Significant Spearman rank correlations were not found for com- 

 parison of aerial to larval and acoustical survey data for 1963-72. 

 Comparison of aerial and acoustical survey indices for the period 

 1972-78 gave a significant correlation (r, = 0.810, P = 0.05). Dur- 

 ing this period, only three larval surveys were conducted, not an 

 adequate sample for calculating a correlation. MacCall et al. (1976) 

 calculated a correlation coefficient of +0.30 for larvae vs. aerial 

 (night) surveys during 1962-66, and for 1968 and 1969. More 

 recently, an anchovy spawning biomass estimate based on egg pro- 

 duction has been developed (MacCall et al. 1982). The correlation 

 between the aerial (night) anchovy index with the new biomass esti- 

 mate is very high (Fig. 64). 



The aerial night index appears to be closely correlated with the 

 acoustical index developed during the years since 1971 . Larval sur- 

 veys cover a larger geographical area than either the aerial or acous- 

 tical surveys, generally extending further offshore. The aerial 

 survey involves only the nearshore area where the purse seine fish- 

 ery operates. This area commonly has large concentrations of near- 

 surface schooling fish and suitable sea-state conditions for purse 

 seining, conditions which are not common in the offshore areas. 



The anchovy night aerial abundance index was not unusually 

 high during the first years of the surveys compared with levels 

 observed in 1973-76. The aerial surveys were started about the 

 time the anchovy population was reported by Ahlstrom (1968) to 

 have reached a plateau in about 1962. The anchovy larvae index for 

 the central subpopulation declined during 1965-72. increased 

 slightly in 1975, then declined sharply in 1978. The aerial and 

 sonar indices rose two or more times their former levels to high lev- 

 els in 1973 and 1975, then declined, with the aerial index declining 

 to slightly below pre- 1972 levels. 



The geographical area covered by the aerial survey program con- 

 tained the major commercial fishing grounds. High abundance 

 level indices from the aerial spotter data were not evident for this 

 area, which apparently did not benefit from the high larval index 

 levels that started in 1962 and resulted in population estimates of 

 4.0 to S-OxlO 6 t (Ahlstrom 1968). However, a significant but 

 unexplained change to high aerial and acoustic index trends 

 occurred in the fishery during 1973-75. prior to a rapid decline dur- 

 ing 1976-78, in the larval, acoustical, and aerial indices. 



Pacific Bonito 



Studies have been made using the aerial day index of Pacific 

 bonito observed off southern California, in correlation with recrea- 

 tional partyboat CPUE. using yearly time-lag periods (MacCall et 

 al. 1976). The recreational fleet which fishes nearshore generally 

 catches younger fish than the commercial purse seine fleet. The 

 highest correlation between the recreational fleet CPUE and the 

 aerial apparent abundance index for the commercial fishery was for 

 a 3-yr lag period (r= 0.69) which is shown in Figure 65. We believe 

 this correlation to be useful in predicting recruitment into the 

 commercial fishery, based on partyboat CPUE. 



SUMMARY 



The aerial index data is positively correlated with the trend of 

 other measures of apparent abundance, particularly the acoustical 

 survey (post-1971) for anchovy abundance. For the limited amount 

 of comparable data available, the Pacific mackerel aerial index 

 appears to correlate well with the biomass estimates. The index lev- 

 els of Pacific bonito. a species that is more common to the south, 

 show trends that appear to parallel the trend of the biomass. 



Index trends for both the northern anchovy, beginning in 1974. 

 and Pacific bonito, in 1968 and 1973, show a pronounced down- 

 ward slope one to two years before major declines occurred in these 

 fisheries. 



This program has used the available talents of commercial fish 

 spotters who use standard visual techniques to observe pelagic 

 schooling fish. In recent years, airborne electronic surveillance 

 systems specifically designed to measure the extent of the available 

 near-surface schooling resources at night have been developed. 

 These new techniques, if used in close coordination with 

 commercial operations and research studies, could produce for the 

 program a more refined estimate of apparent abundance, not only 

 for the fishing areas commonly surveyed by the commercial spot- 

 ters but also for areas farther offshore where resources such as the 

 anchovy are commonly observed during the winter-spring spawn- 

 ing season. 



All analyses to date have involved only the production of basic 

 apparent abundance indices, and have not been further adjusted to 

 produce a more refined index or estimates of biomass. The aerial 

 apparent abundance data should be further analyzed to provide 

 more refined estimates of abundance for the major pelagic species. 

 Studies are currently in progress to do this. 



ACKNOWLEDGMENTS 



The cooperation and interest of the commercial aerial fish spot- 

 ters over a period of 16 yr is sincerely appreciated by the author. 

 Spotter pilots who participated in the program are some of the best 

 talents in the profession: John Bourgois, C. L. Devillier, Ed Dur- 

 den, Leon Durden, Jim Ferreri. Roger Hillhouse, Frank Iacono, 

 Jack Mardesich, Paul Mardesich. Tony Marinkovich, Joe Miles, 

 John O'Connor. Chuck Rogers, Jack Whalen, and Andy Witmer. 



In addition to the Acknowledgments given in the earlier review 

 (Squire 1972), I would like to acknowledge the assistance of Jim 

 Zweifel who gave valuable advice relative to statistical processing, 

 and to Michael Klicpera for conducting the analysis of trends for 

 the acoustical, larval, and aerial indices. 



LITERATURE CITED 



AHLSTROM. E. H. 



1968. Anevaluaiion of fishery resources available to California fishermen. In 

 D. Gilbert (editor). The future of the fishing industry of the United States, p. 

 65-80. Univ. Wash. Publ. Fish., New Sen 4. 

 MacCALL. A.. G. D. STAUFFER. D. HUPPERT. and H. FRY. 



1982. Draft fishery management plan for the northern anchovy fishery. Pac. 

 Fish. Manage. Counc. 

 MacCALL. A. G. D. STAUFFER. and J -P. TROADEC. 



1976. Southern California recreational and commercial marine fisheries. Mar. 

 Fish. Rev. 38(1): 1-32. 



MAIS. K. F. 



1974. Pelagic fish surveys in the California Current. Calif. Dep. Fish Game. 

 Fish. Bull. 162. 79 p. 



MARR, J. C. 



1 95 1 . On the use of the terms abundance, availability and apparent abundance 

 in fishery biology. Copeia 1951:163-169. 

 MILLER. F R.. and R. M. LAURS. 



1975. The El Nino of 1972-1973 in the eastern tropical Pacific Ocean. [In Engl, 

 and Span.] Inter-Am. Trap. Tuna Comm. Bull. 16:403-448. 



SMITH. P. E.. and S. L. RICHARDSON. 



1977. Standard techniques for pelagic fish egg and larvae surveys. FAO Fish. 

 Tech. Pap. 175. 100 p 



SQUIRE. J. L .JR. 



1967. Observations of basking sharks and great white sharks in Monterey Bay, 



1948-50. Copeia 1967:247-250. 

 1972. Apparent abundance of some pelagic marine fishes off the southern and 

 central California coast as surveyed by an airborne monitoring program. 

 Fish. Bull. U.S. 70:1005-1019. 



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