University of California Santa Cruz Implications of Climate Change for Antarctic Krill and Their Cetacean Predators

John Wiedenmann Implications of Climate Change for Antarctic Krill and Their Cetacean Predators Antarctic krill are the dominant prey for many predators in the Southern Ocean. A changing climate may affect the biomass of krill available to both predators and the fishery, and being able to predict such changes, and subsequent impacts on krill predators is essential for the effective management of the krill fishery. I model the growth and reproductive success of krill in relation to a changing climate. Specifically, I explore the effects of a warming Southern Ocean on krill growth, and a decline in sea ice coverage on krill reproductive success using standard fisheries models. The effects on growth are predicted to vary spatially, with increased growth in colder areas and decreased growth in warmer areas in response to rising temperatures. A loss of sea ice is predicted to result in substantial reductions in krill recruitment. These changes, combined with an expanding fishery may affect the recovery of endangered blue whales. I develop a state-dependent behavioral model for blue whales to predict the impacts of reductions in krill biomass. Declines in krill biomass will likely reduce whale reproductive success and increase adult mortality through starvation, which will act to slow their recovery.