Spatial and temporal catch concentrations for Antarctic krill: Implications for fishing performance and precautionary management in the Southern Ocean

• Published in: Ocean & coastal management Vol. 223; p. 106146
• Main Authors: Santa Cruz, Francisco, Krüger, Lucas, Cárdenas, César A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-05-2022
• Subjects: Catch per unit effort; Euphausia superba; Fleet concentration; Local depletion; Southern Ocean fisheries; Catch per unit effort; Local depletion; Southern Ocean fisheries; Fleet concentration; Euphausia superba
• ISSN: 0964-5691; 1873-524X
• DOI: 10.1016/j.ocecoaman.2022.106146

The undergoing rapid climate changes recorded along the Western Antarctic Peninsula (WAP) in combination with the increasing seasonal catches reported by the krill fishery have raised concerns as to whether the management strategy established by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is effectively avoiding impacts on the krill stock and related ecosystem.
Despite the current fixed catch limit being spread across fishing areas to reduce spatial catches concentrations, our 38-year analysis revealed the highest historical spatial (ton/km2) and temporal (ton/day) fishing concentration levels across the WAP and South Orkney Islands. Higher seasonal catches in recent decades removed persistently within the same small fishing areas and during shorter fishing seasons are key factors influencing this situation.
We used the catch per unit effort (CPUE) as a measure of fishing performance. CPUE was standardized using a GAMM model taking into account operational factors such as fleet composition, trawling methods, seasonality and daily catches, and we detected negative CPUE trends over time and across the different fishing areas. Our results suggest that the fishing performance have responded to the elevated spatio-temporal fishing concentration and changes in sea-ice. We discuss whether the negative CPUE trends are caused by fishing-induced depletion or driven by other factors such as krill flux, reduction and contraction of krill abundance and increased cetacean foraging (due recovery of whale populations). Finally, we also highlight the need to expand the survey's coverage (by acoustic or net-based methods) to the new, highly fished, and non-monitored areas such as Gerlache Strait, which is an important area for krill and dependent predators.
•Spatial and temporal concentration of Antarctic krill catches have reached the highest levels in 38-years.•Catch per Unit Effort (CPUE) of the krill fishery in the Antarctic Peninsula is reducing across the fishing sectors.•Reduction of CPUE was associated with changes in sea-ice and the increased fishing concentration.