In films and TV shows, police investigators dust crime scenes for fingerprints to catch criminals. Now, conservationists are using a similar method to tackle the illegal overfishing of sharks and rays (鱼).
Overfishing is when too many of a particular type of fish are caught, putting that species in danger. Many sharks and rays are killed because of a high demand and a high price for their fins. In some countries, the fins are used as an ingredient in shark fin soup, which some people believe can cure certain illnesses.
About 100 species of sharks and rays are protected by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), an agreement between 184countries to limit sales of wildlife that may be at the risk of dying out. CITES has teams of people who visit ports and fish factories to look for evidence of protected species being illegally caught and sold. The idea is to punish those responsible and stop it from happening, but finding evidence is difficult. If a fish is already cut up and ready for sale, it 's hard to tell which species it was. Often, fish are sold before inspectors arrive.
Scientists have come up with a process that analyzes "fish dust"—tiny traces of fish that get left on the floor at ports and factories, even after the fish are no longer there. Using a process called metabarcoding (宏条形码技术), they examine the chemical that carries all the information about a living thing's body and characteristics in the dust and can tell if it is from a protected species.
The scientists tested the method in Indonesia, where many sharks and rays are caught and sold. They studied dust from seven sites and found evidence of 61 species of sharks and rays. More than 80% of them were CITES protected species. Dr. Andhika Prasetyo, the scientist who led the research, hopes the new method will be helpful in protecting endangered sea life.
