British Columbia

Pacific Ocean 'blobs' will escalate loss of fish stocks, study says

The research, released in the journal Scientific Reports, concludes that by 2050 marine heat waves may double the impact of climate change on species that are highly valued for fisheries.

Marine heat waves intensify effect of climate change, UBC researcher’s modelling shows

Researchers used advanced modelling to measure the combined effect of climate change and marine heat waves, nicknamed "blobs", on the survival and distribution of 22 Pacific fish stocks that are important to regional fisheries. (UBC)

A new study co-authored by a University of B.C. researcher predicts increased death rates for Pacific fish stocks from marine heat waves like the mysterious "Blob" that disrupted the marine ecosystem from 2013 to 2015.

The research, released in the journal Scientific Reports, concludes that by 2050 the large masses of warm water may double the impact of climate change on species that are highly valued for fisheries.

"So, for example, for sockeye salmon we may be seeing a decrease in potential catch for more than 30 per cent," co-author and UBC associate professor William Cheung told CBC Radio West host Sarah Penton on Tuesday.

"The Blob" was the nickname given to a large marine heat wave that occurred in 2013 and affected marine life on the West Coast from Alaska to Baja California for several years. 

Since then, similar marine heat waves have developed off the Pacific coast. 

"This is not a one-off event," said Cheung, who is the Canada research chair in ocean sustainability at the UBC Institute for Oceans and Fisheries.

UBC associate professor William Cheung's article estimates that warm water masses similar to the "blobs" measured off the West Coast could double the loss of important Pacific fish stocks. (UBC )

The study used advanced climate and ocean systems modelling and simulations of abundance and distribution of 22 fish stocks that are important to fisheries. In the simulation, the distribution of fish stocks changed in response to changes in ocean conditions. 

The study found the impact of climate change combined with the effect of marine heat waves caused a decrease in the size of the fish stocks and changes in their distribution patterns, which would affect regional fisheries.

Cheung highlighted the importance of early prevention in cases of episodic events like marine heat waves, and drew comparisons with the preparedness required to deal with pandemics such as COVID-19. 

"There are lots of parallels that can be joined between the two," he said. 

To halt the loss of fish stocks, Cheung and study co-author Thomas L. Frölicher suggested measures such as altering fishing quotas, as well as changing fishing grounds and which species are targeted. 

With previous research showing the link between climate change and the occurrence of marine heat waves, a reduction in human-caused greenhouse gas emissions would be needed to limit the impact of future "blobs" on fish stocks and fisheries, they wrote. 

With files from Radio West and Matt Allen

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