SACF and Sydney Aquarium teamed up with scientist David Harasti to establish a world first breeding program for seahorses to be released into the wild in Sydney Harbour. Baby seahorses have a high mortality rate within the first few weeks of life in the wild. This reseach aims to find out if a captive breeding program of seahorses will help reduce early mortality rates and in turn boost wild population numbers of seahorses in Sydney Harbour.
Permits were obtained from the NSW DPI to collect four breeding pairs of White's Seahorse from Sydney Harbour. The pairs were maintained in Sydney Aquarium for display where they mated and had their young. Babies that were produced were moved into a quarantined nursery tank made especially for their juvenile needs which enhanced their survival rate.
Into the Wild
On the 13th of November 2007, at only six months of age, thirty White's Seahorse babies were released onto the nets at Manly Cove. At a mere 5cm long they were tagged so they can be regularly monitored . As any parent of a newborn knows, babies grow very quickly, which is why the tags implanted into the seahorses will expand as the babies mature into adults. Monitoring will involve frequent measuring of the youngsters length for the following two years. Seahorses are territorial and many stay within a 5 metre zone of where they have been released, this makes finding them again easier. Harasti hopes for a 20-25% survival rate of the 30 that were released, so they can live until the ripe old age of four years.
In 2009 twenty-two babies aged between four to six months old were released at Clifton Gardens. They were bred from four pairs of seahorses taken from Clifton Gardens a year prior with permission from NSW DPI Fisheries.
Did you know Sydney Harbour is home to some thriving 'seahorse cities'?
Despite there being some healthy populations of seahorses in the harbour we still know so little about how they live.
Dave Harasti, of University of Newcastle, and with financial support from SACF, has been monitoring seahorses of Sydney Harbour, particularly on artificial habitats to see how humans are impacting upon these populations. His findings to date have enabled better management of seahorse habitat so as to be able to conserve them more effectively.
Seahorse cities thrive on man made structures
Two species of seahorses are found within Sydney Harbour, Hippocampus abdominalis and Hippocampus whitei. These two species thrive on artificial structures which they colonise, such as nets as well as jetty pylons. Seahorses eat tiny epibiota which can build up on the pylons and the nets. Every so often, local councils which are responsible for the maintenance of these nets employ divers to clean the nets and in some cases remove and replace them with new ones. The cleaning of the nets and the removal of them is detrimental to the seahorse populations which call the nets home. David Harasti has seen for himself that population numbers plummet when cleaning happens and it took up to fifteen months for the recovery of a White's seahorse population on a replaced net. |
