Energetic Requirements for Growth and Maintenance of the Cape Gannet (Aves; Sulidae)

Cooper, John

doi:10.1080/00445096.1978.11447631

Cited by 43 publications

(18 citation statements)

References 25 publications

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“…For this reason we have simply converted energy intake to grams of fish in proportion to the frequency of each species in the diet (averaged over the year), assuming that 1 g of fish is equivalent to 8 Kj. This is approximately the energy value of anchovy (Cooper, 1978), the main species in the diet of all 3 seabirds. Diets and consumption figures are given in Table 5.…”

Section: Energy Costs and Fish Consumptionmentioning

confidence: 99%

“…Species statistics required for energetics calculations (Table 2) were extracted from Rand (1960a, b), Jarvis (1971), Berry (1976), Cooper (1977Cooper ( , 1978, Nel- son ( 1978) and observations of the foraging activity budgets of these species made by the authors. Of the input data in Table 2 the estimated hours of each daily foraging activity are poorly known.…”

Section: Model Inputmentioning

confidence: 99%

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Interactions Between Breeding Seabird and Pelagic Fish Populations in the Southern Benguela Region

Furness¹,

Cooper²

1982

Mar. Ecol. Prog. Ser.

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A bioenergetics model was used to estimate the quantity of pelagic fish eaten and the energy consumed by 3 species of breeding seabirds in the Saldanha Bay fishing ground in the Southern Benguela Region off the west coast of South Africa. The 3 species -jackass penguin Spheniscus demersus, Cape gannet Sula capensis, and Cape cormorant Phalacrocorax capensis -were estimated to consume a total of 16,500 t of fish yr-', of which 11,800 t were anchovy Engraulis capensis Gilchrist. This represented a total consumption of 1.3 X 108 Kj. Annual consumption of fish by the 3 seabird species was estimated to represent 30 % of the mean annual catch in the Saldanha Bay fishing ground, based on a mean commercial fishery landing of 55,000 t per year. This figure is similar to that estimated for several other oceans where breeding seabirds and a commercial fishery coexist.

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Section: Energy Costs and Fish Consumptionmentioning

confidence: 99%

Section: Model Inputmentioning

confidence: 99%

Interactions Between Breeding Seabird and Pelagic Fish Populations in the Southern Benguela Region

Furness¹,

Cooper²

1982

Mar. Ecol. Prog. Ser.

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“…For gannet, we used a value for cape gannet (Morus capensis) chicks (Cooper 1978). The empirical data available were used for all age classes of the species, with adult kittiwake assimilation efficiency used for immature birds.…”

Section: Assimilation Efficiencymentioning

confidence: 99%

The impact of the sandeel fishery closure on seabird food consumption, distribution, and productivity in the northwestern North Sea

Daunt¹,

Wanless²,

Greenstreet³

et al. 2008

Can. J. Fish. Aquat. Sci.

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Abstract:In the North Sea, the lesser sandeel (Ammodytes marinus) is the target of an industrial fishery and the principal prey of many top predators. Because of concerns about potential effects on predators, the sandeel fishery off eastern Scotland was closed in 2000, and local sandeel abundance increased subsequently. To examine whether closure benefitted sandeel-dependent seabirds, we compared summer sandeel consumption, at-sea distributions, and breeding success of seven species with fishery removals and abundance of older (1+ group) and young-of-the-year (0 group) sandeels from 1996 to 2003. Breeding success of black-legged kittiwake (Rissa tridactyla), a species that has declined in recent decades, was related to abundance of both 1+ group (the age class targeted by the fishery) and 0 group sandeels. The proportion of 0 group consumed by kittiwakes and proportion of the kittiwake population foraging in the area were linked to 0 group abundance. None of these parameters in the other seabird species were associated with sandeel abundance. Our results suggest that fishery closure can have a beneficial impact on top predators sensitive to variation in abundance of the target species, although environmental conditions before and after closure are also likely to be critically important.Résumé : Dans la mer du Nord, le lançon équille (Ammodytes marinus) fait l'objet d'une pêche industrielle et il constitue la principale proie de plusieurs prédateurs supérieurs. À cause de préoccupations concernant les effets potentiels sur les prédateurs, la pêche commerciale aux lançons équilles au large de la côte est de l'Écosse a été fermée en 2000 et l'abondance locale des lançons a alors augmenté. Afin de vérifier si cette fermeture a été bénéfique aux oiseaux marins dépendants des lançons, nous avons comparé la consommation de lançons pendant l'été, la répartition en mer et le succès de la reproduction chez sept espèces en fonction des retraits de la pêche et de l'abondance des lançons de l'année (groupe 0) et des lançons plus âgés (groupe 1+) de 1996 à 2003. Le succès de la reproduction de la mouette tridactyle (Rissa tridactyla), une espèce en déclin au cours des dernières décennies, est relié à l'abondance des lançons, tant ceux du groupe 1+ (la classe d'âge ciblée par la pêche) que ceux du groupe 0. La proportion des lançons d'âge 0 consommée par les mouettes et la proportion de la population de mouettes qui recherche sa nourriture dans la région sont reliées toutes deux à l'abondance du groupe 0. Aucune de ces variables chez les autres espèces d'oiseaux marins n'est reliée à l'abondance des lançons. Nos résultats indiquent que la fermeture de la pêche peut avoir un effet béné-fique sur les prédateurs supérieurs qui sont sensibles à la variation de l'abondance de l'espèce ciblée, bien que les conditions du milieu avant et après la fermeture puissent être aussi vraisemblablement d'importance primordiale.[Traduit par la Rédaction] Daunt et al. 381

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“…Nagy (1987) assumed a metabolizable energy for birds on a diet of fish of 16,2 kJ· g-I, which implies an assimilation efficiency of 74 per cent given a mean energy value of 22 kJ' g-I dry mass for fish. Cooper (1978) measured an identical assimilation efficiency for Cape gannets, and in the present analysis, the value of 74 per cent was used for all seabirds. The balance (26%) was taken to be egested or excreted.…”

Section: Consumption and Productionmentioning

confidence: 99%

Seabird consumption and production in the Benguela and Western Agulhas ecosystems

Crawford¹,

Ryan²,

Williams³

1991

South African Journal of Marine Science

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Energetic Requirements for Growth and Maintenance of the Cape Gannet (Aves; Sulidae)

Cited by 43 publications

References 25 publications

Interactions Between Breeding Seabird and Pelagic Fish Populations in the Southern Benguela Region

Interactions Between Breeding Seabird and Pelagic Fish Populations in the Southern Benguela Region

The impact of the sandeel fishery closure on seabird food consumption, distribution, and productivity in the northwestern North Sea

Seabird consumption and production in the Benguela and Western Agulhas ecosystems

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