RE-COLONISATION OF VONDELING ISLAND (WEST COAST, SOUTH AFRICA) BY THE CAPE FUR SEAL (ARCTOCEPHALUS PUSILLUS PUSILLUS): ITS CONSERVATION AND MANAGEMENT IMPLICATIONS Mduduzi Seakamela
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The Cape fur seal (Arctocephalus pusillus pusillus) • Only pinniped breeding in southern Africa • Algoa Bay (South Africa), through Namibia to Baia dos Tigres in southern Angola
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Cape fur seal range ©Kirkman et al. 2012
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The Cape fur seal (Arctocephalus pusillus pusillus) • Only pinniped breeding in southern Africa • Algoa Bay (South Africa), through Namibia to Baia dos Tigres in southern Angola • Historically island breeders
• Deliberate disturbance at certain island colonies for guano • Harvested in Namibia, SA moratorium in 1990 • 23 colonies in 1973; increased to 40 in 2009
• 1.5 to 2 million animals (Butterworth et al. 1995)-fluctuating • Recolonisation of some colonies
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Recolonisation • 2 new breeding colonies (Vondeling Island, Robberg Peninsula) and one haul out (Robben Island) • Disturbance • Space limitations • Environmental stresses affecting prey availability • Site fidelity vs. Survival
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Vondeling Island • West Coast of South Africa • 0.21 Km2
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• Dual Mandate • Provincial reserve (Protected Areas Act, Cape Nature) • Seals and seabirds (Seabird and Seals Protection Act 46 of 1973) • Endangered/endemic seabirds: African penguin, Cape cormorant, Bank
cormorant and Crowned cormorant • 13 seals 1991
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Vondeling Island • Seabirds monitored since 1990
Land based surveys 1991 Aerial Surveys Initiated in 2011
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Land Based Survey
Aerial Survey
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Vondeling Island
Cape fur seal pup trends at Vondeling Island
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Vondeling Island
Seabird trends at Vondeling island
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West Coast Situation • Anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax) key prey for seals and seabirds • Eastward movement •
Percentage of the total sardine biomass located to the east and west of Cape Agulhas showing the gradual increase in the proportion of sardines and abrupt increase of Anchovies east of Cape Agulhas and the recent reversal in 2008 (sardine) ©van der Lingen et al. 2011
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West Coast Situation
Spawner biomass survey 2012 © DAFF
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Movements relative to the island ID 66310
ID 66407
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Movements relative to the island ID 66354
ID 66354
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Movements relative to the island ID 66393
ID 66394
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Vondeling Island • 2 new breeding colonies (Vondeling Island, Robberg Peninsula) and several haul outs (e.g. Jutten, Robben Islands) • Disturbance: unlikely to cause dispersal • Space limitations: West Coast mainly island colonies except Kleinsee • Environmental perturbation affecting prey availability • Site fidelity vs. Survival (abandon colonies/locality)
• Immigration: Possible explanation
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Interactions and mitigation • Possible competition for food with some seabirds • No evidence of predation by seals on seabirds • Breeding space limitations • Artificial nests and platforms
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Thank You
