Update: This story was edited on Jan. 11, 2023 to include more information from the Scottish study.
Half a world away from Alaska in the North Atlantic Ocean, the salmon with which Alaskans love to farm the sea is defining the term “opportunistic species.”
Yes, we’re talking humpies here – the everywhere Alaska salmon, the species best known for that impossible-to-miss humped males develop upon entering freshwater to spawn, the fish that made Alaska canned salmon famous.
Norwegian media is warning of the return of up to 1 million of this new invasive species caught by the tens of millions in Pacific waters and sold as pink salmon not humpbacks or humpies, neither of which sounds like a particularly good name for any product.
Such marketing might make the fish as unpopular everywhere as they are now in Norway, which they long ago invaded, and the United Kingdom, where they appear to have grabbed their latest foothold. Scientists there early this month reported in the peer-reviewed Journal of Fish Biology that young pink salmon were intercepted as they head to sea from “the Rivers Thurso and Oykel in Scotland between 13 and 17 March.
“To our knowledge, this is the first observation of O. gorbuscha smolts in Europe outside the Scandinavian and Kola peninsulas…. It also provides evidence of successful spawning in 2021, completion of the freshwater phase of the life cycle, and indicates the possibility for potential establishment of an O. gorbuscha population in Great Britain.”
This was not taken as good news, especially given that the researchers had been hopeful the UK could avoid the humpy bullet.
Early research led to the conclusion “that the warmer water temperatures of Scottish rivers compared with North Norwegian rivers would result in…smolts migrating to the sea at the beginning of winter. As the arrival of O. gorbuscha juveniles in the marine environment would coincide with a period of low productivity, ” the researchers thought the young fish would be doomed to starve to death, thus preventing the species from establishing a reproducing population.
Young humpies in the Thurso and Oykel have now, however, been found to over-winter in the gravel as in Alaska. Worse are indications that the young humpies might be developing and feeding in-river before going to sea.
“This contrasts with the situation in the species’ native range, where many O. gorbuscha juveniles emerge as alevins with residual yolk,” they observed….”Considering the time interval between spawning and the capture of O. gorbuscha smolts (in Scotland) , this may suggest that the captured O. gorbuscha had been actively feeding whilst in the river.
“Initial risk assessment of the potential impacts of O. gorbuscha on native species assumed that O. gorbuscha would migrate downstream more or less immediately after emergence, as reported in the native range,” preventing any issue of food competition with native and already struggling Atlantic salmon. Food competition now appears to be a potential problem.
This just adds to the “great concern” about the arrival of pinks in Scottish rivers, the scientists wrote:
“Contrary to expectations, those spawning can produce viable offspring capable of migrating to the sea at the smolt stage in spring, thus completing the freshwater stage of the life cycle in Scotland. It is not known if these Scottish smolts survive to adulthood and successfully return to breed in their natal rivers, although in the current period of range expansion of O. gorbuscha in the North Atlantic, it is clear that homing behavior has yet to become the norm; Scottish smolts may eventually breed in rivers elsewhere and vice versa, with vagrant adults helping to support the colonization of Scottish rivers. Only time will tell if the species establish a self-sustaining population in Great Britain.”
Kill ’em all
The Algonquian Indians of 1607 might have observed the same of the Jamestown Colony, the first permanent English settlement in North America. The Indians made peace with the English instead of crushing them, and the rest is history.
The Brits and the Scots today share the view of the Norwegians that the way to deal with humpies is to wipe them out. Scientists in Norway in December authored a 15-page report on the “invasion” (their term) of Norway that was published in the peer-reviewed ICES Journal of Marine Science.
“We found that pink salmon have spread throughout the Norwegian Sea and along the Norwegian coast, and abundance increased by several orders of magnitude in 2017, with no signs that it has peaked,” they warned.
Elimination attempts are now underway.
The Norwegians hung the same label on pink salmon that Alaska biologists hung on northern pike in the Cook Inlet region – “invasive species,” although the latter are less evasive than the former. Pike were long in Alaska north of the Alaska Range and west of the Aleutian Range, but humans are blamed for helping them get over the mountains into the drainage of the Susitna River and from their spread although it is not impossible they arrived by natural means or accident.
The origins of pinks in the North Atlantic is, on the other hand, clear.
The leaders of what was the Union of Soviet Socialist Republics (USSR) began efforts to establish pinks in the Atlantic not long after World War II for food and economic reasons. For some time, they operated a put-and-take commercial fishery for pinks with fishermen trying to scoop up all the fish that returned.
As a result, the Norwegians noted, the stocking of young pinks in rivers draining into the White Sea and Barents Sea in the period 1955 to 1979 was “seen as largely unsuccessful, as self-sustaining populations were not achieved. (However), in 1985 (about six years before the Soviet Union collapsed), the stocking activity in northwestern Russia was re-initiated, but this time using eggs taken from a river further north on the Russian Pacific coast.
“This resulted in self-sustaining populations, and the stocking was stopped in 1999. Pink salmon fry entering the White Sea resulted in adult pink salmon straying into Norwegian rivers and the Atlantic Ocean, with the first observations in Norwegian rivers in 1969. The number of pink salmon in Norwegian rivers remained low until a sudden increase in 2017, when more than 6000 individuals were caught or observed in Norwegian rivers.”
Global warming is thought to have been a key factor in the sudden increase in pink productivity. Sea surface temperatures in the Barents Sea have risen dramatically since 2005. A peer-reviewed paper in Nature’s Scientific Reports this summer called the warming “exceptional” and identified the Barents as a “hotspot.”
Humpies appear to enjoy an advantage over Chinook, coho, sockeye and chum salmon in a warming Pacific, and it appears no different in the Atlantic, though pinks are there an introduced species.
“The marine phase of pink salmon’s life cycle in the Atlantic Ocean is poorly understood,” the Norwegians wrote, but ” individuals emigrating from rivers in northern Norway or northwestern Russia enter the Barents Sea or the White Sea. Recent observations of pink salmon around Greenland and Ireland showed that pink salmon can perform long-distance migrations in the northeast Atlantic Ocean. Large parts of the northeast Atlantic Ocean are therefore potential feeding habitats.
“These productive areas are used as feeding grounds by several large fish stocks such as Norwegian spring-spawning herring, mackerel, blue whiting, capelin, and polar cod. These ocean areas are also important feeding areas for Atlantic salmon. Pink salmon are known to impact the marine ecosystem through competition for prey with other fish and bird species in the North Pacific Ocean.”
There are valuable commercial fisheries for those species in the Atlantic. Eurofish reported the 2020 “catch amounted to over 2.6 million tonnes valued at 2.1 billion euros ($2.3 billion). The most important fisheries today are those for cod (coastal and high seas), herring, capelin, and mackerel.” Cod accounted for about half the value.
The Norwegians are understandably worried about pinks causing chaos in those fisheries.
In river catches since 2005 indicate a booming, if unwanted, odd-year fishery for pinks in Norway.
From a catch of 88 in 2015, the harvest grew to 112,485 in 2021. That was slightly above the tightly controlled catch of struggling wild Atlantic salmon in Norway’s streams and rivers.
This might be good for in-river fishermen, but the scientists don’t think it’s good for the ecosystem off Norway’s coast.
“In the North Pacific Ocean, pink salmon are known to impact the marine ecosystem through competition for prey with other fish and birds,” they wrote. “In the Norwegian and Barents Seas, pink salmon, based on the diet found here, can potentially compete with other abundant pelagic fish species such as herring, capelin, polar cod, blue whiting, and Atlantic salmon.
?In numbers, these other species, except Atlantic salmon, are at present several orders of magnitude more numerous than pink salmon returning to Norwegian and Barents Seas rivers. Pink salmon in the Atlantic Ocean are therefore not expected to have a large-scale effect on the ecosystem (at present), due to their relatively low numbers in the sea until now. However, pink salmon may still have local effects from grazing on fish larvae and other prey in estuaries, fjords, and other coastal areas, particularly given that pink salmon abundance has constantly increased since 2015. Pink salmon have a diet that most likely overlaps with other coastal pelagic species such as saithe, sea trout, and Artic charr, which feed on small fish and various zooplankton species, and are present in estuaries and coastal regions throughout the year. Pink salmon feeding in Norwegian coastal waters can potentially impact both prey abundance and the competitors for prey.”
In the Pacific, pinks have been blamed for triggering “trophic cascades” that have led to declines in other species of salmon and massive seabird die-offs. Atlantic populations now are a long way from big enough to cause such events, but the rapid and unexpected boom in humpies after years of failed efforts at stocking has Norwegians troubled.
In a warmer ocean, humpies seem to now be taking off as if they are destined to become some sort of Old World Frankenfish.
What spawning stops could be on their agenda next? Greenland, Nova Scotia and then the U.S. East Coast?
The Norwegians note the Canadians tried to introduce humpies there in the 1950s and failed, but the North Atlantic is a different ocean now than it was then.