AbStr3Ct.— Winter flounder were 

 acclimated to two temperatures (2° 

 and 7°C) for a period of about 7 weeks 

 prior to spawning. Embryos produced 

 at two acclimation temperatm-es were 

 incubated through the yolksac stage 

 at three incubation temperatures 

 (4°, 7°, and 10°C). Both adult accli- 

 mation temperature and embryo and 

 larval incubation temperature were 

 found to have an effect on larval size 

 and biochemical composition. In many 

 cases the effects of acclimation tem- 

 perature and incubation temperature 

 were nonadditive. RNA content at 

 first feeding indicated that larvae 

 produced by adults acclimated to low 

 temperature (2°C) were better suited 

 for growth at low temperatiu-es, while 

 larvae produced by adults acclimated 

 to higher temperature (7°C) were 

 better suited for growth at higher 

 temperatures. At first feeding larvae 

 were larger (higher standard length) 

 and in better condition (high protein 

 and RNA content) when incubated at 

 lower temperatures. 



Effects of Water Temperature 

 on Size and Biochemical 

 Composition of Winter Flounder 

 Pseudopleuronectes amehcanus 

 at Hatching and Feeding Initiation 



Lawrence J. Buckley 

 Alphonse S. Smigielski 

 Thomas A. Halavik 

 Geoffrey C. Laurence 



Narragansett Laboratory, Northeast Fisheries Center 



National Marine Fisheries Service, NOAA, Narragansett Rhode Island 02882-1 199 



Manuscript accepted 11 June 1990. 

 Fishery Bulletin, U.S. 88:419-428. 



The effects of water temperature on 

 the size and viability of fish eggs and 

 larvae have been the subject of con- 

 siderable interest. Water tempera- 

 ture is the environmental variable 

 most often linked to recruitment in 

 retrospective empirical analyses of 

 recruitment variability in temperate 

 marine fish (Sissenwine 1984). Yet in 

 most cases causation is not established 

 and the mechanisms involved are 

 poorly understood. Studies of effects 

 of water temperature prior to spawn- 

 ing suggest an inverse relation be- 

 tween water temperature and egg 

 size in several species (Hempel and 

 Blaxter 1967, Gushing 1967, Bagenal 

 1971, Southward and Demir 1974, 

 Ware 1975, Tanasichuk and Ware 

 1987). The effects of water tempera- 

 ture during the embryonic period on 

 larval size and yolk conversion effici- 

 ency have been examined in a variety 

 of species (Lasker 1962, Sweet and 

 Kinne 1964, Alderdice and Forrester 

 1968, May 1974, Laurence and Rogers 

 1976, Linden et al. 1980, Johns et al. 

 1981, Laurence and Howell 1981, 

 Buckley et al. 1982). While maximum 

 efficiency is generally achieved at in- 

 termediate temperatures within the 

 range of thermal tolerance, the exact 

 shape of the relation between tem- 

 perature and utilization is variable 

 (Heming and Buddington 1988). Blax- 



ter and Hempel (1966) found that the 

 effect of temperature on yolk conver- 

 sion efficiency was dependent upon 

 egg size in Atlantic herring Clupea 

 harengus, cold temperatures favor- 

 ing small eggs and warm tempera- 

 tures favoring large eggs. The effects 

 of water temperature have been ex- 

 amined in combination with salinity, 

 oxygen levels, and other environmen- 

 tal variables. None of these studies, 

 with the exception of Tanasichuk and 

 Ware 1987, considered a possible in- 

 teractive effect of watci temperature 

 during gamete mattu'ation with water 

 temperature during the embryonic 

 and larval periods. It is widely known, 

 however, that acclimation tempera- 

 ture mediates many thermal effects, 

 including upper and lower lethal tem- 

 peratures and metabolic rate (Brett 

 1970). 



This study was undertaken to exam- 

 ine the effects of water temperature 

 during the latter stages of gamete 

 development and during the embry- 

 onic and yolksac periods on the size 

 and biochemical composition of 

 winter flounder larvae produced. 

 Standard length, RNA, DNA, and 

 protein content were determined at 

 hatching and first feeding. These in- 

 dices were chosen because of their 

 relation to fitness, growth, and sur- 

 vival potential of fish larvae. Length 



419 



