based on continued monitoring is necessary to 

 confirm this point. Periodic increases in shark 

 attacks of the magnitude found in these two 

 studies may be related to several possible factors: 

 The well-documented increase in elephant seals 

 (Le Boeuf and Bonnell 1980), an increase in abun- 

 dance of sharks, or to one or a few relatively inept 

 predators at work. 



Acknowledgments 



We thank Sea World of San Diego for permit- 

 ting us to use data from their shark collecting 

 expeditions; Walter Ward for bringing the 

 beached shark to our attention and for providing 

 measurements; Keith Skaug, C. Leo Ortiz, Rob- 

 ert Gisiner, and Anne Hoover in acquiring and 

 examining shark stomach contents; and Jack 

 Ames, Ellen Chu, Daniel Miller, and Breck Tyler 

 for comments on the manuscript. This study was 

 supported in part by the National Science Foun- 

 dation grant BNS 74-01363 402 to B. J. Le Boeuf. 



mals of the sea: Biology and medicine, p. 3-204. Charles 

 C. Thomas, Springfield, 111. 

 Townsend, C. H. 



1885. An account of recent captures of the Cal ifornia sea- 

 elephant, and statistics relating to the present abun- 

 dance of the species. Proc. U.S. Natl. Mus. 8:90-93. 



Burney J. Le Boeuf 



Center for Coastal Marine Studies and Crown College 

 University of California, Santa Cruz 

 Santa Cruz, CA 95064 



Marianne Riedman 



Center for Coastal Marine Studies 

 University of California, Santa Cruz 

 Santa Cruz, CA 95061, 



Sea World 



1720 South Shores Road 



San Diego, CA 92109 



Raymond S. Keyes 



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VERTICAL stratification of three 



NEARSHORE SOUTHERN CALIFORNIA 



LARVAL FISHES (ENGRAULIS MORDAX, 



GENYONEMUS LINEATUS, AND 



SERIPHUS POLITUS) 



Length measurements of larval fish are most fre- 

 quently used in describing life stages (Moser and 

 Ahlstrom 1974), and the subsequent develop- 

 ment of population estimates (Kumar and Adams 

 1977). Field and laboratory observations are 

 used to construct growth models of larval fishes, 

 which are useful in predicting rates of growth 

 under various environmental conditions (Hunter 

 1976). When combined with observations of lar- 

 val abundance and distribution, length measure- 

 ments can be indicators of both larval and adult 

 ecology. Larval length-frequency data provide 

 information about adult distribution and abun- 

 dance, spawning periodicity, food preferences, 

 and behavioral transitions that occur during de- 

 velopment (Gj^saetor and Saetre 1974; Tanaka 

 1974). 



Larval length-frequency distributions of three 

 species of fish were determined in conjunction 

 with a study of the effects of a power plant off- 

 shore cooling water intake on local nekton popu- 

 lations. The three species chosen [northern an- 



FISHERY BULLETIN: VOL. 80, NO. 4, 1982. 



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