Tango-Tiger

Scientists have known for เว็บทดลองเล่นสล็อต decades that the number of sharks is declining. But a new study shows that global shark populations have declined severely over the past 50 years.

Data from a study recently published in the journal Nature showed that the number of sharks and stingrays in the world's oceans decreased by more than 70 percent between 1970 and 2018.

Stuart Sandin, a marine biologist at the Scripps Institution of Oceanography, said sharks are great predators. Be a fast swimmer And has a special senses They can be aware of any change In the ocean from a distance Either it is a slight change in the smell or the flow of water.

The ability to quickly recognize what has changed from the normal allows sharks to forage in the open ocean. But it puts them at risk, especially as international fisheries increase.

Sandin said that when fishing in the open ocean Sharks are always hooked first, whether they are the main target of fishermen or not.

26 of the 31 sharks and stingrays are in danger of extinction.Three sharks - the white-tip sharks, the hammerhead sharks and the sledgehammers - are the most vulnerable.

Nathan Pacoureau, a biologist at Simon Fraser University in Canada and one of the authors of the study, said the past 50 years have been a catastrophic time for the global shark population.

Sometimes sharks are deliberately caught by fishing boats. But often they are caught while fishermen are catching other fish. Exist, such as tuna and sharp mouth fish or swordfish

However, both sharks and rays are fish with a cartilaginous skeleton. Unlike other fish That is, they are not able to reproduce as often. And still produces only a few babies at a time

Pacoureau said sharks share a similar breeding pattern with mammals rather than fish. Therefore, the population will not be able to replenish as quickly as other fish.

The number of fishing vessels in the open ocean has increased dramatically since the 1950s. The 1950s, and climate change and pollution put the lives of sharks at risk. But the growing pressure of fishing is the greatest threat to any shark. Ocean species

Stuart Pimm, an ecologist at Duke University who was not involved in the study, said the removal of a predators like sharks from the ocean affects all living organisms in the sea. And that sharks are like lions, tigers and bears of the ocean world. And they also help keep the marine ecosystem in balance.