12:00a.m. 5th December 2008

| By Nathan Woulfe

Photo Gallery: Stingray release

UnderWater World staff release six black stingrays of Mooloolaba as part of an ongoing breeding program.

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Everyone knows about the breeding propensity of rabbits.

Leave a pair alone, turn the lights down (or don't – they're not fussy) and two quickly becomes four becomes six and so on.

Maybe it is something in the water, but you can add Underwater World's black stingrays to a similar reproductive basket.

Six metre wide rays were released off Mooloolaba yesterday, the result of an ongoing – and highly successful – breeding program.

The six were among 31 rays born in captivity after a breeding pair captured by fishermen off Mooloolaba almost a decade ago was donated to the aquarium.

Of those offspring still in captivity, between them they call Sea World and Busan Aquarium, South Korea, as well as Underwater World, home.

Underwater World head curator Rod Mort said the rays had proven quite comfortable when it came to captive breeding.

"They've had five or six litters over the years – they are certainly good breeders, although they've been slowing down in the last few years," he said.

The breeding program also brought success on a much smaller scale, with Underwater World collaborating with researchers in South Australia to identify two new species of monogeneans – small animals that live on the surface of rays and sharks.

"We've done some research into the species, and discovered a new external parasite, so we've been able to include a bit of science," Mr Mort said.

"They came in as donations, so we've basically had them breeding ever since.

"They are part of the collection for education of school groups and visitors."

The juvenile rays were released about three miles off the Mooloolaba coast.

"They are just about (breeding age) – we don't know exactly what age they start at, but they haven't breed yet in captivity so we wanted to make sure we released them before they did," he said.

The black rays grow to about 3.3m long, and 1.8m wide, and can be found in inshore and reef waters along the length of the Queensland coast.

While not officially regarded as endangered or at risk, Mr Mort said the black ray was not overly common.