A study led by Professor Nick Dulby from Simon Fraser University has found that the population of sharks and stingrays has decreased by 71% since 1970 due to overfishing, with over three-quarters of species at risk of extinction. The research used the Earth Life Index and the Red List Index to evaluate the population trend and risk of extinction of 31 species. The team emphasized the need for immediate measures to prevent the collapse of shark and stingray populations, given their slow reproductive rate and importance in maintaining the balance of marine ecosystems.