Illegal, unreported, and unregulated (IUU) fishing is considered to be a major barrier to global long-term sustainability for marine fisheries. While it is difficult to estimate the full extent of the problem, a 2009 abstract estimated the value of IUU fishing to be between $10 and $23.5 billion annually.
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Similarly, a recent study by See Around Us estimated that 30 percent (or around 32 million metric tons per year) of the global catch is unreported in official statistics.
Dr. Clive Trueman and PhD student Katie St. John Glew of the University of Southampton have completed research that shows how jellyfish can help combat the problem of seafood fraud.
According to the study, published in journal Methods in Ecology and Evolution, all animals build their bodies from carbon and nitrogen, which they get from food. Carbon and nitrogen has two chemical forms (isotopes), and the relative amount of these isotopes varies across the seas and oceans.
“We show that we can map these natural variations in the chemical forms of carbon and nitrogen by measuring jellyfish,” says Dr. Trueman. “The jellyfish eat small plankton and lock in the chemical signals. We can then measure the same signals in a fish, shellfish, or fish product and compare this to our maps. We can then either test if the chemistry of the fish is consistent with the chemistry of the place where it is reported to have from.”
Alternatively, if there is no prior information, the team can estimate the most likely location that the fish or shellfish came from.
Dr. Trueman notes understanding the origins of fish or fish products are of great importance.
“IUU fishing impedes our ability to sustainably manage fish stocks, and disadvantages nation states and fishers adhering to regulations,” he says. “In addition as consumers globally are more aware than ever of sustainability concerns around marine fisheries, many cite concerns about sustainability as reasons to avoid buying fish. If consumers were confident that marine products were indeed from sustainably managed resources, fishers may also benefit from increased sales.”
Seafood fraud comes in different forms, including species substitution—often a low-value or less desirable seafood item swapped for a more expensive or desirable choice— and improper labeling, including hiding the true origin of seafood products. Also a possibility is adding extra breading, water, or glazing to seafood products to increase their apparent weight.
Dustin Cranor, communication director of Oceana, notes the organization is calling for full-chain traceability for seafood sold in the U.S.
“Seafood fraud is a serious global problem that undermines honest businesses and fishermen that play by the rules. It also threatens consumer health and puts our oceans at risk,” he says. “Without full-chain traceability for all seafood, consumers will continue to be cheated, hardworking, honest fishermen will continue to be undercut, and the long-term productivity of our oceans will continue to be in jeopardy.”
Chemical testing of the source of marine food products could be a powerful tool to help to fight food fraud.
While these kinds of approaches have been used in land animals for a long time—including studying movement and migration in birds, butterflies, and in archaeology and forensics to look at human migrations—until now it has been difficult to apply them in marine settings.
“We realized that jellyfish would make an excellent model species to build out isotope maps because they are found everywhere, grow fast, and don’t move very far in their lifetimes,” Dr. Trueman says. “Now that we have established how to test the origin of marine food, the next challenge is to apply the methods. We are working both to extend the areas of our maps across different seas, and also to start to test for origin in landed and traded fish and shellfish.”