EHRLICH ET AL: THERMAL BEHAVIORAL RESPONSES OF FISHES 



cate tighter aggregation, it could also result from 

 individuals of a normally solitary species with a 

 narrow preferred temperature range being com- 

 pressed into a tight aggregation by a steep tem- 

 perature gradient. Comparison of the coefficient 

 of dispersion and the measures of eury- or 

 stenothermal preference (the standard deviation 

 about the mean selected temperature and the 

 coefficient of kurtosis) (Table 1) helps to distin- 

 guish between behavioral aggregation and com- 

 pression of individuals with stenothermal prefer- 

 ences. Juvenile topsmelt, for instance, aggregated 

 closely, but the close association of the individual 

 fish was not the result of thermal compression 

 since they showed a wide temperature preference 

 (Table 1 ). Greater caution, however, must be used 

 in interpreting the coefficient of dispersion for 

 species such as pile surfperch with a narrow (lep- 

 tokurtic) range of preferred temperatures (Table 

 1 ). The occurrence of pile surfperch in the field at 

 temperatures of 12°-18°C (Stephens'-) shows that 

 the close aggregation in the gradient was not due 

 to thermal compaction of fish with an obligatory 

 stenothermal preference. These fish in King Har- 

 bor were associated with the coolest water avail- 

 able (Stephens, see footnote 6). Coordinated 

 laboratory and field studies provide greater un- 

 derstanding of the factors that affect fish popula- 

 tions and distributions than either investigation 

 alone. 



ACKNOWLEDGMENTS 



The authors wish to express their gratitude to 

 Don Alderdice of the Pacific Biological Station 

 (Nanaimo, British Columbia) for his critical re- 

 view of an early draft of this manuscript and to 

 John Stephens of Occidental College, Los Angeles, 

 Calif., for his support during this investigation, as 

 well as his reviewing of the manuscript. Special 

 thanks is given to Deirdre McDermott-Ehrlich of 

 the Lockheed Center for Marine Research for her 

 help in both reviewing and editing. The authors 

 also wish to acknowledge the technical assistance 

 of Douglas Johnson and Nancy Conrad of Occi- 

 dental College. 



^Stephens, J. 1977. Effects of thermal effluent from South- 

 em California Edison's Redondo Beach Steam Generating Plant 

 on the warm temperate fish fauna of King Harbor marina. Field 

 study report for Phase II. Annual Report for 1 March 1975-29 

 February 1976. Unpubl. manuscr., 11 1 p. Southern California 

 Edison Res. Contract No. U0654902. 



LITERATURE CITED 



BEITINOER, T. L. 



1976. Behavioral thermoregulation by bluegill expwsed to 

 various rate of temperature change. In G. W. Esch and 

 R. V/. McFarlane (editors), Thermal ecology II, p. 176-179. 

 Tech. Inf Cent., U.S. Energy Res. Dev. Admin. 



1977. Thermopreference behavior of bluegill [Lepomis 

 imicrochiriis) subjected to restrictions in available tem- 

 perature range. Copeia 1977:536-541. 



BEITINOER, T. L., AND J. J. MAGNUSON. 



1976. Low thermal responsiveness in the bluegill, Lepo- 

 mis macrochirus. J. Fish. Res. Board Can. 33:293-295. 



Bl.A.XTER, J. H. S. 



1969. Development: eggs and larvae. In W. S. Hoar and 

 D. J. Randall (editors). Fish physiology, Vol. Ill, p. 177- 

 252. Academic Press, N.Y. 



1970. Light - Fishes. In O. Kinne (editor). Marine ecolo- 

 gy. Vol. I, p. 213-320. Wiley-Interscience, N.Y. 



BLAXTER, J. H. S., AND K. F. EHRLICH. 



1974. Changes in behaviour during starvation of herring 

 and plaice larvae. In J. H. S. Blaxter ( editor). The early 

 life history offish, p. 575-588. Springer- Verlag, Berl. 



Blaxter, J. H. S., and F. G. T. Holliday. 



1958. Herring iClupea harengus'i in aquaria. II. Feed- 

 ing. Scott. Home Dep. Mar. Res. 1958(6), 22 p. 



Brett. J. R. 



1952. Temperature tolerance in the young Pacific salmon, 

 genus Oncorhynchus. J. Fish Res. Board Can. 9:265- 

 323. 



1956. Some principles in the thermal requirements of 

 fishes. Q. Rev. Biol. 31:75-87. 



1970. Temperature - Fishes, /n 0. Kinne (editor), Marine 

 ecology. Vol. I, p. 515-616. Wiley-Interscience, N.Y. 



1971. Energetic responses of salmon to temperature. A 

 study of some thermal relations in the physiology and 

 freshwater ecology of sockeye salmon {Oncorhynchus ner- 

 ka\. Am.Zool. 11:99-113. 



BRETT, J. R.. AND D. A. HiGGS. 



1970. Effect of temperature on the rate of gastric digestion 

 in fingerling sockeye salmon, Oncorhynchus nerka. J. 

 Fish. Res. Board Can. 27:1767-1779. 



Brett, J. R., J. E. Shelbourn, and C. T. Shoop. 



1969. Growth rate and body composition of fingerling 

 sockeye salmon. Oncorhynchus nerka. in relation to tem- 

 perature and ration size. J. Fish Res. Board Can. 

 26:2363-2394. 



Cherry, D. S., K. L. Dickson, and J. Cairns, Jr. 



1975. Temperatures selected and avoided by fish at vari- 

 ous acclimation temperatures. J. Fish. Res. Board Can. 

 32:485-491. 



COUTANT. C. C. 



1973. Effect of thermal shock on vulnerability of juvenile 

 salmonids to predation. J. Fish. Res. Board Can. 

 30:965-973. 

 1975. Temperature selection by fish - a factor in power 

 plant impact assessments. In Environmental effects of 

 cooling systems at nuclear power plants, p. 575-597. Int. 

 At. Energy Agency, Symp., Vienna. 



1977. Compilation of temperature preference data. J. 

 Fish. Res. Board Can. 34:739-745. 



CRAWSHAW, L. I. 



1975. Attainment of the final thermal preferendum in 



847 



