The Sydney Seahorse Project

The Problem

The White’s Seahorse (Hippocampus whitei), otherwise known as the Sydney Seahorse, is a medium-sized seahorse species endemic to the Eastern coast of Australia. In recent years, populations of White’s seahorse have declined significantly.

These population declines are largely attributed to the loss or degradation of critically important habitats such as seagrass and soft corals. In 2020, the White’s seahorse was listed as an Endangered species, the second seahorse species globally.

(Image credit: David Harasti)

The Solution

The Sydney Seahorse Project addresses the key issue of habitat loss through the provision of artificial habitats named “Seahorse Hotels”, and the collaborative restoration of habitats including the Endangered seagrass, Posidonia australis.

The project also aims to increase wild seahorse populations through a conservation stocking project, where seahorses are bred and reared in captivity then released into the wild.

The Sydney Seahorse Project has a strong focus on using rigorous scientific practice to develop the ideal conservation methodologies.

(Image credit: Tom Burd)

The Science

The Sydney Seahorse Project collected three pregnant male seahorses in January 2023, which then birthed seahorse fry in the SIMS aquarium facility. The juvenile seahorses have been reared under experimental conditions including temperature, feeding regimes and stocking densities to optimise the husbandry of juvenile White’s seahorses in captivity, and improve their growth rate and survival.

Experiments have also been conducted to assess the ontogenetic shift in habitat preference of juvenile seahorses to inform habitat protection. The project is aiming to develop techniques to condition captive-born seahorses to the natural environment prior to their reintroduction, through introduction to naturally occurring habitats such as seagrass and macroalgaes, and exposure to predators such as cuttlefish. 

The Sydney Seahorse Project has also collaborated with researchers from the Marine Sensory Ecology Group at the University of Queensland to assess how light affects seahorse behaviour, including feeding success under different wavelengths and intensities.

In July 2023, over 350 juvenile White’s seahorses were released into Chowder Bay, Mosman. Each seahorse was tagged using a visual implant elastomer tag, enabling researchers to monitor their survival, growth and reproductive success in the wild.

The rigorous scientific approach employed by the Sydney Seahorse Project will inform best practice conservation for the White’s seahorse, ultimately aiming to improve post-release survival of captive-bred seahorses and assist in recovering wild seahorse populations, whilst increasing the opportunity for future persistence of the species. The science may also provide a framework for the conservation of other threatened marine fishes.

(Image credit: David Harasti)

Citizen Science

There is also an exciting citizen science aspect where Local SCUBA divers are encouraged to participate in monitoring of the seahorses by submitting photographs of seahorses in Chowder Bay. Images can be submitted to the Sydney Seahorse Project on iNaturalist.

This valuable information will assist researchers to have more eyes on our seahorse babies as they settle into their new home!

(Image credit: David Harasti)

The Future

The Sydney Seahorse Project, and its collaborators, will continue to take positive action for the conservation of the Endangered White’s seahorse, including the continuation of the captive-breeding and conservation stocking program at the Sydney Institute of Marine Science aquarium facility, habitat provision through seahorse hotel installation, the restoration and protection of critically important natural habitats, and the on-going development of scientific methods.

The Sydney Seahorse Project aims to provide the necessary framework for White’s seahorse population recovery and long-term species persistence.

(Image credit: Peter Hutchins)


The Sydney Seahorse Project has been generously funded by a Mosman Environmental Foundation grant, the Lim-Sutton Initiative, SailGP, the Australian Wildlife Society and Taylors wines.