First Observations of Cooperative Circle Feeding in Southern Right Whales (Eubalaena australis)

ARGÜELLES, B.; FIORITO, C.; COSCARELLA,M.; FAZIO, A.; BERTELLOTTI, M.

AQUATIC MAMMALS

European Association for Aquatic Mammals

Año: 2023 vol. 49 p. 1 - 6

0167-5427

Marine mammals have developed various feeding strategies, including cooperative foraging in groups. Cooperative feeding is more common in social marine mammals like odontocetes that include smaller oceanic dolphins. Cooperative feeding allows these species to hunt more efficiently by working together to gain access to food. For example, common bottlenose dolphins (Tursiops truncatus) can create waves and simultaneously rush towards the shore to catch fish. Dusky dolphin (Lagenorhynchus obscurus) behavior has been studied in Argentina and New Zealand where they exhibit considerable plasticity in feeding behaviors by using diverse feeding tactics that include herding prey, using the shore as a barrier, and feeding individually. Killer whales are found in several different ecotypes which feed on varying items, including fish, seals, dolphins, whales, and birds, and have been observed knocking seals into the water from ice floes or herding dolphins cooperatively. Contrary to odontocetes, which often feed in large groups, most mysticetes forage singly and independently. Nevertheless, cooperative feeding, for example, by using bubble-net feeding, is relatively well described for humpback whales (Megaptera novaeangliae). Mysticetes exhibit one of the most energetically efficient foraging strategies by feeding on aggregations of zooplankton and small fish, and many strategies and tactics are used to locate and capture prey. Humpback whales, like other baleen whales (Balaenopteridae), use intermittent ram feeding or lunge feeding, techniques in which an individual animal engulfs a large volume of prey- laden water. Another strategy is trap-feeding, reported in Chile, where herding with pectorals increases concentrations of diffuse schools of small fish towards the whale’s open mouth, used as a trap. Contrary to Balaenopteridae, gray whales (Eschrichtius robustus) use suction to consume benthonic prey by sucking the prey into their mouth while bottom feeding, whereas bowhead (Balaena mysticetus) and right (Eubalaena spp.) whales use a continuous filter feeding approach at the water’s sur- face called skim feeding. This technique involves the continuous filtration of water to skim dense swarms of zooplankton (Werth, 2000). In the present study, we report the observation of a large group of southern right whales (Eubalaena australis; SRWs) cooperatively foraging in Bahía Nueva (Puerto Madryn), Argentina. By “cooperating,” we refer to SRWs being able to work together to concentrate their prey and obtain more food with less expenditure of time or energy than they could invest alone. This feeding behavior that we propose to be termed cooperative circle feeding behavior is, to our knowledge, the first record of this activity for this species.