In 1984, there was a marked decrease in the abundance of larval anchovy, cunner and tautog but this 

 decrease was also observed in other parts of LIS. The reasons for this decline were not known but 

 during this time ctenophores, a plankton predator, were abnormally abundant. 



Impacts from the construction and operation of MNPS were assessed using representative collections 

 of fish assemblages during the operation of Units 1 and 2. Except for larval sand lance, there was no 

 indication that catches of the most abundant fish taxa were consistantly below historic levels and for 

 sand lance, the observed fluctuation occurred along the entire Atlantic coast. Thus the operation of two 

 nuclear power plants at MNPS has not adversely affected fish abundance, distribution or species 

 composition in the Millstone area of LIS. 



WINTER FLOUNDER STUDIES 



The life history and population dynamics of the winter flounder (Pseudopleuronectes americanus) 

 have been studied intensively since 197.1, 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. 



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

 abundance index based on the stochastic model of Jolly for open populations showed that numbers 

 were relatively stable from 1976 through 1980, increased to a peak in 1982, and subsequently declined 

 to an 11-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 

 .lolly estimates. The influence of potential biases on both estimators were examined. A third measure 

 of abundance was provided from trawl monitoring program data using time-based harmonic regression 

 models. However, models from most stations 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 on the winter flounder. Throughout southern New 



