Investigating the influence of minor krill-predators on the krill-predator dynamics of the Antarctic ecosystem in the International Whaling Commission's Management Area II

Abstract

Krill ( Euphausia superba), a small pelagic crustacean. is the largest food resource serving many predators in the Antarctic ecosystem. Given the recent slow expansion of the krill fishery, interest is increasing on how best to harvest krill without unduly impacting its natural predators. The Mori–Butterworth Antarctic ecosystem model attempted to explain the dynamics of the “major” predators through predator–prey interactions alone. That model considered blue, fin, humpback, and minke whales, and crabeater and Antarctic fur seals. Here, this model is expanded to include “minor” krill-predators, such as mackerel icefish. It focuses on a smaller scale, roughly corresponding to International Whaling Commission Management Area II. Results suggest a meaningful difference (historical abundance trajectories differing by more than 5% on average over time) when including “minor” predators. Hence, at an area-specific level, “minor” predators should be considered for further models of at least certain sectors of the Antarctic, as they may meaningfully influence the dynamics of krill and its “major” predators. This in turn could impact management decisions for the krill fishery, as regards optimal krill harvesting.