http://news.discovery.com/earth/manta-rays-fate-worse-than-shark-120125.html

As the population of sharks has depleted, fishermen are turning more and more to Manta Rays - animals unfit, in the most Darwinian sense of the word, to handle the pressure.

Manta Rays take 10 years to reach maturity and females give birth to “a single pup every two to three years,” ray researcher Mike Bennett of the University of Queensland told ABC Science.

By comparison, a Great White Shark, which is widely considered to be one of the world’s most vulnerable marine species, may produce as many pups in one litter as a Manta Ray does over its entire lifetime.

http://blogs.scientificamerican.com/extinction-countdown/2012/01/17/manta-rays-endangered-by-sudden-demand-from-chinese-medicine/

Demand for the gills of manta and mobula rays has risen dramatically in the past 10 years for use in traditional Chinese medicine (TCM), even though they were not historically used for this purpose, a team of researchers from the conservation organizations Shark Savers and WildAid has discovered.