A New Record of Atlantic Bluefin Tuna (Thunnus thynnus) Consuming a Seabird in the Northwest Atlantic Ocean

Nathan D. Stewart^1,*, Louise Chavarie^1,2, Alex Hanke^1,3, Ana Storch⁴, François Turcotte⁵, and Aaron T. Fisk¹

¹Kentucky Department of Fish and Wildlife Resources, Frankfort, KY 40601.²Norwegian University of Life Sciences, NMBU, Faculty of Environmental Sciences and Natural Resource Management, PO Box 5003, NO-1432 Ås, Norway. ³Fisheries and Oceans Canada, St. Andrews Biological Station, 125 Marine Science Drive, St. Andrews, NB E5B 0E4, Canada. ⁴Fisheries and Oceans Canada, North Atlantic Fisheries Centre, 80 East White Hills Road, St. John’s, NL A1A 5J7, Canada. ⁵Fisheries and Oceans Canada, Gulf Fisheries Centre, 343 Université Avenue, Moncton, NB E1C 9B6, Canada. *Corresponding author.

Northeastern Naturalist, Volume 31, Issue 4 (2024): N42–N50

First published early online: 4 December 2024

Abstract
Thunnus thynnus (Atlantic Bluefin Tuna) is an opportunistic generalist predator in the pelagic zone of the Atlantic Ocean. In the northwest Atlantic Ocean, Atlantic Bluefin Tuna diets are primarily based on small pelagic prey. Seabirds often prey on the same pelagic forage fish as tuna, leading to an overlap in the timing and location of both seabird and Atlantic Bluefin Tuna foraging activity and the potential for tuna–seabird interactions. Here, we present the first documented evidence of Atlantic Bluefin Tuna consuming a seabird in the Northwest Atlantic Ocean. This is the second report of Atlantic Bluefin Tuna consuming a seabird in the entire species’ range. The evidence for this interaction comes from the stomach contents of a commercially harvested Atlantic Bluefin Tuna caught ~1.6 km offshore of Newfoundland in October 2022. The unknown bird in the Atlantic Bluefin Tuna stomach was identified through DNA metabarcoding as Fratercula arctica (Atlantic Puffin), a diving seabird for which an overlap with pelagic predatory fish is credible. While rarely observed, it is important to identify such interactions between seabirds and predatory fish to gain a more complete understanding of food-web interactions in marine pelagic ecosystems.

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