More than 400 dead fish have been found in the Nowendoc River at Caffrey’s Flat.
Luke Everingham, who owns the Rotating House situated on the banks of the river at Caffrey’s Flat, found the disturbing fish kill on his property on Tuesday, February 14. He immediately reported it to the relevant authorities.
On Friday, February 17, aquatic ecologist Dr Keith Bishop visited the site to collect data to determine the nature of the kill and the most likely cause. He found the kill was mostly confined to one pool, and the fish appeared to have been dead for seven to 10 days.
“Australian bass fishermen would be horrified at the losses – at least 300 dead in one pool alone!” Dr Bishop said.
The kill had a “clear signature of being caused by dissolved oxygen depletion” due to only larger fish of larger species being primarily affected.
Dr Bishop’s data confirmed severe oxygen depletion in the water.
“I have never recorded such poor dissolved oxygen conditions in all my time working on NSW east coast rivers!” he said.
The oxygen depletion was caused by a very heavy load of aquatic plants, low river flows due to insufficient rainfall, and very high water temperatures, Dr Bishop concluded.
I have never recorded such poor dissolved oxygen conditions in all my time working on NSW east coast rivers!Dr Keith Bishop
“Basically, the river starts cooking,” he said.
In addition to the fish, Luke Everingham said he also found dead eels and a dead platypus, however Dr Bishop said he didn’t see any dead platypus at the site.
“I don’t necessarily see the connect there,” Dr Bishop said, adding that dissolved oxygen depletion would not kill a platypus. “They don’t have gills; they breathe the atmosphere.”
Luke Everingham is concerned about the “ramifications of the river reaching this state”.
“I’ve owned this place for 31 years and I’ve never seen it like this,” he said. “My big concern is people using the river for domestic use. Can we use this water for domestic purposes?
“We’re scrambling for alternative sources of water. We’re having to buy water in.”
Mr Everingham said that drawing water from the river for irrigation is the “only explanation.”
“It’s very clear that times have changed and our present weather patterns dictate that we can’t keep using this river for irrigating,” he said.
Mr Everingham has been in contact with the NSW Department of Primary Industries in regard to water testing and removal of the fish.
“There’s no-one saying they’ll come get the dead fish,” Mr Everingham said.
“It would be nice for the fish to be removed.”