Acknowledgments 



Howard Sears helped us collect the water sam- 

 ples, and William R. Heard and Roy Martin lo- 

 cated the random sites and determined the density 

 of alevins at each site. 



Literature Cited 



Bailey, J. E., S. D. Rice, J. J. Pella, and S. G. Taylor. 



1980. Effects of seeding density of pink salmon, Oncorhyn- 

 chus gorbuscha, eggs on water chemistry, frj' characteris- 

 tics, and fry sur\'ival in gravel incubators. Fish. Bull., 

 U.S. 78:649-658. 



BRICKELL, D. C. and J. J. GOERING. 



1972. Chemical effects of salmon decomposition on aquatic 

 ecosystems. In R. S. Murphy and D. Nyquist (editors). 

 International Symposium on Water Pollution Control in 

 Cold Climates, p. 125-138. U.S. Gov. Print. Off., Wash., 

 D.C. 



McNeil, W. J. 



1962. Variations in the dissolved oxygen content of intra- 

 gravel water in four spawTiing streams of southeastern 

 Alaska. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 402, 

 15 p. 



1964. A method of measuring mortality of pink salmon 

 eggs and larvae. U.S. Fish Wildl. Serv., Fish. Bull. 

 63:575-588. 



McNeil, W. J., R. A. Wells, and D. C. Brickell. 



1964. Disappearance of dead pink salmon eggs and larvae 

 from Sashin Creek, Baranof Island, Alaska. U.S. Fish 

 Wildl. Serv., Spec. Sci. Rep. Fish. 485, 13 p. 



PEN.^Z, M. 



1965. Influence of ammonia on eggs and spawns of stream 

 trout Salmo trutta M. Fario. Zool. Listy, Folia Zool. 

 14:47-53. [Translated by and available from Foreign 

 Fisheries (Translations), U.S. Dep. Commer., Wash., D.C] 



Rice, S, D., and J. E. Bailey. 



1980. Survival, size, and emergence of pink salmon, On- 

 corhynchus gorbuscha, alevins after short- and long-term 

 exposures to ammonia. Fish. Bull., U.S. 78:641-648. 



Rice, S. D., .>\nd r. m. Stokes. 



1975. Acute toxicity of ammonia to several developmental 

 stages of rainbow trout, Salmo gairdneri. Fish. Bull., 

 U.S. 73:207-211. 



U.S. Environmental Protection Agency. 



1974. Methods for chemical analysis of water and wastes. 



U.S. Environ. Prot. Agency EPA-625-16- 74-003, 298 p.. 



Wash., D.C. 

 Vaux, W. G. 



1968. Intragravel flow and interchange of water in a 



streambed. U.S. Fish. Wildl. Serv., Fish. Bull. 66:479- 



489. 



Stanley D. Rice 

 Jack E. Bailey 



Northwest and Alaska Fisheries Center 



Auke Bay Laboratory 



National Marine Fisheries Service, NOAA 



P.O. Box 155 



Auke Bay. AK 99821 



EGG CANNIBALISM IN THE 

 NORTHERN ANCHOVY, ESGRAULIS MORDAX 



Anchovies feed on their own eggs. Egg canni- 

 balism has been reported for the Argentine an- 

 chovy, Engraiz/is anchoita fde Ciechomski 1967) 

 Japanese anchovy, E. Japonicus (Hayasi 1967) 

 anchoveta, E. ringens (Rojas de Mendiola et al/) 

 and the northern anchovy, E. mordax (Loukashkin 

 1970). These studies give no indication whether 

 this cannibalism was a significant part of natural 

 mortality and incidence of cannibalism was in- 

 cluded only as part of a general description of food 

 habits. We provide evidence that egg cannibalism 

 may account for a considerable proportion of 

 natural egg mortality in the northern anchovy. 



Northern anchovy feed by biting larger prey 

 and by filtering smaller ones ( Leong and O'Connell 

 1969). If both large and small prey are offered in 

 the laboratory, northern anchovy in the front of 

 the school bite the larger prey, whereas those at 

 the end of the school feed by filtering the smaller 

 prey (O'Connell 1972). Our laboratory observa- 

 tions indicate that adult northern anchovy feed on 

 their eggs by filtering, whereas even the smallest 

 anchovy larvae (ca. 3-4 mm long) are bitten. Such 

 small larvae are digested beyond identification in 

 30 min, whereas the identifiable whole chorions 

 and fragments may remain in northern anchovy 

 stomachs up to 8 h although the contents of the 

 egg ( embryo and yolk ) are digested after about 2 h. 

 Northern anchovy eggs are prolate spheroids and 

 can be easily distinguished from the spherical 

 eggs of other pelagic spawners in the Southern 

 California Bight. 



Methods 



The incidence of cannibalism in northern an- 

 chovy was estimated from an examination of 31 

 sets of stomach samples, usually of 10 adults each. 

 Samples were taken at the peak of the spawning 

 season, in the Southern California Bight, during 

 March 1976 and 1977 (Table 1). Northern anchovy 

 were collected in a midwater trawl or a commercial 

 lampara net: 28 sets of collections were taken at 

 night between sunset and sunrise and 3 sets 

 during the day. Fish were frozen in liquid nitrogen 



'Rojas de Mendiola, B., N. Ochoa, R. Calienes, and O. 

 Gomez. 1969. Contenido estomacal de anchoveta en cuarto 

 areas de la costa Peruana. Inst. Mar. Peru Inf. Espec. 

 (IM-27),29p. 



FISHERY BULLETIN: VOL. 78, NO. 3, 1980. 



811 



