Seahorse 'hotels' dropped into Sydney Harbour to help conservation efforts

A new conservation project in Sydney Harbour is providing homes for the White's seahorse, an endangered species.

Eighteen bio-degradable seahorse "hotels" have been dropped to the ocean floor in recent days and guests are already moving in.

A dozen dwellings are already in place and up to 100 will be deployed over the next couple of years in the harbour and at Port Stephens, where numbers have also declined.

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It's part of a new partnership between Sydney's SeaLife Aquarium and the Department of Primary Industries which is helping to rebuild the population.

The primary cause for the decline in abundance of White's seahorse is the loss of natural habitats across their range in eastern Australia.

Senior marine scientist Dr David Harasti has captured some incredible underwater footage of the hotel deployment.

"A lot of marine growth such as sponges and coral will accumulate, and that provides a lot of food and shelter for the seahorses," he told 9News.

"Hopefully that will provide conditions for them to mate and improve their declining numbers in the wild."

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White's seahorse, also known as the Sydney seahorse, is a medium-sized seahorse that is endemic to the east coast of Australia, according to the NSW DPI.

It grows to up to 16 centimetres long and has been totally protected in NSW since 2004.

Over time, the seahorse hotels simulate the natural habitats of White's seahorse, becoming rapidly encrusted with local sponges and algae.