SALMON AND TROUT IN ALASKA. 



61 



arrangement of the gillrakers, and the few observations made on feed- 

 ing fish, it may be surmised that the hirger part of their nutriment is 

 derived from pelagic Crustacea and associated forms. They are 

 known to feed at times on small fishes. In striking into a school of 

 small fish from below they might be led to broach the surface. In 

 towing for plankton food there would be no such occasion. No 

 authentic observation of sockeyes in open ocean has been reported, 

 but inasmuch as no search has been made for them the matter 

 remains without evidence. It is probable that they do not jump in 

 feeding, and thus they are unobserved up to the time they start for 

 the spawning beds. 



FOOD AND FEEDING. 

 THE SOCKEYE. 



It is reported that the Fraser River schools, even before leaving 

 Juan de Fuca Strait, have ceased to feed. In Southeast Alaska it was 

 found that a certain percentage of the earlier catches, even at the 

 mouths of the rivers they were presumed to be entering, were still 

 feeding:. This is shown in the followinp; table: 



Food op Adult Sockeyes. 



a Ammodytes. 



b Ammodytes, except 1 with herring. 



c In the last 111 examined, .\ug. 20 and 21, the stomachs were all empty. 



d Many stomachs with medusa?, some with purple ctenophores (?), which occur in about 50 fathoms 

 of water in daylight. 



< Mostly larval crabs; also some small schizopod (?) fonns. 



/ In the 5" examined on Aug. 29, all stomachs empty. 



,7 Mostly a small shrimp-like form. 



h Ammbclytcs. Crustacea, mostly as above, but also crab larv;t>. No food in stomachs of the 69 

 examined on July 24. 



» The 100 examined Aug. 21 were empty. 



