One million fish killed at Menindee Weir pool near Broken Hill

Hundreds of thousands of dead fish have been found floating in a river with calls for authorities to investigate the cause.

A massive fish kill has occurred at a weir in rural NSW.

Countless fish have been found floating on top of the water at the Menindee Weir pool near Broken Hill.

Video footage of the kill shows endless bodies of fish covering the area around the weir, with locals outraged by the event.

The large-scale fish death event is estimated to have reached millions of deaths, the NSW Department of Primary Industries confirmed to NCA Newswire.

“This event is ongoing as a heatwave across western NSW continues to put further stress on a system that has experienced extreme conditions from wide-scale flooding,” a DPI spokesperson said.

“NSW DPI understands that fish death events are distressing to the local community, particularly on the Lower Darling-Baaka.”

Bony herring (bony bream) have been predominantly affected, as well as smaller numbers of other large-bodied species such as Murray Cod, Golden Perch, Silver Perch and Carp.

“Well, it’s happened again; dead fish in their thousands at the main Weir and in the river towards town,” local photographer Geoff Looney said on social media.

Fish kills are not uncommon around the Menindee Weir.

A fresh maior fish kill at Menindee Weir pool near Broken Hill. Locals say one million dead. @[e-mail]/YCkA78NbgL

— Chris O'Keefe (@cokeefe9) March 17, 2023

“The sad difference this time is that they are mostly native fish. Bony herrings, Murray Cod and large Golden Perch.

“Maybe this time we will get an official state inquiry into what is killing our native fish – lack of oxygen, pollution or whatever.

“It worries me a lot, as this water is used for our town supply of water and a lot of people drink it.”

Fish kills are defined as a sudden mass mortality of wild fish and are more likely to occur in summer or following sudden changes in temperature, according to the NSW Department of Primary Industries.

It's believed up to a million fish have died in this event. Picture: Chris O'Keefe

The DPI said the fish deaths were caused by hypoxia, when flood waters recede, causing low oxygen levels in the water.

“Significant volumes of fish including Carp and Bony Herring, nutrients and organic matter from the floodplain are being concentrated back into the river channel,” the DPI said.

“The current hot weather in the region is also exacerbating hypoxia, as warmer water holds less oxygen than cold water, and fish have higher oxygen needs at warmer temperatures.”

Bony herring are more susceptible to environmental stresses such as low oxygen levels especially during increased temperatures.

Menindee is no stranger to events of this nature, with tens of thousands of fish dying in multiple kills in February.

It was also the site of a major fish kill in January 2019 which made national headlines.