Figure 15. — Food web involving commercially important and abundant fish, 

 birds, mammals, and squid Loligo opalescens (modified from Morejohn et at. 

 1978). 



birds in the eastern North Pacific Ocean. Seabirds are oppor- 

 tunistic feeders, foraging on smaller abundant schooling orga- 

 nisms such as euphausiids, squids, clupeids, and engraulids. 

 Ainley (1980) described seabirds as marine organisms (similar 

 to fish and marine mammals) because they are full-time parti- 

 cipants in marine energy cycles as they derive all their food 

 from the sea. Seabirds however, travel above the sea's surface 

 instead of being confined to water, spending some time on 

 land to raise their young, as do pinnipeds. 



Northern anchovy. — The northern anchovy is one of the 

 major forage species utilized by fur seals wintering off Califor- 

 nia and has been among the top four forage species consumed 

 by fur seals during every monthly collection (January through 

 June) off California (Fig. 7). The locations where fur seals 

 were taken whose stomachs contained anchovy is shown in 

 Figure 16. The northern anchovy is also the most abundant 

 and largest fishery resource in the California Current System 

 based on CalCOFI surveys and on acoustic-midwater surveys 

 (Ahlstrom 1968; Frey 1971; Mais 1974). Anchovies, which are 

 extremely abundant off southern California are heavily preyed 

 upon by most predatory species (fishes, seabirds, squids, pin- 

 nipeds, and whales) in the California Current (Fig. 15). This 

 species contributed 74% of the total stomach content volume 

 in fur seals taken off California in 1966 (Marine Mammal Bio- 

 logical Laboratory 1969). Anchovy are also cannibalistic, feed- 

 ing on their own larvae and eggs (Hunter and Kimbrell 1980). 

 The extensive use of anchovy as bait in commercial and sport 



ot» 



Figure 16.— Locations off California where 843 northern fur seals were collected 

 whose stomachs contained northern anchovy, 1958-66. 



fisheries also shows its acceptance as food for a wide variety of 

 fishes. 



The largest concentrations of anchovies are usually found 

 between San Francisco and Magdalena Bay, Baja California, 

 with general distribution from the Queen Charlotte Islands, 

 British Columbia, south to Cape San Lucas, Baja California, 

 Mexico. The anchovy biomass increased tremendously during 

 1952-62 from about 640,000 to over 6 million tons (Fig. 17). 

 Since 1962, the anchovy biomass has remained high, fluctu- 

 ating between 5 and 8 million tons in a population consisting 

 of three subpopulations (Fig. 17). North of the CalCOFI sur- 

 vey area, large concentrations of the anchovy have also been 

 reported along the Oregon and Washington coasts. The an- 

 chovy is also one of the principal forage prey of fur seals off 

 Washington during February, March, and April (Fig. 9). Al- 

 though most fishes and squids rise toward the surface after 

 darkness, the anchovy is also known to form large dense sur- 

 face schools during daylight hours. 



The known or suspected predators of anchovies including 

 marine birds, mammals, fishes, and invertebrates have been 

 summarized by Huppert et al. (1980). During pelagic fur seal 

 operations off California, Pacific whiteside dolphins, Lage- 

 norhynchus obliquidens, California sea lions, Zalophus cali- 

 fornianus, fur seals, and seabirds have been observed feeding 

 in the same school of anchovies. In many instances, concentra- 

 tions of birds in the distance usually indicated schools of an- 



15 



