WINTER FLOUNDER STUDIES 

 INTRODUCTION 



The purpose of this report is to summarize research completed by Northeast Utilities Environmental 

 Laboratory (NUEL) and various consultants on the winter flounder {Pseudopleuronectes americanus) prior 

 to 3-unit operation of MiUstone Nuclear Power Station (MNPS). Due to its local abundance, this species 

 has been studied intensively since 1973 and considerable data have been collected on its life history, 

 population dynamics, and impact assessment. The large effort devoted to winter flounder studies is related 

 to its importance for the Coimecticut sport and commercial fisheries. It is the most valuable commercial 

 finfish in Connecticut and on average makes up about lOVa of the total fmfish landings. The winter 

 flounder is also one of the most popular marine sport fishes in the state with an estimated aimual catch 

 iu 1979 of almost 1.4 million fish weighing 412,234 kg (Sampson 1981; Blake and Smith 1984). Its 

 particular life history also makes it potentially susceptible to various types of localized impacts. 



The winter flounder ranges from Labrador to Georgia (Leim and Scott 1966) and is one of the most 

 common demersal fishes in inshore waters along the northeastem coast from Nova Scotia to New Jersey 

 (Perhnutter 1947). The population of winter flounder is composed of reproductively isolated stocks which 

 spawn in specific estuaries and coastal areas (Lobell 1939; Perlmutter 1947; Saila 1961). Most adult winter 

 flounder enter natal estuaries in fall and early winter and spawning occurs in late winter and early spring. 

 Females usually mature at age 3 and 4 and males at age 2. Average fecundity is about 500,000 eggs per 

 female with as many as 2.3 mUlion eggs for a 45-cm fish. Winter flounder eggs are demersal and hatch 

 in about 15 d, depending upon water temperature. Small larvae are planktonic and remain in natal estuaries 

 to a great extent, although some may be carried out into open waters by tidal currents. Some of these 

 larvae may return to the estuary on subsequent incoming tides, but the rest are lost from the system. The 

 larval stage lasts about 2 mo, depending upon water temperature. Larger larvae maintain some control 

 over their position by vertical movements and also may spend considerable time on the bottom. Following 

 metamorphosis, most demersal juveniles remain in the estuary in shallow waters. Juveniles are resistant 

 to warm summer water temperatures found there to at least 30.4 °C (Huntsman and Sparks 1924). 

 Immature yearling winter flounder become photonegative and though many remain within the estuary, are 

 usually found in deeper water than young-of-the-year (Pearcy 1962; McCracken 1963). Many adults stay 



