Researchers from Kobe University, Teikyo University of Science, the Norwegian Institute of Marine Research, the University of St. Andrews, the Zoological Society of London, and the University of Tokyo's Atmosphere and Ocean Research Institute have discovered that humpback whales are "grabbing" around fishing boats. .
Many marine predator species are known to forage around fishing boats, as they can easily catch food such as fish that have fallen from fishing boats.Baleen whales, including humpback whales, are one such species, and baleen whales normally hunt for small fish and zooplankton by lunging at them, using a method called lunge feeding.Lung-feeding around fishing boats not only risks colliding with fishing boats, but is also not efficient at catching scattered bait.In this study, we investigated how humpback whales actually hunt for food around fishing boats in fjords off the coast of Norway.
Three humpback whales were attached with devices such as video and behavioral recorders using suction cups, and the devices fell off naturally after a few hours to obtain behavioral and video data.Analysis of the data revealed that the whales that swam around the fishing boats remained around the boats, picking up fish and other spills that fell from the boats and eating them.Additionally, this individual whale never lunged for food near the fishing boat.On the other hand, data from two other individuals that were not swimming around the fishing boat showed records of lunge feeding, indicating that humpback whales flexibly change their feeding behavior depending on the situation. Ta.
It has been found that pick-up feeding, which targets scattered prey, yields less food at one time than lung feeding, which targets prey in schools, but it also consumes less energy due to tail fin movements and swimming speed.In other words, gleaning can be said to be an energy-saving foraging style that consumes less food with less energy.
However, scavenging carries the risk of whales getting entangled in fishing gear and dying, and the fishermen risking accidents.In environments where whales gather around fishing boats, it is recommended to take measures to avoid approaching whales (such as making noises that whales dislike).
Paper information:【Ethology】Non-lunge feeding behavior of humpback whales associated with fishing boats in Norway
