Captive born seahorses released into wild

Nick Squires, The Telegraph 14 Nov 07;

A world-first experiment to assess whether captive-bred baby seahorses can survive in the wild is underway in Australia.

Thirty juvenile White's seahorses were released into a sheltered bay in Sydney Harbour this week and will be regularly checked by divers for the next two years.

The success or failure of the experiment will have implications for the reintroduction of endangered seahorse species around the world.

The animals are under threat globally, particularly in Asia where they are prized as a traditional Chinese medicine.

At least 25 million seahorses are traded each year, many after being caught as "by-catch" by Asian fishing fleets.

Dried and crushed into a powder, the Chinese believe they are effective in treating everything from asthma to impotence, despite little scientific evidence of their medicinal benefit.

White's seahorses (Hippocampus whitei) are found only along the coast of New South Wales but are locally abundant and not considered endangered.

They live in seagrass meadows and around sponges and soft coral. They also favour the shark-proof nets which protect popular swimming beaches.

The 30 juveniles, aged six months and barely an inch long, were released into the water at Manly Cove in Sydney Harbour by seahorse researcher David Harasti from the New South Wales Department of Primary Industries, in conjunction with the conservation group Project Seahorse.

The 18 males and 12 females were transferred to the sea from their tank at Sydney Aquarium. Scientists injected them with tiny traces of fluorescent green dye so that they can be distinguished from their wild-born counterparts.

"It's a pilot study to see if captive-bred animals will survive in the wild," said Mr Harasti.

"If we do see high survival rates, we may be able in the future to reintroduce other seahorse species in areas where they've disappeared. This is the first time internationally that a project has been developed to look at survival rates."

Wild seahorses are preyed on by a range of animals, including fish and octopus. The researchers hope that at least 25 per cent of the released animals will still be alive by Christmas.

Divers will count them on Saturday and then on a weekly basis for the next two years.

The animals are highly territorial and are unlikely to stray more than 15ft from where they were first released. If the project is successful, another 100 seahorses will be released next year.

Worldwide there are around 40 known species of seahorse, many of them threatened by habitat destruction and their popularity as aquarium pets.

"New species are being found all the time, for example in countries like Papua New Guinea," said Mr Harasti.

White's seahorse was named after John White, the surgeon general of the First Fleet of British convicts which sailed into Sydney Harbour in 1788. He was a keen amateur naturalist and collector.

Seahorses are unique in that the female deposits her eggs into the male's pouch for gestation. Male seahorses give birth to up to 100 offspring four times a year.