Trophic niche overlap among dolphinfish and co‑occurring tunas near the northern edge of their range in the western North Atlantic

摘要: We present the first quantitative analyses of dolphinfish (Coryphaena hippurus) foraging habits and trophic interactions with co-occurring yellowfin (Thunnus albacares) albacore (T. alalunga) tunas in Southern New England region western North Atlantic Ocean. Fish caught by recreational anglers offshore waters Massachusetts were sampled during summers 2007–2010. Diet analysis revealed that shortfin squid (Illex illecebrosus) small pelagic crustaceans principal prey to dolphinfish, tuna, tuna. A wide variety Sargassum-associated fishes also important tuna diets. Dietary (Schoener’s index: 0.82–0.86) isotopic niche (isotopic ellipse overlap: 53.6–64.7 %) overlap was high, occupied equivalent positions (TP = 3.4–3.6). Relative size diets exhibited convergence ontogeny. Overall, had greatest width, which twice as large three times tuna; consumed range sizes. Results quantify near northern extent their geographical range, are relevant for ecosystem-based management guild context shifting fish populations fisheries response climate ecological change.