MEPS 550:163-174 (2016)  -  DOI: https://doi.org/10.3354/meps11723

ABSTRACT: The feeding ecology of 3 coastal shark species—Atlantic sharpnose Rhizoprionodon terraenovae, bonnethead Sphyrna tiburo, and blacktip Carcharhinus limbatus shark—was examined in the northwest Gulf of Mexico (GOM). A total of 601 sharks (305 Atlantic sharpnose, 239 bonnethead, and 57 blacktip) were collected over 2 yr from recreational anglers in Galveston, TX. All individuals had stomach contents examined and a subset (50 Atlantic sharpnose, 50 bonnethead, and 36 blacktip sharks) was analyzed for stable isotopes (carbon, nitrogen, and sulfur) in muscle tissue, revealing short-term and long-term feeding strategies. Both blacktip and Atlantic sharpnose shark stomach contents consisted of teleost fishes with percent index of relative importance (%IRI) of 98.95 and 91.16, respectively, whereas bonnethead diets were dominated by crustaceans (%IRI = 87.20). Stable isotope analysis revealed bonnetheads had higher mean carbon (δ¹³C) and lower sulfur (δ³⁴S) values, indicating inshore feeding and a preference for benthic invertebrates, respectively. Atlantic sharpnose and blacktip sharks were shown to feed on similar prey using stomach content analysis, yet Atlantic sharpnose sharks had a broader diet, including cephalopods and crustaceans in addition to teleost fishes. Differences were further established using nitrogen (δ¹⁵N) values, which were significantly lower for Atlantic sharpnose than blacktip sharks. Collectively, stomach contents and stable isotope analyses supported different feeding strategies of 3 common shark species. δ³⁴S appeared to serve as a natural tracer, distinguishing benthic versus pelagic feeding patterns in elasmobranchs. This study provides important ecosystem-based feeding information of upper trophic-level predators in coastal waters of the northwestern GOM.

KEY WORDS: Feeding ecology · Stable isotopes · Stomach contents · Gulf of Mexico

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Cite this article as: Plumlee JD, Wells RJD (2016) Feeding ecology of three coastal shark species in the northwest Gulf of Mexico. Mar Ecol Prog Ser 550:163-174. https://doi.org/10.3354/meps11723 Export citation Share:    Facebook - - linkedIn