Table 20. Results of larval winter flounder entralnment mortality study 



Stage 2 larvae collected, 8 were alive following capture but none 

 survived the 2 to 4-h effluent holding period. Stage 3 larvae had 

 greater survival than Stage 2 following capture and the effluent holding 

 period, but all survivors died during the first 24 h of the 96-h latent 

 holding period. All 24 Stage 4 larvae were alive following capture, 

 with 19 (79%) surviving effluent and 96-h latent holding periods. No 

 Stage 5 larvae were collected but their survival most likely would have 

 been at least as great as that of Stage 4. It appeared that a large 

 portion of Stage 4 and 5 larvae could survive entrainment and passage 

 through the Millstone quarry. Approximately 15% of all winter flounder 

 larvae entrained during 1983 were in these later stages of development. 

 Pearcy (1962) found the winter flounder mortality rates decreased with 

 increasing larval development. Therefore, the later stages would have 

 had a greater probability of being recruited to the adult stock than 

 earlier stages. Survival of larger winter flounder larvae passing 

 through the MNPS cooling-water system would have reduced the effects of 

 entrainment as estimated in previous assessments (Sissenwine et al. 

 1975; Saila 1976) which assumed 100% mortality for entrained larvae. 



Harmonic regression models 



The fluctuations in the catch of winter flounder in several 

 monitoring programs from October 1976 through September 1982 were 

 analyzed using time-based harmonic regressions (Table 21) . All models 

 contained terms describing a 12-month cycle, although both longer 

 (72-mo) and shorter (4-, 6-mo) period harmonic terms were also 

 significant in some models. The best models of the log-transformed 

 impingement counts included a 12-mo cycle and MNPS cooling-water flow as 



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