- Sharks in some reefs functionally extinct
- About the study
- The cause of shark absence or low populations
- Governance as a factor
- Shark populations are reversible
- What now?
Sharks in some reefs functionally extinct
Sharks have been reported as “functionally extinct” in certain areas that were sampled because they have been missing in 19% of coral reefs in the world. Animals become functionally extinct when they no longer play a significant ecological role in their ecosystem.
About the study
The study group that conducted this research consisted of Mike Heithaus and Demian Chapman of Florida International University and the Global FinPrint. The goal of the group was to survey all reef shark species like tiger sharks and hammerhead sharks. This is mostly because reef sharks are easier to spot than other sharks that swim in the high seas. Six researchers administered surveys of coral reefs in numerous parts of the world by more than 120 scientists. Researchers lowered video cameras attached to poles with shark bait on the far end.
After reviewing the thousands of hours of video feed, they discovered that 69 reefs, which is 19% of all coral reefs, caught no sharks on video.
The cause of shark absence or low populations
It was determined that the absence of the sharks in the coral reefs were as a result of overfishing. The study concluded that “destructive and unsustainable” fishing strategies across 58 countries were to blame.
Demand for shark fins has increased among the Asian middle class. In the British West Indies, long-line fishing hurts shark populations. This could be fixed by using strategies to target specific fish so that sharks are not accidentally caught. Large nets that catch fish by their gills are also dangerous to sharks because the nets are nearly invisible to fish underwater. Sharks are especially vulnerable to other smaller fish because they grow slowly and don’t reproduce a lot throughout their lifetimes.
Governance as a factor
Additionally, reefs close to countries with dense populations and poor government policies were impacted the worst. “The worst ranked nations for reef sharks included Qatar, the Dominican Republic, continental Colombia, Sri Lanka and Guam.” Of the 58 poorly governed countries, 34 had shark populations that were half the amount scientists had expected.
However, the study’s results were not all bad. The Great Barrier Reef of Australia, the largest coral reef in the world, and French Polynesia still had high shark populations and the Bahamas and continental Australia even found “increased abundances of reef sharks.” Experts from the study linked this to good government management and enforcement of shark fisheries and sanctuaries due to the ban on commercial fishing.
Shark populations are reversible
In some more good news, experts say that the loss of shark populations is not irreversible. However, in order to meaningfully reverse this, efficient and strong policies must be implemented in ways that they will be accepted and enforced properly. Experts recommend actions such as increased fisheries management and national bans on targeting or trading sharks.
It is important to not lose our shark populations because they provide many ecosystem services that keep the ocean’s ecosystem healthy. This matters because many countries rely on seafood for their diets and most countries’ diets include seafood. Sharks are also crucial to the tourism industry because many economies rely on diving activities. If we want to salvage these benefits and many more that sharks provide, we must lower the amount of sharks we target for their fins and meat.
With the research effort completed, the researchers of the study are now using their data to determine what happens to reef ecosystems when shark populations disappear. Regardless of the results of this current study, it is clear that sharks have a value for humans and conservation efforts must be implemented in order to allow shark populations to thrive. Nick Dulvy, a conservation biologist at Simon Fraser University, says, “We really need to substantively move towards conservation and recovery in the next decade.” He warned, “or else we’re going to be in real trouble.”