Search

Antarctic krill (krill) are important within Southern Ocean ecosystems and support an expanding fishery. Toward understanding krill's response to environmental change, it is necessary to identify regions that support high krill larval production (spawning habitat). We develop a mechanistic model combining thermal and food requirements for krill egg production, with predation pressure post‐spawning, to predict regions of high‐quality spawning habitat. We optimize our model regionally and generate circumpolar predictions of spawning habitat quality. Our results indicate the southwest Atlantic accounts for almost half of all predicted high‐quality spawning habitat. Small‐scale management units (SSMUs) around the Antarctic Peninsula had high coverage of high‐quality spawning habitat. In contrast, the remaining SSMUs (except around South Georgia) were poorly covered, suggestive of population sinks reliant on input from external sources upstream. This implies strong potential for downstream impacts of fishing in key spawning areas, with implications for management of SSMUs and the krill fishery. Plain Language Summary: Antarctic krill (krill) are a key prey item for many Southern Ocean marine predators and also support an expanding commercial fishery. However, there is a need to identify areas of the Southern Ocean that are best for both the production of eggs, and subsequent survival until free‐swimming larvae. We create a model for spawning habitat which considers the temperature and food conditions that adult female krill need to successfully produce eggs, as well as the density of predators feeding on spawned eggs. We optimize our model using existing regional‐scale data of krill eggs and larvae and use this to predict where good spawning habitat may exist around the whole Southern Ocean. Our model found that nearly half of the best spawning habitat occurs in the southwest Atlantic. Within this area, small‐scale krill fishing management areas around the Antarctic Peninsula contain good‐quality spawning habitat. Krill fished here are likely to be locally produced. But, other small‐scale management areas contain little good‐quality spawning habitat (except around South Georgia) and probably rely on krill being imported by ocean currents. This is important for understanding how fishing may impact both local ecosystems and those that are downstream. Key Points: Mechanistic model for Antarctic krill spawning habitat uses thermal and food constraints on egg production, and predation on egg survivalOptimizing from regional data we generate circumpolar predictions to show half of quality spawning habitat is in the southwest AtlanticSpatial management units for the krill fishery do not all represent optimal spawning habitat, suggesting some areas rely on recruit import [ABSTRACT FROM AUTHOR]