Around 380 endangered White's seahorses, bred and cared for in captivity, have been moved into “hotels” in their natural habitat in Australia.

The juvenile seahorses were released at Chowder Bay in Mosman, New South Wales, by the Sydney Seahorse Project, which is seeking to reverse their population decline.

The artificial hotel habitats are made from biodegradable metal, which over time, will accumulate natural growth such as sponges and algae. They boost seahorses’ chances of survival by creating new habitats, to counteract the loss of seagrass meadows and soft corals, which serve as crucial shelters and food sources.

The White's seahorse, commonly known as the Sydney seahorse, is native to Australia's eastern coast and has been grappling with decline due to habitat loss and pollution. Listed as an endangered species in 2020, it became the second seahorse species globally to receive this classification.

The Sydney Seahorse Project is led by the Sydney Institute of Marine Science (SIMS) in collaboration with the University of Technology Sydney (UTS) and the New South Wales Department of Primary Industries.

In January 2023, the project collected three pregnant male seahorses, which subsequently gave birth to seahorse fry within the controlled environment of the SIMS aquarium facility. This allowed project manager and UTS PhD candidate Mitchell Brennan to work with scientists to study the growth and survival rates of the juveniles.

Prior to their release, Brennan and his team carefully tagged each seahorse using a visual implant tag. The tags are visible and can fluoresce under UV light and will be used to monitor seahorse survival growth and reproductive success post-release. Locally, the dive community is also being asked to help.

Brennan said, “I will be doing weekly dives to monitor the seahorses but as researchers, we are limited in how often we can dive.

"However, in Chowder Bay there are divers in the water daily, so we have launched a citizen science portal inviting local divers to submit their seahorse photos to assist with data collection and analysis and help build a bigger picture.”

UTS professor David Booth said while there have now been several instances of White’s seahorses being nurtured for release, the element that has been missing has been the fine-tuning of how to rear them effectively.

He said, "Mitchell and his team have really worked on determining the optimal temperature, growth and the food required, which has resulted what we’ve called super seahorses – because they’ve grown bigger and stronger than others that have been released before.

“Hopefully, that translates to them doing very well in the wild.”