The reintroduction of over hundreds of endangered White’s Seahorses into the waters of Australia is one of the largest releases of captive-bred seahorses in history!
Numbers of these fairy-like aquatic creatures have declined dramatically in recent decades. In an extraordinary move marine conservation have taken major strides and boosted their hope of their survival in the wild.
As Australia’s only threatened seahorse species and second worldwide the introduction has given hope for the survival of these iconic species.
1. Why are White’s Seahorses endangered in NSW?
Once present in high numbers, the White Seahorse population in Australia has now declined by 95% or more in recent years because of the loss of natural habitats including the seagrasses and soft coral in which they live. In NSW the White’s Seahorse is now listed as an endangered species.
Over the past 50 years, Sydney’s native marine ecosystems have been drastically impacted by poor water quality because of stormwater run-off and chemicals like oil and pesticides that wash into the water.
Thought of as an Australian icon the authorities are keen to reverse the trend and get them re-established. As an endangered species, there are heavy penalties for harming, possessing, buying, or selling them. If someone is found harming their habitat, especially around organically occurring areas such as seagrass meadows, sponge gardens, and soft corals then they also must pay penalties.
2. Who has led the way in reintroducing White’s Seahorses?
Australian scientists at the Sea Life Aquarium in Sydney have been at the forefront of breeding White’s Seahorses. They have led the way into releasing them into specially designed underwater habitats and then releasing 100 of these tiny animals into Sydney Harbor. This landmark project marks the largest release of captive bred seahorses in history.
Seahorses are also known to dwell in artificial habitats such as protective swimming enclosures. Using this idea Sydney Sea Life Aquarium also released baby seahorses into Clontarf protected tidal pool in Northern beaches and Chowder Bay in the Mosman, a region of Sydney. In 2023 the seahorses were released into waters north of Sydney into “hotels” and is included in being part of the largest release of captive-bred seahorses in history.
The seahorses bred at the Sea Life Aquarium in Sydney is just one of several already done in NSW and several more are planned this year.
3. How reintroduction of White’s Seahorses carried out?
The breeding program for White’s Seahorses has been undertaken at Sea Life Aquarium in Sydney along with the University of Technology Sydney, the University of NSW, and the Department of Primary Industries.
Before the seahorses are released aquarium vets ensure that the seahorses are healthy, between 7-9 months old and 5-6 centimetres in length before they are released.
Before the seahorses are released aquarium vets ensure that the seahorses are healthy, between 7-9 months old and 5-6 centimetres in length before they are released.
The movement of the seahorses is tracked through a tagging system using a silicone-based fluorescent paint. The tracking of the seahorses is carried out using ultraviolet touch and does not harem them. The researchers gather information including where they swim and establish themselves, as well as study their feeding patterns.
They are carried in water filled plastic bags and are carefully released.
4. What plans are in place to increase the White’s Seahorse numbers?
Seahorse hotels and captive breeding program project is underway in Sydney Harbour to reverse the decline of White’s Seahorses.
At first in October 2019, 5 breeding pairs, including pregnant males were collected from Clifton Gardens swimming net and taken to a custom-built breeding facility at Sealife Sydney Aquarium. Dozens of juvenile White’s Seahorses were successfully bred, and these baby seahorses thrived.
In March 2020 the second stage to provide a habitat for the seahorses was carried out by constructing artificial purpose-built hotels and installing them on the seafloor. Designed to be completely biodegradable their lives start in artificial habitats which are rapidly encrusted by algae, sponges and coral once placed in a marine environment. As time goes by the weight of this marine growth causes the artificial structure to collapse leaving a new natural habitat behind and an ideal home for seahorses.
In March 2020 the second stage to provide a habitat for the seahorses was carried out by constructing artificial purpose-built hotels and installing them on the seafloor. Designed to be completely biodegradable their lives start in artificial habitats which are rapidly encrusted by algae, sponges and coral once placed in a marine environment. As time goes by the weight of this marine growth causes the artificial structure to collapse leaving a new natural habitat behind and an ideal home for seahorses.
5. When are the juvenile Seahorses big enough to be released into their hotels?
After 2 months the juveniles are big enough to be tagged and released onto their new five-star hotels as well as protective swimming nets in the Harbour. The monitoring program has been implemented and their growth, survival, and breeding, is recorded and is showing promising results. Surveys conducted in November 2020 revealed that some of the captive bred juveniles are now pregnant with babies of their own.
After 2 months the juveniles are big enough to be tagged and released onto their new five-star hotels as well as protective swimming nets in the Harbour. The monitoring program has been implemented and their growth, survival, and breeding, is recorded and is showing promising results. Surveys conducted in November 2020 revealed that some of the captive bred juveniles are now pregnant with babies of their own.
The captive breeding program is well underway now with more adults being held at Sydney Aquarium to supplement the original adults. Several more releases are planned for 2024 with many more Seahorse Hotels in Sydney Harbour Posidonia seagrass beds. The hotels provide vital housing for the colonies of seahorses, in a bid to recover their population in Sydney Harbour.
6. What else is causing the decline in numbers of White’s Seahorses?
Climate change, pollution, and plastic pollution is causing the soft coral and sponge habitats the decline. The White’s Seahorse habitat is within coastal estuaries and the recesses in coastline forming a bay. Adding to the threat of habitat lost, these coastal areas are subject to coastal development as well as installation of boat moorings and boat anchors as well as destructive fishing gears such as trawls and dredges.
Overharvesting of White’s Seahorses have been overharvested for Traditional Chinese Medicine. They are believed to treat anything from asthma to erectile dysfunction. Their popularity for aquariums and souvenirs also impacts numbers.
Seahorses are sometimes found tangled in fishing and shark nets. The nets which are periodically cleaned to remove marine growth and repair holes can lead to further displacement of seahorses causing populations to decline. The fishing industry have been working with council to develop practices which avoid damage to the seahorses during net cleaning and repair.
7. How do you identify a White’s Seahorse?
White’s seahorse (Hippocampus Whitei) is also know as Sydney Seahorse and named after John White, Surgeon General to the First Fleet. They are one of four species of seahorses known to occur in NSW waters.
They are found on the east coast of Australia and are a medium sized seahorse, growing up to 16cm from the top of the seahorse crown to the tip of the tail.
Their colour is greatly variable, ranging from pale to black, depending on the habitat colouration it is living and their mood. Their ability to camouflage along with their secretive behaviour, often makes them difficult to spot in their natural habitat.
Male seahorses can be identified by the presence of a pouch below and abdomen which is absent in female seahorses.
They are known to be the slowest swimming fishes in the ocean usually only a very small anal fin for propulsion.
Other characteristics include a long snout and a tall coronet arranged in a five-pointed star at the apex. Their spines are variable ranging from quite sharp being low to moderately developed.
8. What can you do to help?
Seahorses live in soft corals, seagrasses, or sponges so be wise when in their habitat zones.
- If you are swimming, diving, or snorkelling neat the seahorse, do not touch or interfere with them or their habitat.
- When driving your boat at low tide near seagrass beds, lift the propellor and do not drop the anchor in seahorse habitats.
- Seek planning approval for any waterway’s structures like pontoons, jetties, or dry docks.
- Pontoons and dry docks must not be built over seagrass as they will create shade, and this will cause the seagrass to die. Also, as if seagrass does not have light there will be no photosynthesis and no oxygen in the water that the seahorses need.
- Contact your local Fisheries office by phoning the Fishers Watch phone line1800 043 536 if you suspect any illegal or suspicious fishing.
9. Why do seahorses tangle?
The seahorse has a unique muscular tail that can grip objects the way you a human hand does.
Seahorses can wrap their tails around coral heads, sea grass stems, sponges, mangroves, or any other suitable objects when they need to anchor themselves and hold themselves in place.
Seahorses are also skilled hitchhikers, travelling long distances across the ocean by attaching themselves to floating seaweed and debris.
Male and female seahorses can often be seen swimming in pairs with their tails linked together. Adult male and female seahorses use their tails to grasp each other in mating and greeting rituals and so as not to lose each other and reinforce their bond and synchronize their reproductive cycles!
They can be seen promenading and pirouetting as a couple in a courtship dance which includes swimming side by side, spinning around and changing colours. The seahorses can even meet in midstream and tangle their curling tails. Then just as gracefully uncoil them demurely.
Some scientists believe that this upright swimming posture evolved shortly after the expansion of sea grasses in the western Pacific roughly 25 million years ago. These plants gave seahorses useful hiding places where they can also camouflage to avoid enemies and to capture unsuspected prey.
10. What is the role of the seahorse in the ecosystem?
Seahorses are important predators on bottom dwelling organisms consuming tiny fish, small shrimp, and plankton. They are preyed upon by invertebrates, larger fish such as rays, tuna, skates, crabs, sea turtles, marine mammals, and seabirds. As they are ecologically important in food chains If they were to disappear entire ecosystems would be disrupted.
Seahorses provide income and humans in certain parts of the world where they are used as medicines and ornamental adding value to the economy of subsistence fishers.