Assessment of the north – center stock of Peruvian anchoveta (Engraulis ringens Jenyns) using an age structured model

Abstract

An age – structured model was carried out to estimate the mean abundance, biomass, spawning biomass and recruitment of the north – center stock of Peruvian anchoveta from 1962-63 to 2007-08, based on biological years (October to September). The model used a forward approach, and was optimized by minimizing the departures of modeled estimations from independent observations of biomass, landing and age structures of landings. Results showed the existence of three productivity regimes: the first from 1962-63 to 1970-71 with the highest mean abundance, biomass, spawning biomass and recruitment; the second, from 1971-72 to 1990-91, with the lowest population levels; and the third, from 1991-92 to 2007-08 with medium population levels. It seems clear that after the 1970 and 1980 collapse, the stock has recovered significantly but not to the 1960s levels. Since 2001-02 the spawning biomass has been maintained above five millions tones whilst fishing mortality shows a decreasing trend. It is shown that the model was able to capture the population dynamics of the north – center stock of the Peruvian anchoveta, proving its usefulness for the monitoring and assessments of the anchoveta population