Impact of Escaped Salmon on Tasmanian Ecosystems

News report – Institute of Marine and Antarctic Studies (IMAS), 3 February 2022

INVESTIGATING IMPACT OF SALMON ESCAPEES ON TASMANIAN ECOSYSTEMS

A new IMAS report has found that Atlantic Salmon involved in two large escape events in south east Tasmania during late 2020 do not appear to have caused significant ecological issues, with minimal feeding on native species impacting their ability to survive in the wild.

The recent study assessed potential environmental impacts caused by the escape of around 180,000 salmon from two Huon Aquaculture pens in the D’Entrecasteaux Channel and Storm Bay in 2020.

The first event, in November 2020, was caused by a fire in a D’Entrecasteaux Channel holding pen and resulted in the loss of an estimated 50,000-52,000 fish averaging about 4kg each. The second event, in December 2020, was the result of a net tear in a Storm Bay pen and saw the loss of 120,000-130,000 fish averaging about 550g each.

Fisheries scientist and report author, Associate Professor Jeremy Lyle, said the study involved surveying recreational fishers and sampling escaped salmon at different times post-escape to understand their dispersal, feeding activity, size, condition and survival rates.

“The salmon dispersed rapidly from the farm sites but appeared to be largely restricted to the D’Entrecasteaux Channel, Storm Bay and associated freshwater tributaries, with recreational catches dominated by larger fish,” Assoc Prof Lyle said.

“We found that catches dropped off significantly in the first four to six weeks after the escapes, which is likely associated with dispersal and declines in the number of surviving fish. However, some salmon survived for almost four months, with small numbers possibly still alive after about five months.

“Despite the survival of some salmon for several months, evidence tells us the escapees didn’t thrive in the wild. We found there was very limited evidence to suggest active feeding on native species, meaning any ecological impacts caused by salmon preying on marine life were likely to be minimal.

“Based on this lack of feeding and general declines in physical condition, it was likely surviving fish exhausted energy reserves and were effectively wasting away.”

Large escape events attract increased fishing effort that can impact the populations of other species taken as bycatch, with surveyed fishers primarily targeting salmon through line fishing and gillnetting.

“While it was not feasible to assess the magnitude or survival of bycatch in this study, heavy and locally concentrated fishing activity, especially by gillnets, is expected to have some ecological impacts for inshore and estuarine fish species taken as bycatch by fishers targeting escaped salmon.”

Assoc Prof Lyle also noted that recreational fishers expressed general concerns about ecological impacts of escape events in their survey responses.

“Our surveys of recreational fishers showed most fishers were motivated to take advantage of the opportunity to catch Atlantic Salmon, a premium table fish, but to also remove this introduced species from the environment and therefore limit any potential ecological impacts.”

Read the latest study report, which confirms findings reported following a 2018 escape event.

Media release – Tasmanian Alliance for Marine Protection, 3 February 2022

IMAS report on salmon escapes needs close scrutiny

Reports of massive salmon kills being investigated

The astonishing claim that the escape of more than a quarter of a million kilos of live, farmed salmon from Tasmanian feedlots caused “minimal” ecological damage demands much closer scrutiny.

The Institute of Marine and Antarctic Studies (IMAS) report that makes the claim is based heavily on voluntary reporting by amateur fishers. The report is based on two major escapes of industrial salmon from Huon Aquaculture feedlots more than a year ago.

That IMAS can report conclusions heavily reliant on such flimsy evidence utterly undermines perceptions of the institution’s scientific credibility and flies in the face of reason.

It’s known that escaped farmed Atlantic salmon survive for many weeks and sometimes months, are often found a long way from where they escaped and that their guts frequently contain native marine life.

Yet again, IMAS gives the industry a green light to maintain practices that in any other responsible jurisdiction would attract heavy penalties in the thousands, if not hundreds of thousands of dollars. Yet again, the perception is that IMAS is much too close to the salmon industry to reassure Tasmanians that their waterways are being independently and transparently monitored.

Meanwhile, TAMP is now investigating reports of at least one and possibly two major fish-kills in the salmon industry over the past few weeks.

Some reports allege more than a million salmon have died as a result of asphyxiation caused by jellyfish infestations that occur in warming waters.

Atlantic salmon producers have to report salmon escapes of 500 or more to the Tasmanian EPA and also major salmon die-offs, but there is no requirement for public disclosure and the industry actively resists that.

TAMP continues to insist that public reporting of such major events and the public health hazards and environmental damage they may pose should, by law, be publicly disclosed. Secrecy discourages public trust and encourages dishonest industry practice.

Media release – Bob Brown Foundation, 3 February 2022

‘WORLD’S BEST PRACTICE’ WOULD HIT HUON AQUACULTURE WITH MULTIMILLION-DOLLAR FINE OVER MASS FISH ESCAPE

Today’s report from the Institute for Marine and Antarctic Studies (IMAS) saying escaped salmon caused ‘minimal’ ecological impact is a let-off which will see Huon Aquaculture go scot-free for a major environmental invasion, according to Bob Brown Foundation’s Fish Farms and Marine Campaigner Rebecca Howarth.

The IMAS report, titled ‘Fishing for Atlantic salmon: inferences about dispersal, survival and ecological impacts following two large-scale escape events’, surveyed a minority of recreational fishers who caught escaped salmon and examined the contents of their stomach and not the marine ecosystem itself.

The investigation found that 1-in-5 fishers discovered native marine life in the stomachs of the escaped salmon and highlighted the issue of wild fish by-catch fish after the mass salmon escape. Fishers surveyed also expressed ‘concerns over environmental impacts of large-scale marine farming and escapees’ and ‘very little support expressed for the current regulations as they relate to escapees.’

“There are many more questions that need answering about the wider impact of escaped predatory salmon,” Ms Howarth said

“More data is needed before we can accurately assess the environmental damage of these escapes. A survey of fishers is a start but not conclusive. How were native fish populations impacted? How many different species were eaten? How were critical habitats like seagrass impacted? Where is the evidence that there is no damage? There is nothing in the report on whether any of Tasmania’s world-famous, and extremely rare, handfish were eaten by the voracious large salmon escapees.

In Norway and Chile, salmon giants Mowi were fined $750,000 and $9.5 million respectively over mass fish escapes. In Tasmania, the salmon barons get away scot-free. We call on the Tasmanian government to levy similar penalties on Tasmanian companies for these repeated mass escape events,” Ms Howarth said.