{"id":32545,"date":"2026-05-23T10:15:00","date_gmt":"2026-05-23T15:15:00","guid":{"rendered":"https:\/\/www.ecoticias.com\/en\/?p=32545"},"modified":"2026-05-22T17:59:40","modified_gmt":"2026-05-22T22:59:40","slug":"researchers-opened-decades-old-canned-salmon-from-alaska-and-found-a-hidden-ocean-record-inside-dead-anisakid-worms-that-let-them-track-food-web-change-over-42-years-with-parasite-counts-rising-in-c","status":"publish","type":"post","link":"https:\/\/www.ecoticias.com\/en\/researchers-opened-decades-old-canned-salmon-from-alaska-and-found-a-hidden-ocean-record-inside-dead-anisakid-worms-that-let-them-track-food-web-change-over-42-years-with-parasite-counts-rising-in-c\/32545\/","title":{"rendered":"Researchers opened decades-old canned salmon from Alaska and found a hidden ocean record inside, dead anisakid worms that let them track food web change over 42 years, with parasite counts rising in chum and pink salmon but staying flat in coho and sockeye"},"content":{"rendered":"\n

What could a forgotten can of salmon possibly tell us about the ocean? Quite a lot, it turns out. Researchers at the University of Washington opened old canned salmon, some linked to fish caught decades ago, and found something far more useful than a spoiled pantry item.<\/p>\n\n\n\n

Inside the preserved fish were anisakid roundworms, tiny marine parasites that helped scientists track changes in Alaskan marine food webs across more than 40 years. The big surprise was not that the worms were there, but that their numbers rose in chum and pink salmon while staying stable in coho and sockeye salmon.<\/p>\n\n\n\n

A strange scientific archive<\/h2>\n\n\n\n

The cans came from the Seafood Products Association<\/a>, a Seattle-based trade group that had kept them for quality control purposes before donating them to researchers. Instead of ending up in the trash, those old cans became a rare biological archive.<\/p>\n\n\n\n

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Natalie Mastick, who led the work while at the University of Washington, said researchers had to “get creative” about what could count as ecological evidence. That is exactly what made the project so unusual. A shelf of old seafood turned into a time machine for ocean science.<\/p>\n\n\n\n

The team examined 178 cans containing four salmon species caught in Alaskan waters, including the Gulf of Alaska and Bristol Bay. The samples covered a 42-year period, giving scientists a look at marine conditions that would otherwise be very hard to reconstruct.<\/p>\n\n\n\n

The worms were the clue<\/h2>\n\n\n\n

Anisakid worms are not exactly dinner table conversation. They are small marine parasites, about 0.4 inches long, and they often coil up inside fish muscle. In this case, the canning process killed them, but left enough of their bodies intact for scientists to count them.<\/p>\n\n\n\n

Researchers pulled the salmon fillets apart and used a dissecting microscope to record how many worms appeared per gram of fish tissue. That careful counting gave them a way to compare parasite levels from year to year, almost like reading entries in a long-running ocean diary.<\/p>\n\n\n\n

This may sound unpleasant, but it is not the same as finding dangerous live worms in fresh seafood. These parasites had already been killed by the canning process, and the University of Washington noted that they would have posed no danger to a human consumer in canned fish.<\/p>\n\n\n\n

Why parasites can mean good news<\/h2>\n\n\n\n

Here is the twist. In ecology, parasites are not always a sign that something has gone wrong. Sometimes, they show that many parts of a food web are still connected.<\/p>\n\n\n\n

Anisakids have a complicated life cycle. They move through small ocean animals like krill, then into fish, then into larger predators, and finally marine mammals, where they reproduce. If one of those links is missing, the parasite cannot complete its journey.<\/p>\n\n\n\n

Chelsea Wood, a University of Washington associate professor, described their presence as a sign of a “healthy ecosystem.” In practical terms, that means the worms can act like tiny witnesses to the broader condition of the sea.<\/p>\n\n\n\n

What the salmon revealed<\/h2>\n\n\n\n

The study found that anisakid levels increased over time in chum and pink salmon. In coho and sockeye salmon, the levels stayed about the same.<\/p>\n\n\n\n

That difference matters. It suggests that not all salmon species are experiencing the same ecological pressures, feeding patterns, or parasite exposure. A salmon is not just a salmon when it comes to where it feeds, what it eats, and which parts of the food web it touches.<\/p>\n\n\n\n

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The researchers also warned that the results are not simple to interpret. The canning process preserved the tough outer parts of the worms, but degraded softer features that would have helped identify them by species. That means some fine details remain hidden.<\/p>\n\n\n\n

Marine mammals may be part of the story<\/h2>\n\n\n\n

One possible explanation involves marine mammals. Anisakids reproduce in the intestines of animals such as seals, sea lions, and whales, so a rise in those hosts could give the parasites more chances to reproduce.<\/p>\n\n\n\n

The timing is interesting. The Marine Mammal Protection Act was passed in 1972, helping protect U.S. marine mammals after years of decline. Researchers said, recovering marine mammal populations could be one reason some salmon species carried more anisakids over time.<\/p>\n\n\n\n

\"A
By analyzing 178 cans of Alaskan salmon spanning 42 years, researchers used preserved parasites to reconstruct historical changes in marine food web connectivity.<\/figcaption><\/figure>\n\n\n\n

But that is not the only possible cause. Warming waters, shifts in prey, and improvements linked to environmental laws could also play a role. The ocean rarely gives scientists one neat answer.<\/p>\n\n\n\n

What consumers should know<\/h2>\n\n\n\n

Nobody wants to picture worms in fish, especially while opening a can for lunch. Still, the safety point is clear. Properly canned and cooked fish kills anisakids, so these preserved worms were not a food safety threat.<\/p>\n\n\n\n

Raw or undercooked fish is different. Live anisakids, sometimes called “sushi worms,” can cause illness in rare cases if eaten alive. That is why proper handling<\/a>, freezing, and cooking remain important for seafood safety.<\/p>\n\n\n\n

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At the same time, the study is not saying people should fear salmon. It is saying that even something unappetizing can carry useful information about the ocean if scientists know how to read it.<\/p>\n\n\n\n

Old cans, new questions<\/h2>\n\n\n\n

This research shows how ordinary objects can become scientific records. A forgotten storage room, a quality-control shelf, even an old can label can hold clues about ecosystems that have changed quietly over decades.<\/p>\n\n\n\n

The same approach could possibly be used with other canned fish, such as sardines. That matters because long-term environmental records are hard to find, especially for small organisms like parasites that most surveys ignore.<\/p>\n\n\n\n

At the end of the day, these salmon cans were not just relics from the past. They were snapshots of an ocean food web, sealed in metal, waiting for someone to ask the right question.<\/p>\n\n\n\n

The study was published in the journal Ecology and Evolution<\/em><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

What could a forgotten can of salmon possibly tell us about the ocean? Quite a lot, it turns out. Researchers … <\/p>\n