Abstract:
This dataset contains processed acoustic backscatter data that reflect integrated density estimates for Antarctic krill (Euphausia superba). The acoustic backscatter data are from the Western Core Box (WCB), comprising 8 acoustic transects that span the shelf-break at South Georgia. The data were obtained from a time series of 22 cruises carried out between 1996/97 and 2019/20. Data were collected using either a Simrad EK500 or EK60 echo sounder by biological oceanographers working at the British Antarctic Survey under the Ecosystems scientific research programme and predecessor Discovery 2010 and Dynamo research programmes.
Funding was provided by the NERC/BAS Antarctic, Logistic, Infrastructure (ALI) Science and predecessor Long Term Monitoring Science research programmes.
Keywords:
Acoustic backscatter, Antarctic krill, EK500, EK60, Euphausia superba, Scotia Sea, South Georgia, WCB, Western Core Box
Fielding, S., Enderlein, P., Stowasser, G., Tarling, G., & Manno, C. (2022). Antarctic krill (Euphausia superba) biomass density estimates derived from acoustic backscatter data collected in the Western Core Box survey, South Georgia, South Atlantic: 1996 - 2019 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/e85a9312-8531-4261-a2f6-1c58f40cfc71
| Access Constraints: | No restrictions apply. |
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| Use Constraints: | Data are released under Open Government Licence V3.0: http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. |
| Creation Date: | 2022-09-27 |
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| Dataset Progress: | Complete |
| Dataset Language: | English |
| ISO Topic Categories: |
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| Parameters: |
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| Personnel: | |
| Name | PDC BAS |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Dr Sophie Fielding |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Peter Enderlein |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Gabriele Stowasser |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Prof Geraint A Tarling |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Clara Manno |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Parent Dataset: | N/A |
| Reference: | Trathan, P.N., Fielding, S., Warwick-Evans, V., Freer, J., Perry, F (2022) Seabird and seal responses to the physical environment and to spatio-temporal variation in the distribution and abundance of Antarctic krill at South Georgia, with implications for local fisheries management. ICES Journal of Marine Science. https://doi.org/10.1093/icesjms/fsac168. Fielding, S., Cossio, A., Cox, M., Reiss, C., Skaret, G., Demer, D., Watkins, J. and Zhao, X. (2016) A condensed history and document of the method used by CCAMLR to estimate krill biomass (B0) in 2010. Working Paper WG-EMM-16/38 submitted to the Working Group on Ecosystem Monitoring and Management, CCAMLR, Hobart. https://meetings.ccamlr.org/en/wg-emm-16/38. Fielding, S., Watkins, J.L., Cossio, A., Reiss, C., Watters, G., Calise, L., Skaret, G., Takao, Y., Zhao, X., Agnew, D., Ramm, D. and Reid, K. (2011) The ASAM 2010 assessment of krill biomass for Area 48 from the Scotia Sea CCAMLR 2000 synoptic survey. Working Paper WG-EMM-11/20 submitted to the Working Group on Ecosystem Monitoring and Management, CCAMLR, Hobart. https://meetings.ccamlr.org/en/wg-emm-11/20. Fielding, S., Watkins, J.L., Trathan, P.N., Enderlein, P., Waluda, C.M., Stowasser, G., Tarling, G.A. and Murphy, E.J. (2014) Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013. ICES Journal of Marine Science 71(9), 2578-2588. https://doi.org/10.1093/icesjms/fsu104. Reid, K., Watkins, J.L., Murphy, E.J., Trathan, P.N., Fielding, S. and Enderlein, P. (2010) Krill population dynamics at South Georgia: implications for ecosystem-based fisheries management. Marine Ecology-Progress Series 399, 243-252. https://doi.org/10.3354/meps08356. Saunders, R.A., Brierley, A.S., Watkins, J.L., Reid, K., Murphy, E.J., Enderlein, P. and Bone, D.G. (2007) 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. CCAMLR Science 14, 27-41. https://www.ccamlr.org/en/publications/science_journal/ccamlr-science-volume-14/ccamlr-science-volume-1427-41. Trathan, P.N., Brierley, A.S., Brandon, M.A., Bone, D.G., Goss, C., Grant, S.A., Murphy, E.J. and Watkins, J.L. (2003) Oceanographic variability and changes in Antarctic krill (Euphausia superba) abundance at South Georgia. Fisheries Oceanography 12, 569-583. https://doi.org/10.1046/j.1365-2419.2003.00268.x. |
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| Lineage: | Acoustic surveys targeting Antarctic krill (Euphausia superba) within the Western Core Box (WCB; an area covering 132 km by 80 km) to the northwest of South Georgia have been described previously (Trathan et al., 2003; Reid et al., 2010; Fielding et al., 2014). Here we extend the time series from 1997 to 2020, using only acoustic surveys that took place within a fixed time window (1 December to 16 February), given that known intra-annual variation in the timing of peak summer biomass can affect estimates of krill mean density at South Georgia (Saunders et al., 2007; Reid et al., 2010). The WCB includes on-shelf and off-shelf areas sometimes used by predators foraging from Bird Island. During each survey, acoustic data were collected along eight transects, although in some years not all transects could be completed. Also, the location of some transects changed after the first few years. Acoustic data were depth integrated to 250 m (or to 2 m above the sea floor if shallower) with a horizontal average integration distance of 500 m. Estimate of krill density in each acoustic sampling interval were derived using the 3 frequency (38, 120 and 200 kHz) identification model and the ASAM TS model (Fielding et al., 2011; 2014; 2016). |
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| Temporal Coverage: | |
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| Start Date | 1996-12-29 |
| End Date | 2019-12-07 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -54.06044 |
| Northernmost | -53.14326 |
| Longitude | |
| Westernmost | -39.60605 |
| Easternmost | -37.59114 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | 250 m |
| Max Depth | 250 m |
| Location: | |
| Location | Southern Ocean |
| Detailed Location | Scotia Sea |
| Location | Southern Ocean |
| Detailed Location | South Georgia |
| Data Storage: | This dataset is held as a set of 3 csv files, cruise_data, density_data and readme_fields. |
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