The plentiful Alaska pink/ADF&G art

KENAI RIVER – An unusual, odd-year flood of pink salmon into Alaska’s most popular river has state fisheries biologists scratching their heads, but a fishing guide here thinks he has the answer: strays.

“I will tell you from being on the river daily for the past 29 years, the number of pinks is unprecedented for an odd year,” said Kenai River guide Mark Glassmaker. “They have been present since early June and are showing up (Cook) Inlet wide.”

Alaska Department of Fish and Game officials are concerned enough about the possibility of strays that they have begun sampling fish.

“Soldotna staff have collected a sample of pink otoliths from the sockeye-sonar fishwheel, in-river netting, and sport harvest to take a look at the question of wild or hatchery,” Sport Fisheries Division Regional Supervisor Tom Vania emailed on Friday. “It may be a while before those samples can get processed.”

Straying pink salmon from private, non-profit hatchery operations in Prince William Sound showed up all over lower Cook Inlet in 2017, a big year for pink returns.

They weren’t exactly welcomed with open arms. A low-value, commercial species largely destined to be stuffed into cans, pinks are the palest fleshed of salmon (other than rare “white kings”), comparatively bland tasting, and the lowest in fat.

A pink has about half the fat of the average farmed, Atlantic salmon; less than half the fat of a wild Alaska sockeye (red salmon); and about a third the fat of wild Alaska Chinook (king salmon), according to the Community Seafood Initiative.

Given all of these things, pinks are looked down on by Alaska resident anglers and personal-use dipnetters. Pinks aren’t quite considered trash fish, but it’s close. The view of most non-residents anglers (non-residents are not allowed to dipnet) is only slightly higher.

Worried that a mushrooming pink population boosted by hatchery production could lead to more valued species being displaced from spawning areas or losing out in the competition for food at sea,  the Kenai River Sportfishing Association, the Fairbanks Advisory Committee and others last year petitioned the Alaska Board of Fisheries to cap hatchery production until more is known about potential problems.

The Board turned down the request after Bill Templin, the state’s chief fishery scientist, told them there is no ironclad evidence linking declines in Gulf Coast sockeye, Chinook and coho to increases in pinks.

Even if there looks to be a connection, he cautioned, “correlation is not causation.”

Scientists, he said, don’t know what will happen once fish disappear into the big black box of the Pacific, and thus they can’t say whether adding ever more hatchery pink salmon to the ocean will harm wild fish.

Big eaters

The smallest and shortest lived of the Pacific salmon, pinks spawn in late summer in Alaska. The eggs hatch over winter and the young go to sea in the spring, unlike sockeyes, Chinook and coho which spend at least a year in freshwater.

The young pinks spend 18 months in the ocean eating all they can in order to grow big enough to return as 3- to 5-pound spawners the next year.

Over the ages, the species has evolved into two genetically distinct populations. University of Washington scientists studying the fish theorize “that the last glacial maximum separated pink salmon populations, with one group surviving in Asia and North Alaska, and another group extending from southcentral Alaska to Washington.”

If each group formed a genetically distinct population, the team led by Carolyn Tarpey concluded, it would explain why “even-year salmon all across the North Pacific are more closely related to each other than to odd-year pink salmon spawning in the same rivers,” the Washington School of Aquatics and Fisheries reported last year.

Odd-year pinks are the dominant Alaska population. State record salmon harvests of 223 million to 280 million salmon in 2017, 2015 and 2013 have been driven by huge pink catches. Almost 224 million pinks made up 80 percent of the record statewide catch of 280 million salmon in 2013. 

Pinks played a similar role in 2015 when the pink harvest topped 188 million and in 2017 when it passed 139 million.

Historically, all-species salmon catches of over 100 million were considered a good year in the 49th state and before that the Alaska Territory. But a warmer Pacific Ocean, hatcheries and better management of wild stocks are credited with altering the nature of nature to boost state salmon harvests.

Pacific Northwest scientists Greg Ruggerone and James Irvine in a ground-breaking, peer-reviewed paper last year reported there are now more salmon in the Pacific than at any time in recorded history. 

Most of them are pinks.

“During 1990–2015, pink salmon dominated adult abundance (67 percent of total) and biomass (48 percent),” the scientists reported in the journal Marine and Coastal Fisheries. 

Bucking the trend

While most of the rest of the state goes odd on pinks, the Kenai goes even.

Though returns have not been counted until recent years, former state fishery managers say they well remember even-numbered years when lots of pinks returned, but the fish were historically hard to find in odd-numbered years.

Fishery managers didn’t pay much attention to pinks until 2016 when a new, improved, fish-counting sonar was installed on the river, and it was pointed out that large numbers of big pinks passing that sonar might be mistakenly counted as sockeye, thus inflating the sockeye escapement number.

The state at then set out to develop a plan to fine-tune the sonar count by identifying the percentage of pinks in the run.

“In past years, species apportionment was not considered a significant source of error in KenaiRiver sockeye salmon passage estimates because sonar counts were typically only apportioned by species during even-numbered years when pink salmon were abundant in August (by which time the sockeye run is usually fading). However, in recent years, sockeye salmon have been entering the river later ( 11 days late in 2006; five
days late in 2007; either days late in 2014; and eight days late in 2015) leading to greater overlap between sockeye and pink salmon in-river run timing,” that apportionment study reported. 

After that plan was written, Fish and Game developed an apportionment policy that called for daily counting the catch of individual species as soon the proportion of non-sockeye salmon reached 5 percent for three consecutive days.

That didn’t happen until Aug. 7 of last year, a traditionally big year for pinks on the Kenai. On that day, state officials noted that a little more than 5,000 of the more than 60,000 salmon headed upstream were pinks.

A tidal wave of them was destined to follow. By the time the sonar was shut down on Aug. 26 with a plummetting sockeye count down to 1,486 for the day, the cumulative pink count had topped 600,000, and it was doing anything but fading.

A record daily count of 74,226 humpies – as Alaskans often call these fish that develop a characteristic humpback when they enter the spawning phase – had been set the day before, and the last days count was 60,338.

Wild salmon returns when graphed usually take on the shape of a bell curve. If 74,226 humpies was the peak of the curve last year, there is no telling how much was in the tail, but there were 469,000 before the peak.

What’s happening this year, the scientists admit, is anyone’s guess. The counting started a month earlier when almost 3,000 of the 15,000 fish entering the river were pinks. They’ve come at a steady rate since with a peak of almost 13,000 pinks passing the sonar on July 14.

About one out of four salmon going upriver on that day was a humpy. The count has fallen since. The cumulative total stands at 52,000.

Commercial fisheries biologist Brian Marston was hopeful that maybe the 14th was the peak, but he sort of admitted in an email that might be wishful thinking.

“Probably they will come in pulses for a week or so and then drop off,” he wrote. “Not likely to be as many as last year.”

Last year, however, set a pretty high bar.