Tuesday , May 18 2021

Researchers from B.C. Salmon in hot water – Terrace Standard

Anomaly or a new norm, researchers carefully monitor the permanent hot water in the northeastern Pacific Ocean and what it means for salmon.

In the last two months, a high-pressure ridge developed across the coastal area of ​​B.C. resulted in an extended warm flight. The storm season is late, and the water is two to three degrees warmer.

Richard Devei, Assistant Director of Science at Ocean NetWorks Canada, and the University of Victoria, carefully monitors about 2,000 miles of unusually warm space that first appeared in the autumn of 2013 and became much more pronounced in the spring of 2014 – when the researchers cheered the term "mud."

"This event has awakened us to what's happening here. The atmosphere, the storm and jet streams are merging and becoming weaker winds over the bay and that's why we do not mix cold water, and things keep warm," Devei said.

Now they pay attention. By 2017, oceanographers began to see that the warm mass scattered in depth, but this year it returned to the northeastern Pacific and the Bering Sea.

"Maybe it's a trend. So maybe climate change is reflected in our backyard, but we still do not know it," Devey said.

Ocean NetWorks Canada has instruments along the bottom and near the shores of the ocean. They did not pick up the 2014 blob on the sensor until a few months later, so researchers carefully monitor satellite data and temperature charts on the sea surface for Alaska Bay.

Effects on salmon

The warming of the ocean also affects the fresh water temperatures.

Sue Grant is the leading fisheries and ocean Canada program (DFO). Her role is to integrate what we know about salmon and their ecosystems. Oceographers and freshwater explorers see co-existence between mud and warming in rivers and streams.

"The mud itself is an oceanographic phenomenon, but it is caused by a merger with the atmosphere, and it also has repercussions in fresh water," Grant said.

The salmon is anadromous, with fresh water and sea phases, and they are warmer in most habitats. Grant said that the effects of warm blossoms for 2014 and 2015 differ in salmon stocks in B.C. and Yukon territory.

"The answers are mixed, although some of our southern reserves and some of our northern ones have not worked so well this year. We saw the remaining survival in salmon stocks in Fraser's watercourse last year across different species, and this year we saw in Fraser the average survival below There are other examples in the north, "she said.

Grant uses a marathon analogy to describe what temperature temperatures of 3-5 degrees Celsius work on salmon.

If she runs a marathon at 50 degrees Celsius, she may not survive because she is 50-60 degrees Celsius beyond her optimal temperature range. Salmon also has an optimal temperature range, and when trying to migrate upstream during the summer period, it can have a negative impact on their migration.

Water temperatures that are warmer than average also affect the level of nutrients.

When the ecosystem shifted from 2014 to 2015, the surface layer of the Alaska Bay was weaker in nutrients. Ocean NetWorks Canada saw that cold water types that require an environment rich in nutrients were not too large, while hot water types that could adapt to low feeding conditions that had dominance.

"When salmon there in the bay and along the coast feeding under these conditions returned in the period 2016-17, a little less than the usual ones," Devei said.

"The numbers I've seen say that these hot conditions can result in smaller fish sizes, so it has some impact."

Both Grant and Devey say they pay attention, but it is too early to make projections and what is the warm mud from 2018 for salmon.

However, they can take data from the past few years – the salmon response to freshwater and marine ecosystem warming – and watch out to see if there is a pattern and what it can mean for the future of salmon stocks.

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