Koi fish and your cat may eat shark meat for a long time without you knowing it

Not because Koi fish have teeth, escaped from sewers and evolved into marine killers, but whether you own a Koi or aquarium fish, including other pets such as dogs, cats, birds, Rats may indirectly cause the extinction of some rare shark species. at sea.

That’s because their food is mixed into shark meat, which has been unknown to consumers and management agencies, conservation units. The truth was only revealed after a team of researchers at the National University of Singapore traced the DNA in cans of animal food they bought in supermarkets.


The results showed that one in three samples contained DNA from sharks, even the shark species listed in the Red Book. Researchers suspect some pet food manufacturers are helping shark hunters get their fins.

Every year, worldwide, about 70 million sharks are hunted for their fins. But if only the fins are taken, the meat will be wasted. As a result, hunters often grind shark meat and resell it to pet food companies.

The company will deftly heat these cuts of meat, on the one hand, for sterilization and mildew. On the other hand, the process also breaks the DNA strands and obscures the obvious origin of the meat so that no one knows that they used shark meat.

What is fish meal in pet food products?

If you read the ingredients on pet food cans, you will see that they have very common ingredients. In addition to macronutrients such as protein, fat, carbohydrates, elements such as iron, zinc… manufacturers will also list ingredients that are not classified, from “fish”, to “fishmeal”. ” to “white fish”, “sea fish “… as a way to promote the natural origin of their products.

Usually, manufacturers will write common fish as “tuna”” or “salmon” to increase the price of the product. But with shark meat, on the other hand, they would write it down to blur the trail.

Singaporean scientists discovered this when they collected 45 samples of Thai animal food products, which were labeled with 16 different popular brands, and analyzed the DNA they contain.


Thus, heat treatment from feed manufacturers will destroy most of the shark’s DNA if the meat is used. But researchers have a way to restore it.

They used PCR gene amplification (similar to COVID-19 testing) to multiply the number of small fragments of shark DNA remaining. The researchers will then extract this DNA and compare it to a short list of DNA barcodes from known shark species.

The results showed that 31% of the pet food samples they collected at the market contained shark DNA. In some cases, this DNA code matches a shark species classified as endangered by the International Union for Conservation of Nature (IUCN).

For example, the Blue Shark (Prionace glauca) appeared up to seven times, the most common among test samples classified as Vulnerable by the IUCN. Other studies have shown that blue sharks are often caught for their fins. Samples of shark fin products in Southeast Asia often also come from blue sharks.

Combined, this evidence suggests that pet food producers in Southeast Asia are consuming by-products of the shark fin processing industry. This will prevent blue sharks from being found, after they have been killed for their fins.


After the blue shark, the silk shark (Carcharhinus falciformis) and the white head reef shark (Triaenodon obesus) are the next most common species used as pet food. In total, Singapore researchers found nine shark species in all, including the spotted-tailed shark (C. sorrah), the red-eye shark (Loxodon macrorhinus) and the sand tiger shark (Carcharias taurus).

They also identified 16 product samples containing DNA from sharks, but were unable to identify the species because the DNA samples were too heavily damaged. DNA comparisons can only identify their genus as Carcharhinus.

Choose your pet’s food wisely and you’re doing your part for shark conservation

Although pet food companies don’t specifically mention shark meat in their products as legal or not, scientists suspect that given the ambiguity in product labels, it’s likely that manufacturers have an incentive to hide their origin. This may be due to the movement to protect the environment and marine life, causing many pet owners to refuse to buy products derived from sharks.

Terms like “sea fish” prevent pet owners from making “informed and conscious decisions” about what they give their animals“, wrote the scientists.We think many pet owners and hobbyists will be surprised to learn that they are potentially abetting unsustainable fishing practices.”


In fact, marine shark populations have declined by 71% since 1970, and three-quarters of shark species are now considered globally threatened with extinction. In that context,Pet food is definitely not suitable for this shark“, wrote the researchers.

We need to take steps to force pet food manufacturers to better label their products, to avoid ambiguous summary terms being used as they are today, thus enabling consumers to make informed decisions. This will benefit the shark population by helping to reduce unsustainable fishing and use of resources that are incompatible with their conservation.”

Referring Science beet-20220310200940083.chn

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