A shortfin mako shark circling a finless porpoise with damaged caudal fin

• Published in: Ecology and evolution 2024-07, Vol.14 (7), p.e70024-n/a
• Main Authors: Okamura, Taro, Tokunaga, Soma, Ogawa, Takaya, Yoda, Ken
• Format: Article
• Language: English
• Subjects: Amputation; Animal bites; Aquatic mammals; Behavior; Cephalopods; Cetacea; Dolphins & porpoises; finless porpoise; Fishing equipment; Hunting; Injuries; Isurus oxyrinchus; Marine mammals; Nature Notes; Porpoises; Predator-prey interactions; predator–prey interaction; Prey; Seto Inland Sea; Sharks; shortfin mako shark; Sport fishing; Zoology
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.70024

Research on predator–prey interactions between sharks and cetaceans remain limited. Here, we report on a video of a shortfin mako shark circling a finless porpoise with a damaged caudal fin in the Seto Inland Sea, Japan. The finless porpoise was neither emaciated nor inactive, but unable to swim effectively due to the complete lack of a caudal fin. Some circumstantial evidence, including a bite mark on the porpoise's head, strongly suggests that the mako shark attacked it. Furthermore, the possible time difference between the two injuries the porpoise sustained may reflect the shark's hunting tactics. While mako sharks primarily feed on small fish and cephalopods, this observation suggests they also may prey on live cetaceans more often than previously thought. We report a video documentation of a shortfin mako shark circling a finless porpoise with a damaged caudal fin in the Seto Inland Sea, Japan. The wounds on the porpoise suggest that the shark attacked it while it was alive. While mako sharks primarily feed on small fish and cephalopods, this observation suggests they also may prey on live cetaceans more often than previously thought.