Climate change could cause drastic drop in fish catches: UBC

VANCOUVER (NEWS1130) – A new UBC study suggests climate change could create a boom in tropical fish species in BC, but an overall drop of up to 35 per cent in catches in some places due to increasing acid and decreasing oxygen in the world’s oceans.

Professor William Cheung with UBC’s Fisheries Centre presented his findings Saturday at the annual meeting of the American Association for the Advancement of Science, held at the Vancouver Convention Centre.

The predictions were generated by a computer simulator that accounted for increases in the ocean’s temperature, decreasing oxygen levels, and acidification, which is caused by the increasing absorption of carbon dioxide from the atmosphere.

“What we find is that if we just look at warming, the animals will shift their distribution, because for fish and for some of the shellfish, they like to live in a certain temperature of the water, and if water gets warmer, they will very likely move to a higher latitude or move north, so that they can find cooler water to live,” Cheung said.

“In addition, with less oxygen and with more acidic waters in some regions, that may also reduce their capacity for growth, so overall it may actually reduce the potential catch in some regions of the world.”

The study predicts a 20 to 35 per cent reduction in maximum catch potential by 2050 relative to 2005, depending on the region and individual species’ sensitivity to ocean acidification. Researchers noted that one-third of the carbon dioxide produced by the burning of fossil fuels is being absorbed by the ocean, gradually causing the water to become more acidic.

“There is a study that shows that more acidic water may affect animals that form shells, specifically, for example, the mussels or the oysters, which form shells when they grow,” Cheung explained. “Also, with some fish species, their larvae will be affected by more acidic water as well.”

Cheung said BC can expect an influx of tropical species from California over the next 50 years, while the species that have historically called BC home may move further north to the coast of Alaska.

He says the only ways to prevent future drastic drops in maximum catches are to curb overfishing and for countries to cooperate to reduce their greenhouse gas emissions.