Physical, biological and economic interconnections in the ecosystems and fisheries off California, 1877-2004

摘要

Comparisons of variation in physical, biological and economic indicators from 1877 to 2004 indicate that events in the physical ocean environment off California can be traced through the ecosystem to the commercial fishers' economic environment. The annual landed weight of 29 commercial fish and invertebrate species, with various life histories and trophic associations, were used in an empirical orthogonal function analyses to isolate two major patterns of variation in the landings and form a graphical ecospace. This ecospace shows that dominant species associations have occurred in the landings during particular time intervals. These changes in ecospace are closely correlated to variation in physical environmental indices (r~2 ＞ 0.8). The analysis indicates that 50% of the landings variability is summarized in the two patterns, which represent variation at intervals greater than 40 years and less than 20 years. When the independently derived fish landings series are lengthened using published data and proxies, the physical to ecological to economic linkages are shown to occur from the late 19th century until 2004. When the purse seine fishery failure of the early 1920s and the growth of sardine cannery infrastructure from 1900 to 1945 are examined, results are consistent with perturbations beginning in the physical environment that are transferred through the ecosystem to influence the fishers' harvest opportunities. These harvests will then influence future fisheries investment.