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Krill population dynamics at South Georgia: implications for ecosystem-based fisheries management

Reid, Keith; Watkins, Jon L.; Murphy, Eugene J.; Trathan, Phil N.; Fielding, Sophie; Enderlein, Peter. 2010 Krill population dynamics at South Georgia: implications for ecosystem-based fisheries management. Marine Ecology Progress Series, 399. 243-252. 10.3354/meps08356

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Abstract/Summary

The South Georgia region supports a large biomass of krill that is subject to high inter-annual variability. The apparent lack of a locally self-maintaining krill population at South Georgia means that understanding the mechanism underlying these observed population characteristics is essential to successful ecosystem-based management of krill fishery in the region. Krill acoustic-density data from surveys conducted in the early, middle and late period of the summers of 2001 to 2005, together with krill population size structure over the same period from predator diet data, were used with a krill population dynamics model to evaluate potential mechanisms behind the observed changes in krill biomass. Krill abundance was highest during the middle of the summer in 3 years and in the late period in 2 years; in the latter there was evidence that krill recruitment was delayed by several months. A model scenario that included empirically derived estimates of both the magnitude and timing of recruitment in each year showed the greatest correlation with the acoustic series. The results are consistent with a krill population with allochthonous recruitment entering a retained adult population; i.e. oceanic transport of adult krill does not appear to be the major factor determining the dynamics of the adult population. The results highlight the importance of the timing of recruitment, especially where this could introduce a mismatch between the peak of krill abundance and the peak demand from predators, which may exacerbate the effects of changes in krill populations arising from commercial harvesting and/or climate change.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3354/meps08356
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > DISCOVERY 2010 - Integrating Southern Ocean Ecosystems into the Earth System
ISSN: 0171-8630
NORA Subject Terms: Marine Sciences
Zoology
Ecology and Environment
Date made live: 23 Aug 2010 08:14
URI: http://nora.nerc.ac.uk/id/eprint/10619

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