See pink in the North Atlantic | Outbreak Magazine

Fisheries biologists have been wringing their hands for decades in cold-water regions of the Pacific Ocean due to the proliferation of farmed Atlantic salmon and the threats it poses to native fish and the health of the waters coastal, both in North America off the coasts of the United States and Canada, and in South America, where salmon farms are common off the coast of Chile.

The threats are real, and they are many, from the creation of oceanic “dead zones” under the net pens to the increased population of sea lice which attach to captive fish and spread in numbers that do not. are just not natural. . And, of course, there have always been concerns about the diseases that often accompany large-scale aquaculture, and the escapees gaining a foothold in the Pacific, where five native species of salmon perform a fragile ecological dance in the icy waters of the region. In southern Chile, non-native Atlantic Ocean and North Pacific salmon do move up coastal rivers and spawn, which likely impacts native fish, but also provides a sport fishing opportunity popular with many anglers.

But, until recently, the presence of Pacific salmon in the North Atlantic has not moved the needle of “environmental disaster” much. That is changing, thanks to an invasive Pacific salmon appearing in greater numbers in traditional Atlantic salmon rivers in Scandinavia, as far south as the British Isles and even as far as the east coast of Canada. The culprit in question is pink salmon, the smallest and most numerous of the Pacific salmon family.

Although they are harvested in large numbers for canning, used in prepackaged dishes, for freezing in nuggets and the like, pink salmon has a lower market value due to its low oil content and the fact that its flesh loses its luster when fish enter freshwater to spawn. King salmon (chinook), coho salmon and sockeye salmon are more popular with consumers.

The roses were introduced for the first time in the North Atlantic in 1959 – the former Soviet Union introduced them to the rivers flowing into the White Sea off the Kola Peninsula as a potential source of protein for a nation often on the brink of famine. This effort to repopulate Russian fisheries managers continued for 40 years. Non-native fish have appeared in Scandinavian waters almost every year since 1960. Their numbers are increasing and since 2017 there has been a noticeable increase in the number of these exotic salmon that have found their way into the rivers of Scandinavia, from Ireland and Great Britain.

The concern in these regions of the North Atlantic largely reflects the concerns shared by fisheries managers in the North Pacific regarding introduced Atlantic salmon – what impacts will non-native salmon have on salmon? indigenous?

Some fear that the natives of the Pacific will crowd out an already struggling Atlantic salmon population, or that these exotic fish will bring parasites or pathogens with them. In addition, roses are prolific and return after only two years at sea to spawn. They are by far the most abundant of the five species of Pacific salmon. This year alone, in Alaska, fisheries managers forecast a commercial pink salmon harvest of more than 124 million fish. In the North Atlantic, if the demographic trend continues, fisheries managers fear that roses will be eaten outside the home and out of the house – roses in the North Pacific will eat plankton, krill and other small crustaceans in sea.

Although the North Atlantic has the same prey base for salmon, this prey base is primarily used by native Atlantic salmon, and there may not be enough for everyone if the roses continue to grow. ” extend their range in the Atlantic Ocean.

Since roses were first introduced to the White Sea, they have been seen regularly in the waters of Finland, Sweden and Norway. But 2017 appears to have been a pivotal year for non-native fish – they have been seen in large numbers along the entire Norwegian coastline. It is also the year that roses were first seen by many in Ireland and Britain and even in Iceland and as far west as the east coast of Canada. These waters are all within the native range of Atlantic salmon. Biologists fear that if the roses continue to proliferate, the invaders could harm an important commercial and recreational fishery.

And there is no doubt: roses are pioneers.

“In an Alaskan creek made available by a receding glacier, pink salmon spawners entered the creek 10 to 12 years after sighting the first invertebrates (chironomid larvae) and the maximum water temperature was reached 8.7 degrees Celsius, “reads a compilation study titled,” Pink Salmon: The Reluctant Invader, ” published in SpringerLink in December 2018. “In the great Fraser River, the removal, after many years, of a migratory barrier caused by a landslide, allowed pink salmon to recover upstream after one to two generations (2 to 4 years) (Pess et al. 2012). ”

Right now, however, there are probably more questions than answers to the North Atlantic pink salmon dilemma. For example, will global warming help or harm the growing fish population of the Pacific? “Climate change may also improve the possibilities of spread and establishment in a larger area than seen so far, or global warming may act against this species of cold-water fish,” the study said.

But there are real concerns in Ireland and the British Isles about roses, which are often described as ‘aggressive’ when seen by fishermen and fisheries managers. In June alone, a pink salmon was caught by angler in famous Ridge Pool on the Moy River in Ireland, and Inland Fisheries Ireland has issued an alert asking anglers to keep and kill any roses they catch, as “pink Pacific salmon could force Atlantic salmon and the trout to leave the retention ponds in smaller channels “.

It goes beyond fishing, of course. The SpringerLink study documents a noticeable decline in the food available to native fish during the years when roses prepare to return to freshwater to spawn.

“The impact on native anadromous salmonids is likely related to the abundance of pink salmon,” the study said. “High numbers of aggressive pink salmon on native salmonid spawning grounds can cause native spawning to be interrupted or failed. In addition, a high abundance of pink salmon fry feeding in rivers for a few weeks will most likely reduce the availability of suitable space and zoobenthos for other salmonids. In the North Pacific Ocean, it has been shown that in years when pink salmon are exceptionally abundant, food resources are reduced, with a negative impact on other species of Pacific salmon, other pelagic fish and seabirds (Springer et al. 2018; Ruggerone and Irvine 2018). ”

Nonetheless, the impact – or the potential impact on salmonids native to the North Atlantic – remains largely a mystery. But the concerns, backed by science, are real and another example of how human manipulation could negatively affect native fish species. A well-intentioned effort to feed a starving nation more than 70 years ago could impact wild and native salmon populations that cross international borders.

For now, fishermen in Scandinavia and the British Isles are urged to harvest any pink salmon they catch. But, if roses behave in the Atlantic as in their native Pacific waters, angling will not be enough to control them. Only time will tell.