70 



60 



50- 



40 



30- 



20 



10 



CPUE 

 (>15 cm) 



76 



77 



78 



79 



80 



n 82 

 YEAR 



83 



84 



85 



86 



87 



Fig. 4. Median trawl CPUE (±2 standard errors) for Niantic River winter flounder larger than 15 cm from 

 1976 through 1987. For comparisons with the Jolly index, the CPUE was adjusted downwards by deleting 

 fish between 15 and 20 cm during 1983-87 (shown by a *). 



The median CPUE of winter flounder smaller 

 than 15 cm. was calculated for fish taken during 

 the adult winter flounder surveys in the Niantic 

 River from 1976 through 1987. Nearly all of the 

 fish in this size group were age 1 yearlings and 

 represented the year-class spawned during the pre- 

 vious year. Data were restricted to the mid- March 

 to mid-April period for comparability among 

 years and to stations 1 and 2 because small winter 

 flounder were less abundant than adults in the 

 upper river. Inclusion of data from upper river 

 stations could have biased inter-year comparisons 

 because few or no tows were made there prior to 

 1981. 



Juvenile catches were more variable than those 

 of adults (Table 6). Abundance reached a peak 

 during 1981 through 1983 (50.1-87.2), but fell to 

 previous levels in 1984 (16) and 1985 (27.7). 

 CPUE declined to 3.6 in 1986 and 5.5 in 1987. 

 The small numbers of juveniles suggested poor 



reproductive success in recent years. However, 

 this measure of winter flounder abundance may 

 be affected by differential distribution of the ju- 

 veniles. Unlike adults, juveniles do not necessarily 

 enter the river during the spawning season and 

 other factors, such as water temperature, may in- 

 fluence their movements. Although temperature 

 is an important factor in winter flounder distri- 

 bution, annual differences in late winter through 

 early spring water temperature were not signifi- 

 cantly correlated with abundance inside or outside 

 of the river. During the past several years, juve- 

 niles have been found in greater numbers through- 

 out the entire river. As their distribution in area 

 increased, concentrations in the lower river most 

 likely decreased. This confounded the use of an 

 abundance index based on tows from only the 

 lower river channel stations. Using data from the 

 trawl monitoring program, a comparison between 

 the number of juveniles inside and outside the 

 river during the spawning period was made and 

 is presented below. 



162 



