A stylised illustration of what a tunnel net is and how it works.
A tunnel net is a large net designed to funnel and trap fish as they swim off shallow coastal flats with the falling tide. It consists of up to 1.6 km long mesh net “wings” that guide every fish on the flat, regardless of size or species, into a tunnel holding chamber net where they cannot escape. The only fish that are not trapped are any little fish that manage to pass through the small mesh gaps without injury.
Imagine closing every lane of a major highway during peak-hour and funnelling all traffic into a single dead-end to be processed for market — that’s how tunnel nets operate for fish moving with the tide.
What Is A Tunnel Net?
What fish do tunnel nets catch?
At present, the only use of tunnel nets in QLD is a small-scale fishery in the south-east that targets mainly plate-sized fish like whiting and bream. Most licences for this fishery are in Moreton Bay. However, in 2025, the Queensland Government conducted 16 successful deployments of tunnel nets on the Great Barrier Reef World Heritage Area flats of Central & North Queensland, including within the GBR Marine Park and Dugong Protection Areas.
The 2025 trials caught approximately 30,000 fish, spread across more than 50 different species. This included a staggering 6,000 + fish, weighing more than 2 tonnes, in a single net shot. The average catch was 1886 fish / 772 kg per shot.
Importantly, fish that are considered either “by-catch” (discarded) or “by-product” (lower commercial fishing value) within QLD’s northern regions commercial fishery made up approx. 97% (by weight) of the total tunnel net catch. By weight, the top six species caught were trevally (goldens, GTs and others), barred javelin, biddies, sickle fish, blue salmon and permit. The only northern regions seafood “target” species in the catch were barra (approx. 3% by weight) and king threadfin (minimal catch).
The economic reality - harvest every fish
How can a tunnel net fishery that captures 97% lower value seafood species, but has very high operating costs (each net shot requires 3+ operators working for over 8 hours) make money?
The only way is volume.
Make no mistake: everything that can be sold from each tunnel net shot will be harvested, regardless of species.
This isn’t greed. It’s mathematics. The high operating costs, and the low commercial value of the fish, will leave the commercial operators with no other choice. Their hands are tied.
In other words, for most net shots, what appears to be contemplated is a high take harvest of fish that have low value as seafood, like trevally & permit. In addition to seafood, this may involve tunnel nets being used to source crab bait and petfood.
The scientific reality - little or nothing is known
No baseline data exists for the stock biomass of golden trevally, giant trevally, permit and most of the other 50+ species that will be caught by tunnel nets. Nor do any total allowable catch limits or individual catch quotas apply. Most have no commercial size limits, meaning juveniles can be taken. Little or nothing comprehensive is known about the species biology, breeding and connectivity too. These factors, and other issues including localised depletion, make the risk that tunnel nets pose to our flats fish stocks and ecosystem unacceptable.
" The 2025 trials caught approximately 30,000 fish, spread across more than 50 different species. This included a staggering 6,000 + fish in a single net shot. The average catch was 1886 fish / 772 kg per shot."
A holding pen from the Bowen trial showing a large school of Permit, Golden Trevally, Milkfish and other smaller fish such as Juvenile Milkfish, Garfish, Queenfish etc - Photo John Haenke
Why are tunnel nets so harmful?
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Their extraordinary size: the highly visible net wings are up to 1.6 km long. This is almost 3 times longer than the gillnets being phased out in mid-2027
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The intended use area: the shallow coastal flats on which tunnel nets are used provide essential habitat for juvenile fish, turtles, dugongs, rays and sharks, plus iconic recreational fishing species (e.g. permit & trevally) that hold low value to the commercial sector as seafood, but very high value to the recreational fishing and tourism sectors
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The lack of selectivity: tunnel nets capture every fish within the huge area of the wings, resulting in a high proportion of by-catch, while also posing a risk to threatened, protected and endangered species which must be manually released.
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Localised depletion: tunnel nets can catch over 6,000 fish, weighing well over 2 tonnes, in a single net shot. With the economic pressure to harvest every fish, this presents the serious risk of flats fish populations being quickly depleted in the areas where tunnel nets are used. As stated above, the lower value tunnel net catch species, plus higher tunnel net operating costs compared with other gear types (tunnel nets require 3+ operators to be paid for a full days’ work) will create the economic necessity to harvest large numbers of lower value fish per net shot, increasing the likelihood of localised depletion.
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Post release mortality & predation: imagine 6,000 + fish of all shapes and sizes, crowded together in the small and narrow tunnel net sock, colliding into one another as they thrash about in panic. Unwanted fish risk being killed or seriously injured by this process, or by being man-handled on the fisher’s metal sorting tray under the hot tropical sun. Further, fish face the additional risk of sharks and birds preying upon them if they are released. In one of the trial shots, over 25% of the fish were observed dead prior to release. In a quarter of the trial shots, over 50% of the fish were not in the ‘best/healthy’ category prior to release.
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The lack of science: little or nothing comprehensive is known about the stock biomass size, biology and connectivity of the by-product and by-catch species that will make up nearly all of the tunnel net catch. Nor does any data exist about tunnel net post-release survival and post-release predation rates, despite an earlier tunnel net study (FRDC, 2022) recommending that post-release mortality trials occur. Nor does any science exist about the impact on species if tunnel nets remove juvenile fish that use our inshore flats as nursery areas.
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Spatial conflict with other uses: the 1.6 km long tunnel net wings are barriers that will prevent recreational fishers, traditional owners and other users from accessing flats while tunnel net operations are underway. They will also prevent marine life outside the wing area from accessing their natural feeding grounds and movement corridors.
Pelicans queued up at at the end of the Moreton Bay tunnel net, taking advantage of the released fish as an easy meal!
What about TEPS?
A metal grid at the mouth of the tunnel aims to prevent threatened, endangered and protected species (TEPs) like turtles, dugongs and rays from entering the tunnel component of the net. However, the grid cannot prevent these animals from being trapped temporarily within the area of the wings, where they risk harm (for example, becoming entangled in the mesh wings, or stranded as the tide drops).
In 2021, Fisheries QLD assessed the Moreton Bay tunnel net fishery as posing a medium risk level to turtles and dugongs. In justifying the risk level as medium, the assessment referred to the fact that the preferred dugong habitats in Moreton Bay are closed to tunnel netting, and that the Dugong Protection Areas (DPAs) in Central and North Queensland provide other dugong habitat where tunnel netting is not allowed.
Despite this, commercial fishermean have told Fisheries QLD that tunnel nets will not be viable in Central & North Queensland unless they are used within the DPAs. And Fisheries QLD conducted over half of the tunnel net trial shots within the DPAs. Even though Australia has committed to UNESCO to the keep the DPAs ‘net free’.
Plainly, tunnel nets should not be used within QLD’s sensitive DPAs. Dugongs are a species of outstanding universal world heritage value, and they are vulnerable to extinction. Dugong populations from Mission Beach to Bundaberg show evidence of a long term decline between 2005-2022 of -2.3% per year.
The Inshore Flats Project calls upon Fisheries QLD to publicly release data identifying the number and nature of all TEP interactions that occurred during the tunnel netting trials.
Above: A Dugong feeds on a seagrass bed.
Below: Sea Turtles depend on calm, sandy flats for refuge and laying eggs.
Why a NEW tunnel net fishery makes no sense!
A prized Trachinotus Anak discarded down a hot stainless slide after information was gathered during the trail - Photo John Haenke
"Starting a new tunnel net fishery for low value species like Giant Trevally, Golden Trevally and Permit (Snub nose Dart) using 1.6 km long nets along our sensitive inshore flats makes no sense."
REMEMBER: 97% of the tunnel net trial catch was “by-product” and “by-catch” with lower value, or no value, as seafood. Starting a new tunnel net fishery for low value species like Giant Trevally, Golden Trevally and Permit (Snub nose Dart) using 1.6 km long nets along our sensitive inshore flats makes no sense. No modern fishery should be managed this way, especially within a World Heritage Area*
More broadly, establishing a new tunnel net fishery on Central & North Queensland’s inshore flats is counterproductive from an environmental, social, and economic perspective.
Environmentally, it places a new high-impact commercial net in one of the most vulnerable and valuable habitats in the state - the Great Barrier Reef World Heritage Area,. This is a new and preventable threat that the Reef just doesn’t need.
Socially, it undermines the experiences of the large number of local and tourist recreational users who depend on healthy flats.
Economically, it jeopardises a thriving, high growth tourism and eco-friendly recreational fishing sector that delivers substantially greater long-term benefits than a new tunnel net fishery ever could.
Simply put, the costs—ecological, social, and economic—far outweigh any potential gains, which are likely to be small or non-existent, and risk being unsustainable due to reduction or depletion of fish stocks at tunnel net sites.
What about local seafood for local communities?
Just like you, many of us love buying local seafood.
But supporting QLD seafood does not require supporting all ways to source it. Some things cross a line.
And tunnel nets are not necessary to sustain local seafood supply. The gillnet fishery being phased out in mid-2027 (which tunnel nets would replace) contributes just 2.6% of the entire QLD east coast wild seafood harvest.
Other more (sustainable) commercial fishing practices can be used, such as commercial line fishing. Aquaculture also presents many exciting opportunities in QLD - QLD farmed barramundi alone grew by 400 tonnes in just 12 months.
*SOURCE: “Tunnel net - Catch composition by weight” data presented by Dr Sam Williams as Slide 17 at the Reef Ecologic Webinar held on 9 December 2025, available at https://www.youtube.com/watch?v=nujJb86PNpE&t=11s. Our description of the tunnel net catch species as “target”, “non-target”, “by catch” or “by product” is made according to the definition of those terms in Tables 1 and 2 plus page 20 of QLD’s East Coast Inshore Fishery Harvest Strategy: 2021-2026.