Beating the heat: colder ocean good news for salmon, DFO says

By Ian Holmes
July 10, 2017 - 5:32pm Updated: July 10, 2017 - 9:30pm

Juvenile West Coast salmonDFO

NANAIMO — A continuous trend toward more normal ocean temperatures is viewed as a positive for the iconic West Coast salmon.

Nanaimo-based Department of Fisheries and Oceans senior research scientist Dr. Ian Perry said record-breaking warm ocean temperature between 2014 and 2016 stressed salmon and weakened their food sources.

But he noted a trend towards colder temperatures, where salmon do better, has continued into this year.

“There are traces of it (warm ocean) at depth at about 100 meters or so, which has some influence on the supply nutrients, but by and large that warm water is generally gone.”

The warm ocean was created in large part by a huge "blob" of warm water which settled off the West Coast, as well as a La Nina weather pattern in 2015 and 2016.

Perry said a "triple whammy" battered juvenile salmon in 2015, leading to less food sources and also an increased number of predators.

“We expected reduced survivals and lower abundances of those fish coming back in 2017,” Perry said.

He said a cooling ocean bodes well for future stocks.

“If the trends to cooler temperatures and more normal plankton composition continue the hope would be that the salmon that went to sea in Spring of 2017 may do better and that we may see more of them return in 2019.”

 

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