were carefully checked for squid beaks, fish 

 otoliths, and other small remains of food items. 

 After excess fluid was drained off, the total weight 

 of stomach contents was recorded and a total vol- 

 ume determined by water displacement. Indi- 

 vidual food items were identified, counted, and the 

 percentage of the total volume represented by 

 each type of food item estimated. Fragments of 

 prey species may remain in the stomachs of these 

 animals from 12 to 24 h after feeding; hence hard 

 parts of prey species consumed over the shelf, such 

 as chitinous beaks of squids, fish otoliths, and par- 

 ticularly dense fish bones, may still persist in the 

 stomachs of animals taken well offshore of the 

 shelf. Identification was made by comparison with 

 reference specimens and to descriptions in 

 taxonomic keys or other references. 



Of the 33 dolphin taken off California, 25 were 

 females (9 adult, 15 subadult, 1 probably adult) 

 and 8 were males (3 adult, 5 subadult). Of 11 dol- 

 phin taken off Washington, 8 were females (2 

 adult, 6 subadult) and 3 were males (1 adult, 2 

 subadult). All nine of the Ball's porpoise were 

 adults. 



Scientific names of marine mammals follows 

 Marine Mammal Commission^; of fish, Bailey et 

 al. (1970) and Fitch and Lavenberg (1971); of 

 cephalopods. Young (1972). 



Results 



Pacific White-Sided Dolphin and Northern Fur Seal 



Northern anchovy, Engraulis mordax, was the 

 most frequently occurring fish in the stomachs of 

 white-sided dolphin and northern fur seal taken in 

 all collection months and across the latitudinal 

 range of the collections off California. Most dol- 

 phin were taken off central California between Pt. 

 Conception and Pt. Reyes in the following num- 

 bers by month: 1 in January, 11 in February, 18 in 

 March, 2 in June, and 1 in December. Seal used in 

 comparisons were taken in the same localities at 

 the same times. Northern anchovy remains were 

 identified from 58% (19 occurrences) of the dolphin 

 stomachs and 32% (13 occurrences) of seal 

 stomachs collected in the same localities. 



Pacific whiting, Merluccius productus, was 

 found in 33% (10 occurrences) of the dolphin 



''Marine Mammal Commission. 1976. Marine mammal 

 names. Unpubl. manuscr., 8 p. Marine Mammal Commission, 

 1625 Eye Street, NW, Wash., DC 20006. 



stomachs and 34% (14 occurrences) of the seal 

 stomachs. Pacific whiting was particularly impor- 

 tant in the March 1966 collections at lat. 35° to 38° 

 N (Morro Bay to San Francisco). Pacific saury, 

 Cololabis saira, the third ranking fish, was found 

 in 28% (9 occurrences) of the dolphin but in only 

 7% (3 occurrences) of the seal from the same area. 



Squids of the family Gonatidae were the most 

 frequently occurring cephalopods. Both Loligo 

 opalescens (64% occurrence) and Onychoteuthis 

 borealijaponicus (45% occurrence) were found 

 in the dolphin stomachs in trace amounts only 

 (beaks); however, both species are important seal 

 prey. Abraliopsis sp. was identified only once in 

 seal but found in 16 dolphin stomachs from seven 

 collection locations off California. Stomachs of the 

 nine dolphin collected 25 February 1966 off Pt. 

 Reyes contained a greater variety of fishes and 

 squids than those collected in other locations. 



The food items consumed by 11 dolphin and 14 

 seal collected in the same locality off Washington 

 show salmonids, Oncorhynchus spp., composed 

 most of the stomach contents of 10 dolphin and 12 

 seal taken 25 and 26 February 1968 over the As- 

 toria Canyon, approximately 37-44 km west of the 

 Columbia River (8 occurrences in dolphin, 3 in 

 seal). Flatfishes (Pleuronectidae) were present in 

 one seal stomach. Squid beaks representing nine 

 families, genera, or species of squids were iden- 

 tified from the stomachs of dolphin, but these taxa 

 were of minimal importance in the stomachs of 

 seal collected from the same area, occurring in 

 only 4 of 12 stomachs. One dolphin, taken off the 

 continental shelf, 25 April 1972, contained trace 

 amounts of unidentified fishes and squids repre- 

 senting at least five genera. The stomachs of two 

 seal collected in the same area the same day were 

 empty. 



Dall's Porpoise and Northern Fur Seal 



The stomach contents of 9 Ball's porpoise and 17 

 northern fur seal taken from the same location off 

 California and Washington from 1964 to 1968 were 

 examined. One porpoise was taken in January off 

 southern California and four were taken in Feb- 

 ruary and one in April off central California. 

 Three were taken off Washington, two in January 

 (one taken in the entrance to the Strait of Juan de 

 Fuca) and one in February. Off California, north- 

 ern anchovy. Pacific whiting. Pacific saury, and 

 squids, L. opalescens and O. borealijaponicus, 

 formed major portions of the most recent feedings. 



954 



