WINTER FLOUNDER POPULATION STUDIES 



INTRODUCTION 



The winter flounder ( Pseudopleuronectes americanus ) ranges from 

 Labrador to Georgia (Leim and Scott 1966) . It is one of the most common 

 demersal fishes along the northeastern coast from Nova Scotia to New 

 Jersey (Perlmutter 1947) and is particularly abundant in Long Island 

 Sound. It is one of the most valuable commercial species in Connecticut 

 with annual landings from 1973 through 1983 between 221,807 and 413,537 

 kg (Connecticut Department of Environmental Protection, unpublished 

 data) . It is also one of the most sought-after marine sport fishes in 

 the state with an estimated annual catch in 1979 of 190,626 kg (Sampson 

 1981). 



The abundance of the winter flounder in the Greater Millstone Bight 

 has been evident from the beginning of environmental studies conducted 

 at the Millstone Nuclear Power Station (MNPS) .. The species dominates 

 the trawl catch of demersal fishes and is the most numerous fish 

 impinged on the traveling screens of the MNPS cooling-water intakes. 

 Its larvae are very abundant in spring, particularly in the Niantic 

 River, and many are entrained through the MNPS cooling-water system. 



Winter flounder populations are composed of geographically Isolated 

 stocks which spawn in specific estuaries and coastal areas (Lobell 1939; 

 Perlmutter 1947; Saila 1961). Other local fish stocks have greater 

 geographical range and abundance or life histories making them less 

 susceptible to impact by MNPS. Special emphasis has therefore been 

 placed on understanding the dynamics of the winter flounder stock 

 spawning in the nearby Niantic River. The dynamics of this population 

 have been studied extensively to determine if MNPS impacts have or would 

 cause changes in local abundance beyond those expected from natural 

 variation. 



Studies of the winter flounder began at Millstone in 1973 and 

 included the development of a predictive mathematical population 

 dynamics model (Sissenwine et al. 1975; Saila 1976). Preliminary field 

 studies to estimate population abundance began in 1973 and were expanded 

 in scope in 1975 (Table 1). Studies of age structure, reproductive 



