to the Millstone area (Table 31). Larval to egg 

 ratios were also low indicating poor egg survival. 

 The egg abundance index at SNPS in 1986 was 

 the lowest compared to other years, but the esti- 

 mated annual abundance fluctuated much more 

 than at Millstone. I^arval abundance did not 

 decline at SNPS in recent years as it has here, 

 but similar to Millstone, some of the lowest 

 catches by trawl at SNPS occurred in 1985 and 

 1986. 



TABLE 31. Annual abundance indices of cunner eggs 

 and larvae, both expressed as an annual sum of means, 

 and trawl catch as annual CPUE at Shoreham Nuclear 

 Power Station. 



Sums for 1977-82 based on mean density per sam- 

 pling trip (Geomet Tech. 1983) and for 1983-86 based 

 on monthly mean density (EA Eng., Sci., and Tech. 

 1987). 



Abundance not reported (Geomet Tech. 1983) appar- 

 ently due to low densities. 



In summary, the abundance of all life history 

 stages of cunner at stations close to MNPS has 

 recently declined. The decrease in impingement 

 can, in part, he attributed to an overall decline in 

 impingement at Unit 2 since the start-up of Unit 

 3, but also may be related to an apparent decrease 

 in the cunner population near MNPS. Some of 

 the decline of juveniles and adults was likely the 

 result of several changes in physical habitat near 

 IN trawl station. Concurrent with the decrease 

 in trawl catch was a reduction in mean length. 

 If changes in juvenile and adult abundance were 

 related to entrainment losses, then juvenile re- 

 cruitment would decrease arid cause the mean 



length to increase. The cause of the change in 

 the cunner population is not known, and moni- 

 toring of its abundance will continue to determine 

 if the decrease was a result of natural long-term 

 fluctuations or the operation of MNPS. 



Conclusions 



The life history stages of fishes collected in the 

 fish ecology programs were examined to determine 

 which species were most susceptible to potential 

 impact due to the operation of MNPS, with par- 

 ticular emphasis on the period of three-unit op- 

 erations, lliere was a significant decrease in the 

 total impingement at Unit 2 starting with the 

 removal of the Unit 3 cofferdam in the summer 

 of 1983 and a continuing decline through 1987, 

 possibly due to a change in water circulation pat- 

 terns with the start-up of Unit 3. Because the 

 objectives of the impingement program were com- 

 pleted. Unit 2 impingement monitoring was dis- 

 continued on December 11, 1987. 



Eiglit taxa were selected for detailed examina- 

 tion: American sand lance, anchovies, 

 sticklebacks, Atlantic tomcod, sUversides, grubby, 

 tautog, and cunner. There was no apparent 

 change in the distribution or abundance of the 

 silversides in Jordan Cove related to the increased 

 thermal plume with three-unit operations. As ex- 

 pected, increased cooling water demands of three- 

 unit operations increased annual entrainment es- 

 timates for most of the abundant ichthyoplankton 

 taxa. The sand lance and cunner were the only 

 taxa that showed a decline concurrent with three- 

 unit operations. The decrease in sand lance larvae 

 has been occurring throughout the 1980s and was 

 attributed to a regional decline in adults. The 

 cause for the cunner decline was not ascertained, 

 but monitoring will continue to determine if the 

 decrease was due to natural long-term fluctuations 

 or the operation of MNPS. 



288 



