Dr. Robert Hanner
Progress is being made on addressing serious fraud in the international fish market and industry supply chain.
DNA barcoding – which involves comparing short gene sequences from a sample fish filet to a library of known species’ barcodes – is being used to verify the identities of various fish being caught, distributed, and sold in North America. A recent article in The Guardian highlighted this technology’s application in the field. The story profiled fishermen in British Columbia who are sending their catches to the Hanner lab at the University of Guelph for analysis. The lab confirms the fish’s identity and posts the results on the Oceana website, an organization set on decreasing fish fraud and increasing transparency to the public.
“Regulators are realizing that these tools for molecular biodiversity assessment can have value in applications around food authenticity, traceability, and safety,” says Dr. Robert Hanner, a professor in the Department of Integrative Biology.
Hanner has led multiples studies on fish fraud and seafood mislabeling, beginning back in 2005 when he became campaign coordinator for the fish barcode of life project, aiming to identify and sequences the DNA barcodes of all fish species. In every experiment, he has found that at least 25 percent of all tested samples are mislabeled.
And this is no mistake; seafood mislabeling appears to be economically motivated. Fish of lower economic value are substituted for fish of higher value in almost every case that Hanner has studied. This is cause enough for concern, but the issue also has implications for human health.
Occasionally the fish that act as substitutes can harm the person who eats them. For example, escolar is marketed as tuna, but escolar contain a waxy ester in its flesh that many people cannot digest. They may end up experiencing a condition called Keriorrhea, which involves symptoms such as diarrhea or stomach cramps. Pregnant women may be at an even greater risk if a fish such as king mackerel is mislabeled. King mackerel are known to accumulate and contain more heavy metals, which can negatively impact the developing fetus’ growth.
The fish’s environment can also pose health risks depending on how and where they were raised and caught. Aquaculture species are raised in more contained spaces than wild fish and as a result are more prone to interactions, injuries, and infections. If antibiotic or antifungal agents are used to treat said infections, the fish may not be safe for the human food supply chain, especially if banned veterinary drugs are used to treat them. While declared aquaculture products may be tested for these substances, “dirty” fish could be mislabeled as wild to circumvent screening while also commanding a higher market price.
There are clearly a number of factors to consider when approaching an issue as complex as fish fraud. Multiple pathways exist that show the interconnectedness of human, fish, and environmental health, a great illustration of One Health – that is, the recognition of these three pillars of health. The One Health approach is a promising one for understanding these relationships and developing a holistic solution.
Significant barriers are present though. Hanner first illuminated the prevalence of mislabeled fish back in 2007 and yet little has changed. The fishing industry remains poorly regulated in comparison to other traditional food industries such as beef. There is significant disconnect between suppliers and retailers and fraud occurs just about anywhere along the supply chain.
Hanner’s work with DNA barcoding technology hopes to reduce that disconnect, preventing fish from being mislabeled before they reach consumers. Hanner has recently begun collaborating with the Laboratory Services Division at the University of Guelph to develop testing capabilities for industry use. Amanda Naaum, a former PhD student and postdoctoral fellow in the Hanner lab has designed PCR tests that can confirm the identity of a given species using portable equipment that can be deployed at multiple points in the supply chain and provide results in real-time. This would hold suppliers responsible for any mislabeling and could inform stricter regulations.
“Molecular biodiversity tools are becoming so powerful,” says Hanner.
Moving beyond standard DNA barcoding, techniques such as high-throughput DNA sequencing are able to profile multiple species simultaneously. This is useful for analyzing foods containing fish mixtures, such as fish sausages, or for interrogating entire communities from microbes to fish.
“That’s where the science is evolving in a way to support a One Health paradigm,” says Hanner, “I find it really interesting.”
Learn more about Prof. Hanner and his lab here: https://www.hannerlab.net/home
Read the article from The Guardian about DNA barcoding in practice: https://www.theguardian.com/environment/2021/mar/16/fish-detectives-the-sleuths-using-e-dna-to-fight-seafood
By: Anna McMenemy
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