NOTE Withered and Burnett Growth and maturation of Pleuronectes amencanus 



819 



tially removed from populations (Ricker, 1975), and 

 thus we were unable to separate the effects of crop- 

 ping faster growing fish from potential density depen- 

 dent effects. 



Winter flounder in Massachusetts waters mature at 

 larger sizes than winter flounder from other coastal 

 populations. For winter flounder in Massachusetts, only 

 50^ of the females were mature at 28 to 29 cm; L 50 's of 

 females in Newfoundland were 25cm (Kennedy and 

 Steele, 1971) and 27 cm in New Jersey (Danilla, 1978). 

 Maturity ogives derived from our age-specific mean 

 length at maturity data were similar to those reported 

 from pooled length at maturity observations for Mas- 

 sachusetts winter flounder during the period 1985-89 

 (O'Brien et al, 1993). They found lengths at 50% ma- 

 turity of females to be 27.6 cm south of Cape Cod and 

 29.7 cm north of Cape Cod. Because populations of long 

 lived, late maturing fish are more susceptible to 

 overexploitation than are populations with early ma- 

 turity and shorter life spans (Pitcher and Hart, 1982), 

 each substock of winter flounder may require different 

 management strategies (including size limits) for opti- 

 mal harvest levels. 



Sex ratios of winter flounder favored females at 

 older ages (Fig. 1), indicating a higher natural mor- 

 tality rate for males. An increasing proportion of fe- 

 males by size was observed for winter flounder in 

 Rhode Island, but the differences in sex ratios were 

 thought to be related to the faster growth of females 

 (Berry et al., 1965). Female winter flounder on 

 Georges Bank live longer than males (Lux, 1973). A 

 number of mature male winter flounder in Concep- 

 tion Bay, Newfoundland, failed to produce gametes, 

 and there was a trend towards an increasing propor- 

 tion of nonreproductive individuals with advancing 

 age, leading to the possibility that males enter senes- 

 cence at younger ages than do females, and thus have 

 a higher natural mortality rate (Burton and Idler, 

 1984). A higher natural mortality rate for males has 

 been found for other flounders, including European 

 plaice, Pleuronectes platessa , (Bidder, 1925) and sum- 

 mer flounder, Paralichthys dentatus, (Poole. 1966b), 

 and it may be a general pattern that male flounders 

 have shorter life spans than females. 



Acknowledgments 



This project was partially funded by the Commercial 

 Fisheries Research and Development Act, Project 3- 

 375-R, the Interjurisdictional Fisheries Act, Project 3- 

 IJ-3, and the Sportfish Restoration Act, Project F-56- 

 R. We thank Arnold Howe, Tom Currier, and Steve 

 Correia for their help with data collection and edi- 

 torial assistance. Special thanks to personnel at the 



NMFS, Northeast Fisheries Science Center, for pre- 

 paring scale samples for ageing. 



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