Relationship between anchovy and other components of the ecosystem

Abstract

 It is hypothesized that the fishing mortality has ecosystem effects, not only on the anchovy but also on other ecosystem components, such as top predators. The objective is to carry out simulations with a multispecific ecotrophic model for the decade of the years 2000, changing fishery mortality and analyzing biomass variations in seabirds and pinnipeds. The Peruvian Oscillation Index was used to include a mediation affecting the vulnerability of anchovy preys. The fit of observed data was compared using two types of anchovy diet (phytoplanktophagous and zooplanktophagous). Biomass projections were carried out varying fishing mortality from 0,0 to 1,4 y-1. Simulations with the zooplanktophagous diet, which increased the trophic level of the anchovy from 2,35 to 3,36, produced a lower fit between observed and simulated data. The inverse relationship between fishing mortality and anchovy spawning biomass showed that fishing mortalities between 0,8 and 1,4 y-1 were associated to a minimum spawning biomass of anchovy, taking into account its multispecific relationships. An inverse relationship was also found between the fishing mortality and populations of seabirds and pinnipeds.