A small fleet of Norton Sound purse seiners will test the waters for a new pink salmon fishery this summer. Pink returns to the region’s rivers have skyrocketed in recent years to well over 10 million fish. It will be a first experiment for seine gear and humpies so far North. For the pink salmon, fish managers say it’s all about the food.
“They’re definitely the colonizers, for sure. And I’ve had calls from people on the North Slope asking about pink salmon fisheries up there because pink salmon are showing up there. / I don’t know that they’re going to persist because it’s still freezes down up there and so the eggs that are deposited in those rivers won’t generally survive because they’re frozen. But they’re trying.”
Sam Rabung is director of the commercial fisheries division at the Alaska Dept. of Fish and Game. As ocean waters warm, he says it changes the makeup of plankton the pink salmon feed upon. The fish are following their healthier food sources northward.
“As the warmer water moves north, the warmer water copepods, which is one of the main foods for salmon, moves North with it. The cold water copepods have a high lipid, high fat content, so they’re very energy dense, they have a lot of bang for the buck for eating on them.”
Warm water plankton don’t. And since salmon are a cold water species, warm waters also boost their metabolism, meaning they need more food to grow.
Rabung points to the 2018 Gulf of Alaska cod collapse that science has linked with a multi-year, warm water blob. The resulting food imbalance wiped out two cod year classes, and water temperatures that topped 60 degrees prevented cod eggs from hatching.
He says a changing ocean brings big challenges and paying attention to the impacts on fish can help managers better react.
“It’s a tough ship to turn around. So it’s not going to probably reverse course in in my career. But what we can do is understand what the changes are and try to not exacerbate any negative effects by not being responsive in our management. Just knowing what’s happening with the stocks.”
Meanwhile, the changes mean a new pink salmon fishery at Norton Sound.