999 



Abstract.— Continuous observations 

 in a large research aquarium (121 kL) 

 over a 14-week period were combined 

 with field collection in the Navesink 

 River estuary, New Jersey, to explore the 

 behavior of winter flounder [Pseudo- 

 pteuronectes americanus) during and 

 after the spawning season. Ten males 

 and ten females held in the aquarium 

 spawned over a 60-day period, with an 

 average of 40 spawns per female and 

 147 spawns per male. Males initiated 

 all observed spawning events, which 

 occurred throughout the night, but pri- 

 marily between sunset and midnight. 

 Spawning by one pair frequently elic- 

 ited sudden convergence and spawning 

 by secondary males (up to six individu- 

 als!; consequently, strictly paired 

 spawning was uncommon (22'?^ of 

 events). Males and females were almost 

 entirely nocturnal during the reproduc- 

 tive season but became increasingly di- 

 urnal during the postspawning season. 

 Males and females arrived in the es- 

 tuary in ripe spawning condition; fish 

 with high gonadosomatic indices were 

 collected during most of February and 

 March 1997. All of the ripe females 

 were >20 cm in total length and at least 

 two years old, whereas ripe males mea- 

 suring 10-15 cm were common. Ripe 

 males were found throughout the sys- 

 tem whereas ripe females were concen- 

 trated in the middle reach of the estu- 

 ary Field collections revealed that fe- 

 males began feeding, primarily on 

 ampeliscid amphipods and on siphons 

 of the clam Mya arenaria earlier in the 

 season than males. Males in the labo- 

 ratory also began feeding late in the 

 season, after most spawning had ended. 

 Field and laboratory results combine to 

 indicate that male spawning strategy 

 is adapted to maximize numbers of eggs 

 fertilized. There is probably high ge- 

 netic diversity in the offspring from any 

 one female owing to frequent spawn- 

 ing and to multiple males participat- 

 ing in individual spawning events. 



Behavior of winter flounder, 

 Pseudopleuronectes americanus, 

 during the reproductive season: 

 laboratory and field observations on 

 spawning, feeding, and locomotion 



Allan W. Stoner 

 Allen J. Bejda 

 John P. Manderson 

 Beth A. Phelan 

 Linda L. Stehlik 

 Jeffrey P. Pessutti 



Northeast Fisheries Science Center 



National Marine Fisheries Service, NOAA 



74 Magruder Road, Highlands. New Jersey 07732 



E-mail address (for A W Stoner) al stoner a noaa gov 



Manuscript accepted 24 March 1999 

 Fish. Bull. 97: 999-1016 (1999). 



Winter flounder, Pseudopleuronectes 

 americanus. is an important commer- 

 cial and recreational fishery species 

 in estuarine and continental shelf 

 habitats along the Atlantic coast of 

 North America from Labrador to 

 Georgia (Scott and Scott, 1988). A 

 large number of investigations have 

 been devoted to this species and its 

 life history is relatively well known 

 (Klein-MacPhee, 1978; Able and 

 Fahay, 1998 ). Winter flounder popu- 

 lations include several substocks 

 that mix during summer residence 

 on the shelf, but adults return to 

 natal estuaries to spawn ( Saila, 1961; 

 Poole, 1966; Howe and Coates, 1975; 

 Pierce and Howe, 1977; Phelan. 

 1992). In the Mid-Atlantic Bight, 

 adults make seasonal migrations 

 into the estuaries of New York and 

 New Jersey (Perlmutter, 1947; 

 Phelan, 1992) where they spawn in 

 shallow inshore waters during late 

 winter (Scarlett and Allen, 1992). 



Winter flounder in the mid-Atlan- 

 tic region are believed to mature at 

 2-3 years, at 20-25 cm total length 

 (Perlmutter, 1947, Danila, 1978; 

 Witherell and Burnett, 1993). Con- 



siderable attention has been given 

 to seasonal movement (Perlmutter, 

 1947; Saila, 1961; Howe and Coates, 

 1975; Phelan, 1992) and to fecun- 

 dity and reproductive state in wild 

 populations (Kennedy and Steele, 

 1971; Danila, 1978; Burton and 

 Idler, 1984; Nelson et al., 1991); 

 however, information on spawning 

 behavior is limited to observations 

 made by Breder (1922) of fish in 

 small laboratory tanks. 



In this investigation we expanded 

 Breder's ( 1922 ) description of spawn- 

 ing and courtship in winter flounder 

 by making continuous observations 

 on a population of winter flounder 

 in a large research aquarium for a 

 14-week period during and after the 

 reproductive period. We determined 

 the total number of spawning 

 events for males and females in the 

 population and examined seasonal 

 and diurnal variation in spawning, 

 feeding, and locomotory activity. On 

 the basis of field collection we de- 

 scribed population structure, go- 

 nadal development, feeding, and 

 localized movements by a wild 

 population of winter flounder in an 



