Unwreck the Beach: Researchers sound alarm as climate crisis hits global fish stocks

In a recent study, researchers from UBC and the University of Bern have warned global fish stocks will be unable to recover without urgent climate action.

The study looked at how global fish stocks are changing due to factors related to the climate crisis and other human activities over a 150-year period, finding over half of the regions studied have already seen reduced fish stocks.

Researchers considered fish stock responses from 1950–2100 and applied three different projected global temperature increases in their model. These alternative emission pathways — 1.8, 4.5 and 6.2 degrees celsius of warming relative to pre-industrial temperatures — account for multiple levels of fisheries conservation and allowed the authors to create a sliding scale with different thresholds predicted for different possible futures.

Put simply, they are predicting what action would be required at different warming levels to avoid disaster for global fish stocks.

“Climate change is affecting the fish stock’s abundance and distribution … what it means is that it is harder for fisheries to rebuild the biomass of the fish stocks,” said associate professor at the Institute for the Oceans and Fisheries Dr. William Cheung, a co-author on the paper.

Part of this problem is the current practice of operating under maximum sustainable yield limits, which refer to the greatest amount of fish that can be harvested without destroying a stock.

But these limits, which are already controversial, are ill-suited to deal with the climate crisis. According to Cheung, if this practice continues, most global fish stocks will be unable to recover once the world reaches the threshold of 1.8 degrees of warming.

Current estimates place warming in 2021 at over a full relative degree to pre-industrial levels.

While the research shows addressing the climate crisis is critical, putting less stress on fish stocks can also buy us time.

“Instead of aiming for a maximization of fisheries catches protection we should shift the mentality to have more of a conservation focus,” said Cheung, “further reducing the fishing level so that we give a better chance for the fish stocks to recover.”

If a more “sustainable target” was adopted, then the majority of fish stocks have the potential to recover until 2.6 degrees of warming — a threshold that is just below the current middle estimate for warming under current policies in place.

Importantly, not all regions of the world are experiencing the climate crisis equally. The study notes that the situation is especially urgent in tropical areas such as West Africa, the Indo-Pacific, the central and south Pacific and the Eastern Tropical Pacific.

Cheung noted these regions have warming limits that are much lower than the global average, saying “a challenge in our paper is that in many of these regions, they also rely on the fish stocks as a source of livelihood and to support food security.”

He advocated international cooperation on the management of large-scale commercial fisheries and climate mitigation as a means of alleviating this burden from local communities, stressing that “many of these countries are not the main contributors of carbon emissions.”

This situation is not confined to the global south either, with Cheung advocating for support “to the most vulnerable and sensitive communities and regions, including coastal First Nations in Canada who are strongly dependent on seafood, and that we need to find ways to help adapt.”

To Cheung, all of this means it is critical to limit warming to the 1.5-degree goal set out in the Paris Agreement. However, he conceded this to be unlikely.

“There’s a likelihood we will overshoot the Paris Agreement so what it means is that we need to do all we can in order to both mitigate but then also to help adapt to situations when global warming levels go beyond these limits.”

Unwreck the Beach is The Ubyssey’s sustainability column. Send pitches or topics you’d like covered to sustainability@ubyssey.ca.