306 



Economic Aspects 



sance, sonar, and other devices. This same 

 short supply of sardines resulted in an in- 

 creased catch of anchovy and jack mackerel 

 as sardine substitutes. 



The tunas are also well-known products 

 of the California fishery, with the bulk of 

 those caught in the southern California re- 

 gion being albacore. Others that occur here 

 but are usually obtained more abundantly in 

 Mexican and more southerly waters are the 

 bluefin, yellowfin, and skipjack tunas. Large 

 number of tunas, chiefly albacore, are caught 

 by sportfishing party boats; these are not 

 included in Figure 236, but they usually con- 

 stitute only about one-tenth of the commer- 

 cial catch. Because the tuna fishery de- 

 creased markedly about the same time as 

 did the sardine fishery, a Scripps Tuna 

 Oceanography Program sponsored by the 

 U. S. Fish and Wildlife Service was initiated 

 in 1957 to learn more of these fish and the 

 factors that control their abundance. 



Among the "other fish" of Figure 236 are 

 croaker, halibut, rockfish, salmon, sea bass, 

 shark, sole, swordfish, crab, lobster, abalone, 

 and squid, each of which totaled more than 

 100 tons for waters off" southern California in 

 1956. Abalone, a marine gastropod, is more 

 or less characteristic of southern California 

 and has been landed commercially in 

 amounts that have increased from 9 tons in 

 1926 to 2100 tons in 1956, mostly at Santa 

 Barbara. An unknown but probably larger 

 catch of abalone has been made by skin 

 divers whose activities have largely elimi- 

 nated abalones in easily accessible areas and 

 depths off the mainland shores. A similar 

 depletion of lobsters has resulted from skin 

 diving by the large number of week-end 

 enthusiasts. 



The decrease in sardine catch, paralleled 

 by other fishes, since 1950 cannot reliably be 

 ascribed to either overfishing or to natural 

 variation produced by population cycle or 

 migration induced by changes in water tem- 

 perature or other water characteristic. In 

 order to determine the cause and thence to 

 predict the return of sardines, a program of 

 study of oceanographic and fishery factors 

 was initiated in 1947 as the California Co- 

 operative Oceanic Fisheries Investigations, 



financed by a special tax on fish landings and 

 by appropriations of the California Legisla- 

 ture. This is a combined project of Scripps 

 Institution of Oceanography, the California 

 Department of Fish and Game, the Califor- 

 nia Academy of Sciences, and the U. S. Fish 

 and Wildlife Service. The six progress re- 

 ports published between 1950 and 1958 

 (Marine Research Committee, 1958) sum- 

 marize many data on oceanic temperatures 

 and currents, plankton crop, and fish eggs 

 and size classes. However, in general the 

 findings so far have been inconclusive. An 

 estimated 15 to 20 per cent of the total stand- 

 ing population is caught annually, regardless 

 of effort beyond a certain point, but it is still 

 not clear whether variations in the standing 

 population are due to man's fisheries or to 

 other causes. An example of the difficulty 

 of evaluation is the fact that low tempera- 

 ture of water is commonly related to intense 

 upwelhng and high concentrations of nutri- 

 ents which should produce much phyto- 

 plankton, zooplankton, and finally sardines, 

 but the same low temperatures may inhibit 

 spawning of sardines if spawning occurs in 

 the same areas as feeding. Empirical rela- 

 tionships between water temperature and 

 sardine catch may indicate that the two are 

 directly related, particularly for 1958 when 

 the high water temperatures (Fig. 120) (Stew- 

 art, Zetler, and Taylor, 1958; Marine Re- 

 search Committee, 1958) are reflected in un- 

 usually large catches of sardines, which are 

 evident even though the catch data are in- 

 complete. Coupled with the return of warm 

 water, high sea level, and sardines was the 

 first appearance off southern California for 

 many years of many tropical fishes such as 

 dolphin fish, sailfish, manta rays, hammer- 

 head sharks, and green turtle. When placed 

 on a longer time scale (Fig. 236), the tem- 

 perature of the water is less clearly related 

 to the catches of sardines. It is evident that 

 new efforts, perhaps with a new orientation, 

 are needed to solve the problem of sardine 

 populations. 



Recent studies of the sea floor topography 

 aboard R/V Velero IV using the Precision 

 Depth Recorder (Luskin, Heezen, Ewing, 

 and Landisman, 1954) showed the common 



