Scientists Found a Rise in Parasitic “Sushi Worms” When They Opened 40 Years’ Worth of Salmon Cans: “Good News”

**Increase in Parasitic Worms in Canned Salmon: A Surprising Conservation Success Story**

Recent scientific research has revealed a notable rise in the number of parasitic worms found in canned salmon over the past several decades, a finding which, rather than being a cause for alarm, is being celebrated as a sign of successful marine conservation efforts.

The study, published in the April 2024 edition of the journal *Ecology and Evolution*, indicates that the prevalence of these worms, often referred to as ‘sushi worms,’ has increased markedly since the 1970s. According to Chelsea Wood, the lead researcher and a faculty member at the University of Washington’s School of Aquatic and Fishery Sciences, the increase in the worm population is a reflection of the recovering numbers of marine mammals, which are the final hosts for these parasites.

While the thought of consuming worms, even in canned salmon, may evoke discomfort in some, Wood reassured the public that most individuals will experience no adverse effects after consuming properly prepared fish. “For the vast majority of us, we can eat live worms with no ill effects,” she stated.

The impetus for Wood’s research came somewhat serendipitously. The Seafood Products Association, which represents seafood producers, had been collecting canned Alaskan salmon since the 1970s and reached out to Wood when they learned of her interest in old fish specimens. Access to these historical cans allowed researchers to examine how the prevalence of parasitic worms in salmon has evolved over the years.

Wood highlighted that the study measured how many worms were present in each gram of salmon tissue. Findings indicated that while chum and pink salmon showed an increase in parasites, the levels remained stable in sockeye and coho salmon. This suggests variations in the health of different salmon populations and their exposure to marine mammals.

The increase in these parasitic worms is linked to the impact of conservation initiatives, particularly the passage of the Marine Mammal Protection Act in the 1970s. Wood noted that prior to this act, marine mammals had been extensively hunted, which disturbed the marine ecosystem. With the protection measures in place, populations of these mammals have rebounded, likely contributing to the increased worm populations as they return to their natural habitat.

Despite concerns over food safety, Wood explained that the worms found in canned salmon are typically dead and pose no threat to consumers. However, individuals with specific allergies to proteins found in these worms may experience reactions. “A lot of people who think they have seafood allergies actually have allergies to these worms,” Wood added, underscoring the importance of consulting an allergist for proper diagnosis.

When it comes to raw fish consumption, the risks associated with these parasites heighten. Wood warned that when fish is consumed raw, such as in sushi or sashimi, the worms could potentially still be alive, which increases the chances of health complications. She elaborated on the dangers posed by live worms, stating they can penetrate the intestinal wall, sometimes resulting in severe gastrointestinal symptoms or hospitalisation—a rare outcome but still a risk.

Nevertheless, for the average consumer, Wood was adamant that the risk posed by these worms is minimal. In fact, she embraces eating fish herself, including sushi, confidently asserting that this level of risk is manageable. “We do a lot of things that entail risk in our lives. Getting into a car is way riskier than eating a piece of sushi,” she concluded, encouraging seafood lovers to savour their meals without undue concern about the worms.

This research not only sheds light on the dynamics of marine ecosystems, but also encourages a greater understanding of the complexities surrounding food safety in relation to seafood consumption. As conservation efforts continue to show positive results, it becomes evident that increased populations of marine life can have unexpected, albeit mightily interesting, ramifications for human dietary patterns.