Humboldt (Northern)

Long–term dynamics are controlled by alternate cool and warm regimes which occur over periods of 25 years and restructure the entire ecosystem from phytoplankton to top predators. During the latest warm period (1975-late 1990s) the system was characterized by the approach of warm subtropical oceanic waters to the coast of Peru and the dominance of larger species like sardine and horse mackerel. A shift back to a cool regime occurred in the late 90s which is characterized by the retreat of oceanic waters and the dominance of small, short-lived and very abundant species like anchovy. Positive trends in biomass and negative trends in life span are consistent with anchovy dominance. Positive trends in TL and proportion of predators are explained by the outburst of the jumbo squid population since 1998.