tion, entrainment mortality, thermal tolerance and offshore distribution. 

 Special winter flounder studies have been conducted because of their 

 local importance, and a more detailed evaluation on winter flounder 

 larval studies is presented in the Winter Flounder Evaluation. The 

 Millstone ichthyoplankton studies have been continously improved through 

 evaluation and modification. 



Woods Hole Oceanopgraphic Institution Entrainment Studies 



Woods Hole Oceanographic Institution (WHOI) conducted the first 

 ichthyoplankton entrainment studies at Millstone Unit 1 from April 1973 

 through June 1975. The numbers of fish eggs and larvae entrained were 

 estimated from 30 weekly, plankton samples (0.333-mm-mesh, 1-m diameter 

 net, single TSK flow meter). Once each week three day and three night 

 tows were taken at Unit 1 Intake (at 1, 3, 5 m depths), Discharge, and 

 Quarry Cut (Figure 1) . 



Entrainment larval mortality was estimated for Unit 1 by capturing 

 larvae at the Intake, Discharge and Quarry Cut (Carpenter 1975). After 

 a 24 hour holding period at Intake water temperatures, the average 

 mortality was 20% in the Intake group (control) , 70% in the Discharge 

 group, and 41% in the Quarry Cut group. Some mortality was likely 

 induced by net capture. Based on these data, entrainment larval mortality 

 ranged from about 20 to 50%. 



Laboratory thermal tolerance studies were conducted on larvae of 

 the silverside ( Menidia menidia ), mummichog ( Fundulus sp . ) , and winter 

 flounder ( Pseudopleuronectes am eric anus ) (Carpenter 1975) . These studies 

 were designed to assess thermal effects of power plant entrainment. 

 Larvae were subjected to a 13 C temperature increase for time periods 



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