Changes in habitat preference of tuna species and implication for regional fisheries management: southern bluefin tuna fishing in the Indian Ocean

ABSTRACT

Changes in the ocean’s physical environment and its impact on ecosystems are well recorded in the literature and are likely to impact on the range and distribution of tuna species. This paper examines the impacts of these factors on the southern bluefin tuna (SBT) (Thunnus maccoyii), a species of low population abundance that is the focus of a high-value fishery. Oceanic warming has been projected to facilitate the expansion of such tropical tunas whilst reducing the northern distribution of temperate tunas such as the SBT. The study analysed the distribution of SBT using historical fisheries data collected by the Commission for the Conservation of SBT and the Indian Ocean Tuna Commission with the latitudes of fishing events and catches used as a proxy for SBT presence. Whilst these data do not provide conclusive evidence of a southerly shift in habitat preference, they do show increasing overlap between the SBT and with yellowfin tuna (Thunnus albacares). The paper concludes that while shifts in fishing effort in the Indian Ocean have a number of potential drivers, including changes in fish habitat, they highlight potential challenges to current regional management arrangements.

Acknowledgments

I would like to thank Professor Marcus Haward for assistance, guidance and support as well as thank Sarah Wilson and Indie O’Shea for their constant assistance and support.

This manuscript was produced as a result of an undergraduate research thesis at the University of Tasmania and as such no funding has been received for it.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributor

Eldene James Alan O'Shea is a honors student at the University of Tasmania. He completed his bachelor's degree in Antarctic Science at the same academic institution. Eldene has received two scholarships from the Australian Research Council Centre for Excellence for studying oceanography. Before his academic studies Eldene spent a considerable amount of time in Samoa teaching water safety and aquatic rescue techniques. It was in Samoa where his interest in sustainable fisheries management began. He currently resides in Hobart, Tasmania, where he enjoys the uncrowded waves and spectacular temperate water diving.