Long‐term associations of common bottlenose dolphins with a fish farm in Hawaiʻi and impacts on other protected species

Abstract

The global expansion of mariculture offers numerous potential benefits but may also pose a threat to wildlife populations. There is currently only one commercial finfish mariculture facility in Hawaiʻi, a nearshore kanpachi ( Seriola rivoliana ) farm off the west coast of Hawaiʻi Island. This farm lies within the range of several resident odontocete species, and almost daily common bottlenose dolphin ( Tursiops truncatus ) associations with the farm have been reported since 2007. We analyzed photographs of 35 bottlenose dolphin groups at the farm sighted between 2008 and 2021 in the context of 20 years of survey effort and extensive community science contributions from Hawaiʻi Island. Thirty‐six bottlenose dolphins were identified associated with the farm, representing almost one‐quarter of the estimated total population size. The discovery rate of new individuals at the farm indicates this is a conservative estimate of the total number of individuals associating with the farm, and social network analysis suggests that associations may continue to spread within the population. We also found a high frequency of farm associated bottlenose dolphins showing aggression towards several other species of dolphins, demonstrating impacts to multiple protected species.

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