Climate change-driven redistribution of key commercial tuna species will deliver an economic blow to the small island states of the Western and Central Pacific and threaten the sustainability of the world’s largest tuna fishery, a major international study has found.
The study, published in Nature Sustainability last month, combines climate science, ecological modelling and economic data to provide a comprehensive analysis of the impact of climate change on Pacific tuna stocks and on the small island states that depend on them.
A consortium of institutions and organisations from across the Pacific, North America and Europe contributed to the research that found that the ten island states of the Western and Central Pacific – the Cook Islands, Federated States of Micronesia, Kiribati, Marshall Islands, Nauru, Palau, Papua New Guinea, Solomon Islands, Tokelau and Tuvalu – are so reliant on their tuna fisheries for economic development and food security that they are considered “tuna dependent”.
The management of most of the Islands’ tuna fisheries through a cooperative agreement has been a sustainable development success story over several decades, providing reliable and much-needed revenue for development while preventing the depletion of fish stocks through overfishing.
Around half of the world’s tuna catch comes from the waters of the Western and Central Pacific, and for those ten small island states, fishing fees from industrial fishing fleets to gain access to their waters account for an average of 37 per cent of all government revenue (ranging from 4 per cent of government revenue for the relatively large economy of Papua New Guinea to 84 per cent for Tokelau).
Study lead author Dr Johann Bell, Senior Director, Pacific Tuna Fisheries, Conservation International Center for Oceans, and Visiting Professorial Fellow at UOW’s Australian National Centre for Ocean Resources and Security (ANCORS), said the key species of skipjack, yellowfin, and bigeye tuna were highly migratory and move over large swaths of the ocean according to oceanographic conditions.
“Currently, these tuna stocks are found largely within the waters of the ten island states. However, under climate change, they are projected to shift eastward, progressively moving out of sovereign waters and into the high seas,” Dr Bell said.
“By 2050, under a continued high greenhouse gas emissions scenario, the total biomass of skipjack, yellowfin, and bigeye tuna in the waters of the ten states could decline by an average of 13 per cent as a greater proportion of fish move into the high seas.”
The potential implications for Pacific Island economies in 2050 include an average decline in purse-seine catch of 20 per cent, a loss in regional tuna-fishing access fees of up to US$140 million, and reductions in government revenue of up to 17 per cent for individual Pacific Island states.
The future for the Pacific Island states looks more promising under lower greenhouse gas emission scenarios, which would lead to smaller losses. Reductions in greenhouse gas emissions in line with the Paris Agreement would provide a pathway to sustainability for tuna-dependent Pacific Island economies.
“Many of the island states have very few opportunities to earn income other than from their tuna resources, which are expected to move from their jurisdictions due to ocean warming. Tuna is also a staple target species for fishing tourists, another source of income for the island nations.
Study co-author Assistant Professor Katherine Seto, from the University of California Santa Cruz, says preventing overfishing, and ensuring compliance with fisheries management measures, is more difficult outside the exclusive economic zones of the island states because the sole responsibility for compliance rests with the states that flag the fishing vessels, often resulting in self-regulation.
Photo credit: Steve Hathaway.
02 August 2021