The Spam of the sea

The North Pacific Anadromous Fish Commission (NPAFC) this week posed a question that has been on the minds of some fisheries scientists for years now:

“Are There Too Many Salmon in the North Pacific Ocean?”

The question is a good one wrongly phrased. It should actually ask this:

“Are There Too Many Pink Salmon in the North Pacific Ocean.”

As is detailed in a six-page report to the Commission that follows the question in the January newsletter, the ocean is now overrun with pinks, the smallest and shortest-lived of the six species of Pacific salmon, five of which are native to North America.

“Overall, pink salmon represented approximately 74 percent of total salmon abundance in 2018/2019. Most pink salmon are of natural origin, but abundance of hatchery pink salmon during 2005 to 2015 was greater than abundance of wild chum salmon and approximately equal to abundance of wild sockeye salmon,” the report said.

“Total chum and sockeye salmon represented only 14 percent and 12 percent, respectively, of total salmon abundance in 2018/2019. These values exclude Chinook and coho salmon, whose combined reported commercial catch  was 1.5 percent of total salmon catch from the North Pacific during 2018/2019 and approximately 5 percent of total salmon catch, on average, during 1925 to 2020.”

Chinook are those big “kings” – the largest and longest-lived of salmon – that made famous the Columbia River of the Pacific Northwest and the Kenai River of Alaska, a far, far smaller river system than the Columbia that in 1985 produced a world-record king weighing 97-pounds, 4 ounces. 

For more than a decade that followed, the Kenai became a hunting grounds for anglers from around the globe looking to land a bragging-size trophy king.

“The Kenai River supports the largest freshwater recreational fishery in Alaska…,” the Alaska Department of Fish and Game boasted in a 1995 report. “The majority of the angler-effort occurs in the section of the river between the outlet of Skilak Lake and Cook Inlet during a fishery directed primarily at returning Chinook salmon during May, June, and July.”

All gone

This was the middle of the glory years for the Kenai.

For two decades from 1986 to 2006, the returns of late-run Kenai kings dropped below 40,000 fish a year only once, according to Alaska Department of Fish and Game reports. And in 17 of those years, the return to the relatively small, blue-green, glacier-fed river topped 50,000.

Then, in 2004 it peaked near thhe 100,000 mark.

Sadly, the end was just over the horizon. In 2008, after five years in which the return to the river averaged more than 80,000 fish per year, the number dropped to 60,000.

There was no cause for alarm. That was still a very healthy number.

The next year it was 51,000; still no cause to worry. But the year after it fell to 39,000; and by 2012, it was under 30,000.

By then, fishery managers had noticed something else odd. The big kings were getting smaller and smaller. Worried about the egg-carrying capacity of smaller females kings, five years later convinced the state Board of Fisheries to change the way Kenai spawners were counted.

Out went the old goal of putting 17,800 to 35,700 kings on the spawning beds, and in came a new rule lowering the minimum to 15,000, but stipulating that only kings over 34 inches in length would be counted. That goal was met the next year when just shy of 17,000 fish made it through the commercial fisheries in Cook Inlet and the sport fisheries in the river.

It has not been met since despite stiff restrictions on sport fishing, reductions in commercial fishing, and sometimes closures of both fisheries. The collapse is in line with a peer-reviewed study published in 2020 that reported Chinook production dropped 65 percent all along the North American West Coast over the course of the last half-century.

That study has proven controversial in that it suggests ocean survival might have as much or more to do with faltering Chinook runs than hydroelectric dams, agriculture, climate change and urban development.

“Intriguingly, the higher smolt-to-adult-return rates (SARs) of the two coastal Oregon sub-yearling populations (in the study) and Chinook from California all involve populations that apparently do not migrate far north,” the authors of that study wrote. “The SARs of California Chinook are particularly noteworthy because freshwater survival is exceedingly low; for overall SARS to be higher than Snake River stocks suggests much higher survival during the marine phase.”

Previous studies of the Oregon stocks in question have found them spending the ocean phase of their lives in the California Current instead of moving north as do Columbia River basin salmon and Canadian fish. They are then caught up in the Alaska Coastal Current which spins counter-clockwise around the Gulf.

“It…seems plausible that specific salmon populations home to distinct feeding grounds, some of which may confer better survival,” the authors of the 2020 study wrote. 

The northern Gulf is where it has been theorized problems have arisen because of too many salmon competing for too little food.

Smaller and smaller and smaller

The aforementioned Kenai kings could well be the poster fish for shrinking Pacific salmon.

Where once kings of 50 pounds or larger were so common state officials overwhelmed with requests for “Trophy Fish” certificates had to amend the “Trophy Fish” records to make a special exception for Kenai kings requiring they reach 75 pounds or more to qualify for a certificate.

The standard remained, and to this day remains, 50 pounds for kings caught anywhere else in the state. It could probably now be lowered for the Kenai, too, given how few fish over 50 pounds are now caught there.

The problem, however, isn’t just in the Kenai.

The shrinking size of Chinook is a well-documented, coastwide phenomenon. A peer-reviewed paper published in the journal Fish and Fisheries in 2018 documented a steady, almost two-decade decline in the size of the big fish. 

And kings aren’t the only Pacific salmon getting smaller. A peer-reviewed paper published in Nature Communications in 2020 reported significant declines in the size of coho (silver) and sockeye (red) salmon as well since the 1980s.

That study fingered the growing abundance of pink salmon as a potential issue.

After examining a dozen reasons why bigger, longer-lived salmon might be getting smaller, the team of researchers from Alaska; British Columbia, Canada; Washington state, California and the Virginia Polytechnic Institute said the only consistently negative effect they could find “across all species was that of Alaskan pink salmon abundance, although this effect was weak in most species.

“(But) intriguingly, the shared acceleration of size declines post-2000 occurred during a period of unusually high (though variable) pink salmon abundance in Alaska, suggesting high pink salmon abundances could be accelerating or exacerbating size declines. Our results provide further evidence that wild and hatchery-enhanced pink salmon abundance in the North Pacific has reached such high levels that they appear to be exerting an influence on ecosystem structure and function.”

Fishery scientists for the state of Alaska – which in the late 1970s and early 1980s built a massive hatchery system to farm the ocean before largely turning it over to commercial fishermen to run – defend free-range ranching the pasture of the North Pacific with predominately pinks and chums by offering up the old scientific truism that the correlations between pink numbers and declines in the size and number of other salmon does not prove causation.

And indeed that is true, but correlation is most certainly a cause for investigation.

Particularly when the size and falling production facing Alaska’s most famous salmon river fades when compared to the problems facing the  Columbia River basin with its long, rich history of huge runs of Chinook and British Columbia, where the Fraser River was once famous for sockeye returns that sometimes outnumbered those of Alaska’s Cook Inlet and the state’s fabled Copper River combined.

No more.

A sockeye return of 34 million to the Fraser in 2010 has steadily declined since and hit rock bottom in 2020 when Canadian salmon managers reported only 293,000 of the fish returned – less than 1 percent of the number a decade before.

“…Three of the last five years will have had record-breaking low returns for Fraser River sockeye,” the Narwhal, a Canadian environmental publication reported that year. Reporter Stephanie Wood suggested sea lice from Canadian fish farms might be the cause or warmer ocean temperatures or overfishing in Canadian waters or a landslide that cut-off access to some spawning habitat.

A team of researchers led by Brendan Connors from the Institute of Sciences of Fisheries and Oceans Canada the same year offered some different explanations.

As noted in the NPAFC report, his team of researchers found that a “1.5-degree Centigrade (about three degrees Fahrenheit) increase in sea-surface temperature was associated with a 23 percent increase in sockeye productivity in the Bering Sea, a 9 percent productivity increase in the Gulf of Alaska, but with a 12 percent decline in productivity in the southern region (British Columbia and Southeast Alaska).”

The warm water improvements in survival, however, came with a significant pink salmon offset.

“The research by Connors et al. (2020) also found that a 119 million increase in pink salmon abundance was historically associated with a 9 percent decline in sockeye productivity in the Bering Sea and the Gulf of Alaska, and a 21 percent decline in British Columbia,” the report said.

“This finding is consistent with a trophic cascade caused by abundant pink salmon and other studies indicating adverse effects of pink salmon on the growth, age-at maturation, survival, and abundance of sockeye salmon, Chinook salmon, coho salmon, chum salmon, marine fishes, seabirds, and potentially southern resident killer whales.”

The work of Connors and colleagues indicated sockeye returning to streams in Southeast Alaska and those farther south were getting hit with a double whammy: First that 23 percent decrease due to warming waters, and then on top of that a 21 percent decline due to competition with pink salmon.

Speculation

But, of course, correlation is not causation.

Declines in the size of Chinook, sockeye and coho due to competition with pinks is all theory. So, too, the idea North Pacific salmon are shrinking in size due to this competition.

At this time, no one can produce enough evidence to be able to prove to the standards required by an American court of law that management of pink salmon for maximum production, plus the boosting of their numbers through hatcheries in Alaska and Russia, has directly caused the salmon declines in British Columbia and the Pacific Northwest.

So far, this is all theory pushed by scientists to the south of Alaska where salmon runs are facing serious declines. Connors, it should be noted, was one of the authors of the report to the NPAFMC along with James Irvine, another British Columbia-based scientist, and Greg Ruggerone from Washington state.

It could be they are unfairly blaming Alaska fishery managers for helping to stuff the North Pacific with pinks. Bill Templin, the chief fisheries scientist for the Alaska Department of Fish and Game, seems to believe that. He has publicly questioned some of their science.

At a state Board of Fisheries meeting in 2008, he attacked the theory of a “trophic cascade” as a hypothesis pushed far beyond the edge of the evidence. Scientists know little about what happens once salmon disappear into the big black box of the Pacific, he told the people who write Alaska’s fishing laws, and thus no one can say for certain whether adding large numbers of hatchery  pink salmon to the ocean is hurting other fish.

In their NPAFC report Ruggerone, Irvine and Conners now counter that “additional evidence of adverse interactions between pink salmon and other species is shown by the biennial patterns in marine species that are consistent with the biennial pattern in pink salmon; a pattern that cannot be explained by physical oceanography alone.”

The clincher, they add, might be a “tipping point” reached in 2020 when salmon runs crashed Pacific-wide. Total salmon abundance, which averaged 806 million adults per year from 2016 through 2019, dropped to an estimated 454 million in 2020.

The tipping-point hypothesis follows basic range theory. A plague of European rabbits, as in Australia, devours so much of the food on the range that not only do rabbits start dying but a lot of sheep and cows are done in as well. 

The ocean, thankfully, appears more resilient than the land. For one thing, there is no dirt to blow away after the ground is denuded.

Pinks, at least, bounced back strongly in 2021.

“Commercial harvests of pink salmon in Alaska and Russia rebounded and led to the largest harvest of pink salmon on record since 1925 (approximately 515 million pink salmon, all regions combined),” the researchers reported to the NPAFC.

It was, however, a different story for the bigger species that spend more time at sea.

“In contrast, overall commercial harvests of Chinook, chum, and coho salmon, as well as
non-Bristol Bay sockeye salmon, remained low throughout Asia and North America during 2021,” Connors, Irvine and Ruggerone observed. “Relative to harvests during 2010 to 2019, chum salmon harvests declined the most ( minus 38 percent), followed by Chinook (minus 33 percent), coho ( minus 25 percent ) and sockeye salmon beyond the Bristol Bay and the Alaska Peninsula management area (minus 27 percent).

“In British Columbia, harvests of all five species appear to have been very low in 2021, with preliminary estimates of total commercial harvest being less than 10 percent of the
average harvest during 2010–2019.”

This could all be due to no more than a massive shift in the currents of the ocean’s whims.

“The jury is still out on the validity of our tipping point hypothesis in which the combined effects of high back-to-back pink salmon abundance (2018 and 2019) and frequent marine heatwaves led to large reductions in the abundance of all species in 2020,” the scientists admitted. “The record-high harvest of pink salmon in 2021 represented approximately 81 percent of all salmon harvests, and approximately 87 percent of all harvests if the large harvest of Bristol Bay sockeye salmon are excluded.”

It remains to be seen what this will mean for other species of salmon who spend years instead of months at sea. Time will tell.

As the scientists observed, “the exceptional abundance of pink salmon in 2021 raises the concern for rapid recovery of salmon in many regions, but it is difficult to predict whether high pink salmon abundance will exacerbate poor feeding conditions for other salmon
species in the near future or partially offset the benefit of favorable ocean conditions if conditions improve.

“Regardless, with such high abundances of pink salmon returning from the North Pacific as it warms and their effect on the growth and survival of other salmon species, we ask: are there too many salmon in the ocean and if so, should hatcheries continue to release up to 5.5 billion salmon each year of which nearly 1.5 billion are pink salmon?”

The question is now left to be pondered by the the NPAFC, a treaty organization of which the U.S., Canada, Japan, the Republic of Korea, the Russian Federation are members. It is tasked with promoting “the conservation of anadromous stocks (Pacific salmon and steelhead trout) in the…international waters of the North Pacific Ocean and its adjacent seas north of 33 degrees North (and) beyond the 200-mile zone (exclusive economic zones) of the coastal states.”

Even if it were to answer “yes” to that question of “too many” salmon in the North Pacific, there appears there is little it could do to change the behaviors of the member countries.