Archives for July 2015

Hot water causes massive sockeye salmon die-off at Columbia River

SEAFOODNEWS.COM [CSMonitor] By Courtney Sherwood, Reuters- July 28, 2015
Unseasonably hot water has killed nearly half of the sockeye salmon migrating up the Columbia River through Oregon and Washington state, a wildlife official said on Monday.
Only 272,000 out of the more than 507,000 sockeye salmon that have swum between two dams along a stretch of the lower Columbia River have survived the journey, said Oregon Department of Fish and Wildlife fisheries manager John North.
“We’ve never had mortalities at this scale,” said North.

Salmon are dying from high water temperatures Credit: seattletimes.com

Salmon are dying from high water temperatures
Credit: seattletimes.com

The die-off comes as U.S. West Coast states grapple with drought conditions and the Columbia is seeing the third-highest count of sockeye returning from the ocean to spawn since 1960, federal figures show.
Hot air combined with abnormally low mountain snow melt has increased water temperatures and prompted fishing restrictions and efforts to save beleaguered fish, including trucking salmon to cooler waters.
The Columbia River hit 70 degrees Fahrenheit in mid-June, about a month earlier than usual, and the fish were not able to adjust, North said.
Warm waters are at least partially to blame for more than 400,000 additional salmon deaths this year, hatchery officials say.
The sockeye were counted between the lower Columbia’s Bonneville Dam and McNary Dam, about 150 miles upstream, en route to the Snake River tributary.
Snake River sockeye, which lay their eggs in lakes, in 1991 became the first salmon named to the U.S. Endangered Species List.
In 1992, just 15 sockeye were counted passing the Snake River’s Lower Granite Dam, and only one, nicknamed “Lonesome Larry” by officials, survived the swim to Idaho’s Redfish Lake, where the species historically spawned, North and federal figures show.
Last year, 2,788 sockeye passed Lower Granite Dam, North said, in what some state, federal, and tribal leaders say is a sign that investment in habitat restoration and other fish-boosting efforts were paying off.
But sockeye are especially vulnerable to the warm waters that this year have killed hundreds of other fish and hundreds of thousands of hatchery-spawned salmon, said North. Only 363 have made it past Lower Granite Dam so far this year.
By contrast, North attributed the death of fewer than 2,000 wild Chinook salmon to warm rivers, out of about 109,000 that passed Bonneville Dam.
The sockeye “are not as hardy, and they don’t seem to want to pass upstream when water temperatures get too high,” North said.

Dissolving food source = bad news for pink salmon

Fish Radio

Dissolving pteropods =  bad news for pink salmon

July 29, 2015

Pteropods make up 45% of young pink salmon diets.  Credit: UAF

Pteropods make up 45% of young pink salmon diets.
Credit: UAF

This is Fish Radio. I’m Laine Welch – Pink salmon diets take a direct hit.  More after this –

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Argue all you want about climate change – even a Toys R Us chemistry set will prove that the oceans are more acidic.  Recent reports cited dissolving oyster larvae that are devastating west Coast shellfish growers. A new federal study reveals its first findings on how corrosive oceans are  affecting sea life – and it points to big trouble for pink salmon.  NOAA recently announced the first evidence that the high acid content in the Pacific Ocean is dissolving the shells of tiny free-swimming snails called pteropods.

You might say, who cares about  pteropods?   Well, it happens to be a primary food source for juvenile pink salmon. So you take away the pteropods and you take away the pink salmon.

Mark Green is a marine scientist at St. Joseph’s College in Maine. The tiny snails comprise 45% of the diet of pink salmon; they also are a food source for herring and mackerel.

The researchers at NOAA’s Pacific Marine Environmental Lab in Seattle said the percentage of   pteropods with corroded shells has doubled in areas close to shore since the pre-industrial era.

Study co-author William Peterson said they   did not expect to see pteropods being affected to this extent for several decades.  The number of snails with dissolving shells is likely to triple by 2050, he said, when near shore waters are projected to be 70% more corrosive.

The problem stems from carbon dioxide being released into the air by human industry that is absorbed by the ocean and turned into carbolic acid.   Combine the corrosion with increasing ocean temperatures and the entire marine ecosystem is affected.    Bob Foy is director of the NOAA Fisheries Science Center at Kodiak.

  In a 10% increase in water temperature, which is what most people fear in terms of climate change, there would be about a 3% drop in mature salmon body weight. On the other hand, a 10% drop in pteropod production would lead to about a 20% drop in body weight. Obviously the system is fairly dynamic, but the loss of pteropod population would be extremely detrimental to pink salmon populations.  

Pinks make up Alaska’s largest salmon fishery by volume and second only to sockeyes in value. Last   year’s pink salmon catch was  over 95 million fish valued at nearly $100 million at the docks.

Fish Radio is also brought to you by Ocean Beauty Seafoods – serving Alaska’s fishing communities for 104 years.  On the web at www.oceanbeauty.com .. In Kodiak, I’m Laine Welch.

 

http://www.seafoodsource.com/news/environment-sustainability/26042-noaa-research-finds-acid-dissolving-snail-shells