Abstract
Antarctic krill Euphausia superba, a keystone species in the Southern Ocean, is highly relevant for studying effects of climate-related shifts on management systems. Krill provides a key link between primary producers and higher trophic levels and supports the largest regional fishery. Any major perturbation in the krill population would have severe ecological and economic ramifications. We review the literature to determine how climate change, in concert with other environmental changes, alters krill habitat, affects spatial distribution/abundance, and impacts fisheries management. Findings recently reported on the effects of climate change on krill distribution and abundance are inconsistent, however, raising questions regarding methods used to detect changes in density and biomass. One recent study reported a sharp decline in krill densities near their northern limit, accompanied by a poleward contraction in distribution in the Southwest Atlantic sector. Another recent study found no evidence of long-term decline in krill density or biomass and reported no evidence of a poleward shift in distribution. Moreover, with predicted decreases in phytoplankton production, vertical foraging migrations to the seabed may become more frequent, also impacting krill production and harvesting. Potentially cumulative impacts of climate change further compound the management challenge faced by CCAMLR, the organization responsible for conservation of Antarctic marine living resources: to detect changes in the abundance, distribution, and reproductive performance of krill and krill-dependent predator stocks and to respond to such change by adjusting its conservation measures. Based on CCAMLR reports and documents, we review the institutional framework, outline how climate change has been addressed within this organization, and examine the prospects for further advances toward ecosystem risk assessment and an adaptive management system.
Highlights
The Southern Ocean is a region of high physical and biological variability (Hempel 1985, Constable et al 2003)
Based on CCAMLR reports and documents, we examine how climate change has been addressed within this organization, with an emphasis on its ecosystem-based risk assessment of krill fisheries and its advances toward a feedback management system capable of responding to climate variability
We focus on the rising attention paid to climate change within the decisionmaking and advisory bodies of CCAMLR; the need for regularly updated assessments of risks posed by fishing under a changing climate, based on monitoring of the ecosystem; and the advances made toward an adaptive management system capable of adjusting management actions in response to the best available information on the status of krill and its predators
Summary
The Southern Ocean is a region of high physical and biological variability (Hempel 1985, Constable et al 2003). The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has established precautionary catch limits on the krill fishery in most of the areas where fishing has occurred, but these catch limits apply to large statistical subareas. It is 3 decades since the CCAMLR stated its ambition to advance from a precautionary approach to a feedback management system capable of continuously adjusting krill conservation measures in response to new knowledge on krill stocks and associated species (CCAMLR 1991a). Based on CCAMLR reports and documents, we examine how climate change has been addressed within this organization, with an emphasis on its ecosystem-based risk assessment of krill fisheries and its advances toward a feedback management system capable of responding to climate variability
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