November 2005 MODEL Workshop, Tokyo Japan

Background and Objectives:

Large scale, global fluctuations in populations of sardines and anchovies have been observed for the past century. The amplitude of fluctuation is high and contribute a disproportionate share of the total variability of the world harvest of fish. There are several intensive fishery grounds for sardine and anchovy and sardine and anchovy show asynchrony in all areas. Moreover, sardine shows synchrony in the whole Pacific (Humboldt Current, California Current, and Kuroshio Current areas). On the other hand, sardine does not show any systematic synchrony between Pacific and Atlantic. The out-phase asynchrony between sardine and anchovy reflects not only the differences of the life histories of them, but also bottom-up process driven by climate shifts. The in-phase synchrony of sardine population in the whole Pacific also suggests a bottom-up, climate driven component. This climate induced variability have attracted many scientists in the world and an international symposium "Long-term variability of pelagic fish populations and their environment" was held in Japan more than 15 years ago, in 1989. In the symposium, the sardine variability in the world were synthesized and some factors cause the variability were discussed. However, in recent decade, model techniques represent ecosystem response to the climate changes and computer powers have been evolved rapidly. For example, PICES MODEL Task Team built up an community ecosystem model "North Pacific Ecosystem MODEL for Understanding Regional Oceanography (NEMURO)", embedded with a fish bioenergetics model and applied to herring and saury, and compared their responses to the same climate scenarios. In this workshop, focused on sardine and anchovy, 1) inter-annual and inter-decadal variability of marine ecosystems in key regions in the world are re-reviewed as the revisit of the 1989's symposium, 2) factors may cause the variability are discussed, 3) models applied to the variability are reviewed and 4) common model approaches applied to the world wide synchrony and asynchrony of sardine and anchovy are discussed and compare the response of them to the climate change in the model are compared in the key areas.

The files presented here are copies of the model code, data files and output that were generated at the meeting. Full details of the workshop and detailed documentation of the model can be found in the workshop report.