DNA barcode identifies endangered shark species secretly added to pet food – YubaNet



Pet owners may be unknowingly feeding their pets meat from endangered shark species, shows a new study published in Frontiers in Marine Science. Researchers used DNA barcoding to investigate the presence of sharks in different pet food products purchased in Singapore, which revealed a considerable prevalence of ingredient mislabelling. They suggested implementing global standards for pet food labels to avoid overexploitation of endangered sharks.

Bar chart showing the proportion of shark species identified in this work along with their IUCN Red List status

If you ever read the ingredient list of your pet’s favorite food, you may come across ambiguous terms such as “fish”, “sea fish” or “whitebait”. Have you ever wondered what exactly these ingredients are? A team of researchers from Yale-NUS College in Singapore analyzed pet food products purchased in Singapore and found that these terms may refer to endangered shark meat.

The shark population is decreasing

Sharks are crucial for the functioning of healthy marine ecosystems. As apex predators, they are at the top of the ocean food chain. By shifting the distribution of their prey, which changes the feeding strategy of other species, they maintain the balance of the food chain. The disappearance of sharks has led to the decline of seagrass beds and coral reefs.

The growing trade in shark fins and meat is endangering shark populations. Research suggests that around 100 million sharks may be killed each year. Overfishing is the greatest threat to sharks worldwide, and the lack of effective monitoring and management of fishing practices is increasing the burden on vulnerable shark species.

“Shark populations are overexploited worldwide, with declines of over 70% over the past 50 years documented. This is indicative of the current disregard in which we hold our oceans,” said the authors, Dr Ben Wainwright and Ian French, of Yale-NUS College.

Shark meat in everyday products

A silent contributor to declining shark populations is the use of shark products in everyday products such as pet food and cosmetics. For example, many people may not be aware that some body care and beauty products may use shark-derived squalene (as opposed to plant-derived squalane).

Research has also found shark meat in pet food products. A previous study from 2019 found the presence of sharks in 78 pet food samples collected in the United States.

“Given the results of a previous study in the United States, we wanted to see if endangered sharks are also sold in Asian pet foods,” the authors explained.

Researchers used DNA barcoding to determine if there was shark DNA in 45 different pet food products from 16 different brands on sale in Singapore.

“None of the products purchased listed shark as an ingredient, only using generic catch-all terms such as ‘fish’, ‘ocean fish’, ‘whitebait’ or ‘whitefish’ to describe their contents”, have said Wainwright and French.

Of the 144 samples taken, 31% contained shark DNA. The most identified sharks were the blue shark (Prionace glauca), followed by the silky shark (Carcharhinus falciformis), and the white tip shark (Triaenodon obesus).

The silky shark and the whitetip shark are listed as “vulnerable” in the International Union for Conservation of Nature (IUCN) Red List. The silky shark is also listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which means its trade must be controlled to prevent over-consumption that would threaten the survival of the species.

Transparent labels

The results demonstrate the strong overfishing pressure to which sharks are increasingly subject.

“The majority of pet owners are likely nature lovers, and we suspect most would be alarmed to discover that they may be unknowingly contributing to overfishing of shark populations,” the authors commented.

The authors urge more transparency in the ingredient labels of pet food products. Avoiding vague catch-all terms in ingredient lists to allow consumers to make informed purchasing choices and implementing global standards for pet food labels are two steps to avoid shark overfishing .

Greater accountability along seafood supply chains for food and feed is needed, which would mitigate unsustainable fishing and resource use incompatible with the survival of shark populations.

JOURNAL: Frontiers of Marine Science:

DO I10.3389/fmar.2022.836941