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Standing stock of Antarctic krill (Euphausia superba Dana, 1850) (Euphausiacea) in the Southwest Atlantic sector of the Southern Ocean, 2018–19
Antarctic ecosystem
Biomass
Fisheries management

Standing stock of Antarctic krill (Euphausia superba Dana, 1850) (Euphausiacea) in the Southwest Atlantic sector of the Southern Ocean, 2018–19

Summary

A large Antarctic survey in 2018-19 measured how much krill exists in specific regions of the ocean. Researchers found a total of 62.6 million tonnes of krill in the Southwest Atlantic, with an average density of 30 grams per square meter.This is roughly the same amount they found in a similar survey in 2000 (60.3 million tonnes). The krill population appears stable over time, though the distribution has changed somewhat geographically. They found the most krill around the South Orkney Islands and the least around South Georgia.Current krill harvesting is 300,000-400,000 tonnes per year, which is well below the precautionary limit of 620,000 tonnes set by researchers. This suggests that fishing does not threaten the krill population.The survey shows no clear signs that the overall krill population is declining, but regional variations do exist.
This figure shows the spatial distribution of Antarctic krill density across the Southwest Atlantic sector during the 2018-19 survey, with color-coded circles representing krill biomass measurements in 1 nautical mile bins. The highest densities (up to 5000 g m⁻²) were found on continental shelves north of the South Shetland Islands, around Elephant Island, and north of the South Orkney Islands, while lower densities occurred in offshore waters. The survey covered multiple CCAMLR subareas and strata, revealing significant spatial heterogeneity in krill distribution across the region.
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This figure shows the spatial distribution of Antarctic krill density across the Southwest Atlantic sector during the 2018-19 survey, with color-coded circles representing krill biomass measurements in 1 nautical mile bins. The highest densities (up to 5000 g m⁻²) were found on continental shelves north of the South Shetland Islands, around Elephant Island, and north of the South Orkney Islands, while lower densities occurred in offshore waters. The survey covered multiple CCAMLR subareas and strata, revealing significant spatial heterogeneity in krill distribution across the region.

Key Findings

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Total krill biomass estimated at 62.6 megatonnes (mean density of 30 g/m² over 2 million km²) with 13% sampling coefficient variation
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Biomass comparable to CCAMLR 2000 survey (60.3 megatonnes), but with regional distribution differences
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No evidence of overall stock decline despite climate warming concerns
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Current harvest (300,000-400,000 t/year) substantially below precautionary catch limit (620,000 t)

Abstract

Estimates of the distribution and density of Antarctic krill (Euphausia superba Dana, 1850) were derived from a large-scale survey conducted during the austral summer in the Southwest Atlantic sector of the Southern Ocean and across the Scotia Sea in 2018–19, the ‘2018–19 Area 48 Survey’. Survey vessels were provided by Norway, the Association of Responsible Krill harvesting companies and Aker BioMarine AS, the United Kingdom, Ukraine, Republic of Korea, and China. Survey design followed the transects of the Commission for the Conservation of Antarctic Marine Living Resources synoptic survey, carried out in 2000 and from regular national surveys performed in the South Atlantic sector by the U.S., China, Republic of Korea, Norway, and the U.K. The 2018–19 Area 48 Survey represents only the second large-scale survey performed in the area and this joint effort resulted in the largest ever total transect line (19,500 km) coverage carried out as one single exercise in the Southern Ocean. We delineated and integrated acoustic backscatter arising from krill swarms to produce distribution maps of krill areal biomass density and standing stock (biomass) estimates. Krill standing stock for the Area 48 was estimated to be 62.6 megatonnes (mean density of 30 g m–2 over 2 million km2) with a sampling coefficient variation of 13%. The highest mean krill densities were found in the South Orkney Islands stratum (93.2 g m–2) and the lowest in the South Georgia Island stratum (6.4 g m–2). The krill densities across the strata compared to those found during the previous survey indicate some regional differences in distribution and biomass. It is currently not possible to assign any such differences or lack of differences between the two survey datasets to longer term trends in the environment, krill stocks or fishing pressure.

Published in

Journal of Crustacean Biology

2021

Authors

Krafft B. A., G. J. Macaulay, G. Skaret, T. Knutsen, O. A. Bergstad, A. Lowther, G. Huse, S. Fielding, P. N. Trathan, E. J. Murphy, S.-G. Choi, S. Chung, I. Han, K. Lee, X. Y. Zhao, X. Wang, Y. Ying, X. Yu, K. Demianenko, V. Podhornyi, K. Vishnyakova, L. Pshenichnov, A. Chuklin, H. Shyshman, M. J. Cox, K. Reid, G. M. Watters, C. S. Reiss, J. T. Hinke, J. A. Arata, O. R. Godø, and N. Hoem.

Institutions

Institute of Marine Research Norwegian Polar Institute British Antarctic Survey National Institute of Fisheries Science Chonnam National University Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences Institute of Fisheries and Marine EcologyNational Antarctic Scientific Center of Ukraine Limited liability company “IKF” Australian Antarctic Division CCAMLR Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric AdministrationAssociation of Responsible Krill harvesting companies (ARK) AKER Biomarine AS

Methods

DataAcousticBiological sampling

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