Spatial and temporal dynamics of the Antarctic krill fishery in fishing hotspots in the Bransfield Strait and South Shetland Islands

Abstract

Antarctic krill is a vital part of the food web and supports a significant fishery in the Southern Ocean. Shifts in historical fishing grounds and spatial distribution of catches have occurred as a result of recent changes in fishery practices. To understand these shifts, fishery spatial dynamics and fishing fleet behavior evaluated on different spatial and temporal scales are critical. We examine the catch distribution on three spatial-temporal scales. At the Western Antarctic Peninsula (WAP) scale, we assessed the fleet’s southward expansion, identifying the Bransfield Strait (BS) as the main current fishing ground, replacing the historical Drake sector. At the BS scale, we identified fishing hotspots (FHs) that concentrated 48%–57% of the total catch over a period of 2–6 months and had high catch densities (2.2–30.3 ton km−2). At the FH scale, we tracked the spatial distribution of the fleet within FHs, demonstrating a shift of fishing vessels to contiguous zones as a result of a decrease in daily catch rates (CPUE). Such shifts (allowing the fleet to increase CPUE) occurred every 4–17 days. Previously exploited fishing grounds were revisited based on FH persistence and sea ice conditions. This paper concludes with a discussion of the potential impact of fishing fleet behavior and catch concentration, considering the recent spatial shift towards less-exploited areas, the overlap with critical zones for predator feeding, and several implications for fisheries management.