SQUIRE: PELAGIC MARINE FISHES OFF SOUTHERN AND CENTRAL CALIFORNIA 



Northern anchovy (Figure 8) — Data indicate 

 that the northern anchovy is observed more fre- 

 quently and in abundance during the night; 

 therefore, the night index should better reflect 

 the apparent abundance of this species. The 

 night index increased from 2.99 in 1963 to 4.30 

 in 1967, declined in 1968 to 1.46, and increased 

 to a high level of 4.35 in 1969. 



1963 



1964 



1965 



1966 



1967 



1966 



1969 



Figure 8. — Total catch and average index values for the 

 northern anchovy. 



Yellowtail and barracuda — Indexes have de- 

 clined for both species (see Table 7) ; however, 

 the frequency of observation was low, and no 

 comparisons can be made with trends in abun- 

 dance. 



The relation between the trend of the apparent 

 abundance index and of the trend of abundance 

 estimates, where available, are discussed for the 

 following species: 



Pacific sardine — During the period 1963-1969, 

 the Pacific sardine population continued to de- 

 cline to a very low level, and the population is 

 now at a fraction of that calculated for the 1930's 

 and 1940's. Since no recent annual estimates 

 are available (latest is 190,000 tons for 1959), 

 a direct comparison of the estimates of total 

 abundance with the index of apparent abun- 

 dance cannot be made; however, the trend of 

 the index follows closely the downward trend 

 of the commercial catch. 



Pacific mackerel — The Pacific mackerel fishery 

 in southern California has been the subject of 

 comprehensive research by the California De- 



partment of Fish and Game for many years. For 

 purposes of comparison between trends of the 

 index and population estimates, the more recent 

 data for Pacific mackerel provides the best 

 source of comparative statistics. 



The Pacific mackerel catch has declined to a 

 low level in recent years, and the trend of the 

 index follows closely the catch decline (see Fig- 

 ure 5). Population estimates have been calcu- 

 lated by a number of workers. Blunt and Par- 

 rish (1969) summarized the knowledge of this 

 fishery and reported estimates of total spawning 

 biomass of 160 million pounds in 1963. Blunt' 

 (personal communication) computed revised es- 

 timates for California waters using a modifi- 

 cation of the Murphy method (Murphy, 1966). 

 Revised figures indicate a spawning biomass of 

 64.5 thousand tons in 1962 and 78.5 thousand 

 tons in 1963 reducing to less than 5,000 tons in 

 1968, an 84% or more, decline from 1963. The 

 night index follows this 847^ decline in estimated 

 spawning biomass with an 89% index decline 

 from 1.26 in 1963 to 0.14 in 1966 and to less 

 than 0.00 in 1968. 



Jack mackerel — Jack mackerel total abun- 

 dance estimates are derived from egg and larval 

 surveys. Ahlstrom (1968) estimated the adult 

 spawning population in 1951-1954 for the Cal- 

 ifornia area to be between 1.4 and 2.4 million 

 tons and that the resource was "much to moder- 

 ately underutilized." In 1968 he estimated the 

 population level to be approximately the same as 

 was found in the earlier years. 



The commercial fishery has experienced a sub- 

 stantial decline in catch over the past years and 

 has extended its fishing grounds further offshore. 

 Ahlstrom (1968) indicated the spawning popu- 

 lation is centered in the oceanic waters. Blunt 

 (1969) reported that in this offshore area the 

 population is comprised of mature adults, some 

 reaching the age of 30 years. The young fish 

 remain inshore until 3 to 6 years old and then 

 inhabit the offshore waters where they are out- 

 side the range of the normal fishery. The night 

 aerial index shows a decline in apparent abun- 



* C. E. Blunt, Jr., California Department of Fish ana 

 Game, Marine Resources Brancsh, 1416 Ninth St., Sac- 

 ramento, CA 95814. 



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