Sharks are practically no longer found in the reefs of the Windward Islands.
Sharks, no matter how terrifying some species, are not always a match for humans. In a new study, published in the journal Nature , researchers come to a worrying conclusion: sharks appear to be ‘functionally extinct’ on nearly one in five reefs surveyed.
The Global FinPrint organization was founded in 2015 with the aim of capturing sharks, rays and other marine life inhabiting coral reefs using underwater video systems. “We usually place between thirty and a hundred cameras on a reef and then record the animals that swim by for sixty minutes,” the organization explains. “With this data, we can then map out the factors that affect the number and species of sharks and rays we see.”
The international team of more than 120 researchers focused on the four major coral reef regions: the Western Atlantic, Indian Ocean, Western Pacific and Central Pacific. Here, the team studied 371 reefs in 58 countries. The findings are worrying. For example, it appears that sharks were rarely seen on nearly 20 percent of those reefs. “This doesn’t mean that sharks don’t visit the reefs at all,” explains researcher Colin Simpfendorfer. “But it does mean that they are ‘functionally extinct’: they no longer play their normal role in the ecosystem.”
The researchers found that on 69 reefs in six countries – the Dominican Republic, the French Antilles, Kenya, Vietnam, the Windward Antilles, and Qatar – sharks had all but disappeared. “We saw only three sharks in more than 800 hours,” says Simpfendorfer. And that is shockingly little. Reef sharks are mainly absent in several countries with a high population density and where the ocean is poorly managed. “It is clear that the main problems are high human population density, destructive fishing and poor governance,” emphasizes researcher Damian Chapman.
Recent estimates suggest that 100 million sharks are caught annually for their fins and meat. As a result of this unregulated fishing, the numbers of many shark species have plummeted. The problem is that without careful control of fisheries, too many sharks are killed. As a result, shark populations can no longer recover, causing the numbers to continue to decrease. It means that a quarter of the sharks and their relatives are currently listed as endangered on the IUCN Red List of Threatened Species.
The loss of this important predator is worrying for several reasons. His absence can disrupt the balance of food webs, causing major changes in the living environment. Moreover, it threatens the food security of people who depend on fish. Finally, sharks attract a huge amount of tourists. It means that diving tourism also decreases when sharks disappear and this industry can get quite difficult.
According to Global FinPrint, the study highlights the importance of working with local people and governments to address the underlying social and economic causes of overfishing. And then there may still be a future for the reef shark. In various parts of the world, measures have been successfully taken – such as better regulations, shark fishing bans and the establishment of protected areas – to prevent reef shark extinction. “We found that robust shark populations can exist if people have the will, the means, and a plan to take conservation measures,” says Chapman. Therefore, the organization is currently working with local researchers and administrators to improve fishing rules, implement protected areas and trade controls based on the findings of this study. In addition, the researchers have mapped the locations where reef sharks are still very common and which may promote the recovery of populations in other areas if new measures are observed.
While the results of the study have revealed a tragic shark loss on many global reefs, they also give some hope, according to researcher Jody Allen. “The findings could guide meaningful conservation plans to protect the remaining reef sharks,” she concludes.