Wide-ranging report warns of shark extinction risk
A team of researchers analyzing almost 400 coral reefs found significantly declining numbers of certain shark species, warning that they face a risk of extinction because of overfishing.
The researchers released a report in the academic journal Science on Thursday after analyzing the presence of five common species of sharks that live by coral reefs. They surveyed 391 reefs across 67 countries and territories using almost 23,000 underwater video stations.
The report states that the researchers found global declines between 60 and 73 percent for the five species, and individual shark species were not detected in 34 to 47 percent of reefs.
The decline in shark species has also caused rays to increasingly dominate these reefs, having further implications for the ecosystem at large.
The researchers reviewed four key ray species — yellow and southern stingrays in the Atlantic, and blue spotted mask and blue spotted ribbontail rays in the Indo-Pacific region — and found that their populations only increased with the depletion of one or more shark species.
The report also states that the depletion levels of the shark species were closely tied to socioeconomic and management factors of their environment.
Reefs are more likely to be dominated by sharks in wealthy, well-governed countries and in marine protected areas or shark sanctuaries, where targeted shark fishing and trade is prohibited. However, countries struggling with poverty and poor governance were more likely to have reefs dominated by rays.
The report states that previous studies of reef sharks and rays have been geographically limited, only finding high abundances or local extinction among surveyed reefs. But this study evaluates the global extinction risk for the shark species.
The researchers concluded that reef shark species are at a much higher risk of extinction than previously thought. All major reef shark species have declined enough that they qualify as endangered under the standards set by the International Union for the Conservation of Nature, an international organization that works to promote sustainability and conservation efforts.
The report did state that the potential to rebuild the shark populations is high if protected areas or stronger fishing management are implemented in a region.
“This study builds the case that species-specific reef shark management provides the best way forward for conservation and rebuilding of reef sharks in places where they have declined, among nations with the desire and capacity to do so,” the report states.
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