Saving Seafood

Chinook salmon are getting smaller, and researchers say killer whales may be to blame

December 31, 2019 — Chinook salmon, also known as king salmon, are getting smaller, and a team of scientists at the University of Washington think they know why. A new study says killer whales might be behind Chinook’s declining size.

Chinook salmon are an important part of life in Southeast Alaska. Part of the prized fish’s value is its size. Chinook are the largest Pacific salmon.

But in the last two years, returns have been low. Ketchikan, Wrangell and Petersburg all saw their king salmon derbies cancelled in 2018 and 2019. And forecasts for 2020 don’t look much better.

But it’s not just their numbers that are declining.

University of Washington researcher Jan Ohlberger published a paper last year that shows Chinook are getting smaller, too. Up to 10 percent smaller.

That discovery intrigued the researcher.

“The question is, what is the cause of that?” said Ohlberger in a recent phone interview.

A causal claim is difficult to make. Correlation, of course, doesn’t always imply causation.

Read the full story at Alaska Public Media

This Is Why You Don’t See People-Size Salmon Anymore

March 13, 2018 — While the orcas of Puget Sound are sliding toward extinction, orcas farther north have been expanding their numbers. Their burgeoning hunger for big fish may be causing the killer whales’ main prey, Chinook salmon, to shrink up and down the West Coast.

Chinook salmon are also known as kings: the biggest of all salmon. They used to grow so enormous that it’s hard to believe the old photos now. Fishermen stand next to Chinooks almost as tall as they are, sometimes weighing 100 pounds or more.

“This has been a season of unusually large fish, and many weighing from 60 to 70 pounds have been taken,” The Oregonian reported in 1895.

Now, more than a century later, “it’s not impossible that we see individuals of that size today, but it’s much, much rarer,” University of Washington research scientist Jan Ohlberger says.

Ohlberger has been tracking the downsizing of salmon in recent decades, but salmon have been shrinking in numbers and in size for a long time. A century’s worth of dam-building, overfishing, habitat loss and replacement by hatchery fish cut the size of the average Chinook in half, studies in the 1980s and 1990s found.

Dam-building and fishing have tailed off, but Chinooks have been shrinking even faster in the past 15 years, according to a new paper by Ohlberger and colleagues in the journal Fish and Fisheries. Older and bigger fish are mostly gone.

Read the full story at KUOW

 

No more ‘Kings of the Columbia’: Chinook salmon much smaller, younger these days, study finds

March 1, 2018 — They used to tip the scales at 80 pounds: June Hogs they were called. The kings of the Columbia River.

But the big chinook that used to lumber up and down the Columbia and cruise the northeastern Pacific from California to western Alaska have dwindled away over the past 40 years, researchers have learned.

Published in the journal Fish and Fisheries, researchers have documented a trend in decreasing body size in chinook over the past 40 years. The trend was remarkably widespread, affecting both wild and hatchery fish in the northern Pacific from California to western Alaska.

“It is a quite grand phenomenon, not just observations here and there, it is the signature we see along the coast,” said Jan Ohlberger of the University of Washington’s School of Aquatic and Fishery Sciences, lead author on the paper.

Chinook are the biggest and most prized species of salmon in North America — and the most sought-after, whether by killer whales, eagles or bears. And certainly by every fisherman, whether commercial, recreational or ceremonial.

But big isn’t what it used to be.

Both wild and hatchery chinook are smaller and younger today, researchers have found, examining 85 chinook populations along the West Coast of North America.

The big chinook that stay out in the ocean four and five years before returning home to spawn have decreased both in numbers and in size — as much as 10 percent in length, and substantially more in weight.

Read the full story at the Seattle Times