Dead salmon pumped into crates at Tassal pen as environmentalists warn of heatwave

Environmentalists believe thousands of farmed salmon have died in the waters off Tasmania’s east coast due to a marine heatwave.

Video captured by the Bob Brown Foundation (BBF) on Wednesday shows a barge with crates of dead salmon onboard parked next to one of Tassal’s fish farm pens at Okehampton Bay, near Triabunna.

The fish appear to be sucked from the bottom of one of the pens and pumped out onto the barge before being packed into crates.

BBF Antarctic and Marine campaigner Alistair Allan was out filming on Wednesday and estimates the number of dead fish to be in the thousands.

“What we saw was numerous pens on the Okehampton industrial fish farm lease filled with rotting fish on the surface, but even more morbidly, what we did see was a large industrial barge pumping thousands of dead fish,” Mr Allan said.

“So, fish that have died and sunk to the bottom are then getting pumped out into these big skip bins on the barge and they are just stacking these bins on top of each other.”

EPA alerted to deaths in November

Tasmania’s Environment Protection Authority (EPA) has confirmed it was notified of a “fish mortality incident” at the farms as far back as November 28 and said it was “working on the extent of the impact with Tassal”.

The EPA only needs to be notified after three consecutive days of fish deaths that make up 0.25 per cent of total fish stock.

EPA director Wes Ford told ABC Radio Mornings he was unaware of the cause but fish deaths are typically caused by a combination of things, including elevated water temperatures, the presence of jellyfish, increased algal blooms and potentially minor disease issues.

He also said the EPA did not know how many fish had died in Tassal’s pens.

“Typically when you do get a large mortality event there is going to be info in the public arena because there are going to be large amounts of fish that are going to need to be disposed of,” he said.

“This is not the case at this point in time.

“This is leading into summer, we’re going to see a number of these across the growing areas. It’s the nature of summer in Tasmanian waters.”

More frequent, intense heatwaves predicted

CSIRO sustainable marine futures expert Alistair Hobday has been working with the state’s aquaculture industries to prepare them for marine heatwaves.

“There is a lot of manipulation that you do of the system, you can decide what to feed them, where to grow them, when to harvest them, how much oxygen to provide and all kinds of things like that,” he said.

“So, if we can provide forecasts, aquaculture have got a lot of things they can do in response.”

Mr Hobday said with “climate change and Tasmania being an ocean warming hotspot” there will be more marine heatwaves in the future.

“They’re going to occur more often, they’re going to last longer and they’re going to be more intense,” he said.

“All of the levers that you’ve got to pull will generally get harder and harder to pull over time because we’ll have fewer options as the temperatures get warmer.

“But there are still lots of adaptations that can be done in the ocean and we’re just learning about some of those now in summers like this where temperatures will be extreme in the Tasmanian ocean.”

Fish mortality event is ‘minor’, Tassal says

Warming waters was one of the concerns raised by the Bob Brown Foundation and other environmentalists, when Tassal was looking to expand its fish farming operations into Okehampton.

BBF argued the bay was too hot and too shallow for fish farming, but their challenges failed.

Mr Allan believes this latest incident proves environmentalists right.

“This is the future that we’re staring at when it comes to fish farming in Tasmania,” he said.

“As our waters get warmer as climate change accelerates, this problem is only going to exacerbate.

“Just looking at those pens, they were crammed full of fish, all of which are suffering … this is not a clean or green or lovely food source, this is instead factory farming in Tasmania’s oceans.”

In a statement, a Tassal spokesperson said the company was dealing with a fish mortality event that it described as “minor”.

“As farmers, we sometimes have events that impact our fish — particularly in summer,” it said.

“We manage and we will continue to manage these events with fish health and welfare as our primary focus.”

“The event — even though minor — is unfortunate, and is being managed responsibly by our fish health and aquaculture experts.”