and adult population parameters. The development of a stochastic population dynamics model for impact 

 assessment will continue to be an important goal for NUEL. 



SUMMARY 



1. The life history and population dynamics of the winter flounder has been studied intensively since 

 1973, due to its importance to the sport and commercial fisheries of Connecticut and potential for 

 impact. Because winter flounder stocks are localized, most work has concentrated on the population 

 spawning in the Niantic River to determine if MNPS impacts of impingement and entrainment have 

 caused or would cause changes in abundance beyond those expected from natural variation. 



2. Annual estimates of the Niantic River spawning population have been made since 1976. An abundance 

 index based on the Jolly (1965) model showed that numbers were relatively stable from 1976 through 

 1980, increased to a peak in 1982, and subsequently declined to an ll-yr low in 1986. Abundance 

 determined by trawl CPUE generally paralleled the Jolly index through 1982. The decline in CPUE 

 was greater through 1985 and less in 1986 than for the corresponding Jolly estimates. 



3. Evaluation of both abundance estimators indicated that bias due to failures to meet assumptions and 

 errors due to low sampling intensity may have affected the Jolly estimates. CPUE values may have 

 been influenced by changes in sampling methodologies, varying distribution of winter flounder, and 

 variable annual conditions in the Niantic River. 



4. Data from the trawl monitoring program were used with time-based harmonic regression models. 

 However, most models were unsatisfactory due to insufficient data or a lack of a repetitive pattern of 

 abundance. High variability in catch, relatively low effort, and the mixture of stocks found at most 

 stations at certain times of the year make these trawl data difficult to interpret and of limited use in 

 assessing MNPS impact. 



5. Tlirougliout Southern New England, winter flounder abundance has recently declined because of 

 natural fluctuations and also most likely from increases in commercial fishing. 



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