Further sustained expansion of landings of yellow- 

 fin tuna IVoni domestic vessels thus being unlikely, there 

 was now an imperative need to increase the harvest of 

 underutilized species of tuna or face an ever-increasing 

 dependence upon foreign-cauglit fish. Fortunately, it 

 appears possible that the skipjack tuna (Katsuwonus 

 pclamis) population and perhaps those of the temperate 

 tunas are not fully harvested and ways of increasing the 

 take of these species by California vessels are now being 

 studied within the Fishery-Oceanography Center. 



This work is aimed at the solution of two related 

 but different sets of problems. First, the problems with 

 the search for new fishing grounds for skipjack tuna in 

 the tropical waters to the west of the present fishing areas 

 off Central America, along the routes by which they mi- 

 grate to and from the Central Pacific. This search in- 

 volves seasonal surveys of the biological and physical 

 oceanography of wide areas of the eastern tropical Pacif- 

 ic, and also studies of methods for artificially aggregating 

 the rather widely dispersed skipjack tuna in these oceanic 

 regions so that they may be caught. Second, the prob- 

 lems of how tuna react to changes in the environment 

 while migrating and feeding must be studied so that 

 week-to-week movements of fish in response to moni- 

 tored environmental conditions may be predicted in real 

 time and the United States fishing vessels so advised (as 

 are the Japanese on their fishing grounds). 



The salmon fishery off northern California has 

 maintained ratiier stable landings since the late 1930's, 

 thougli their value has increased. State agencies and the 

 Bureau of Sport Fisheries & Wildlife are both active in re- 

 search in this fishery and so far the Fishery -Oceanography 

 Center has not been asked to participate. 



In comparison with the others, the industrial fish- 

 ery is deeply in trouble; known in California as the 

 "wetfish fishery." it uses many pelagic species in the 

 California Current, which are reduced to fish meal and 

 oil, canned as inexpensive canned products (largely for 

 export) and processed into various animal foods. The 

 decline of this fishery from the days of its great pros- 

 perity in the 1930"s and I940's (the heyday of Cannery 

 Row) to its present state is well known. In 1939, 

 the landings exceeded half a million tons and by 1966 

 they had fallen to little more than 60,000 tons. 



Most of this decline is attributable to the cata- 

 strophic collapse of the northern subpopulation of the 

 Pacific sardine (Sardinops caemleits) which began during 

 the 1940's and reached a nadir in the I950"s. In 1939, 

 the landings of this species were 79 percent by weight 

 and 34 percent by value of the total California landings; 

 from just half a million tons in 1939 they fell to a few 

 hundred tons in 1966. 



In 1949, in response to the evident decline in land- 

 ings, the Fish and Wildlife Service and State laboratories 

 began intensive and cooperative research on the California 

 sardine within the framework of CalCOFI, thus formaliz- 

 ing cooperative sardine research that began earlier. It be- 

 came evident after some years of work that the prob- 

 lem of the Pacific sardine was due to an interaction 

 among heavy fishing, climatic changes which reduced 

 spawning success, and subsequent ecological competition 

 of a related species, the northern anchovy (Engraulis 

 mordaxj. That a fishery has not developed for the ex- 

 panding anchovy population is caused by a complex set 

 of constraints; the low price of the raw product com- 

 pared with the sardine, both inherently and because of 



lH^ 



Purse seiners. 



G. Mattson 



