FISHERY BULLETIN: VOL. 87. NO. 3, 1989 



growth or mortality can be quantitatively tested 

 for significant deviations from the average ex- 

 pected values presented here. In addition, catch- 

 ability of fish larvae by various plankton 

 samplers can be compared with the expected 

 mortahty to determine serious biases. 



The three major hypotheses suggested as 

 mechanisms that control survival of larval fishes 

 are starvation, predation, and advection into un- 

 favorable environments. Clearly, advection is a 

 special case which differs little from predation in 

 its effects on the larval population and may be 

 viewed as simply an abiotic "predator". The 

 predator-prey interactions in the pelagic eco- 

 system may then be partitioned, in terms of mor- 

 tality, into starvation and predation. It is often 

 not clear whether larvae actually die from lack of 

 adequate food supplies or become more vulner- 

 able to predation as a result of starvation. In any 

 case, larval mortality increases with increasing 

 temperature, thus a major and consistent agent 

 of mortality must be associated with water tem- 

 perature. If the assumptions of size-dependent 

 mortahty, as explained by the "cube root rule", 

 are valid, and there is no reason to reject them, 

 predation rates on larvae must be the primary 

 agent of mortality. Since metabolic rates in- 

 crease with temperature (Qiq = 2-3; Hoar 1966), 

 predator consumption rate would also increase. 

 Thus increased gi'owth due to increases in tem- 

 perature would appear to impart no advantage 

 to reduce larval mortahty because of the con- 

 comitant increase in consumption rates of the 

 predator field. Pauly's (1980) conclusions for 

 juvenile and adult fishes support this hypothesis. 

 An interesting consequence of this hypothesis is 

 that, within the pelagic ecosystem, mortality 

 rates will change with temperature without al- 

 tering the predator field. Thus investigations of 

 predator-prey interactions must account for the 

 confounding effects of temperature on growth, 

 consumption, and mortality. 



ACKNOWLEDGMENTS 



It is an honor to submit this contribution in 

 dedication to Dr. Reuben Lasker, a pioneer in 

 the study of early life history dynamics of fishes. 

 His insight into the oceanic processes affecting 

 larval fish survival has provided inspiration for 

 this study. 



I wish to thank the many people who, over the 

 years, have participated in the MARMAP pro- 

 gram; without their dedication and professional- 

 ism, this study would not have been possible. In 



particular, I wish to thank Ken Sherman and 

 Wallace Smith for their unfailing efforts to sup- 

 port research in ichthyoplankton and marine 

 ecosystems and for their critical reviews of this 

 manuscript. Special thanks to M. Fahay, J. 

 O'Reilly, M. f^ogarty, M. Sissenwine, and two 

 anonymous reviewers for their helpful sugges- 

 tions. 



LITERATURE CITED 



Ahlstrom, E. H. 



1954. Distribution and abundance of egg and larval 

 populations of the Pacific sardine. Fish. Bull., U.S. 

 56:83-140. 

 Bailey, K. M., and C. L. Stehr. 



1986. Laboratory studies on the early life history of 

 the walleye pollock, Theragra chalcogramina (Pal- 

 las). J. exp. mar. Biol, Ecol, 99:233-246. 



Barkley, R. A. 



1972. Selectivity of towed-net samplers. Fish. Bull., 

 U.S. 70:799-820. 



Beverton, R. J. H.. and S. J. Holt 



1957. On the dyiiamics of e.xploited fish populations. 

 Fish. Invest. Minist. Agric, Fish. (G.B), Food Ser. 

 II, 19. ,533 p. 

 Bridger, J. P. 



1956. On day and night variations in catches of fish 

 larvae. J. Cons. Perm. Int. E.xplor. Mer 22:42-.57. 

 Buckley, L. J., T. A. Halavik, A. S. Smigielski, and G. C. 

 Laurence. 



1987. Growth and survival of the larvae of three 

 species of temperate marine fishes reared at discrete 

 prey densities. Am. Fish. Soc. Symp. 2:82-92. 



Checkley, D. M., Jr. 



1984. Relation of gi'owth to ingestion for larvae of 

 Atlantic herring Clupea harevgus and other fish. 

 Mar. Ecol. Prog. Ser. 18:21.5-224. 

 Clutter, R. I., and M. Anraku. 



1968. Avoidance of samplers. Iti D. J. Tranter 

 (editor), Zooplankton sampling, p. 57-76. UNESCO 

 Monogr. Oceanogr. Methodol., Vol. 2. 

 Colton, J. B., W. G. Smith, A. W. Kendall, Jr., P. L. 

 Berrien, and M. P. Fahay. 



1979. Principal spawning areas and times of marine 

 fishes. Cape Sable to Cape Hatteras. Fish. Bull., 

 U.S. 76:911-915. 

 Gushing, D. H. 



1975. Marine ecology and fisheries. Cambridge Univ. 

 Press, Cambridge, 278 p. (see p. 165-182). 

 Ebert, T. A. 



1973. Estimating growth and mortality rates from size 

 data. Oecologia, BERL. 11:281-298. 



Halliday, R. G. 



1970. Growth and vertical distribution of the glacier 

 lanternfish, Benthosema glaciate, in the Northwest- 

 ern Atlantic. J. Fish. Res. Board Can. 27:105-116. 



Hauser, J. W., M. P. Sissenwine, and W. W. Morse. 



1988. A model to evaluate spawiiing stock size esti- 

 mates derived from larval abundance. //( W. G. 

 Smith (editor). An analysis and evaluation of ichthyo- 

 plankton survey data from the northeast continental 

 shelf ecosystem, p. 72-111. U.S. Dep. Commer., 



444 



