Decades-Old Salmon Cans Uncover Unexpected Secrets Of Ocean Life

A simple can of salmon has helped scientists understand big changes in the ocean over many years. By studying fish that were preserved decades ago, researchers have found new clues about how marine life in Alaska has been changing, reported Newsweek.

Scientists have gained a glimpse into Alaska's changing marine ecosystem through canned salmon preserved for nearly 50 years. Researchers at the University of Washington studied vintage cans of salmon-containing fish from four different species-that were caught in the Gulf of Alaska and Bristol Bay over a 42-year period, spanning from 1979 to 2021.

The research team examined 178 cans containing pieces of the four salmon species and counted the Anisakid roundworms, common, small marine parasites, present in their flesh. These parasites were killed during the canning process and pose no harm to humans upon consumption. Nevertheless, counting the number of these roundworms helps scientists understand the health of the marine ecosystem.

The study, published in April 2024 in the journal Ecology and Evolution, revealed that these roundworms remained preserved within the salmon meat, indicating that prior to canning, the fish had inhabited a rich and active ecosystem.

According to the researchers, the abundance of Anisakids in Chum and Pink salmon increased over time, while no significant changes were observed in Sockeye and Coho salmon.

Chelsea Wood, co-author of the study, noted that while there is a common misconception that the presence of worms in salmon signals a problem, the Anisakid life cycle is linked to multiple parts of the food chain, thus, their presence actually indicates that the fish originated from a healthy ecosystem.

Natalie Mastick, lead author of the study, added that the Anisakid life cycle is complex and requires multiple host species, the increasing numbers observed in Pink and Chum salmon over time demonstrate that these parasites were able to find the necessary hosts to reproduce, a sign pointing toward a stable or improving ecosystem.

These findings present a balanced picture, suggesting that an increasing number of parasites in certain salmon species can be viewed as an indicator of a healthy and smoothly functioning marine environment, rather than as a problem.