the Australian Institute of Marine Research (AIMS) reported a five-year study about the result, in which the condition of cartilaginous fish such as sharks and rays was assessed. 77% of these animals live near coral reefs. Of the various sharks belonging to these species, the population of the five most common species has declined by 63 percent globally, mostly due to overfishing. In the course of the research, some 22,000 hours of underwater footage taken near 391 coral reef systems in 67 countries were examined. More than 150 professionals from 120 institutions contributed to the research study.
According to the survey, those reefs in Western Australia where fishing is prohibited (because the reef is in a protected marine area, for example) and where there is the least human disturbance, these sharks and rays feel good, and their healthy population can live there.
“Compared to other parts of the world, Western Australia’s sharks and rays are doing quite well.” said marine ecologist Dr. Konrad Speed, principal investigator for the Indian Ocean for the Global Survey. In a remote, undisturbed, protected reef for 3 decades, populations thrive, and some fish are thrown here from further afield. However, on reefs in a similar location where fishing was not prohibited, there were fewer sharks and their larger prey animals were also less common.
Dr Speed said there was evidence that sharks were helping coral reefs recover from coral bleaching or storm surges. They can do this thanks to the fact that they catch fish that, for example, eat algae that coexist with corals. If an algae-eating fish devours these single-celled organisms, there is nothing to form symbiosis with the coral polyps, and without them, the coral colony cannot regenerate.
During the Western Pacific Basin Survey, sharks were revealed to be intact in most of the Great Barrier Reef. In some places, a very diverse community of 27 species of sharks and rays has been found!
