TABLE 6. Median CPUE of Niantic River winter flounder smaller than 15 cm from 1976 through 

 1987 during the period of mid-March through mid-April (stations 1 and 2 only). 



Zero for symmetrically distributed data. 



An annual 5-mean CPUE was computed for 

 winter flounder of aU sizes taken throughout the 

 year (January- December) at all stations sampled 

 by the trawl monitoring program. This period 

 represented a change from previous reports, where 

 an October-September year was defined. Using 

 a calendar year allowed for direct comparisons 

 with other regional indices of abundsmce. Neither 

 period had particularly strong biological meaning; 

 the winter flounder was ubiquitous in the Mill- 

 stone area and made up about 40% of the catch 

 (ranked first) in the trawl monitoring program. 

 The 5-mean CPUE index showed a pattern of 

 fluctuating abundance (Fig. 5). However, it dif- 

 fered in several respects from the median CPUE 

 for the Niantic River spawning stock. The peak 

 in 5-means persisted from 1979 through 1983 and 

 was not as pronounced as it was for the Niantic 

 River medians, which were highest in 1981 and 

 1982 (Fig. 4). Abundance, as measured by the 

 5-mean for 1985 and 1986 was greater than that 

 for 1977 and 1978, whereas the median CPUE 

 for the Niantic River spawning stock in recent 

 years has been smaller than that during the 1970s. 



Although the trawl monitoring program catch 

 included winter flounder of all sizes, fish larger 



than 15 cm made up about two-thirds of the 

 catch; annual percentages ranged from 55% in 

 1983 to 75% in 1976. On a monthly basis, larger 

 fish comprised 76 to 92% of the catch from June 

 through November. Small ( < 1 5 cm) fish made 

 up two-thirds of the area-wide total from January 

 through March as larger fish congregated on the 

 spawning grounds. Approximately equal numbers 

 of small and large fish were taken in April, May, 

 and December. Based on elcctrophoretic studies, 

 there was most likely a mixture of stocks present 

 at the trawl stations outside of the Niantic River, 

 except for the spawning season (NUSCO 1987). 



A comparison of the trends in abundance of 

 small and large winter flounder taken by the trawl 

 monitoring program during January through April 

 (except station NR) was made with the catch of 

 similar-sized fish during the annual population 

 surveys in the river. This period was chosen 

 because it overlapped the spawning period and 

 the Niantic River station was eliminated because 

 catches in the river were used for the determination 

 of the winter flounder survey median. On the 

 basis of the overlapping 95% confidence intervals, 

 there was little dtfierence among the numbers of 

 larger winter flounder at stations outside the river; 

 catches remained at a low and stable level of 



Winter Flounder Studies 



163 



