Diving with the majestic manta ray is an eco-tourist’s dream come true that may soon be experienced only by viewing pictures and videos of the shark family’s graceful giants.
The International Union for Conservation of Nature (IUCN) Shark Specialist Group (SSG), based at Simon Fraser University, has added the Giant and Reef manta rays to its Red List of Threatened Species.
The IUCN SSG, a worldwide network of scientists co-chaired by SFU biologist Nick Dulvy, has declared manta rays Vulnerable with an elevated risk of extinction. Intense fishing fuelled by international demand is wiping out these iconic species by the hundreds.
Until recently, known as one species, the Giant (Manta birostris) and Reef (Manta alfredi) are among the largest fish in the world. The Giant manta ray can grow to more than seven metres across.
Swimming, diving and filming expeditions with manta rays, the top stars in eco-tourism, especially in developing countries, reportedly generate $100 million annually, worldwide.
Manta rays migrate vast distances, crossing international boundaries, in search of food. Increased fishing is depleting their far-flung feeding stations and fishers seeking their food-gathering gill rakers have become manta rays’ greatest predators.
“Given that manta rays have a very low reproduction rate — they give birth to an average of one offspring every two years — they are very vulnerable to overexploitation,” says Dulvy. “They are a long-lived species with little capacity to cope with modern fishing methods and globalized demand from rising human populations.”
“Increasing demand for these fishes’ filter-feeding system for traditional Chinese medicinal purposes, especially in Hong Kong, is rapidly driving down their population everywhere,” says Lucy Harrison. An SFU alumna and biologist, Harrison is the program officer for IUCN SSG.
Mantra ray populations are in steep decline in several regions, with a reduction in numbers by as much as 80 per cent during the last 75 years. Globally, the decline is believed to be more than 30 per cent.
“We can save manta rays — the solution is in our hands,” says Dulvy. He and his IUCN SSG colleagues recommend the creation of international conservation treaties to protect manta rays. They also recommend the following:
Using the Convention on Migratory Species (CMS) and the Convention of International Trade in Endangered Species of Wild Fauna and Flora (CITIES) to monitor and regulate the trade and exploitation of manta rays.
Enacting legislation in countries to reduce and eventually prevent fishing pressures on manta rays through controlled trade.
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