Starving seabirds: unprofitable foraging and its fitness consequences in Cape gannets competing with fisheries in the Benguela upwelling ecosystem

摘要: Fisheries are often accused of starving vulnerable seabirds, yet evidence for this claim is scarce. Foraging energetics may provide efficient, short-term indicators the fitness status seabirds competing with fisheries. We used approach in Cape gannets (Morus capensis) from Malgas Island, South Africa, which feed primarily on small pelagic fish southern Benguela upwelling region, thereby purse-seine During their 2011–2014 breeding seasons, we determined body condition adult and measured chick growth rates. In addition to these conventional indices, assessed daily energy expenditure adults using a high-resolution time-energy budget derived GPS-tracking accelerometry data. For same individuals, also prey intake rates stomach temperature recordings. found that declined significantly during study period. Crucially, most birds (73 %) studied electronic recorders spent more than they gained through foraging, 80–95 % feeding dives were unsuccessful. Our results therefore point unprofitable foraging gannets, longer-term cost terms reproductive performance corresponds local population decline. Based evidence, advocate revision regional fishing quotas discuss possibility an experimental cessation activities off west coast Africa. These measures needed ecological socio-economical persistence broader ecosystem.