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Marine Ecology Progress Series

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MEPS 391:199-208 (2009)  -  DOI:

Overlap between vulnerable top predators and fisheries in the Benguela upwelling system: implications for marine protected areas

L. Pichegru1,2,*, P. G. Ryan2, C. Le Bohec1, C. D. van der Lingen3,4, R. Navarro4,5, S. Petersen2, S. Lewis6, J. van der Westhuizen3, D. Grémillet2,7

1Centre National de la Recherche Scientifique, Institut pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie, 23 rue Becquerel, 67 087 Strasbourg cedex 2, France
2DST/NRF Centre of Excellence at the Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7701, South Africa
3Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2, Rogge Bay 8012, South Africa
4Marine Research Institute, Zoology Department, University of Cape Town, South Africa
5Animal Demography Unit, Department of Zoology, University of Cape Town, Rondebosch 7701, South Africa.
6Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh Ashworth Labs, The King's Buildings, West Mains Road, Edinburgh EH9 3JT, UK
7Centre National de la Recherche Scientifique, CEFE – UMR 5175, 1919 Route de Mende, 34 293 Montpellier cedex 5, France

ABSTRACT: Industrial-scale fisheries are often thought to reduce food availability for top predators. It is essential to estimate the spatial and temporal overlap over a fine scale between fisheries and predators during their breeding season, when their energy demand is greatest and when they are most spatially constrained, in order to understand and manage this potential impact on their populations. In the Benguela upwelling region, 2 endemic vulnerable seabirds, Cape gannets Morus capensis and African penguins Spheniscus demersus, mainly eat anchovy Engraulis encrasicolus and sardine Sardinops sagax, both of which are exploited by the purse-seine fishery. A recent eastward displacement of small pelagic fish off the South African coast has reduced fish availability for both birds and fisheries along the west coast. Using GPS-recorders, we studied the foraging dispersal of birds from 8 colonies containing 95% of the global Cape gannet and 60% of the global African penguin populations to assess their overlap with fish catches. Despite the fact that bird data were gathered at very fine spatial and temporal scales (meters and hours), and fisheries data were recorded at much coarser spatial and temporal scales (20 km and months), there was clear overlap in areas used. The main foraging areas of both species were located where purse-seine fisheries caught most fish, with most catches occurring during the birds’ breeding season. As birds and fisheries also overlap in the size of the targeted prey and the depth of exploitation, our study suggests the potential for intense competition between purse-seine fisheries and decreasing seabird populations in the southern Benguela. Long-term protection of these seabird species requires the inclusion of a suitable ecological buffer when setting fishery quotas, and implementing marine protected areas closed to fishing around key breeding sites and foraging hotspots may improve their breeding success.

KEY WORDS: African penguins · Biotelemetry · Cape gannets · Conservation · Industrial fisheries · Offshore reserves · Foraging hotspots

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Cite this article as: Pichegru L, Ryan PG, Le Bohec C, van der Lingen CD and others (2009) Overlap between vulnerable top predators and fisheries in the Benguela upwelling system: implications for marine protected areas. Mar Ecol Prog Ser 391:199-208.

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