EFFECTS OF FOOD CONCENTRATION AND TEMPERATURE ON 



DEVELOPMENT, GROWTH, AND SURVIVAL OF 



WHITE PERCH, MORONE AMERICANA, EGGS AND LARVAE 



Daniel Margulies' 



ABSTRACT 



Growth and mortality during the egg and early larval stages of white perch, Morone americana, were 

 examined in relation to food concentration and temperature. Laboratory experiments were conducted 

 utilizing variable food conditions (high, low, and initially delayed rotifer levels) and temperatures (13°, 

 17°, and 21°C). Egg and yolk-sac larva stage durations were inversely related to temperature, and op- 

 timum hatch of eggs occurred at 17°C or lower. Larvae fed initially at low food levels for as little as 

 2 days exhibited significantly reduced survival and growth after 8 days of feeding at all temperatures. 

 Survival rates of well-fed larvae after 8 days of feeding ranged from 43 to 55%. Feeding delays of 4-8 

 days resulted in markedly reduced survival at 17° and 21°C. Growth was slow under any food conditions 

 at 13°C (<0.05 mm/d in length, <5%/d in dry weight). At 17° and 21 °C, well-fed larvae grew at significant- 

 ly higher rates (>0.20 mm/d in length, >15%/d in dry weight). Based on these laboratory data and on 

 seasonal abundance of food in Chesapeake tributaries, it was estimated that optimum temperatures for 

 growth and survival of first-feeding white perch larvae are 15°-20°C. Results suggest that the estima- 

 tion of variability in growth rates of larval white perch in Chesapeake tributaries would make a major 

 contribution to our understanding of white perch recruitment. 



The white perch, Morone americana, is an impor- 

 tant recreational and commercial fish species in the 

 Chesapeake Bay drainage. Fluctuations in relative 

 abundance of white perch are most likely related 

 to survivorship during the early life history, yet 

 surprisingly little is known about the effects of 

 varying environmental factors on growth, devel- 

 opment, and survival of white perch eggs and 

 larvae. 



Past studies on the early life history of white 

 perch have focused on distribution patterns (Man- 

 sueti 1961), descriptions of egg and larval develop- 

 ment (Mansueti 1964), electrophoretic (Morgan 

 1975), and biochemical (Sidell and Otto 1978) 

 characterizations of larvae and temperature ef- 

 fects on hatching (Morgan and Rasin 1982). The 

 interacting effects of temperature and food on 

 the development, growth, and survival of white 

 perch eggs and larvae had not been studied pre- 

 viously. 



Fecundity of white perch, which usually are 100- 

 250 mm SL, is high (50,000-300,000 ova per female). 



'Chesapeake Biological Laboratory, Center for Environmental 

 and Estuarine Studies, University of Maryland, Solomons, MD 

 20688; present address: Inter-American Tropical Tuna Com- 

 mission, c/o Scripps Institution of Oceanography, La Jolla, CA 

 92093. 



Manuscript accepted September 1988. 

 Fishery Bulletin, U.S. 87:63-72. 



thus larval mortality rates are expected to be high 

 (Ware 1975). For most high-fecundity species, if 

 large numbers of larvae are produced in a cohort, 

 small changes in growth or mortality rates during 

 the larval stages may produce large variations in 

 recruitment (Houde 1987). White perch juveniles are 

 large relative to reproductive size, with the greatest 

 relative weight increases occurring in the larval 

 stage. This growth pattern indicates a strong poten- 

 tial for regulation of numbers through variable lar- 

 val growth (Houde 1987). 



In this study, I examined the effects of two vari- 

 able environmental factors, food concentration and 

 temperature, on the development, growth, and sur- 

 vival of first-feeding white perch larvae. White perch 

 spawn in Chesapeake tributaries over a temperature 

 range of 10°-20°C (Hardy 1978). Thus, first-feed- 

 ing larvae can encounter a wide range of develop- 

 mental temperattu-es. Microzooplankton, which 

 forms the bulk of the diet for first-feeding white 

 perch larvae, can fluctuate in Chesapeake tidal 

 freshwaters during spring months from <50 to 

 >1,000/L (Heinle and Flemer 1975; Lippson et al. 

 1980). By examining the interacting effects of 

 temperature and food, the scope for growth and 

 survival potential of white perch larvae were 

 studied. 



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