study was conducted to determine the amount of 

 predation, if any, by dogfish on salmon smolts as 

 they descended the Fraser River, British Colum- 

 bia (Chatvvin and Forrester, 1953). In the river 

 mouth, 249 dogfish were examined and 20 (8 per- 

 cent) had empty stomachs. Of those that con- 

 tained food, 100 percent contained eulachon (a 

 smelt, Tlutleichthys pacificus), or traces of it, 5 

 percent contained sand lance, Ammodytes. and 19 

 percent contained invertebrates, including shrimp, 

 crabs, small crustaceans, squid, and octopus. A 

 large number (21 percent) contained sticks and 

 leaves, no doubt ingested accidentally with the 

 food items. Outside the river mouth, the dogfish 

 diet was much the same : 91 percent eulachon, 29 

 percent invertebrates, and 5 percent sticks and 

 leaves. Miscellaneous food items included a 

 honeybee and polychaete worms. On the basis of 

 their findings the authors concluded the spiny dog- 

 fish was an opportunistic feeder. 



Another study in the same general area was made 

 by Bonham (1954) who examined more than 1,100 

 spiny dogfish stomachs, of which nearly 60 per- 

 cent contained food. He found more than 77 dif- 

 ferent food items; fish constituted two-thirds of 

 the diet. The three most common food items were 

 ratfish, Hydrolagus colliei, (20 percent) ; herring, 

 Olupea harengus paUasii, (18 percent) ; and krill, 

 Euphausiidae, (9 percent). The only evidence of 

 cannibalism was the finding of a 230-mm (new- 

 born?) dogfish pup in the stomach of a large preg- 

 nant female. Bonham concluded, "Large and 

 small dogfish eat much the same kind of food, with 

 the exception of very small dogfish in whose diet 

 worms and other mud-inhabiting organisms ap- 

 pear prominently." 



Sato's (1935) studies of the spiny dogfish in the 

 water around Japan indicate that clupeoids are 

 important in the diet in this area as they are in 

 other parts of the world. He examined the stom- 

 ach contents of 128 dogfish collected in gill and 

 set nets in June and July. Sixty stomachs con- 

 tained fish; 48 contained sardines, Sardinops 

 ■s-aga-x melanosticta; and 12 contained other fishes, 

 including herring, Olupea harengus pallasii, sal- 

 mon OncorhynckvA keta, and cod, Gadus macroce- 

 phalus. Invertebrates were found in 21 stomachs. 



In waters north of Japan, around Sakhalin. 

 food items found in the stomachs of spiny dogfish 

 were noted by Kaganovskaia (1937). The items 



were listed simply as herring, iwashi (sardine), 

 cod, octopus, crab, squid, and sea cucumbers. 



Food habits of the dogfish in the North Atlantic 

 are quite similar to those of the dogfish in the 

 Pacific. From waters around the British Isles, 

 Ford (1921) reported food items from 143 spiny 

 dogfish with recognizable stomach contents. 

 Fishes were found in 137 stomachs and included 

 herring and pilchard (67 percent), mackerel (19 

 percent), and gadids (4 percent). Six stomachs 

 contained Crustacea, and three had mollusks. The 

 stomachs were collected at a time when the clupe- 

 oids and mackerel were abundant and thus readily 

 available to the dogfish. 



In the Northwest Atlantic, around Newfound- 

 land, capelin, Mallotus villosus, are important in 

 the diet of the spiny dogfish. Templeman (1944) 

 made a casual examination of 24 dogfish stomachs 

 collected in July 1942 and found all of them con- 

 tained capelin. During this month the capelin 

 were plentiful on the inshore grounds and the dog- 

 fish appeared to be feeding almost exclusively on 

 them. He notes, "Some of the stomachs were full 

 of capelin, one containing 13 capelin, 1 of 7 cm. 

 and 12 from 14 to 19 cm. long." 



From August to November, Templeman (1944) 

 made a detailed analysis of 1,171 dogfish stomachs 

 of which 665 were empty, 367 contained only the 

 bait used to capture them, and 139 contained food. 

 In the stomachs that contained food, about 60 

 percent contained fishes, about 45 percent con- 

 tained Crustacea, about 8 percent contained coelen- 

 terates, and a few contained mollusks, polychaetes, 

 algae, and miscellaneous items. The recognizable 

 fishes were herring (14 percent), capelin (5 per- 

 cent), and cod (5 percent). 



In the Gulf of Maine, spiny dogfish feed on a 

 wide variety of species and at one time or another 

 prey on practically all species smaller than them- 

 selves. They are regarded as the chief enemy of 

 the cod, and also feed on mackerel, haddock, her- 

 ring, squid, worms, shrimps, and crabs. They are 

 one of the few fishes that eat ctenophores (Bige- 

 low and Schroeder, 1953) 



My own observations of spiny dogfish stomach 

 contents have revealed a curious condition in which 

 the stomachs were distended with a clear watery 

 fluid. Casual observations of 50 dogfish stomachs 

 collected during a cruise of the research vessel 

 Delaware in June 1961 on Stellwagen Bank re- 



LIFE HISTORY OF SPINY DOGFISH 



535 



