and more realistic estimate of potential losses to the winter flounder population caused by the operation 

 of MNPS. 



CONCLUSIONS 



The Niantic River population of the winter flounder has been studied since 1976 because of its 

 importance to the sport and commercial fisheries of Connecticut and the potential for impact by MNPS 

 operations, especially from entrainment of larvae. Studies of adult winter flounder spawning in the river 

 have provided a time-series of data for impact assessment, including adult stock size, reproduction, move- 

 ments, exploitation, and rates of growth and mortality. Similarly, estimates of impingement and entraiimient 

 during the same time period were available to measure impact. Since 1983, increased emphasis was placed 

 on understanding critical early life history stages of winter flounder in the Niantic River. To date, there 

 is no evidence that MNPS has significantly affected the winter flounder population. Periodic cycles in 

 abundance are typical for this species throughout its range. Although numbers of adults have declined in 

 recent years, the decrease apparently has been due to natural causes or perhaps from an increase in 

 commercial fishing in Southern New England. 



Events during the larval stage within the Niantic River are most important in determining the success 

 of a year-class and their understanding is still incomplete. The factors which govern the production and 

 mortality of larvae must be known before assessing the impact of power plant operations. Quantifying 

 larval mortality and partitioning it into density-dependent and -independent components will allow the 

 assessment of entrainment effects. Simileirly, knowledge of the post-larval juvenile stage is also important. 

 The mortality of these fish is intermediate between that of larvae and adults and may play an important 

 part in establishing the success of a year-class. Impingement of juveniles and adults at MNPS has become 

 less of a concern as the installation of fish return sluiceways at Units 1 and 3 has reduced this impact. 

 Recent decreases in impingement were most likely a result of the general decline in abundance, rather than 

 its cause. 



MNPS Unit 3 began commercial operations in late April of 1986, immediately following the adult 

 winter flounder spawning season. Therefore, the data gathered up to that time will serve as the baseline 

 for assessing the full impact of 3-unit operations of MNPS. Future work will focus on larval, juvenile. 



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