SUMMARY 



1. The construction and operation of the Millstone Nuclear Power Station (MNPS) could effect changes 

 in fish assemblages in several ways. Larger fish may be removed from the population by impingement 

 on the intake screens; eggs, larvae and small fish may be removed during entrainment through the 

 cooling water system; and spatial distribution of local fish populations may change in response to the 

 cooling water effluent. 



2. Several programs were established to provide baseline data for assessing impacts of MNPS on fish 

 assemblages: entrainment, offshore plankton, trawl, seine and impingement monitoring programs. These 

 programs provided the data necessary for assessing the effects of two-unit operation and also provide 

 the baseline for three-unit impact assessment. 



3. Over 100 taxa offish have been collected in the various Fish Ecology monitoring programs at MNPS 

 from January 1976 through December 1985. Eight taxa were selected for detailed analysis based on their 

 susceptibility to impact from impingement and entrainment: sand lance, anchovies, sticklebacks, 

 silversides, tomcod, grubby, cunner and tautog. 



4. The abundance of these taxa varied both seasonally and annually in all programs and to separate 

 population fluctuations representing natural variability from those resulting from the construction and 

 operation of MNPS, a time-series approach was developed and applied to the monitoring data. 



5. The abundance of potentially impacted taxa remained relatively stable throughout the 10-yr period, 

 except for larval and juvenile sand lance, and larval anchovy, cunner and tautog. Except for larval sand 

 lance, these abundance changes were short-term. Large annual fluctuations of sand lance have been 

 observed 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. 



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