potentially taken in a total of 468 samples (3 replicate tows x 6 stations 

 x 26 sampling dates) . This total may be compared to the aforementioned 

 calculated sample sizes to give the percent change in means the present 

 trawling program would be able to detect. For an alpha of 0.05 and a 

 beta of 0.80, the present sampling program can detect a difference of 

 15% in the log transformed means of trawl catches (Table 29 ) . Mean 

 trawl catch of winter flounder from October 1977 through September 1981 

 was 21.03 (arithmetic) and 2.41 (In catch + k/2 transformed). The 

 latter mean when transformed back to a linear scale is 10.71. This is 

 the geometric mean and represents the central tendency of the winter 

 flounder trawl catch. Thus the present sampling program can detect at 

 least a change of + 1.60 from this mean. The 15% level of detection can 

 be considered excellent in this type of monitoring program and represents 

 one technique available to measure potential impact of Millstone Power 

 Station operations. 



In previous Annual Reports the winter flounder trawl data has 

 appeared in both the Winter Flounder and Fish Ecology sections. Examina- 

 tion of the analyses used showed that the methodology of calculating 

 catch per unit effort (CPUE) differed between these two sections as well 

 as with that used in the trawl monitoring program evaluation trawl 

 herein. CPUE as used in the winter flounder section was calculated as 

 follows: 



Catch per each replicate x 15 min 

 time of tow 



which gave the CPUE for a standardized 15 min tow. The mean catch per 



station would be the mean of the three replicates for that date. For 



analysis in the Fish Ecology section the CPUE was determined as: 



82 



