Attachment of live sharksuckers (Echeneis naucrates) to Indo-Pacific humpback dolphins (Sousa chinensis) in Xiamen Bay, China

The live sharksucker ( Echeneis naucrates ) is a bony fish that uses a specialized suction disk on its head to hitchhike on marine animals. Although live sharksuckers have been recorded attaching to various cetaceans worldwide, such associations between live sharksuckers and cetaceans have rarely been reported in the East Asia region. From 2011 to 2024, we conducted a long-term survey of Indo-Pacific humpback dolphins ( Sousa chinensis ) in Xiamen Bay, one of the key habitats for this cetacean in the seas around China. From 2022 to 2024, we recorded live sharksucker attachments on four Indo-Pacific humpback dolphin individuals, with a total of 11 events in Xiamen Bay. Specifically, we observed a live sharksucker temporarily detaching from the body of an Indo-Pacific humpback dolphin when the dolphin cleared its body out of the water and landed on one side multiple times. This reaction of the live sharksucker could be an adaptive characteristic to cope with the side breach behavior of their cetacean hosts. Considering the declining population of Indo-Pacific humpback dolphins, further investigation into the potential impacts of live sharksuckers on these dolphins is required.