Alaskan waters are a critical fishery for salmon. These fisheries depend on complex marine food webs, and scientists want to know how climate change is changing them. But finding samples from the past isn’t easy.
Natalie Mastick, a postdoctoral researcher at Yale University’s Peabody Museum of Natural History, said, “We need to really open our minds and get creative about what can be used as an ecological data source.”
As a doctoral student at the University of Washington in Seattle, Mastick looked into Alaskan marine food webs using old salmon cans, which is a very unusual method. Four different kinds of salmon fillets were in the cans. They were all caught in the Gulf of Alaska and Bristol Bay over 42 years. Mastick and her coworkers took the preserved fillets from 178 cans and counted how many anisakid roundworms, a common, tiny marine parasite, were inside the meat.
People would not have been hurt by eating the parasites because they were killed during the canning process. But counting anisakids is one way to gauge how well a marine ecosystem is doing.
“Worms in your salmon is thought to mean something is wrong by everyone,” said Chelsea Wood, an associate professor of aquatic and fishery sciences at the UW. “But the anisakid life cycle integrates many components of the food web. I see their presence as a signal that the fish on your plate came from a healthy ecosystem. ”.
In a paper that came out April 4 in Ecology, the research team says
He said, “Anisakids have a complicated life cycle that needs many types of hosts.” Mastick is the lead author of the paper. “Seeing their numbers rise over time, like we saw with pink and chum salmon, shows that these parasites were able to find the right hosts and have babies.” That could indicate a stable or recovering ecosystem, with enough of the right hosts for anisakids. ”.
Anisakids start out living freely in the ocean. They enter food webs when eaten by small marine invertebrates, such as krill. As that initial host gets eaten by another species, the worms come along for the ride. Krill that is infected could be eaten by a small fish, which would then be eaten by a bigger fish like salmon. This cycle continues until the anisakids end up in the intestine of a marine mammal, where they reproduce. The eggs are then dumped back into the ocean where they will hatch and start the cycle all over again.
That’s because anisakids can’t finish their life cycle without a host, like marine mammals, and their numbers will go down, according to Wood, who is the lead author on the paper.
People cannot serve as hosts for anisakids. Consuming them in fully cooked fish poses little danger, because the worms are dead. Anisakids, which are also called “sushi worms” or “sushi parasites,” can make you sick with food poisoning or a rare disease called anisakiasis if you eat them alive in raw or undercooked fish.
The Seafood Products Association, a Seattle-based trade group, donated the cans of salmon to Wood and her team. The association no longer needed the cans, which had been set aside each year for quality control purposes. Mastick and co-author Rachel Welicky, an assistant professor at Pennsylvania’s Neumann University, tried a number of different ways to cut up the canned fillets and look for anisakids. The worms are about a centimeter (0. 4 inches) long and tend to coil up in the fish muscle. With the help of a dissecting microscope, they were able to accurately count the worm bodies by pulling the fillets apart with forceps.
There are several explanations for the rise of anisakid levels in pink and chum salmon. The Marine Mammal Protection Act, which was passed by Congress in 1972, has helped seal, sea lion, orca, and other marine mammal populations recover after years of decline.
Mastick said, “Anisakids can only reproduce in the intestines of a marine mammal. This could be a sign that, during our study period (from 1979 to 2021), anisakid levels were rising because there were more chances to reproduce.”
Other possible explanations include warming temperatures or positive impacts of the Clean Water Act, Mastick added.
It’s harder to figure out what the stable anisakid levels in coho and sockeye mean because there are so many anisakid species, and each has its own set of invertebrates, fish, and mammals that it feeds on. The tough anisakid skin was not damaged during the canning process, but the soft parts of their bodies that would have allowed for species identification were.
Mastick and Wood think this method could be used to check for parasites in other canned fish, like sardines. They also hope that this project will help make new, chance connections that will lead to more information about ecosystems from the past.
“This study came about because people heard about our research through the grapevine,” said Wood. “The only way to learn about ecosystems from the past is to network and make connections to find historical data sources that haven’t been used before.” ”.
Bruce Odegaard and Virginia Ng from the Seafood Products Association, as well as UW student Aspen Katla, also wrote the paper. The research was funded by the U. S. National Science Foundation, the Alfred P. Sloan Foundation, the Washington Research Foundation and the University of Washington.
When Salmon Gets Wriggly: Understanding Fish Parasites
As a salmon lover, I enjoy seared fillets and poke bowls alike But I’ve paused before biting in when spotting a tiny white worm wiggling within the pink flesh Parasites in salmon are more common than you may think. Should these critters deter us from eating this nutritional powerhouse? Let’s explore what parasites may lurk in salmon, how to spot them, and whether they pose dangers.
The Usual Suspects
Anisakid roundworms are the most prevalent salmon parasite. Also called herring worms or cod worms they appear as tiny threadlike nematodes. Freshwater salmon may host Diphyllobothrium tapeworm larvae. Usually camouflaged in whitefish, anisakids stand out against salmon’s pink meat. Diphyllobothrium larvae are similarly hard to spot.
Wild vs. Farmed: Does It Matter?
Some believe wild salmon harbor more parasites from exposure to varied ecosystems. But farmed salmon feed often contains fish components that may transmit parasites. Ultimately, both can host worms. However, reputable fisheries and farms freeze catch to control parasites per FDA guidelines. So shop wisely, and you’re unlikely to spot either parasite type.
How Parasites Infiltrate Fish
Anisakid worms and Diphyllobothrium larvae dwell in ocean mammals like seals. Their eggs pass into the water in seal feces. When tiny crustaceans eat these eggs, the larvae inhabit their new hosts. Small fish then consume the infected crustaceans, propagating the worms. Bigger fish like salmon ultimately ingest these smaller prey – and the parasites.
The larvae bore into the fish flesh, where they encyst and grow. Diphyllobothrium then forms its final larval stage within salmon. Anisakids cannot mature fully in fish, but salmon provides a temporary waystation for onward transmission when other animals eat them. This cycle perpetuates parasite spread.
Spotting Signs Of Infestation
Visible worms offer the most obvious clue to infestation. Pinpoint white anisakids against pink salmon or use a flashlight to backlight fillets and see shadows. However, not all parasites will be apparent. Larvae also often hide in viscera, not meat. And they can measure just millimeters long when encysted. Consider coarse flesh texture or black specks under the skin as other possible signs.
Are Parasites Dangerous?
Eating live anisakid roundworms or Diphyllobothrium tapeworm larvae can theoretically transmit parasitic infections to humans. Anisakiasis and diphyllobothriasis may cause symptoms like nausea, vomiting, intestinal pain and allergies. But don’t panic. The FDA states risks are very low, especially from commercial frozen fish like U.S. salmon. Basic preparation steps kill parasites.
Minimizing Risks
Cooking fish to 145°F destroys parasites. Also heed FDA guidelines advising freezing at -4°F for 7+ days to kill worms in raw preparations like sushi. Finally, inspect salmon first and tweezer out visible worms if comfortable doing so. Following these tips, you can keep enjoying your favorite fish relatively worry-free.
A Few Parting Tips:
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Seek reputable sellers offering sustainably farmed or ethically wild-caught salmon stored properly frozen.
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Cook salmon thoroughly until opaque and flaky at minimum 145°F internal temperature.
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Freeze salmon at -4°F or below for at least 7 days before eating raw.
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Visually inspect salmon meat and backlight to check for parasites. Remove any you see.
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If texture seems abnormal or black flecks appear under skin, discard the fish to be safe.
Though the notion of worms in salmon understandably elicits disgust, proper handling and cooking drastically reduce risks. These flavorful fillets remain one of the healthiest protein choices out there when guidelines are followed. A few tiny parasites shouldn’t deter us from reaping salmon’s nutritional benefits.
Frequency of Entities:
salmon: 41
parasites: 24
worms: 21
anisakid: 10
roundworms: 7
larvae: 6
Diphyllobothrium: 5
tapeworm: 5
fish: 5
FDA: 4
flesh: 3
meat: 3
wild: 3
farmed: 3
freeze: 3
cooking: 3
raw: 3
nausea: 2
vomiting: 2
infection: 2
seals: 1
feces: 1
eggs: 1
crustaceans: 1
flashlight: 1
shadows: 1
viscera: 1
millimeters: 1
texture: 1
specks: 1
allergies: 1
worry: 1
sellers: 1
guidelines: 1
10 FISH THAT HAVE WORMS AND PARASITES (DON’T IGNORE)
FAQ
Is it common for salmon to have worms?
Can fish worms infect humans?
What is the white stuff on raw salmon?
How can you tell if salmon has worms?
Salmon can have worms, and theworms in cooked salmon look like long, thin strands of cooked spaghetti. In some cases, they may be difficult to spot. They’re usually white or almost clear.
What are the different types of worms in salmon?
There are two main types of worms that you could be infesting your fish with, “Tapeworms” and “Herring worms”. Tapeworms are more dangerous to humans of the two 3. If you introduce wild Salmon into your farm and that Salmon has spent a lot of time in freshwater, they might be carrying Tapeworms or at least the larvae.
How do you get rid of worms in salmon?
As long as the salmon has been cooked properly, then you shouldn’t get parasites from it. Per the FDA, cooking salmon to an internal temperate of 145° F (63° C) kills roundworms. If you don’t have a meat thermometer for an accurate temperature read, we suggest using the flake test. This test requires cooked salmon and a fork.
How do worms get into salmon?
The most common cause for worms in farm-raised Salmon has to do with their diet. You should not feed your Salmon raw fish as this is the easiest way for Salmon to get worms. Salmon that have spent a large portion of their life in freshwater also have the risk of introducing tapeworms to farms.