June 23, 2015

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

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

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

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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 is devastating West Coast shellfish growers.   Now, a federal study reveals its first signs on how corrosive oceans are affecting sea life – and it points to big trouble for pink salmon. NOAA announced this week 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 a 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 becoming 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. Lasts year’s pink salmon catch was a record 219 million fish valued at $277 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.