The most plentiful salmon in the sea/John R. McKillan, NOAA photo

As Alaska putters toward what looks to be its worst commercial salmon season in almost 40 years – despite another banner season for sockeye in Bristol Bay – Cook Inlet streams are once more stuffed with pink salmon.

Why the waterway that cuts deep into the heart of the state to lap at the doorstep of its largest city saw such a large return of what those in the north commonly call “humpies,” no one exactly knows.

But humpies, the smallest of the six species of salmon in the Pacific Ocean, are thought by some to now enjoy a competitive advantage over their larger, longer-lived cousins in an ocean ecosystem in transition in a warming world.

Scientists Greg Ruggerone from Seattle and Canadian colleague James Irvine in 2018 calculated there are today more salmon in the Pacific than at any time in recorded history, and the majority of them are pinks.

The Kenai River saw a record number of those pinks return this year – 1.4 million, according to fisheries biologist Brian Marston with the Alaska Department of Fish and Game.

“This years’ pink salmon count was almost three times the previous largest pink count for the Kenai River,” he messaged. The 1.4 million number is for how many pinks made it past a sonar counter at river mile 14.

How many pinks stayed in the lower river is an unknown, though many Kenai fishermen and guides believe significantly more than 1.4 million of the fish are in the river.

Kenai guide Mark Glassmaker on Wednesday guesstimated 3 to 4 million. Glassmaker has spent the last 30 years on the river. He’s not alone in thinking the count of 1.4 million is low.

Many anglers have been complaining they can’t keep humpies off the hook.

River rats

The smallish, mild-tasting fish with a pinkish flesh are not exactly a 49th state favorite. Bigger, more flavorful, red-fleshed sockeye, coho and Chinook are the fish in demand in the Inlet’s commercial, sport, personal-use and subsistence fisheries.

Commercial prices pretty well define it all with pinks bringing fishermen less than 25 cents per pound, considerably less in some Alaska fisheries this year, and sockeye good for $1.25 per pound or more.

And from a sporting standpoint, the hard-fighting sockeyes and cohoes – not to mention the 30- to 70-pound, trophy-size Chinooks most Alaskans simply call “kings” – are the much-preferred species.

With a staggering 1.85 million sockeye now in the Kenai, the angling would be phenomenal if the more aggressive-to-strike humpies weren’t getting in the way in places.

Oh the indignities Alaska anglers must endure.

A humpy on almost every cast has led some of them to complain that the Fish and Game count of sockeyes versus pinks must be way off, but Marston said the agency is comfortable with the fishwheel set up it uses to catch fish and determine what percent are pinks, sockeyes and cohoes on any given day. Those percentages are then applied to the sonar number to adjust the count by species.

“I understand that the angler accounts of success with rod and reel this year do not mesh with these data,” Marston said. “(But) this year’s in-river run abundance of both pinks and sockeye was extraordinary.”

There is no management goal for pinks. The sockeye goal this year was for 1 million to 1.2 million in-river, and through the end of July, the return looked near on track to hit that goal.

July ended with only 687,000 fish in-river and the 1 million mark wasn’t reached until Aug. 10 when the sockeye return is usually starting to fade. Up until then, even with commercial set gillnet fisheries near the mouth of the river shut down to prevent by-catch of kings in a disastrously weak run –  there hadn’t been a day when the Kenai sonar clicked 50,000 sockeyes or more.

That was a river first, which made it appear the 2020 sockeye run was rather weak and about over. Only days later a flood of sockeye arrived. Almost 66,000 passed the sonar on Aug. 13 followed by days of 107,241; 70,055; 112,174; 134,875; and 56,939.

The fish, Marston observed, were “very late compared to average run timing of sockeye salmon. I do not know what effect the extraordinarily late sockeye salmon run timing and abundant pink salmon had on angler success.”

The view from most anglers appeared to be that it made the fishing great, but not necessarily for the fish they wanted to catch.

The future?

Despite a statewide salmon harvest barely above 105 million so far this year and unlikely to make 110 million, pinks compromised more than half the catch statewide. That appears at first a bit high for an even-numbered year.

Odd- and even-year pinks are genetically distinct fish, and the odd-year fish have long been dominant in Alaska.

Last year they made up 62 percent of the statewide harvest of 207 million salmon. Due to the even-year drop in pinks, the 2018 state catch was only 114.5 million, 36 percent of them pinks. This is an established pattern.

In 2017, an odd year, the statewide catch of salmon was 224.6 million, 63 percent of them pinks. A year earlier, an ever year, it had been 112.5 million of which 35 percent were pinks.

But the low percentages of pinks in even-numbered years mask the reality of how dominant pinks have really become in all years. This is because there is no almost no pink harvest in Bristol Bay, the state’s major sockeye fishery.

More than 39 million sockeye were harvested there on the southern edge of the Bering Sea this year. If they are removed from the catch and the numbers recalculated to show the distribution of the harvest around the rim of the Gulf of Alaska, pinks this year represent 80 percent of the harvest of all salmon originating in Gulf streams and rivers.

It was much the same in 2018 when about two-thirds of the catch of salmon returning to Gulf rivers and streams were pinks. The number for 2016 was about 52 percent; for 2014, about 72 percent.

Much of this pink catch – 40.7 million of 53.5 million pinks this year or about 76 percent – now comes from Prince William Sound and Kodiak where returns have been boosted by hatcheries. There is a growing debate about whether the hatcheries are helping fuel the rise of the humpy in the Gulf.

“Overall pink abundance was phenomenal in 2018…,” Ruggerone said earlier this season, “and 2019 was exceptional too. Nothing compares to the back-to-back large runs in ’18 and ’19.”

The Russians were the big winner in 2018 given that even-year pink runs are stronger there. On the American side of the Pacific, the odd-year runs are overwhelmingly bigger.

There are some scientists who believe this year-to-year oscillation in pink numbers is simply due to the bounty of dominant-year fish.

The theory is that the mass of strong-year pinks grazing the ocean lowers the food supply enough to impact the volume of salmon the ocean can support the next year. Once this was thought to affect only pinks, but other runs have begun to oscillate slightly in response to pink returns in recent years as well.

Alaska scientists Gus van Vliet and Allan Springer in a 2014 peer-reviewed paper published by the Proceedings of the National Academy of Sciences argued that odd-year pinks had so increased in number that the sheer mass of them could influence not just the production of other salmon but birds and marine mammals at an ecosystem level.

“Information from long-term monitoring of seabirds in the Aleutian Islands and Bering Sea reveals that the sphere of influence of pink salmon is much larger than previously known,” they wrote. “Seabirds, pink salmon, other species of salmon, and by extension other higher-order predators, are tightly linked ecologically and must be included in international management and conservation policies for sustaining all species that compete for common, finite resource pools.”

They theorized odd-year pinks are driving a trophic cascade that reduces survival odds for all kinds of fish and birds the next year.

Another theory is that a warmer Pacific Ocean has simply benefitted odd-year pinks, which evolved differently from even-year pinks, more than any other salmon.

“Our results, combined with literature findings indicating a more southerly glacial refugium for odd-year than for even-year pink salmon and temperature-related survival differences between these broodlines, suggest that recent climate conditions are benefiting odd-year returning pink salmon more than even-year salmon, especially in the southern part of their range,” Canadian scientists wrote in a peer-reviewed study published by the American Fisheries Society in 2016.

Bucking the trend

Why Cook Inlet pinks have been running counter to the prevailing odd-even trend for pinks and coming back stronger in the even years when runs elsewhere around the Gulf are weak is unclear.

But the pattern on the Kenai, which saw a sizeable pink return in 2018 and an even bigger one this year, is being seen elsewhere and has been seen before.

More than 150,000 pinks returned this summer to the Deshka River – a small, iron-colored tributary to the big, glacial Susitna River northeast of Anchorage.

The number of pinks in-river there now outnumber the combined total of king, coho, sockeye and chum salmon to the tune of almost 10 to one. The state’s least popular salmon is the river’s most common.

The Desha hasn’t seen pink numbers like this since the early 2000s when it had some monster even-years runs only to be followed by odd years with a near absence of humpies.

What this history portends for the Inlet is impossible to say, but it is interesting.

A 1996 return of 37,000 pinks to the Deshka somehow gave birth to a return that grew to 542,000 in 1998. And that, in turn, spawned what was to be a monstrous humpy cycle.

The 1998 return of even-year humpies more than doubled to 1.2 million of the fish in 2000 before a decline began. The number of spawners dropped to just less than 1 million in 2002, fell to 400,000 in 2004, and by the end of the decade was down to 10,000 only to start ratcheting upward again.

In the odd years, the Deshka returns dropped as low as 3,954 pinks. And for a brief period at the end of the 2000s, the river looked like it might be shifting from a system with even-year dominate pinks to odd-year dominant pinks.

The 2008 (even year) return of less than 13,000 was more than doubled by a 2009 return in excess of 26,000. But the even-year pinks quickly reasserted their dominance in the past decade.

Scientists are still trying to sort out what drives these variations, but it is clear that pinks – buried in the gravel as eggs in August, hatched over winter, and gone to sea as fry in the spring – are highly dependent on conditions at sea where they spend almost two-thirds of their two-year-long life before they return to spawn and die.

What this means for the Kenai – the state’s most popular and most fought over salmon fishery – is impossible to say, fisheries biologists agree. The big return of pinks in 2018 and an even bigger return this year points to a humpy build up.

That begs an obvious question: Was this year the end of a pink bonanza, or only part of the beginning? The Kenai is more than twice the size of the Deshka.

Could 1.4 million pinks spawning in the Kenai this year produce enough young to double the return in 2022 as happened with the Deshka between 1998 and 2000?

Maybe Kenai anglers unhappy about humpies getting in the way now should count their blessings. Just think about a river stuffed with 2.4 million humpies, but then again that’s nothing compared to a system where pinks outnumber all the other salmon 10 to 1.