Fur seals feed primarily at night, perhaps influenced by the 

 fact that many forage species rise toward the surface after dark 

 and become readily available to fur seals and other predators 

 which feed primarily in the epipelagic and mesopelagic zones. 

 The diel vertical migration of cephalopods was confirmed by 

 studies conducted by Roper and Young (1975) and Pearcy et 

 al. (1977). This vertical migration of squids makes them acces- 

 sible to fur seals foraging in the epipelagic and mesopelagic 

 zones and the waters over the continental shelf. Oceanic squids 

 are some of the principal forage foods of fur seals throughout 

 their entire range in the eastern North Pacific Ocean and east- 

 ern Bering Sea. Bathylagids, deepsea smelts, also become 

 available to fur seals because of their vertical migration 

 towards the surface at night. Anchovies also display diel verti- 

 cal movements, rising to the surface at night and dispersing as 

 dawn approaches when they school tightly and return to 

 deeper depths. On occasion, anchovies form large dense sur- 

 face schools during daylight hours. 



Fur seals seeking food are not limited to prey that are found 

 near the surface as depth-time recorders placed on fur seals in 

 the wild recorded depths of dives to 208 m (624 ft) which lasted 

 for 5.4 min. 3 



In the majority of fur seal stomachs examined, the quantity 

 (total volume) of food in stomachs is generally highest in fur 

 seals collected soon after daylight. It gradually diminishes by 

 mid-afternoon and increases again towards dusk as the seals 

 increase their feeding activities. The graph shown in Figure 3 is 

 obtained when the fraction of fur seal stomachs containing 

 food is plotted against time (hour) of collection. 



Fur seals usually swallow small prey whole below the surface 

 and bring larger prey to the surface where they break them into 



■R.L. Gentry, National Marine Mammal Laboratory, Northwest and Alaska 

 Fisheries Center, NMFS, NOAA, 7600 Sand Point Way NE., Seattle, WA 981 15, 

 pers. commun. March 1982. 



smaller pieces before consuming. Fur seals are not necessarily 

 limited to eating small fish. During pelagic sampling one large 

 fish (a 160 cm long king-of-the-salmon, Trachipterus altivelis) 

 was taken away from a fur seal as it was in the process of 

 eating it (Niggol et al. 1959"). 



The predominance of single food items in the stomachs of 

 fur seals may reflect the availability and abundance of fish- 

 squid species more than it reflects the selection or preference 

 of one particular species over another. Location is important 

 when considering diet of fur seals as prey species generally dif- 

 fer in abundance from area to area (north-south; inshore- 

 offshore) and by season of the year. The migratory patterns of 

 forage species must be considered since they may be available 

 to fur seals only at certain times of the year. For example, 

 Pacific (hake) whiting, Merluccius productus, does not 

 become one of the important or leading forage species off the 

 Washington coast until spring when it migrates into the area 

 and then becomes available to fur seals. 



Generally speaking the migration of fur seals is probably not 

 influenced by the movement of migratory fishes on which they 

 feed but is simply dependent on the collective abundance of 

 the forage species in the area, the fur seals waiting to feed 

 where food is abundant and "moving on" when it becomes 

 scarce. Exceptions do occur as fur seals were reported abun- 

 dant in the West Crawfish Inlet in 1950 and 1951 when Tlingit 

 sealers took 148 seals feeding on spawning herring (Kenyon 

 and Wilke 1953). In 1958, fur seals were found in Silver Bay 

 but not in West Crawfish Inlet. The movement of fur seals into 

 restricted bays in pursuit of prey usually involves only a small 

 portion of the population. Most fur seals occupy the open 

 ocean and are usually not found close to land or in protected 

 waters. Notable exceptions are yearlings which may be found 

 in southeast Alaska or British Columbia protected waters. If 

 the animal is injured or is sick, it may appear and haul out 

 some distance from its usual habitat. 



Pike et al. (1961 ! ) reported that yearling seals are known to 

 appear in the vicinity of Knight Inlet, B.C., beginning in 

 December and January and remain until March and April 

 feeding on spawning populations of eulachon, Thaleichthys 

 pacificus. Experience concerning seals "moving on" in 

 response to food abundance or due to changes in oceano- 

 graphic conditions as related to this study occurred off the 

 Washington coast during the April and May spring collections 

 of 1970 and 1972. Fur seals were generally abundant on the 

 continental shelf area off the Washington coast during April 

 of both years. However, during May of both years, seals were 

 nowhere to be found on the continental shelf which necessi- 

 tated surveying offshore waters (beyond the continental shelf 

 over deepwater areas). Seals were located seaward of the shelf 

 feeding on oceanic squids. Oceanic squids thus became the 

 principal food consumed by fur seals off Washington during 



TIME 



Figure 3. — General trends in the percentage of stomachs containing food in 

 relation to time of collection. 



'Niggol, K., C. H. Fiscus, and F. Wilke. 1959. Pelagic fur seal investigations 

 California, Oregon, and Washington, 1959. Unpubl. rep., 92 p. U.S. Fish Wildl. 

 Serv., Mar. Mammal Res., Seattle, Wash. (Avail. Natl. Mar. Mammal Lab., 

 Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 7600 Sand 

 Point Way NE., Seattle, WA 98115.) 



'Pike, G. C, D. J. Spalding, I. B. MacAskie, and A. Craig. 1961. Report on 

 Canadian pelagic fur seal research in 1961. Unpubl. manuscr., 35 p. Fish. Res. 

 Board Can., Biol. Stn., Nanaimo, B.C. (Avail. Pac. Biol. Stn., Dep. Fish. Oceans, 

 P.O. Box 100, Nanaimo, B.C. V9R 5K6 Can.) 



