Skip to content

Research at St Andrews

Significant intra-annual variability in krill distribution and abundance at South Georgia as revealed by multiple acoustic surveys during 2000/01

Research output: Contribution to journalArticle

Standard

Significant intra-annual variability in krill distribution and abundance at South Georgia as revealed by multiple acoustic surveys during 2000/01. / Brierley, Andrew Stuart; Goss, C; Grant, SA; Watkins, JL; Reid, K; Belchier, M; Everson, I; Jessop, MJ; Afanasyev, V; Robst, J.

In: CCAMLR Science, Vol. 9, 2002, p. 71-82.

Research output: Contribution to journalArticle

Harvard

Brierley, AS, Goss, C, Grant, SA, Watkins, JL, Reid, K, Belchier, M, Everson, I, Jessop, MJ, Afanasyev, V & Robst, J 2002, 'Significant intra-annual variability in krill distribution and abundance at South Georgia as revealed by multiple acoustic surveys during 2000/01', CCAMLR Science, vol. 9, pp. 71-82.

APA

Brierley, A. S., Goss, C., Grant, SA., Watkins, JL., Reid, K., Belchier, M., ... Robst, J. (2002). Significant intra-annual variability in krill distribution and abundance at South Georgia as revealed by multiple acoustic surveys during 2000/01. CCAMLR Science, 9, 71-82.

Vancouver

Brierley AS, Goss C, Grant SA, Watkins JL, Reid K, Belchier M et al. Significant intra-annual variability in krill distribution and abundance at South Georgia as revealed by multiple acoustic surveys during 2000/01. CCAMLR Science. 2002;9:71-82.

Author

Brierley, Andrew Stuart ; Goss, C ; Grant, SA ; Watkins, JL ; Reid, K ; Belchier, M ; Everson, I ; Jessop, MJ ; Afanasyev, V ; Robst, J. / Significant intra-annual variability in krill distribution and abundance at South Georgia as revealed by multiple acoustic surveys during 2000/01. In: CCAMLR Science. 2002 ; Vol. 9. pp. 71-82.

Bibtex - Download

@article{a7e24790418b4fe88afb80ae96e4ed90,
title = "Significant intra-annual variability in krill distribution and abundance at South Georgia as revealed by multiple acoustic surveys during 2000/01",
abstract = "Three separate acoustic surveys of Antarctic krill (Euphausia superba) were conducted around South Georgia in the 2000/01 season: in October 2000 (early-season); during late December/early January 2000/01 (mid-season), and in March 2001 (late-season). The surveys were the first in a newly planned five-year series of observations designed to complement and extend an existing time series regularly maintained by the British Antarctic Survey since 1996 (and on a more ad hoc basis since the early 1980s). We hoped that conducting several surveys in one season would provide information on short-term variability that could be used to set data from more restricted once-per-season 'snap-shot' cruises in a broader context. The early- and late-season surveys were associated with logistic support voyages to South Georgia and were restricted to four transects within a box to the northwest of South Georgia. The dedicated mid-season survey covered that box in more detail (twice as many transects) and, in addition, examined boxes to the north, northeast and southwest of the island. Together these surveys provided temporally and spatially extensive coverage around South Georgia. Krill density in the western box in the early-season survey was very low (3.5 g m(-2)) but rose significantly (P = 0.020) by mid-season (to 34.7 g m(-2)). In a pattern that is consistent with observations from previous years, krill density in the western box in the mid-season survey was less than that in the eastern box (80.4 g m(-2)). Analysis of transect data obtained in the western box in the mid-season survey revealed no significant difference in the mean krill density derived from only those four transects surveyed early- and late-season, or from the full eight transects. Our first occupation of a survey box off the central north coast of South Georgia in mid-season revealed a krill density of 47.2 g m(-2) that was intermediate between the eastern and western areas. The size structure of the krill in the central region also reflected a mix of those to the east (generally small) and west (generally large). Krill density to the southwest of South Georgia was 32.1 g m(-2) in mid-season. By March, krill density in the western survey area had fallen significantly (P = 0.037) from the mid-season high to 7.8 g m(-2). Our multiple surveys at South Georgia have revealed major intra-annual changes in krill density at the island and have shown that the timing of the acoustic survey can affect significantly the estimate of krill density. The multiple estimates of krill density will allow reproductive performance indices for top level predators to be compared to prey availability at more appropriate time-scales than previous single 'snap-shot' acoustic survey data have allowed. This is a crucial step in the elucidation of response functions of dependent species to changes in krill abundance, and could be a useful contribution to ecosystem management.",
keywords = "acoustic survey, variability, Antarctic krill, abundance, South Georgia, CCAMLR, SEALS ARCTOCEPHALUS-GAZELLA, SUB-ANTARCTIC ISLAND, EUPHAUSIA-SUPERBA, FISH STOCKS, STRENGTH, SEASON",
author = "Brierley, {Andrew Stuart} and C Goss and SA Grant and JL Watkins and K Reid and M Belchier and I Everson and MJ Jessop and V Afanasyev and J Robst",
year = "2002",
language = "English",
volume = "9",
pages = "71--82",
journal = "CCAMLR Science",
issn = "1023-4063",
publisher = "Comm. for the Conserv. of Antartic Marine Living Resources",

}

RIS (suitable for import to EndNote) - Download

TY - JOUR

T1 - Significant intra-annual variability in krill distribution and abundance at South Georgia as revealed by multiple acoustic surveys during 2000/01

AU - Brierley, Andrew Stuart

AU - Goss, C

AU - Grant, SA

AU - Watkins, JL

AU - Reid, K

AU - Belchier, M

AU - Everson, I

AU - Jessop, MJ

AU - Afanasyev, V

AU - Robst, J

PY - 2002

Y1 - 2002

N2 - Three separate acoustic surveys of Antarctic krill (Euphausia superba) were conducted around South Georgia in the 2000/01 season: in October 2000 (early-season); during late December/early January 2000/01 (mid-season), and in March 2001 (late-season). The surveys were the first in a newly planned five-year series of observations designed to complement and extend an existing time series regularly maintained by the British Antarctic Survey since 1996 (and on a more ad hoc basis since the early 1980s). We hoped that conducting several surveys in one season would provide information on short-term variability that could be used to set data from more restricted once-per-season 'snap-shot' cruises in a broader context. The early- and late-season surveys were associated with logistic support voyages to South Georgia and were restricted to four transects within a box to the northwest of South Georgia. The dedicated mid-season survey covered that box in more detail (twice as many transects) and, in addition, examined boxes to the north, northeast and southwest of the island. Together these surveys provided temporally and spatially extensive coverage around South Georgia. Krill density in the western box in the early-season survey was very low (3.5 g m(-2)) but rose significantly (P = 0.020) by mid-season (to 34.7 g m(-2)). In a pattern that is consistent with observations from previous years, krill density in the western box in the mid-season survey was less than that in the eastern box (80.4 g m(-2)). Analysis of transect data obtained in the western box in the mid-season survey revealed no significant difference in the mean krill density derived from only those four transects surveyed early- and late-season, or from the full eight transects. Our first occupation of a survey box off the central north coast of South Georgia in mid-season revealed a krill density of 47.2 g m(-2) that was intermediate between the eastern and western areas. The size structure of the krill in the central region also reflected a mix of those to the east (generally small) and west (generally large). Krill density to the southwest of South Georgia was 32.1 g m(-2) in mid-season. By March, krill density in the western survey area had fallen significantly (P = 0.037) from the mid-season high to 7.8 g m(-2). Our multiple surveys at South Georgia have revealed major intra-annual changes in krill density at the island and have shown that the timing of the acoustic survey can affect significantly the estimate of krill density. The multiple estimates of krill density will allow reproductive performance indices for top level predators to be compared to prey availability at more appropriate time-scales than previous single 'snap-shot' acoustic survey data have allowed. This is a crucial step in the elucidation of response functions of dependent species to changes in krill abundance, and could be a useful contribution to ecosystem management.

AB - Three separate acoustic surveys of Antarctic krill (Euphausia superba) were conducted around South Georgia in the 2000/01 season: in October 2000 (early-season); during late December/early January 2000/01 (mid-season), and in March 2001 (late-season). The surveys were the first in a newly planned five-year series of observations designed to complement and extend an existing time series regularly maintained by the British Antarctic Survey since 1996 (and on a more ad hoc basis since the early 1980s). We hoped that conducting several surveys in one season would provide information on short-term variability that could be used to set data from more restricted once-per-season 'snap-shot' cruises in a broader context. The early- and late-season surveys were associated with logistic support voyages to South Georgia and were restricted to four transects within a box to the northwest of South Georgia. The dedicated mid-season survey covered that box in more detail (twice as many transects) and, in addition, examined boxes to the north, northeast and southwest of the island. Together these surveys provided temporally and spatially extensive coverage around South Georgia. Krill density in the western box in the early-season survey was very low (3.5 g m(-2)) but rose significantly (P = 0.020) by mid-season (to 34.7 g m(-2)). In a pattern that is consistent with observations from previous years, krill density in the western box in the mid-season survey was less than that in the eastern box (80.4 g m(-2)). Analysis of transect data obtained in the western box in the mid-season survey revealed no significant difference in the mean krill density derived from only those four transects surveyed early- and late-season, or from the full eight transects. Our first occupation of a survey box off the central north coast of South Georgia in mid-season revealed a krill density of 47.2 g m(-2) that was intermediate between the eastern and western areas. The size structure of the krill in the central region also reflected a mix of those to the east (generally small) and west (generally large). Krill density to the southwest of South Georgia was 32.1 g m(-2) in mid-season. By March, krill density in the western survey area had fallen significantly (P = 0.037) from the mid-season high to 7.8 g m(-2). Our multiple surveys at South Georgia have revealed major intra-annual changes in krill density at the island and have shown that the timing of the acoustic survey can affect significantly the estimate of krill density. The multiple estimates of krill density will allow reproductive performance indices for top level predators to be compared to prey availability at more appropriate time-scales than previous single 'snap-shot' acoustic survey data have allowed. This is a crucial step in the elucidation of response functions of dependent species to changes in krill abundance, and could be a useful contribution to ecosystem management.

KW - acoustic survey

KW - variability

KW - Antarctic krill

KW - abundance

KW - South Georgia

KW - CCAMLR

KW - SEALS ARCTOCEPHALUS-GAZELLA

KW - SUB-ANTARCTIC ISLAND

KW - EUPHAUSIA-SUPERBA

KW - FISH STOCKS

KW - STRENGTH

KW - SEASON

UR - http://www.scopus.com/inward/record.url?scp=0346108602&partnerID=8YFLogxK

M3 - Article

VL - 9

SP - 71

EP - 82

JO - CCAMLR Science

JF - CCAMLR Science

SN - 1023-4063

ER -

Related by author

  1. Mercury levels in Southern Ocean squid: variability over the last decade

    Seco, J., Xavier, J. C., Brierley, A. S., Bustamante, P., Coelho, J. P., Gregory, S., Fielding, S., Pardal, M. A., Pereira, B., Stowasser, G., Tarling, G. A. & Pereira, E., 10 Sep 2019, In : Chemosphere. 239, 124785.

    Research output: Contribution to journalArticle

  2. From siphonophores to deep scattering layers: uncertainty ranges for the estimation of global mesopelagic fish biomass

    Proud, R., Handegard, N. O., Kloser, R., Cox, M. & Brierley, A. S., May 2019, In : ICES Journal of Marine Science. 76, 3, p. 718-733

    Research output: Contribution to journalArticle

  3. Spatial variability in total and organic mercury levels in Antarctic krill Euphausia superba across the Scotia Sea

    Seco, J., Xavier, J. C., Coelho, J. P., Pereira, B., Tarling, G., Pardal, M. A., Bustamante, P., Stowasser, G., Brierley, A. S. & Pereira, M. E., Apr 2019, In : Environmental Pollution. 247, p. 332-339 8 p.

    Research output: Contribution to journalArticle

  4. Internal lee waves and baroclinic bores over a tropical seamount shark ‘hot-spot’

    Hosegood, P. J., Nimmo-Smith, W. A. M., Proud, R., Adams, K. & Brierley, A. S., Mar 2019, In : Progress in Oceanography. 172, p. 34-50 17 p.

    Research output: Contribution to journalArticle

Related by journal

  1. ESTIMATING STANDING STOCK OF KRILL USING MAXIMUM ENTROPY IMAGE RECONSTRUCTION RESPONSE

    Brierley, A. S., Heywood, B. G. & Gull, S. F., 2008, In : CCAMLR Science. 15, p. 195-198 4 p.

    Research output: Contribution to journalLetter

  2. Intra-annual variability in the density of Antarctic krill (Euphausia superba) at south Georgia, 2002-2005: Within-year variation provides a new framework for interpreting previous 'annual' estimates of krill density

    Saunders, R. A., Brierley, A. S., Watkins, J. L., Reid, K., Murphy, E. J., Enderlein, P. & Bone, D. G., 2007, In : CCAMLR Science. 14, p. 27-41 15 p.

    Research output: Contribution to journalArticle

  3. Maximum entropy reconstructions of krill distribution and estimates of krill density from acoustic surveys at South Georgia, 1996-2000\

    Wafy, M. H., Brierley, A. S., Gull, S. F. & Watkins, J. L., 2003, In : CCAMLR Science. 10, p. 91-100 10 p.

    Research output: Contribution to journalArticle

ID: 156594

Top