Drive hunting -- when groups of hunters on canoes fan out far off-shore and clap stones together as they round up dolphins -- has been taking place off the Solomon Islands for many years.
Now, researchers who examined detailed hunting records and interviewed locals say more than 15,000 dolphins were killed in just one village's hunts between 1976 and 2013. They published their findings this week in the journal Royal Society Open Science.
Why the hunt? For the people on the Solomon Islands, it's long been about the teeth: Necklaces made of dolphin teeth are "bride prizes," given by grooms to their betrothed.
Jewelry made of dolphin teeth has popped up in markets in the country's capital city, and the value is rising: Over the past decade, the price of dolphin teeth has increased five-fold. Each tooth is worth about 70 cents American and its value creates a further incentive for hunters. The meat is also sold for cash.
"There has been an increased commercialization of the teeth, and that's a little troubling," said study coauthor Scott Baker, associate director of the Marine Mammal Institute at Oregon State University. As the traditional hunt gains a commercial value, it "drives a type of unsustainable exploitation."
This particular study focuses on data from one village where drive hunting is popular. The village, Fanalei, suspended its regular hunt in 2010 as part of an agreement with an international non-governmental organization and received financial compensation in exchange.
But the accord broke down in 2013 and hunting resumed. Local press accounts of new hunts reported hundreds of dolphins killed, and that attracted the attention of researchers. They mounted a fact-finding mission to figure out the scope of the kills.
What they found was troubling: during just the first three months of 2013, at least 1,674 dolphins were killed by Fanalei villagers. Spotted dolphins accounted for most of the kills, followed by spinner dolphins and bottlenose dolphins.
The figure surpasses the total killed in 2013 during Japan's well-known Taiji hunt, the subject of the documentary "The Cove."
"The hunt was large. The numbers are sufficient to raise concerns about the likelihood of local depletion of the populations," Baker said.
The International Whaling Commission regulates the hunting of large whales, but does not for small cetaceans, such as dolphins. The researchers say their findings point to the need to regulate such hunts.
The Solomon Islands have a long history of a systematic hunt, which as much cultural as it is economic, and Baker said there's evidence that dolphin hunting around the world is increasing.
For one, there's the rise of "marine bushmeat": as fisheries' primary targets decline, more and more fishers may be turning to secondary targets, such as dolphins.
"By-catches -- incidental tagging of marine mammals -- has been the primary concern over the past few decades, and that is a big issue," Baker said. Now those by-catches may now becoming the primary target, he added.
"We do see the Solomon Islands as a warning flag of what might be a larger pattern in developing countries," Baker said.