Major New Zealand salmon producer shuts farms as warming waters cause mass die-offs – The Guardian

Posted: June 1, 2022 at 8:28 pm

New Zealands biggest king salmon farmer says it is shutting some of its farms after warming seas prompted mass die-offs of fish, warning that it is a canary in the coalmine for climate change.

New Zealand is the worlds largest producer of king, or chinook salmon, a highly valued breed which fetches a premium on the world market. The countrys farms account for about 85% of global supply, New Zealand King Salmon chief executive Grant Rosewarne said.

Now, increasingly warm summer seas mean the fish at some sites are dying en masse before they can reach maturity, leaving farmers dumping thousands of tonnes of dead fish into local landfills.

There should be alarm bells, Rosewarne said. When I joined this company, I never heard of the term marine heatwave. Recently, theres been three of them.

We thought we had more time, Rosewarne said. Climate change is a slow process but faster than many people think certain industries are canaries in the coalmine.

We thought that climate change is a really slow effect, detected over decades and possibly weve got, two decades before were even impacted. Well, within one decade we were impacted.

Its considered usual for a small percentage of farmed fish to die each year, but warming temperatures have significantly increased those deaths. In 2022, the King Salmon Companys percentage mortality of biomass for the fish was up to 42% in warm water areas where the fish were not towed to cooler zones; compared to 17% in 2018. Even when the fish were towed out to cooler waters, many were dying: 37% in 2022, compared to just 10% in 2018.

Over the summer months, hotter water temperatures, heated by warm currents coming down from the coral sea, had pushed some of the farmed populations over the edge. We see [temperatures] elevated by a full degree I know that doesnt sound much to people, but a full degree is huge for our species, he said. If you get to 18 degrees for two weeks, then you have a mass mortality event on your hands.

According to RNZ, trucks taking dead fish out of the area had dumped 1,269 tonnes of dead fish and waste in Blenheims landfill over the summer 632 tonnes in February alone, seven times last year and up from the 194 tonnes dumped in February 2020.

Now, New Zealand King Salmon will fallow three of its farms in the warmer Pelorus sound area, keeping just one open to run trials. The company is hoping to be allowed consents from the government for water space where it can farm the fish in cooler waters.

View original post here:

Major New Zealand salmon producer shuts farms as warming waters cause mass die-offs - The Guardian

Related Posts