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Sharks More Abundant on Healthy Coral Reefs

A new study by researchers from James Cook University and the Australian Institute of Marine Science has revealed that sharks in no-fishing zones in the Great Barrier Reef (GBR) Marine Park are more abundant when the coral is healthy.

The study, published in PLOS ONE, examined the distribution patterns and habitat associations of sharks using thousands of baited remote underwater video stations (BRUVS) across the entire GBR Marine Park over a 10-year period from the year 2000.

“This study has demonstrated how important the health of coral reefs is for the future of shark populations on the GBR,” said AIMS@JCU student and lead author Mario Espinoza.

“Some shark species that use coral reefs are under pressure from fishing, and maintaining healthy reefs will help populations survive and rebuild,” Espinoza said. “Our results suggest that healthy reefs make good shark habitat, and may be just as important for improving shark numbers as protecting them from fishing. So looking after our reefs will have direct benefits for the sharks that live on them.”

Co-author Prof Colin Simpfendorfer of JCU’s Centre for Sustainable Tropical Fisheries said there had been a 50% decline in coral cover on the GBR since 1985. “Given the decline in coral cover on the GBR over the past three decades there are likely to have been negative effects on shark populations,” he said.

The study also demonstrated that some species of sharks found on coral reefs had increased since the rezoning of the GBR in 2004. “Grey reef sharks, a species known to have been reduced by fishing in the past, have increased in abundance since more of the reef was protected,” said co-author Dr Michelle Heupelof AIMS. “This is a positive sign for this species, and demonstrates the benefit of closing some reefs to fishing.”