An expedition seeking signs of a prehistoric species’ survival was conducted at Manly Dam last week after a mass sediment pollution event threatened its habitat.
Manly Observer tagged along with environmental scientist and consultant, Sonya Ku, in an attempt to find the recently elusive climbing galaxias fish residing in a creek in the middle of a metropolitan city, a rarity in the Sydney region.
“Given the number of pollution events, and the fact there’s been a lot of urban encroachment into the catchment area, and we’ve had droughts, we’ve had fires and whatnot, the fish species has really captured the imagination of the local community. It is very much like an Aussie battler because it’s just holding on despite everything,” Sonya explained.
Also joining the search was a community activist from the Save Manly Dam Catchment Committee (SMDCC) and a herpetologist, Dr Jodi Rowley, who was on a side quest for a frog rumoured to be in the area.
The expedition took place at dusk around the outskirts of Manly Dam where Sonya and Jodi had surveyed the species some years ago. The polluted habitat has prompted them to once again check on their fish friends – but already after venturing down into the moonlit creeks and ponds, it’s not looking good.
“Usually the water is crystal clear, flowing and has plenty of oxygen through the water, it’s just looking a little bit murky,” Sonya said as she shined her torch through the muddied pond.
“I’m concerned about the the amount of silt that’s suspended, because that then stops the fish from being able to hunt.”
Although there were initial signs of life in the tiny pools embedded within the rock beds – hosting tadpoles, some water spiders and an ambitious crayfish – the majority of the systems at the first search spot previously filled with climbing galaxias, were abundant of brown sediment-laden water.
So, who muddied the creeks?
Several weeks ago ADCO Construction, the company contracted to work on the new Forest High School in Allambie, was fined $30,000 by the Environment Protection Authority (EPA) for sedimentation pollution.
Earlier this year, large amounts of excess sediment from the worksite washed into stormwater systems on Allambie Road causing significant damage to Manly Dam’s ecosystem and its surrounding creek systems, raising concerns among locals and community groups.
One of the species put in the spotlight and caught in the crossfire was the unique climbing galaxias, a prehistoric fish capable of scaling land and water with its pectoral fins. The species is estimated to be 60-90 million years old, and its small landlocked population is found nowhere else in Sydney, other than around the Curl Curl Creek area.
Conservation group, Save Manly Dam Catchment Committee (SMDCC), were strong advocates for protecting this species especially after the brown sediment left the surrounding dam waters brown, murky and seemingly devoid of life.
“The fact that the species is only in one little creek in the whole of Greater Sydney is pretty amazing,” Vice Chair of the Save Manly Dam Catchment Committee, Malcolm Fisher told Manly Observer.
“We still don’t know if significant harm has been caused to the galaxias population, because that mud has been thrown into the creek for months.”
SMDCC and local residents first reported the pollution to Northern Beaches Council and the EPA in January after mass rains caused the sediment to flow into the stormwater systems – an official warning from the EPA was only issued to ADCO in July.
The maximum penalty the EPA could provide ADCO for the offence was $30,000 and unfortunately, the Department of Primary Industries and Regional Development (DPIRD) Fisheries NSW stated they would not fund any monitoring resources towards the galaxias as it’s not listed as a threatened species.
A request from both the EPA and Northern Beaches Council was denied.
This is when environmental scientist, consultant, and climbing galaxias expert, Sonya Ku, volunteered and allowed Manly Observer to tag along on the expedition.
“We’re here to go down to the creek, dip our little toes in, and our head torches on, and see whether or not we can find this little creature that’s been living there for millions of years, and somehow may have eluded us now with all the pollution events,” Sonya shared with cautious optimism as we made our way down to a known location of the species at dusk.
Finding Galaxias
Sonya and Jodi were students of Andrew Lo, the man who first discovered the fish at the Northern Beaches location in the 70s. The pair would manage surveys of the species in the area with him.
Sonya even conducted the SMDCC Manly Dam biodiversity survey a few years back. It was safe to say she knew her way around the area, which is what made it even more concerning when we had trouble finding the creatures.
The search ensued for another hour, with the party making its way further down the creek and deeper into the night, stopping only to peer into any water system made available, wiping off spider webs and when Jodie’s keen ear heard the subtle variations of croaks between frogs.
Along the way, Sonya would point out various upstream rock structures as she eagerly listed the determined nature of the prehistoric population against all odds.
“See how fast the water’s running,” Sonya said, pointing her torch to one of the creeks’ rocky miniature waterfalls.
“So the reason why there’s still a population up there is because there’s a lot of introduced predator species that are further down the creek.
“So being able to get up the sloped areas and climb these little waterfalls means that it can escape predation and survive so that little populations clung on. And then in flood events, the eggs wash down further downstream, and then the little fish hatch and they come back up the stream.”
As fun as the facts were, the search was fruitless. The further downstream we were, the less severe the sedimentation, but no signs of the fish.
Things were looking grim until a call from Jodie alerted the group. It seemed her eyes were as keen as her ears as she was “20 per cent sure” she spotted a galaxias scurry under a rock.
After a few moments of shining the torch on the water, a climbing galaxias swam into the light, and then another, and then eventually another.
Thankfully, multiple galaxias were confirmed to still be active in the area, and a sigh of relief from the environmentalists present followed, as they were able to deliver the good news to locals.
“I’m just glad for the locals. I’m glad for the fish, and it’s a good sign that they’re still there,” Sonya shared.
Although Jodie didn’t spot her targeted frog on the first try, she did manage to find a leaf-green stream frog, which was also pretty cool.
What happens now?
After successfully confirming the climbing galaxias are still active in the area, Sonya said the first thing she would do is inform some very concerned locals of their presence. Following this, the environmental consultant will keep tabs on the creek and fish every four weeks as the ADCO Construction works continue.
“It’s just nice to be able to confirm for them that we saw at least four or five individuals hanging out in a pool. Decent quality of water wasn’t as bad as it is further up here. So there’s still a lot of hope,” Sonya explained.
“There’s enough for a breeding population and something viable, because they’re such a fecund species, they produce thousands and thousands of offspring, so there’s a chance they could survive if they just stop with all the filtration coming through.”
As for ADCO Construction, they will continue working on the new Forest High School for another five to six months. Manly Observer reached out to the company to confirm if they will be taking on further pollution prevention procedures other than the water filtration pump they were told to install.
“The filtration system installed on site has been operational since late June. It operates to the maximum discharge rate approved by Council,” ADCO Managing Director Neil Harding wrote in a statement.
“ADCO has made application to Council to increase the maximum discharge capacity to account for extreme weather events. The pump is routinely checked as part of our weekly site inspections and scheduled maintenance is carried out by the plant supplier.”
The statement read that from the beginning of the project the construction company “engaged expert advice to develop and implement erosion and sediment controls and related monitoring to minimise the risk of sediment escaping the Premises and/or discharging into nearby waterways.”
It was further stated that the project was impacted by the extreme rainfall events in the first half of 2024 and other extenuating circumstances.
We also asked if they had conducted an environmental survey which ensures the construction won’t prevent water from entering the stormwater systems, causing surrounding creeks to dry up – an issue evident with previous, separate construction works.
“All necessary environmental impact studies and associated reports were provided by Schools Infrastructure NSW as part of the State Significant Development Application and subsequent planning consent by the Department of Planning, Housing and Infrastructure.”
Despite construction mishaps, it’s good to know an ancient gem of Northern Beaches history still shines. The horrors persist, but so do they…
