Resumen del producto

Some climate models predict that over the next decade natural climate variability may counteract the underlying anthropogenic warming trend in some ocean regions and may even cool slightly during this period. Possible scenarios of fluctuating climate change are distributional and composition changes of pelagic species. A previous large-scale, long-term analysis of the California Current system (CCS) suggests that climatic regime shifts in the northeast Pacific appear to have forced a changing population size associated with major geographical variations in the position of the center of distribution and bulk of the biomass of Pacific sardine (Sardinops caeruleus). This finding allows an explanation of i) the disappearance of the sardine population about 60 years ago from the northern part of the CCS, and also its return after the 1980s, and ii) the inverse relation of sardine and Northern anchovy (Engraulis mordax) abundance. This differs from theories suggesting that environmental regime shifts lead to progressive population-level changes within assumed geostationary stocks. The question arising is if this natural pattern of variation is only recorded in the Pacific sardine. In this work 1) the large-scale, long-term (1931- 1997) variability of tropical species in the CCS is included in the sardine-anchovy analysis, and 2) examples are shown for other pelagic and benthic species and communities from other ecosystems, where changes of abundante are also associated with changes in the center of distribution. We discuss the importance and implications of this spatial process in contrast to simple latitudinal extension shifts into the management of fisheries.

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