stations was expected to reduce variability in calculating catch-per-unit-effort (CPUE), used as an index 

 of abundance. However, because catch data from station 2 were also used for the trawl monitoring 

 program, these hauls were maintained at a tow distance of 0.69 km. Prior to 1983, tows were not 

 standardized. Mostly because of differences in tidal currents, wind, and amounts of extraneous material 

 collected in the trawl, tow times for the standardized disttmces varied and were usually greater in the lower 

 than in the upper river. For 1976-86, the mean duration for tows at stations 1 and 2 was 14.4 min and 

 at stations 4, 51, 52, and 53 was 12.1 min. Tows from 1976-82 that had extremely short or long durations 

 compared to the distribution of tow times from 1983-86, when tow distance was uniform, were excluded 

 from data analyses and calculation of CPUE. For comparisons among years, all catches of winter flounder 

 larger than 15 cm made during a 4-wk period from mid- March through early April were standardized to 

 either 15-min tows (stations 1 and 2) or 12-min tows (all other stations). The annual mean and median 

 CPUE were determined and a 95% confidence interval was calculated for each median using a distribution- 

 free method (Snedecor and Cochran 1967). The catch of winter flounder taken in the trawl monitoring 

 program from October 1976 through September 1985 (see Fish Ecology section for methods) was also 

 used to calculate median CPUE values as indices of abundance for various size groups. 



The winter flounder caught in each tow during the adult abundance survey in the Niantic River were 

 briefly held in water-filled containers. At least 200 randomly selected fish were measured to the nearest 

 0.1 cm in total length during each week of the population abundance survey in all years. During 1983-86, 

 all winter flounder larger than 20 cm were measured and sexed. Non-measured fish were classified into 

 various length and sex groupings, depending upon the year; at minimum all fish caught can be classified 

 as smaller or larger than 15 cm. Since 1977, the sex and reproductive condition of the larger winter 

 flounder were determined either by observing eggs or milt or by the presence (males) or absence (females) 

 of ctenii on the caudal peduncle scales of the left side (Smigielski 1975). Following measurement or 

 classification, all fish 15 (1977-82) or 20 (1983-86) cm or larger were marked with a number or letter made 

 by a brass brand cooled in liquid nitrogen; the mark was changed weekly. Fish recaptured were noted 

 and remarked with the brand designating the week of their recapture. In 1976, fish were fin clipped in 

 various ways and recaptures were marked with a numbered spaghetti tag. 



Estimates of abundance of all winter flounder 1 5 or 20 cm and larger in the Niantic River during the 

 spawning season were obtained from the mark and recapture data using the Jolly (1965) model. The 

 actual computations were done using a computer program (Davies 1971) of Jolly's model with minor 



