1.4m dead in Harbour

ALMOST 1.4 million fish died at Macquarie Harbour in the six months to March — a revelation that has prompted the Environment Protection Authority to dramatically reduce the amount of fish that can be farmed there to just 9500 tonnes, below half of the 2016 limit.

EPA Director Wes Ford said the deaths were largely due to an endemic virus exacerbated by heat, stress and low oxygen. The mostly small dead fish were collected and composted.

“The harbour is showing signs of recovery ... [but] this reduction was warranted to reduce the pressure,” he said.

THE Environment Protection Authority has cut by one-fifth the amount of fish that can be farmed in Macquarie Harbour after the death of more than 1.38 million fish in the six months from October.

Director Wes Ford said yesterday the elevated level of deaths was largely because of the endemic Pilchard Orthomyxovirus virus exacerbated by heat, stress and low oxygen.

The dead fish, which were mostly small, were collected and composted.

In the wake of controversy about “dead zones” in Macquarie Harbour and legal action over biomass levels, Mr Ford announced a 21 per cent reduction in the amount of fish that can be farmed.

The new limit has been set at 9500 tonnes for the next two years to May 2020. It compares with a maximum of 21,500 tonnes set in 2016.

“While the harbour is showing signs of recovery due to the strong seawater surges bringing in oxygen-rich seawater and a general improvement in the health of the benthic [deepest] environment, this further reduction was warranted to reduce the pressure on the harbour and allow for further recovery,” Mr Ford said.

Premier Will Hodgman has acknowledged there is significant environmental stresses at Macquarie Harbour.

“That is why we as a government sought to intervene to reduce caps to increase environmental protections,” he said.

“We’ve ensured that there are stronger protections, the EPA is better empowered.”

However, Environment Tasmania spokeswoman Laura Kelly says the Government has presided over a biosecurity and animal welfare disaster.

“There is no way that 9500 [tonnes] is justifiable given the fish kills,” Ms Kelly said.

The Government and the salmon companies had signed off on the extinction of the Maugean skate, she said.

“There have been only two eggs found in the latest survey so this incredibly rare fish, found only in Macquarie Harbour and Bathurst Harbour, is being forced to extinction,” she said.

The previous biomass limit in Macquarie Harbour was 12,000 tonnes which equated to 13 tonnes per hectare. The new limit is 10.26 tonnes per hectare.

The announcement of the new cap comes as Tassal told the ASX it had experienced elevated mortality because of the POMV and challenging summer conditions.

A spokesman said the fish were juveniles with an average weight of 200g.

Huon Aquaculture executive director Frances Bender said it was hoped the reduced biomass was sufficient to allow improvement in environmental conditions for the long-term sustainability of the waterway.

“Of course we are disappointed that the warnings we sounded in September last year to all farmers and the Tasmanian Government regarding the serious risk of a POMV outbreak were ignored,” Ms Bender said.

She said it was understood that the practice of mixing young fish and old fish on the same site, which led to the POMV outbreak, would cease.

Petuna Aquaculture also supports the new biomass cap.

It said a joint venture with Tassal would enable separation of year classes.

Petuna said POMV had impacted its operations with two pens of fish being culled.

Greens Environment spokeswoman Rosalie Woodruff said the confirmation of fish kill and the decision to reduce the biomass cap was confirmation of the dire state of the marine environment.