Introduction
Anthropogenic changes have greatly altered the abundance
of oceanic species, especially large predators at high trophic
levels . While there are few known
oceanic predator extinctions, exploitation has extirpated many
marine mammal and seabird populations and routinely depletes marine fish populations
by 50% to 70% with
losses exceeding 90% increasingly common . Conversely, species invasions and reductions in exploitation
levels have led to substantial increases of some
predators. Although the magnitude and prevalence of these
predator changes have raised important questions about their
potential for indirect ecological consequences ,
understanding and forecasting outcomes of altered species
interactions has proven challenging .