salmon, which are raised in captivity and released into rivers of the North Pacific, mate with wild salmon, which raises concerns about the future of fish among scientists. A new study published this month about Rosa Lachse in Alaska is predicted that such intersections increase the size of the population of this kind, but will reduce their diversity. This could change the mating behavior of wild fish, which would make it less resistant to climate change and other disasters.

"Too many fish are released," says Peter Westley, a fishing ecologist at the University of Alaska Fairbanks and author of the study. He suggests that the salmon breeding stations reduce their production.

However,

Fishing regulatory authorities defend themselves against demands to restrict the company and refer to persistent unknowns with regard to the ecological interactions between wild and fishing raised in aquacultures as well as to economic competition with neighboring Russia.

"It is a controversial topic, but everyone wants to get to the bottom of it," says Samuel May, a genetic researcher for salmon at the US Agricultural Ministry (USDA) Agricultural Research Service in Oroo, Maine, and main author of the study.

fishing family tree

The salmon breeding stations in Alaska Pumpen each year about one billion pink salmon in the North Pacific and contributed to the increase in harvests for the salmon fishing of the state, which was worth around $ 100 million last year. The fish grow up in the sea and, if they are not captured, try to return to the place of their birth in order to mate. But not all of the fish released find the way back to the facilities in which they were raised. Some, about 1–5% - millions of animals a year - get lost in nearby streams where they can mate with wild salmon.

A group of Alevins pink salmon are newly slipped fish with an adhering yellow otter bladder in Alaska.

Alaska state law prohibits the production of salmon breeding damages the wild laugh populations, and for decades researchers have been trying to find out how practice affects species. In order to understand how genes hike between the aquaculture and wild fish, the Alaska Department of Fish and Game has worked together with scientists from the University of Alaska, local aquaculture associations that operate the breeding, and the National Marine Fisheries Service to form the Alaska Hatchery Research Program.

high harvest yield

Between 2011 and 2020, sub -teams collected the Kadaver of Rosa Lachsen, which had returned and died in streams that result in the Prince William Sound and accommodate the largest salmon breeding program in the world. Researchers created regular trees for 284,867 individual fish through genetic analysis, which was the largest salmon tribe study that was ever carried out. Then May and his colleagues have built up on the population dynamics of this huge data record to model how breeding deviations could affect 25 future generations of pink salmon.

The simulation showed that breeding deviations could increase the overall population of wild pink salmon, which may explain the reports about a recent increase. Last year, the fishing fleet was supposed to catch 19 million fish - both bred and game - in Southeastalaska. Instead, they caught almost 48 million.

"I think that's really good work," says Jim Murphy, a fishing ecologist at Alaska Fisheries Science Center of the National Oceanic and Atmospheric Administration of the USA in Juneau, who was not involved in this study, but previously worked with some of the authors.

genetic erosion

The population boom, however, has potential effects, says May. The team's model predicted that crossings between breeding small and wild fish could reduce the variation in an important reproductive feature - the time when the fish could be reduced to their spawning reasons - by up to 20%. In Prince William Sound, most breeding patties swim about a week later than the average wild fish upstream, a feature that was selected by the breeding companies in part to reduce the chances of the intersection.

Wild fish return at different times during the summer, which contributes to reducing the effects on reproduction in the event of a crisis such as a heat wave, a breakout outbreak or a beaver embankment at the spawning spaces. If more pink salmon return at the same time as the model predicts, such environmental disorders could be devastating.

One of the great risks for salmon is "the genetic erosion of wild diversity," says May. "What could happen in the future if such extreme weather events or warnings become more common?" Asks May. "Will these populations be able to handle it?"

in the pink salmon

John McMillan, a fishing ecologist at Conservation Angler, one in Edmonds, Washington, local interest group that focuses on the protection of wild fish, says he thinks this is a significant statement. "We go through a rapidly changing climate change, and animals will need every ounce of diversity they have," he says.

However,

he adds that the model is limited by simplification. The study only looks at dynamics on the spawning reasons and keeps all other factors constant, such as survival of young fish and the food competition at sea, which are important to fully understand the interactions between breeding and wildlaxes.

and the results should not be torn from the context or applied to other types of salmon such as Sickye, Coho or Ketal axis, says McMillan because Rosa salmon live a more predictable life. They do not spend much time with food intake in streams and return to spawn at the age of two at the age of two. In a review of more than 200 articles on the global effects of salmon breeding of all kinds on their wild counterparts, McMillan and his colleagues found that 83% of the articles reported a slightly or moderate adverse effect.

The Alaska Department for Fishing and Wildlife Management issues permits that allow breeding to allow and determine how many fish they can release. Doug Vincent-Lang, the commissioner of the department, says that he needs further evidence that breeding laxes damage wild populations so that the department reduces the production of breeding varieties.

"We are always a little careful when trying to speculate what many generations will happen to the future," he says. "This information, which has now been collected by my staff and the university, raises some flags that we have to sit back and look at them."

The breeding also supports the coastal communities of Alaska, says Vincent-Lang. Between 2018 and 2023, they financed at least 4,200 jobs and $ 219 million wages a year.

salmon

However, there are other additional factors. This year, the demand for pink salmon did not meet the offer, and the USDA bought $ 70 million in canned pink salmon to stabilize the market. At the same time, Russia has expanded its breeding salmon production. "They flood the market with pink salmon and ketal axes and thus lower the price," says Vincent-Lang.

He adds that questions about the interaction of the fish in the ocean determine many debates. Alaskic and Russian salmon probably compete for food in the North Pacific. If the state would close the breeding companies due to its influence on wild salmon, Russian production could still damage the game population, Vincent-Lang suggests.

"Will we completely set all of our breeding programs for pink salmon in Alaska?" Asks Vincent-Lang. "This is a difficult question if you damage your own economy."