(ORDO NEWS) — Singaporean biologists have found that pet food often contains shark meat and blubber, including rare species. However, their packaging does not say anything about it.
Previously, researchers from the United States came to similar conclusions. As noted in an article for the journal Frontiers in Marine Science, mislabeling of seafood is a widespread problem that prevents consumers from choosing less environmentally friendly products.
Many people are afraid of sharks. However, in reality, these fish themselves have more reason to be afraid of humans, because they are massively caught around the world for their meat, fat and fins.
As a result, the number of sharks (as well as rays) in the open ocean has declined by more than 70 percent over the past half century. Reef shark species are also becoming rarer.
Consumers have the opportunity to influence the situation by refusing products for which sharks are caught. To do this, however, is not always easy.
This is because pet food and cosmetics manufacturers often mislabel products without stating that they contain shark meat or squalene derived from shark liver. Instead, the packaging mentions “fish”, “marine fish”, or “white fish”.
The presence of shark meat and squalene in products can be detected using DNA barcoding. However, pet foods and cosmetics undergo heat treatment that breaks down the genetic material into fragments around 650 base pairs long, too short for analysis. Only recently has a mini-barcoding method been developed that works with genetic fragments of 100-200 bp in length.
Biologists Ian French and Benjamin J. Wainwright of the National University of Singapore used mini-barcoding to find out whether shark meat and blubber are found in pet food available in Singapore stores.
They chose 45 titles made in Thailand and released under 16 brands. Most of them were listed as “fish”, “sea fish” or “white fish”. Shark meat and blubber were not mentioned in any of these foods.
In total, French and Wainwright analyzed 144 food samples (two to five samples per item). Shark genetic material was found in 45 of them, which corresponds to 31 percent. Most often, researchers found DNA from representatives of the genus gray sharks (Carcharhinus) in the feed.
The blue shark (Prionace glauca), silk shark (Carcharhinus falciformis) and reef shark (Triaenodon obesus) were in the lead among specific species. Traces of their genetic material have been found seven, six and four times, respectively.
The silk and reef sharks are listed as vulnerable by the International Union for Conservation of Nature. In addition, the authors identified three more vulnerable shark species in DNA in the feed.
Previously, similar results have been obtained in the analysis of pet food and cosmetics sold in the United States. True, the species composition of sharks in American goods was not so diverse.
The researchers were able to identify only two species, with the genetic material of mako (Isurus oxyrinchus) found in most of the samples. A study by Singaporean scientists confirms that this problem is not limited to the United States.
Apparently, sharks are not caught for the production of feed and cosmetics intentionally. It is more likely that the fish are harvested for their fins, which are highly valued in Asian cooking, and the carcasses of little value are sold to manufacturers of feed and other goods. In addition, sharks can become victims of accidental by-catch, after which their carcasses are processed.
French and Wainwright acknowledge that pet food manufacturers are not required to list the exact ingredients on their packaging. However, the researchers suggest that many buyers would refuse to buy certain foods if they knew that their production is associated with a massive catch of rare sharks.
Producers are not only mislabeling seafood. Recently, we talked about how American biologists sequenced DNA from products that contained wild mushrooms.
It turned out that only five of the 16 products studied had a label that matched the content. For example, champignons or butter mushrooms were sold under the guise of porcini mushrooms, and researchers found potentially poisonous mushrooms in two products.
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