Preventing Doom for Devil Rays

This week, the annual meeting of the world’s largest shark science society (www.elasmo.org) featured a two-day symposium on the most beloved, close relatives of the sharks: the devil rays (including the huge and graceful mantas).   Presenters came from all over the world; most stressed the exceptional vulnerability of these increasingly valuable species. 

An Italian scientist highlighted the problem of entanglement of giant devil rays in illegal driftnets in the Mediterranean.  A Hawaii-based researcher reported that manta rays may produce only one pup every one to three years.  Mantas are not (yet) fished off Hawaii; conservationists and scientists are working to secure state protection for the species (see www.mantapacific.org).  An expert from the Maldives explained that an export ban, low local demand and lack of net fishing allow the thousands of mantas found in his islands to thrive.  He estimates direct revenue from manta-based ecotourism in the Maldives at $9.3 million.  A Brazilian scientist reported that, in her region, devil-ray tails are being dried and used as whips for cattle. 

The most troubling reports came from Indonesia, where devil rays are becoming increasingly valuable for their "gill rakers" (finger-like projections of the gills that help filter-feeding animals retain food), which are exported to Asia for use in Chinese medicine.  Devil rays caught accidentally by gillnet fishermen targeting tuna are now almost always kept.  Meat is dried and salted for human consumption, while ray cartilage is used as a filler for shark fin soup.

Demand for gill rakers has also sparked unsustainable ray fisheries off Mexico and the Philippines.   In 2004, devil rays were identified by the Convention on International Trade in Endangered Species (www.cites.org) as a group associated with significant unregulated, unsustainable fishing pressures and severe population depletion.   

The symposium concluded with a discussion group of international experts from Brazil to Bora Bora, who set up a process for working together to secure protection for manta and other devil rays at several levels in regions all over the world.  Participants pledged to convene another symposium within three years, at which point they hope to report on much progress in conserving these magnificent animals.

PHOTO: A manta ray swims off the coast of French Polynesia.  Photo by David Doubilet/National Geographic/Getty Images

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Q&A With Sonja

Q: My favorite shark has to be the shortfin mako. It is my understanding that they are the fastest fish in the ocean. How fast can they really swim? I love their sleek torpedo-shaped bodies, obviously made for the speed they are known for. Aren't they also able to make their body temperatures rise for efficiency while swimming in cold water?
Posted by Bob Smyth, July 25, 2008

A: Makos are remarkable for several reasons, including their ability to elevate their body temperature, making them somewhat "warm-blooded".  The shortfin mako shark is also the world’s fastest shark, capable of zipping around at up to 30 miles per hour.  This species holds the speed record for long distance travel:  1320 miles in 37 days, an average of 36 miles per day.  Shortfin makos are also among the world’s most economically valuable sharks and as such are being heavily fished.  They are favorites among anglers for their tendency to leap out of the water and their meat is also highly valued.  As is the case for many sharks, mako fins are in high demand for the Asian delicacy, "shark fin soup."  Shortfin mako sharks now make up a significant proportion of the catch of the widespread Spanish longline fleet.

Makos are found throughout the world’s temperate and tropical waters.  IUCN recently declared mako sharks "globally vulnerable" to extinction.  Scientists will review the status of the Atlantic shortfin mako population in September and produce advice for the international Atlantic tuna commission to consider at their annual meeting in November.  You can help by downloading and sending in the Sherman’s Lagoon shark cartoon (see "Safeguarding Oceanic Sharks" entry on this blog ) which urges U.S. fishery managers to propose the first international catch limits for wide-ranging, overfished shark species, such as makos.

Post your questions for Sonja in the Comments section below.  She will be checking in to give you answers.

Comments

[Theresa]

Manta rays are gorgeous. I'm sorry to hear that demand for them is going up - hopefully these conservation measures will work.

There was an awesome picture of a leaping manta on the National Geographic site yesterday:

http://photography.nationalgeographic.com/photography/photo-of-the-day/manta-ray-leap-skerry.html

[judith ridgeway]

I was checking what was on the discovery channel,Iwas upset that these that they had a little critter named Geogie, and the people on the boat they put the poor little in the ocean to see how high the shark would jump getting the poor crittle and toss up and up and down to kill it! Why would they name the critteer? Don't you know he was going to die! How could they do it!Next time let people know ther might be sceren would upset them? It was on last 7-29.

[tania]

are they cold-blooded or warm-blooded?

[tania]

are they cold-blooded or warm-blooded?

[Fred Smilek]

Sad to see a wonderful species facing peril.

Fred Smilek
Email- Fred_Smilek@yahoo.com
Webpage- http://sites.google.com/site/fredjsmilek/

Fred Smilek is the acting president of the Society to Save Endangered Species. It was founded two years ago by Fred Smilek along with his two best friends Charles and Jonathan.

[o be one]

good job

[preor]

thankyou very much

[Marine Radio]

It is sad that we continue to hear of more creatures facing peril from man. As a boating and marine company we get to see some of these magnificent creatures in our work and it sad to see them under threat.

Mike
Marine Radio - Marine Antenna
http://www.outlanderdirect.com