associated with winds from the northwest probably resuUed from the passage of cold fronts with accom- 

 panying falling temperatures and winds from the southwest were perpendicular to the MNPS intakes: The 

 combination of low water temperatures and frequent high winds in winter (NUSCo 1983c), along with 

 less sustained swimming speed and endurance for the winter flounder at colder temperatures (Beamish 

 1966; Terpin et al. 1977) most likely makes it more susceptible to impingement then. Strong winds alone 

 do not necesscirily increase impingement as 3 weeks prior to the December 1983 incident sustained winds 

 of 21 to 35 mi/h from the south to west over a 2-d period only produced a weekly estimate of 145 winter 

 flounder. The water temperature then was 9.5 to 9.8 °C. 



Length and sex distribution 



The length-frequency distribution of impinged winter flounder by 5-cm length groups showed that the 

 proportion of adults (fish larger than 25 cm) has remained relatively constant and made up about a third 

 of each annual total (Table 31). Catch of mid-sized (15- and 20-cm length groups) and small fish (5 and 

 10 cm) varied from year to year. Mid-sized fish made up more than half the total in 1977-78, but only 

 one-fifth in 1984-85. About 40% of the catch in 1978-79, 1982-83, and 1984-85 was comprised by small 

 specimens. As noted above, factors such as plant operating conditions and weather influence impingement 

 to a great extent and relative differences in abundance and size-classes impinged each year probably do 

 not reflect actual changes in the winter flounder population. 



The sex and reproductive condition were examined for 755 winter flounder impinged from February 

 through April of 1982 and 1,675 from December 1982 through April 1983. The sex ratio in 1982 was 

 1:1, but males predominated earlier in the season and females later. In 1982-83, 65% were males and 

 35% females, a ratio opposite to that seen for the Niantic River spawning population. Of the females 25 

 cm or larger examined from mid-February through April of 1982 and 1983, 56 and 59%, respectively, 

 were gravid. This was contrary to fmdings from the trawl monitoring program for the same period, which 

 showed relatively few ripe winter flounder outside of the Niantic River. In addition, a comparison of the 

 weekly percentages of gravid females inside the Niantic River with those impinged showed that a much 

 larger portion of the latter had not spawned (Fig. 30). Although sample size was considerably smaller, 

 relatively higher percentages of gravid females continued to be taken at MNPS until the end of April, 

 whereas most fish in the river spawned earlier in the season. 



105 



