Recent trend of small sockeye continues at Copper River

Alaska’s earliest sockeye run could be a rerun.

Copper River sockeye are even punier than last year’s record-setting slim fish, matching warnings from the Alaska Department of Fish and Game’s preseason forecast.

“The fish are still small,” said Steve Moffitt, Cordova area management biologist for the Alaska Department of Fish and Game. “So far, they’re even smaller than what we got last year.”

The early trend could foretell small fish throughout the state.

Last year, workers statewide from offices of the Alaska Department of Fish and Game, or ADFG, noticed an early in-season trend of smaller-than-average fish.

After the season ended, final tallies for each major salmon-producing area with brood stock from the Gulf of Alaska charted sockeye salmon an average pound less than the most recent 10-year averages.

The Copper River run is still in its early stages, but Moffitt said the Copper River sockeye this year are following the same pattern.

“First period we have about 4.4 pounds for sockeye, second period we had 4.3 pounds,” said Moffitt. “Last year, the year end was a little under 5.1 pounds. And that was the smallest we’d ever seen.”

The average Copper River sockeye weighs an average 6 pounds, and hasn’t been measured smaller than 5.1 pounds anytime prior to 1966.

The Copper River run precedes other major sockeye producing areas like Cook Inlet and Bristol Bay by several weeks. ADFG scientists in other areas have no data yet to compare sockeye size with the Copper River run.

Moffitt emphasizes the fish are smaller across age classes, meaning scientists can’t attribute the size decrease to a prevalence of younger, smaller fish. More of the older and typically larger sockeye are returning this year than previous years, as predicted in ADFG’s area forecast.

“The 2016 run of natural sockeye salmon to the Copper River will be composed primarily of returns from brood years 2011 and 2012. Five-year-old fish (brood year 2011) are expected to predominate Copper River Delta and upper Copper River runs,” the forecast reads.

So far, Moffitt said ADFG forecast is spot on.

“We’ve got a couple age class processed,” Moffitt said. “There’s been no change in the age composition. It pretty much matches the long-term average. We’re seeing the same age classes defining the run. The age five, which is usually predominant, is even more predominant this year.”

Moffitt noted that adaptive fishing techniques could skew numbers downward. A reporting hitch has surfaced.

In response to last year’s small fish, many Cordova area fishermen in 2016 swapped out gillnets for smaller mesh sizes to better catch the small fish. This could let the larger ones go unaccounted for and distort the true average, Moffitt said.

This can produce commercial problems as well as statistical inaccuracies. Selling sockeye salmon nearly one-third beneath their average weight can be a problem for the Copper River brand, founded on high-end fillets that must meet certain marketability requirements for processors and retailers, including size.

The change in mesh size could also affect harvest volume. Fishermen cannot drop smaller mesh sizes as deeply into the water column to snag salmon; many will swim underneath the net to escape warmer water, as fishermen reported last year from several Gulf-adjacent waters, potentially lessening the overall harvest.

Limited supply comes with both benefits and drawbacks. As of May 24, Copper River gillnetters have harvested 72,733 sockeye, a slower beginning than average that has produced a $6.50 per pound price, more than a dollar better than last year’s opening price.

Several factors could contribute to the small sockeye, according to Moffitt and other biologists who observed small fish in 2015. Most scientists link to warm water from the infamous Gulf of Alaska “Blob,” along with food competition between pink salmon and sockeye and among sockeye themselves.

Warmer water has been the most visible marine change, and this year the trend is continuing, if on a smaller level than 2015.

Through February 2016, Gulf of Alaska water was one degree Celsius greater than the most recent 10-year average, according to a majority of area buoy readings. This is an improvement from last year, when the same waters at that time were nearly two degrees Celsius above average.

The so-called “Blob” has largely dissipated and mixed with colder water, though National Oceanic and Atmospheric Administration studies say the effects will linger until a La Niña weather cycle cools the North Pacific. Reports say the cycle has a 75 percent chance of beginning this fall.

Warm water raises sockeye base metabolic rate, Moffitt said. Fish need more food, but the cold water-loving plankton they eat are more scarce. The sockeye can’t beef up as normal.

Small fish also coincide with large runs, lending scientific credibility to the Cordova fisherman’s adage, “Big run, small fish.” Sockeye compete with pink salmon and other sockeye for less available food sources at a time when their metabolism demands more than normal.

Of the seven largest sockeye runs to Copper River, five of them were in the last five years. Prince William Sound pink salmon run was the largest on record in 2015.

This year’s forecast is tamer for the area.  The Alaska Department of Fish and Game 2016 total run forecast of sockeye salmon for the Copper River is 2.56 million, similar to the recent 10-year average total run 2.60 million. If realized, the 2016 forecast total run will be the 11th largest in the last 36 years.

DJ Summers can be reached at [email protected].

Updated: 
05/26/2016 - 9:25am