Depths of despair as 20,000 “ravenous” kingfish hit Port Stephens marine park

Up to 17,000 predatory yellowtail kingfish, used to being fed automatically, are now hunting in the marine park waters after 20,000 escaped last week from a fish-farm sea cage, described as a "fortress pen", that was destroyed in rough seas. About 3000 fish have been recaptured.

The future of the controversial joint NSW government and Tasmania-based Huon Aquaculture project, which is 18 months into a five-year research trial, is under a cloud following the loss of almost half its stock with a retail value of more than $2 million.

Conservation groups and local tourism operators described the multi-million dollar project as a “disaster” threatening the pristine marine park's delicate ecosystem.

Marine Parks’ Association chairman and whale watching tour operator Frank Future said fisheries staff “repeatedly assured” the community the pens could handle waves up to 15 metres.

According to Huon, the “fortress pens” were designed to withstand “high energy, exposed sites, frequently receiving storms swells and gale force winds”.

“The pen that had the release was mangled and now we have thousands of mature kingfish released into the wild, nothing will be safe from them,” Mr Future said.

“They are voracious feeders and from what I understand they are ravenous. Once they realise they won't get any food in the form of pellets they'll be eating anything they can find. I don't want to think about the impact on wild species.”

The commercial-scale kingfish trial at Providence Bay - the result of an existing offshore research lease being boosted to 62 hectares - includes five pens, each about 60 metres across, two that were stocked with 20,000 fish each. There is capacity for 12 sea pens in the trial.

Comment: Commercial seafood demand drives the need for developing aquaculture

Word of the bounty spread quickly prior to the long weekend, via social media, pricking the ears of recreational and commercial fishers who flocked to the area.

With the kingfish - selling for up to $32 per kilogram - churning up the waters seven kilometres off Hawks Nest, fishers set to work scooping them from the sea in any way they could.

Recreational fisherman Jeff Thompson was on his way to Broughton Island on Saturday, January 20, the morning after the pen was damaged, when kingfish started gathering around his boat.

Mr Thompson said he respected the bag limit of five and the fish he caught were all legal size, between 70 and 75 centimetres.

Read more: Eyes in the sky watching for illegal fishing in the marine park

“I’ve never seen anything like it in more than 40 years of fishing,” he said.

“I think it was the sound of the motor that attracted them and anything you threw at them they took, even just a bare hook.

“There’s no doubt 20,000 kingfish would have a big impact on the ecology of the area, I think it’s better if people catch them and get them out of the area. The next day there were dozens of boats out there.”

About two tonnes of the restaurant-quality fish made its way through the Commercial Fisherman's Co-operative before authorities closed down the area to fishing. The ban remains in place until February 7.

A spokeswoman for Huon Aquaculture said the nearest wave buoy to the farm recorded wave heights over 11 metres when the pen was damaged, but others questioned the accuracy of the recording.

Weatherwatch senior meteorologist Don White said given the known weather conditions at the time he doubted there would have been 11-metre swell in the area.

Huon’s spokeswoman declined to comment on the pen’s failure before the release of a review into the incident.

She said the farmed kingfish were of the same genetic stock as wild populations and the company was “researching the behavioural and feeding responses of the escaped fish” as it continues to try and recapture them.

“Early indications suggest that equipment design is not the lead cause of equipment failure,” she said. “Whilst we are disappointed with the recent fish escape following a weather incident, it is an important learning experience and we remain committed to ensuring that there isn’t a repeat of the incident. We will continue to be upfront with the community and we will supply the report to stakeholders once completed.”

Dolphin Swim Australia chief executive Andrew Parker said Bureau of Meteorology data recorded six-metre swell in the area at the time of the incident.

“There might have been some rogue sets come through, but the swell was consistently about six metres for three days at that time,” he said.

“It has always been explained to the community that those pens are designed to withstand much bigger swell than what we had. There are serious questions to be answered about what went wrong.”

Fishers reported the kingfish in “plague proportions” off Broughton Island and schooling at Little Beach, Shoal Bay.

“We have the largest seagrass meadows in NSW and very important mangroves in the Port Stephens area,” Mr Parker said. 

“We are talking about a marine park with sanctuary zones and we're concerned about a cascade effect. This is not the right place for this business.”

Professor Bronwyn Gillanders, of the School of Biological Sciences at the University of Adelaide, said the key concern was the yellowtail kingfish’s predatory nature.

She described the escape as a “natural experiment” and said it was “hard to know” what impact the farmed fish would have on wild stock. 

“They haven’t been brought up to feed on wild fish,” she said. “But they are predatory fish and they would normally eat other fish. Whether they have the impact claimed, it’s difficult to tell.” 

A spokesman for the NSW Department of Primary Industries said 17,000 kingfish was not “significant” in terms of the total wild yellowtail kingfish population in the area.

“The farmed yellowtail kingfish are of the same genetic stock as wild populations with broodfish being sourced locally,” he said.

“The farmed fish are from local parent stock and are health checked on a routine basis, so they are not considered a biosecurity risk.”  

It is the second large-scale fish farm operation in Port Stephens to suffer huge stock losses due to storm damage.

Read more: In 2016 approval was sought to move a farm near Hawks Nest further off shore

Pisces Aquaculture was granted consent in 2001 to operate a commercial fish farm in the Bay, close to Hawks Nest. It folded in 2004 after storms damaged the farm’s pens, snapper escaped and a move to raise funds on the Newcastle Stock Exchanged failed.

The DPI spokesman said “extensive community consultation was undertaken” prior to approval of the kingfish project and environmental monitoring was being independently conducted by the University of Newcastle.

“An incident response review is being prepared for the Department of Planning and Environment and a summary of the findings will be made available to stakeholders once finalised,” he said.

“The recommendations arising from the incident review will be integral in amending current management practices.”

Ross Duffy, a recreational angler from Duff's Salamander Bait and Tackle, said unlike 10 years ago -  when thousands of baby snapper escaped the previous commercial fish-farm trial in the same area - the kingfish put up a good fight.

“They're a good fighting fish even though they have been farmed and I can tell you they're a good feed, I can recommend  them,” he said.