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Lookup NU author(s): Dr Steven Newman
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The trace element requirements of sharks are poorly understood and the dietary intakeof metals from prey items in wild sharks has not been measured. In this study whole prey of nurserybound juvenile lemon sharks Negaprion brevirostris, from Bimini, Bahamas were analysed for carcasstotal protein, lipids, carbohydrates, ash content, energy, and elemental composition. Metalanalysis included 415 prey items from 18 species (fish: Atherinidae, Belonidae, Gerreidae, Haemulidae,Lutjanidae, Scaridae, Sphyraenidae; decapod crustaceans: Penaeidae, Portunidae). There weresome seasonal and location effects (North Sound versus South Bimini shark nurseries), but overallprey metal concentrations were broadly similar to reports for temperate species. Yellow fin mojarraGerres cinereus dominate the shark diet, in which electrolytes were similar (Na 10, K 10, Ca 65, andMg 2 mg g–1 dry weight) but trace metals were higher (Cu 2.4, Zn 96, Fe 63, Mn 0.7 μg g–1 dry weight)than in other prey fish species at Bimini. Swimming crabs (Portunidae) were an important source ofdietary Ca, Mg, Cu and Mn for lemon sharks. The calculated daily dietary metal intakes (mg d–1) forCu (0.17), Fe (1.2) and Mn (0.01) of lemon sharks are below previously estimated requirements ofother fish. Dietary salt intake (272 mg Na d–1, 1% dietary salt) is similar to other fishes, but the Ca andZn intakes are higher. Yellow fin mojarra contained 65% protein, 4% lipid, 23% ash. The averagejuvenile lemon shark (1.85 kg, 24.84 g daily ration) ate a very lean high protein diet (61.9% protein,4.6% lipid, 24.9% ash, 8.6% carbohydrate), with a calculated energy intake of 397 kJ d–1. Overall,the data suggests the gross macronutrient composition of the shark diet is adequate, but some of thetrace metals may be limiting in the diet of wild juvenile lemon sharks at Bimini.
Author(s): Pettitt-Wade H, Newman SP, Parsons KT, Gruber SH, Handy RD
Publication type: Article
Publication status: Published
Journal: Marine Ecology Progress Series
Print publication date: 18/07/2011
ISSN (print): 0171-8630
ISSN (electronic): 1616-1599
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