In Fiji's largest marine reserve, shark populations are benefiting from "no-take" protections that keep their food supply steady, according to a new study.
Compared with waters where fishing is allowed, there are up to four times as many reef sharks in a protected zone called the Namena Reserve, researchers say.
This 23-square-mile (60 square kilometers) reserve was designated in 1997 off the southern coast of Vanua Levu, Fiji's second largest island. For three weeks in July 2009, researchers used underwater video cameras to survey sharks at eight sites within Namena and eight sites outside the reserve.
Hour-long clips from all 16 locations captured images of five different species: grey reef sharks, whitetips, blacktips, silvertips and zebra sharks. By analyzing this footage, researchers found that shark abundance and biomass in the protected zone was twice as great at shallow sites and four times as great at deep sites, compared with similar spots just outside of the reserve. [Images: Sharks & Whales from Above]
Sharks are harvested for their meat, liver oil, cartilage and their famously valuable fins; these cartilaginous parts are hacked off, often from live sharks, to be used in shark fin soup, a prized delicacy in East Asia. Since sharks have slow growth and reproductive rates, it can be difficult for their populations to bounce back from big losses and unsustainable hunting practices. A study published earlier this year estimated that 100 million sharks are killed by fisheries each year.
In Fiji, tradition has kept shark harvesting in check. Many people in the island nation consider sharks to be sacred and see eating the predators as taboo, according to researchers with the Wildlife Conservation Society (WCS) who worked on the new study. Within the Namena Reserve, sharks likely are thriving because restrictions on fishing make their prey plentiful, the researchers say.
"The news from Fiji gives us solid proof that marine reserves can have positive effects on reef shark populations," Caleb McClennen, director of WCS's Marine Program, said in a statement last week. "Shark populations are declining worldwide due to the demand for shark products, particularly fins for the Asian markets. We need to establish management strategies that will protect these ancient predators and the ecosystems they inhabit."
Sharks in Fiji may still be vulnerable to foreign fishing fleets, the researchers warn, and local communities may be driven to hunt the venerated animals as prices for shark parts increase. According to the World Wildlife Fund, a shark's fin can sell for up to $135 per kilogram (about 2 lbs) in Hong Kong.
There has been a recent international push to protect the apex predators. At the meeting of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), conservationists voted to regulate the trade of several shark species that are targeted for their fins.
The study on the Namena Reserve was published online in the journal Coral Reefs.