Calls to help prevent further fish kills

THOUSANDS of dead fish have washed up along the Richmond River in the wake of ex-Tropical Cyclone Alfred, with experts warning the ecosystem could take years to recover.

It is a significant blow for the river which was still recovering from the widespread devastation of the 2022 floods.

Affected areas include the West Ballina canals, riverbanks, Gawandii Beach and Shaws Bay.

Southern Cross University and OzFish Unlimited had just completed three years of recovery work and research before the recent weather event.

Work was set to continue with ongoing restoration projects in the pipeline.

OzFish chief executive Cassie Price said testing has already indicated blackwater as the likely cause of the current fish kills.

Blackwater is caused by flooding washing organic material into waterways.

It strips oxygen from the water as it decomposes, suffocating fish and other aquatic wildlife.

Volunteers from the fishing group have tested the water quality in the weeks after the event.

“The results aren’t good. Healthy water should have at least 5mg of oxygen per litre,” Ms Price said.

“Fish experience distress when it falls below 4mg per litre and start to die at 2mg a litre.

“In the Richmond River, the dissolved oxygen levels are almost nil, sitting at 0.4 mg a litre.”

Information provided has shown dead flathead, bream, whiting, prawns and other marine life washed up on shore.

There were also reports of dying fish gasping on the shoreline with mud crabs and eels walking out of the water to escape smothering.

Ms Price said restoring local swamplands that border the Richmond would reduce the severity of the black water events, and fish kills.

“Healthy swamp bordering rivers acts as a sieve, or a filter, that reduces the blackwater from entering the waterway,” she said.

“Restoring the Tuckean Nature Reserve to a more natural hydrological regime would mean that much of the swamp would process the flood water, so that significantly less blackwater enters the lower Richmond after events like this.”

The Department of Primary Industries is responsible for investigating the cause of fish kills, managing the immediate response, and implementing long-term strategies to prevent future occurrences.

For any further enquiries regarding investigations into the cause of a fish kill, further information is available on the DPI website.

Fish death incidents or observations can be reported to the Fishers Watch Phoneline on 1800 043 536.