With a deadly strike, a heron speared a fish in a rockpool along the Sandy Bay Rivulet.
I had been watching the white-faced heron from the bridge on Parliament St and was so close I could actually see the species of fish that had been swallowed whole by the hungry bird. It was a climbing galaxias (Galaxias brevipinnis).
A hungry heron spearing a fish, nothing particularly unusual in that, a regular occurrence in the waterways of Hobart. But that morning I had read a report from Sydney about a vital population of the fish being wiped out after a building project had polluted a stream in which the fish had recently been discovered.
Watching the heron flashing its dagger-like beak, I was reminded how lucky we are in Hobart to have such wildlife spectacles on our doorstep.
The article in a Syndey newspaper pointed out the galaxias were what it described as “miracle fish” that could climb waterfalls, a fish belonging to a species line reaching back 90 million years to the break-up of Gondwanaland.
The report said isolated shoals of the galaxias had only been discovered in Sydney in 1998, making them the most northerly of the Australian population which extends to Tasmania at its far south.
In Hobart waters, the climbing galaxias is one of three galaxias species found in the city’s Hobart, New Town and Sandy Bay rivulets. They come to the water courses to breed, laying their eggs on reeds in the tidal shallows near the coast. The young spend time in the fresh water before migrating out into the Derwent estuary.
Unlike Sydney, the Hobart Council has moved to protect the galaxias, recognising the importance of the fish to the local ecosystem. They form varied populations of what are known as “white bait’’, in part providing food for bigger, commercial species.
As a conservation measure, a corrugated concrete fish ladder has been constructed by council workers under the Parliament St bridge to aid the movement of the fish upstream.
There are also information panels at the site giving the natural history of the rivulet’s fish. Along with galaxias, other species in Hobart’s rivulets include the shortfin eel, freshwater flathead, or sandy, and the introduced brown trout.
The climbing galaxias – at about 16 centimetres in length – is the biggest of the family found in Hobart waters. It gets its name from its use of large pectoral and pelvic fins as suction cups to scale rapids, even waterfalls.
The wonders of Hobart’s waterways have long been overlooked but the tide is turning after the ABC aired a documentary last year about South Hobart resident Pete Walsh’s campaign to protect platypus in the Hobart Rivulet. The platypus has now become something of a tourist attraction and if local and interstate visitors to the waterway look closely they might see the galaxias, too.