Study of Biological Response to Regime Shifts and ENSO Events in the Peruvian Humboldt Current Ecosystem

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The principal investigator and others have suggested that there has been a strong biological response to the 1997-1998-regime shift in the California Current Ecosystem (CCE) and that analogous changes are likely in the Humboldt Current Ecosystem (HCE) off Ecuador, Peru and Chile. The PI will be collaborating with an international team of scientists familiar with the HCE to analyze available data, based primarily on acoustic survey and zooplankton and phytoplankton net data collected, regularly and intensively, by the Instituto del Mar del Peru (IMARPE) in Callao, Peru between 1983-2003 (for fish distributions from acoustics), and 1960-2003 (for zooplankton and phytoplankton net samples). The primary aim of this project is to examine the long-term pattern in distribution and abundance in the HCE of the two major pelagic fish species, Anchovy (Engraulis ringens), and Sardine (Sardinops sagax) and of the size distribution and abundance of zooplankton, and to determine their relationship to environmental factors (e.g. currents, temperature, bathymetry, eddy vorticity) and, for the fish, to their primary prey resource, zooplankton. To this end, the research team will test hypotheses concerning the spatial aggregation and overlap of these species, expected shifts in fish and zooplankton abundance and biomass distribution during warm and cold regimes (and the extreme temperature anomaly periods of El Nino and La Nina), and the relationship of anchovy stomach fullness and diet to prey availability. The broader impacts resulting from the proposed activity include providing a biological basis for management of the world's most important fisheries in upwelling systems. The collaboration and training opportunities for work in Peru fulfill a great opportunity to trade data resources for analysis capability and improved opportunity for peer publications by IMARPE scientists.