Endangered seahorses released into Chowder Bay in landmark conservation effort.
UTS PhD student Mitchell Brennan and colleagues carefully released around 380 seahorses onto swim nets and ‘seahorse hotels’. Photo: UTS.
In a significant step towards conserving the endangered White's Seahorse (Hippocampus whitei), the Sydney Seahorse Project has released around 380 juvenile seahorses into their natural habitat in Chowder Bay, Mosman.
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, this world-leading conservation effort seeks to reverse the alarming decline of the Sydney Seahorse population.
The White's Seahorse, commonly known as the Sydney Seahorse, is native to Australia's Eastern coast and has been grappling with population decline due to habitat loss and pollution.
Listed as an endangered species in 2020, the White's Seahorse became the second seahorse species globally to receive this classification.
One of the 'super seahorses', just prior to release. Photo: UTS.
At the heart of the Sydney Seahorse Project lies a two-fold strategy: employing a groundbreaking conservation stocking program and addressing the critical issue of habitat loss.
Beginning 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 Sydney Seahorse Project manager and UTS PhD candidate Mitchell Brennan to work with SIMS and UTS scientists to conduct experiments and refine seahorse husbandry techniques to optimize the growth and survival rates of the juveniles.
UTS PhD candidate, Mitchell Brennan at Chowder Bay after the successful seahorse release. Photo: UTS.
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.
"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,” said Professor Booth.
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.
Prior to their release, Brennan and his team carefully tagged each seahorse using a visual implant elastomer tag.
“These tags are visible and can fluoresce under UV light and will be used to monitor seahorse survival growth and reproductive success post-release,” said Brennan.
A White's Seahorse with the elastomer tag visible. Photo: Jayne Jenkins
“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,” said Brennan.
To maximise their chances of survival, the seahorses were released onto swim nets and artificial habitats called ‘seahorse hotels’.
“The seahorse hotels are a significant element of the project, as they work to counteract the loss of seagrass meadows and soft corals, which serve as crucial shelters for the seahorses,” said Professor Booth.
A related SIMS project that UTS is also involved in aims to restore the endangered seagrass species Posidonia australis, a vital component of the seahorses' ecosystem.
The seahorses were released in Chowder Bay, Mosman. Photo: UTS.
Divers are encouraged to capture photographs of any seahorses encountered in Chowder Bay and submit them to the Sydney Seahorse Project on iNaturalist, an online platform facilitating collaborative data collection and analysis.