Biomass of Antarctic krill in the Scotia Sea in January/February 2000 and its use in revising an estimate of precautionary yield

Abstract In January and February 2000, a collaborative survey designed to assess the biomass of Antarctic krill across the Scotia Sea was conducted aboard research vessels from Japan, Russia, the UK and the USA using active acoustic and net sampling. Survey design, sampling protocols, and data analysis procedures are described. Mean krill density across the survey area was estimated to be 21.4 g m −2 , and total biomass was estimated to be 44.3 million tonnes (CV 11.4%). This biomass estimate leads to a revised estimate of precautionary yield for krill in the Scotia Sea of 4 million tonnes. However, before the fishery can be permitted to expand to this level, it will be necessary to establish mechanisms to avoid concentration of fishing effort, particularly near colonies of land-breeding krill predators, and to consider the effects of krill immigrating into the region from multiple sources.

[1]  G. Jolly,et al.  A Stratified Random Transect Design for Acoustic Surveys of Fish Stocks , 1990 .

[2]  Noel A Cressie,et al.  Statistics for Spatial Data. , 1992 .

[3]  W. R. Fraser,et al.  Effects of sea-ice extent and krill or salp dominance on the Antarctic food web , 1997, Nature.

[4]  K. Foote.  Calibration of acoustic instruments for fish density estimation : a practical guide , 1987 .

[5]  F. Fraser.  On the development and distribution of the young stages of Krill (Euphausia superba) , 1936 .

[6]  V. Siegel.  Krill (Euphausiacea) demography and variability in abundance and distribution , 2000 .

[7]  Andrew S. Brierley,et al.  A post-processing technique to remove background noise from echo integration data , 1996 .

[8]  L. Zane,et al.  Molecular evidence for genetic subdivision of Antarctic krill (Euphausia superba Dana) populations , 1998, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[9]  R. Hewitt,et al.  Dispersion and abundance of Antarctic krill in the vicinity of Elephant Island in the 1992 austral summer , 1993 .

[10]  A. Brierley,et al.  Setting a precautionary catch limit for Antarctic krill , 2002 .

[11]  L. V. M. Traykovski,et al.  Effects of orientation on acoustic scattering from Antarctic krill at 120 kHz , 1998 .

[12]  J. Marr.  The natural history and geography of the Antarctic krill (Euphausia superba Dana) , 1961 .

[13]  R. Laws.  The Ecology of the Southern Ocean , 1985 .

[14]  D. Vaughan,et al.  Recent atmospheric warming and retreat of ice shelves on the Antarctic Peninsula , 1996, Nature.

[15]  W. White,et al.  An Antarctic circumpolar wave in surface pressure, wind, temperature and sea-ice extent , 1996, Nature.

[16]  A. W. Murray.  Comparison of geostatistical and random sample survey analyses of Antarctic krill acoustic data , 1996 .

[17]  R. Hewitt,et al.  Krill abundance , 1991, Nature.

[18]  J. Watkins,et al.  Variation in the distribution of Antarctic krill Euphausia superba around South Georgia , 1999 .

[19]  E. Murphy,et al.  Modeling the krill transport pathways in the Scotia Sea: spatial and environmental connections generating the seasonal distribution of krill , 2004 .

[20]  R. Hewitt,et al.  The Fishery on Antarctic Krill: Defining an Ecosystem Approach to Management , 2000 .

[21]  Paul G. Fernandes,et al.  A consistent approach to definitions and symbols in fisheries acoustics , 2002 .

[22]  K. Foote,et al.  Implications of a new acoustic target strength for abundance estimates of Antarctic krill , 1990, Nature.

[23]  D. Agnew,et al.  Review—The CCAMLR Ecosystem Monitoring Programme , 1997, Antarctic Science.

[24]  Kenneth G. Foote,et al.  Spheres for calibrating an eleven-frequency acoustic measurement system , 1990 .

[25]  E. Murphy,et al.  Krill biomass in Area 48 and Area 49: recalculations of FIBEX data , 1993 .

[26]  M. Clarke,et al.  The N.I.O. combination net (RMT 1 + 8) and further developments of rectangular midwater trawls , 1973, Journal of the Marine Biological Association of the United Kingdom.

[27]  D. Demer.  An estimate of error for the CCAMLR 2000 survey estimate of krill biomass , 2004 .

[28]  E. Hofmann,et al.  Foundations for Ecological Research West of the Antarctic Peninsula , 1996 .

[29]  V. Siegel,et al.  Krill demography and large-scale distribution in the southwest Atlantic during January/February 2000 , 2004 .

[30]  A. Grelowski,et al.  Formation of Antarctic Krill Concentrations in Relation to Hydrodynamic Processes and Social Behaviour , 1988 .

[31]  S. Nicol,et al.  DEFINING SMALLER-SCALE MANAGEMENT UNITS TO FURTHER DEVELOP THE ECOSYSTEM APPROACH IN MANAGING LARGE-SCALE PELAGIC KRILL FISHERIES IN ANTARCTICA , 2002 .

[32]  P. Petitgas.  Geostatistics for fish stock assessments: a review and an acoustic application , 1993 .

[33]  Andrew Constable,et al.  Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) , 2018, Yearbook of International Cooperation on Environment and Development 1998–99.

[34]  A. Brierley,et al.  THE CCAMLR-2000 KRILL SYNOPTIC SURVEY: A DESCRIPTION OF THE RATIONALE AND DESIGN , 2001 .

[35]  P. Wiebe,et al.  Acoustic estimates of Antarctic krill , 1991, Nature.

[36]  M. Brandon,et al.  Physical oceanography in the Scotia Sea during the CCAMLR 2000 survey, austral summer 2000 , 2004 .

[37]  A. Brierley,et al.  Concordance of interannual fluctuations in acoustically estimated densities of Antarctic krill around South Georgia and Elephant Island: biological evidence of same-year teleconnections across the Scotia Sea , 1999 .

[38]  N. Bindoff,et al.  Ocean circulation off east Antarctica affects ecosystem structure and sea-ice extent , 2000, Nature.

[39]  R. Hewitt,et al.  The CCAMLR 2000 Survey: a multinational, multi-ship biological oceanography survey of the Atlantic sector of the Southern Ocean , 2004 .

[40]  R. Makarov,et al.  Variability in Population Density of Antarctic Krill in the Western Scotia Sea in Relation to Hydrological Conditions , 1988 .

[41]  M. Gowing,et al.  Southern Ocean Ecology: The BIOMASS Perspective , 1994 .

[42]  Verification of the acoustic techniques used to identify Antarctic krill , 2002 .

[43]  D. Sahrhage,et al.  Antarctic Ocean and Resources Variability , 1988, Springer Berlin Heidelberg.

[44]  Y. Sasai,et al.  Relationships between Antarctic krill (Euphausia superba) variability and westerly fluctuations and ozone depletion in the Antarctic Peninsula area , 1999 .

[45]  R. Francois,et al.  Sound absorption based on ocean measurements. Part II: Boric acid contribution and equation for total absorption , 1982 .

[46]  SOME THOUGHTS ON PRECAUTIONARY MEASURES FOR THE KRILL FISHERY , 1996 .