in the Niantic River early in the season and many 

 left the estuary in March. Surveys during earlier 

 years started after February and missed many of 

 these large winter flounder, resulting in lower av- 

 erages. The mean length of all females 20 cm 

 and larger in 1980 was only 29.7 cm, in comparison 

 to .31.4 to 32.1 cm for 1979 and 1981-85, respec- 



tively. This was additional evidence that fewer 

 large females were sampled during the 1980 survey. 

 In contrast, the means of 33.4 cm in 1986 and 

 32.8 cm in 1987 were particularly large, indicating 

 that along with decreasing abundance, the female 

 population included more larger and older speci- 

 mens than in previous years. 



TABLE 10. Annual indices of female spawners and egg production for Niantic River winter flounder from 1977 

 through 1987. 



From Jolly index of abundance and percentage of mature females, assuming that all 

 females 26 cm and larger were mature. 



For winter flounder larger than 15 cm during 1976-82 and 20 cm thereafter. 



A relative index for year-to-year comparisons and not an absolute estimate of production. 



Relative egg production indices were deter- 

 mined using .lolly abundance indices with the 

 length, maturity, and fecundity data. Since the 

 indices reflect both annual average fecundity and 

 abundance, the value for 1980 was probably un- 

 derestimated. The egg production index peaked 

 in 1982 and declined about 80% since then as 

 the increase in average fecundity was not large 

 enough to olfset declines in abundance of adult 

 females. However, adult abundance and absolute 

 egg production alone were not necessarily the 

 most important factors determining year-class 

 strength (i.e., production of young in a particular 

 year). This is discussed further in the following 

 section. 



Stock and recruitment 



Although not overly long in comparison to 

 data sets typically used in stock assessment studies, 

 the 12 years of abundance estimates for the 

 Niantic River winter flounder allowed for the in- 

 vestigation of a relationship between adult stock 

 SL7,e and the number of offspring they produced. 

 This relationship, termed stock and recruitment, 

 has been described in various forms (e.g., Ricker 

 19.54; Beverton and Holt 1957; Gushing 1973; 

 Shepherd 1982). The parameter estimates of a 

 stock and recruitment model may be used in other 

 fisheries models (e.g., to predict future yields) or, 

 more specifically for MNPS studies, in the 

 stochastic population dynamics impact assessment 



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