Climate change could lead to significant declines in exploitable fish biomass across the world's oceans by the end of the century under a high-emissions scenario, the United Nations' Food and Agriculture Organization has warned.

The study projects that global fish biomass could decrease by over 10% in many regions by 2050 under a high-emissions scenario where global warming reaches between three and four degrees Celsius. By 2100, declines could exceed 30% in 48 countries and territories.

However, if global warming is limited to 1.5 to two degrees Celsius through emissions reductions, biomass losses stabilize at around 10% or less across most countries, the report said.

The findings highlight the "benefits of climate change mitigation measures for fisheries and aquatic foods," said Manuel Barange, an assistant director general at the FAO.

He said top fish producers like Peru and China could see biomass declines of over 30% in coastal waters by 2100 under the high emissions scenario. Small island developing states also face significant vulnerability due to their heavy reliance on fisheries.

But the report indicates that lower emissions could avert between 68% and 90% of those extreme losses among Pacific island countries like the Federated States of Micronesia and Tuvalu.

"This highlights the importance of climate mitigation efforts," Barange said.