black sea bass, butterfish, northern 

 and striped searobin, and fourspot flounder are sum- 

 mer to fall spawners, while spotted hake and summer 

 and winter flounder are fall-winter through early 

 spring spawners. Offshore hake and windowpane 

 belong to none of these groups, but appear to have pro- 

 tracted spawning seasons, i.e., these species' GSI were 

 elevated, ovaries were ripe, and eggs and larvae were 

 collected from spring through fall. Offshore hake in- 

 habit the deeper waters of the Bight which are less in- 

 fluenced by changes in light and temperature. In con- 

 trast, windowpane inhabit the shallow, more seasonally 

 influenced, inshore environs. 



In temperate seas, there are distinct annual cycles 

 of light intensity, temperature, nutrients, and winds 



