Restrict forward facing sonar in Murray cod waters

Summary

This document outlines two policy goals and the justifications for placing restrictions on where forward facing sonar can be used. If we receive significant grassroots support from the cod community, AFET will approach lawmakers to have these policies enacted.

The concern is not that anglers using FFS catch more fish. It is the continual targeting and repeated disturbance of the same individual fish, which was historically impossible using standard down and side scan sonar.

AFET has been in contact with politicians from numerous states and federally. The initial target is the ACT, where 500 signatures will see the issue raised in parliament. If that succeeds, the precedent can be used for NSW and Victorian waterways.

Policy One: a complete ban on FFS in naturally recruiting rivers

Why rivers must come first

While rivers have so far been largely left alone from the pressure and destruction caused by scope, this is unlikely to continue, and it is paramount we are ahead of the curve. Land based and small water livescope is coming. Garmin already sells a portable LiveScope package built around a swivel pole mount and a lithium battery, marketed for kayak and ice use and designed to transition straight onto a boat, and there is now a large third party market of telescoping transducer poles made specifically for kayaks and canoes.1 Some anglers have already mounted units into tinnies and kayaks for the really small water, and larger rivers like the Murray have already been negatively affected. A widely available, portable, low cost setup will leave nowhere safe.

A lot of great anglers who have shied away from the dams due to the changes to pressure and culture need to work together to prevent the rivers reaching the same fate. The effects on river fish are likely to be far worse, with the reduced food supply and fewer large fish overall. This is also where national policy already points: the National Recovery Plan for the Murray Cod notes that while stocking is probably most effective in impoundments, it is the riverine populations that are under threat.2

The stock is already in trouble

Murray cod are listed as a vulnerable species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, listed on 3 July 2003, which makes them a matter of national environmental significance.3 The National Recovery Plan, adopted by the Commonwealth in October 2010, sets a long term objective of self sustaining populations managed for conservation, fishing and culture, with a general aim of restoring native fish populations to 60 percent of pre-European levels. It identifies habitat loss and degradation, barriers to fish passage, flow regulation, cold water releases and fishing among the reasons for the species' substantial decline since European settlement.2

The NSW stock status assessment classifies the NSW Murray cod fishery as depleted.4 That is the baseline condition of the fish we are talking about. FFS would not be arriving into a healthy, resilient population with capacity to absorb a new pressure. It would be arriving as an additional stressor on a stock already carrying every other stressor listed above.

Large cod are not replaceable by an equal number of small cod

Large Murray cod have immense reproductive value, especially in rivers reliant on natural recruitment. Research into the reproductive biology of Murray cod in NSW tributaries of the Murray-Darling system recorded absolute fecundity ranging from 6,800 eggs in a 480 millimetre, 2.1 kilogram fish to 86,600 eggs in a 1,050 millimetre, 22.7 kilogram fish.5 The loss or failed spawning of one large breeding fish can represent the loss of tens of thousands of potential eggs.

A population containing many small fish is not necessarily equivalent to one containing a healthy structure of small, medium and old breeding fish. Fisheries monitoring has found reduced relative biomass since 2001, evidence of a sharp decline since 2020, and a decline in the biomass of mature fish over 500 millimetres.4 These are not fish that should be subjected to this form of highly selective and repeated pressure when they are responsible for keeping the river's population afloat.

Catching cod before and during spawning affects recruitment

Murray cod do not simply release eggs and leave. Male cod guard and fan the fertilised eggs to keep them oxygenated. During this period they become territorial and aggressive, making them particularly vulnerable to lures and repeated targeting.

A five year study in the northern Murray-Darling Basin, running from 2015 to 2019 and combining bio-telemetry with underwater imagery, established that disturbing nesting Murray cod had a negative impact on egg and larval survival.6 Two further findings from that study matter for policy. Breeding behaviour including nest site selection was observed from early August, with spawning from late August through to late October, which the authors describe as considerably earlier than previously reported. And most nests were located in shallow water on hard substrate underneath undercuts along the riverbank edge, frequently in isolated and disconnected pools with little or no measurable flow.6

That combination should concern anyone thinking about FFS in rivers. Nesting fish are shallow, close to the bank, in still and often disconnected water, and they are on the nest earlier in the year than the current closed season assumes. That is exactly the water a kayak or land based FFS user will be working. The authors of that study, working within Fisheries NSW, concluded by recommending a review of current regulations to safeguard the long term conservation of the species across all sections of its range.6

FFS makes it easier to locate fish holding in predictable spawning habitat, to watch their reactions, and to repeatedly cast at and provoke them. Most anglers would not intentionally do this, however FFS allows it to occur at rates in extreme excess of existing pressure. If a guarding male is caught, eggs can be left without protection, oxygenation or defence from predators. A fish repeatedly disturbed before spawning may also leave suitable habitat or expend energy that should have been directed toward reproduction. The result is a direct risk to recruitment: fewer successful nests, fewer larvae and fewer young cod entering the population.

Repeated capture is a mortality problem, not just a disturbance problem

The only experimental study of Murray cod post release survival monitored angled wild fish for five days and recorded overall survival of 98 percent.7 That is a good number, and it is frequently used to argue that catch and release fishing is essentially harmless. But the authors of that study reached a different conclusion. When they combined their survival estimate with creel survey data on how many fish are actually released across the fishery, they found that discard deaths could be at least as important to consider in stock assessments as deaths from directed harvest.7

That finding was based on pre-FFS encounter rates. Post release mortality is a probability per capture, not a fixed annual figure. Any technology that multiplies the number of times a given fish is hooked in a year multiplies that fish's annual risk accordingly. In a river system where the large fish are few, identifiable and tied to known snags and holes, that risk falls on exactly the individuals the population can least afford to lose.

The wider food web

The chain of impact likely to occur in rivers runs as follows: reduced cod abundance or feeding, leading to reduced predation on fish and crustaceans, leading to increased abundance of invasive or mid-level species, leading to increased predation on insects, tadpoles and smaller native fish, and ultimately to disruption of the wider aquatic food web. Murray cod are a top order aquatic predator,2 and changes to their abundance and behaviour do not stay contained to the species itself.

This is what the precautionary principle exists for

The precautionary principle is not an abstract idea, it is written into Australian fisheries legislation. The Queensland Fisheries Act 1994 defines it as the principle that, if there is a threat of serious or irreversible environmental damage, a lack of scientific certainty should not be used as a reason to postpone measures to prevent environmental degradation.8 Several of the rivers we have listed fall within that jurisdiction. In New South Wales, the objects of the Fisheries Management Act 1994 are to conserve, develop and share the fishery resources of the State for the benefit of present and future generations, and they expressly include conserving threatened species, promoting ecologically sustainable development, and promoting quality recreational fishing opportunities.9

We are dealing with a nationally listed vulnerable species, in river populations already assessed as depleted, facing a new technology whose effects have not been quantified in this fishery. Waiting for certainty before acting is exactly the approach the legislation tells managers not to take.

Policy Two: the creation of FFS free lakes and dams

The vulnerable listing does not stop at the dam wall

Nothing in the EPBC listing of Murray cod excludes impoundments. A cod sitting in Copeton or Blowering is the same listed species as a cod sitting in the Macquarie, and it carries the same protections and the same national obligations. The National Recovery Plan's objective of self sustaining populations managed for conservation, fishing and culture2 is a live federal commitment, and it does not switch off at a dam wall.

The most common response we get when raising concerns about dams is that they are stocked fisheries, so the fish do not matter and the answer is simply to stock more. The recovery plan itself answers this. It describes stocking as being often perceived as a "panacea" for declining fish populations, because it is an easy management option that can result in deferring more difficult, expensive and controversial but more effective management measures, and it states plainly that the effectiveness of Murray cod stocking has not been quantified. The plan also acknowledges that cod are known to spawn in impoundments and farm dams.2

The modelling backs this up. A population model built specifically for Murray cod found that stock enhancement was a less effective method of improving fishery sustainability than measures designed to reduce fishing mortality, and further predicted that where angler effort rises in response to increased fish abundance from stocking, fishing mortality increases and eats into the benefit that stocking was supposed to deliver.10 That is precisely the situation FFS creates. Stocking harder into a dam where every fish is now findable does not solve the problem, it feeds it.

Our dams are now insurance for the entire species

The independent assessment of the 2018-19 fish deaths in the lower Darling documented mass mortality events involving very large numbers of native fish, including Murray cod, driven by low flows, stratification and rapid changes in water conditions.11 Rivers remain exposed to flow management, cold water pollution, hypoxic blackwater and mass kill events that can wipe out decades of accumulated fish in a matter of days. Deep dams are buffered from most of that.

Whatever anyone thinks of dams as fisheries, they have quietly become a hedge for the species as a whole. Our large impoundments now hold some of the biggest and most secure populations of large Murray cod left in the country. Those trophy fish represent thirty and forty years of survival that cannot be replaced on any management timeframe, and in a genuine emergency they are the fish that carry the species through.

Deep water was the last refuge and scope has removed it

This is the point that is most often missed. Before FFS, dam cod were realistically caught in a narrow set of situations. Anglers worked the banks, the edges, standing timber close in, points and shallow structure, or occasionally trolled and covered water hoping to run something down. That was the fishery.

The fish living out in the deep basin, suspended off points, sitting in standing timber in forty to sixty feet, were functionally untouchable. Not because anglers did not know they existed, but because there was no way to locate an individual fish out there and put a lure in front of it. Those fish had a refuge. A significant portion of every dam population spent most of the year in water where nobody could reach them, and they only became catchable when they moved shallow or fed actively.

FFS has removed that completely. There is now no part of any dam that is not effectively fished. The deep suspended fish that were previously safe for the entire year are now the primary target, because they are the easiest fish to find and follow on a screen. These fish have gone from zero pressure to being the most heavily pressured component of the population, and they have nowhere left to go.

This matters enormously, because deep water capture is the worst case scenario for fish survival. The 98 percent survival figure discussed above was measured in riverine conditions.7 Deep impoundment capture is a different set of circumstances entirely. It brings barotrauma from rapid pressure change, longer fights, and in summer a fish dragged from cool deep water up through a warm surface layer. Every one of those factors increases the chance a released fish does not survive, and none of them were present in the conditions under which that figure was measured.

The critical point is that post release mortality is a chance per capture, not a fixed annual number. FFS does not change the odds of any single capture, it changes how many times a year the same individual fish is found, followed and hooked. This compounding effect is not theoretical. A mark recapture study of largemouth bass found that survival decreased both with water temperature and with the number of capture events, and that these factors combined produced up to 90 percent cumulative mortality for individual fish captured at five separate events.12

If a big fish goes from being caught once a year to five times a year, and each capture carries a 5 percent chance of death, that fish now faces roughly a 23 percent chance of dying within the year. Nobody has broken a single rule, no fish has been taken, and every fish has been released.

This is also the concern being investigated in the Minnesota research program currently funded to study forward facing sonar, which states that in harvest oriented fisheries increased capture efficiency could lead to increased harvest, and in catch and release fisheries increased captures could increase hooking mortality.13 In a fishery that is almost entirely catch and release, encounter rate is the whole ballgame.

Big cod are already legally protected in our dams

It is illegal to take a Murray cod over 75cm in New South Wales, and that applies in stocked impoundments exactly as it applies in rivers.14 Even in what people describe as put and take fisheries, the state has already decided that large cod are worth protecting and cannot be removed. That protection exists in law right now.

The problem is that protection from being taken only achieves anything if the fish actually survives. That rule was written for a fishery where a large fish might be encountered once or twice a season by chance. It was never designed for a world where the same identifiable fish can be located, tracked and cast at repeatedly across a season. The purpose of the law is being quietly defeated by a change in technology, not by a change in the law. Asking for restrictions on FFS is not asking for a new protection, it is asking to restore the protection that already exists on paper.

We have no control waters left

Once catchability increases, angler catch rates stop being a reliable measure of how many fish are actually there. A 2025 review of live sonar in freshwater recreational fisheries warned that the technology increases catchability and the targeting of previously uncatchable fish, which can lead to hyperstability of catch rates and mask real declines in abundance where managers use angler catch rates as a proxy for abundance.15 Our impoundments are managed heavily on exactly that kind of information: angler reports, tournament results and stocking returns. If FFS holds catch rates up while the big fish component quietly declines, the monitoring will read healthy the entire way down and nobody will know until it is far too late.

This is the core reason we are asking for a small number of FFS free dams rather than a blanket restriction. Right now there is not a single impoundment in the country left as a control. Without one, it will never be possible to separate the effects of FFS from drought, water levels, stocking rates or changes in effort. Setting aside two or three dams costs the government nothing, is completely reversible, and would give fisheries managers the only clean comparison they are ever going to get.

Why the ACT is the right place to start

Murray cod hold Special Protection Status under the ACT Nature Conservation Act 2014, and a Murray Cod Native Species Conservation Plan was produced in 2017 to manage the species, with reporting metrics included in the ACT's Conservation Effectiveness Monitoring Program for aquatic and riparian ecosystems.16 The ACT therefore already has a species specific management framework in place, and a stated obligation toward the fish.

The ACT also contains both waterbody types this document is concerned with. It holds a stretch of the Murrumbidgee, a naturally recruiting river, and a set of artificial urban lakes where the cod stock is entirely maintained by stocking.16 That makes it an unusually clean place to trial both policies side by side, in a jurisdiction small enough for the results to actually be monitored.

Precedent for restricting FFS

International

In Switzerland, the canton of Obwalden banned fishing with echo sounders using live sonar technology in 2023, and the same ban applies on Lake Lucerne, where all four cantons bordering the lake agreed to it. The stated reasoning was that real time sonar systems selectively target large fish, and that those fish matter disproportionately to the population because older fish produce more offspring than younger ones.17 That is the same argument set out in Policy One above, reached independently by a European fisheries regulator, and acted on before the effects were allowed to take hold.

Mississippi became the first American state to change regulations in direct response to forward facing sonar, cutting daily crappie limits on Grenada, Sardis, Enid and Arkabutla from 15 fish to 10, and capping boats carrying three or more anglers at 25 fish instead of 40.18 These were water specific decisions, made on named impoundments. In Minnesota, researchers began a multi year program running through to 2029, supported by state environment and natural resources trust funding, examining how angler technologies including FFS affect capture rates and fish mortality across multiple species and lake types.13

Domestic

In Australia we have bait bans in rivers, and trophy trout fisheries where certain fishing methods are restricted. Trout are not even a native species. It is plausible that similar protections, and the creation of isolated waterways where this technology is banned, would follow this existing precedent.

Another key existing law outlining the possibility to create protections for big cod is the illegality of taking anything over 75cm in any waterway.14 While most fish caught using FFS survive and are caught and released, big cod are protected from being taken and should also be protected from the explosion of constant and repeated harassment by anglers utilising FFS.

Methods considered unethical or in misalignment with fair fishing techniques, such as electrofishing, drum nets and set lines, are currently banned. It is not unreasonable to use this as a legal avenue for further restrictions. AFET does not believe that FFS aligns with the principles of fair chase, which include no unfair advantage, an honest approach, respect for the fish, and respect for the resource. We accept that this particular point is a matter of opinion rather than evidence, and we do not rest our case on it. It is included because the same reasoning already underpins existing gear restrictions in Australian fisheries.

What is forward facing sonar?

It is worth being precise about what we are asking to restrict, because the distinction between FFS and every sonar that came before it is the entire basis of this document.

Traditional sonar, including 2D sonar, down imaging and side imaging, produces a scrolling historical record. The image moves across the screen as the boat moves, showing where the boat has already been. It tells an angler that fish were present at a location a moment ago. It cannot show a fish moving in real time, cannot show a lure, and cannot show the interaction between the two.

Forward facing sonar, also referred to as live sonar or live imaging sonar, provides a real time view of fish movement and behaviour around and directly under the vessel.15 The angler sees the fish, sees the lure, sees the fish react to the lure, and can adjust the presentation before the bite. The transducer is mounted so it can be rotated, typically on a trolling motor shaft or a dedicated pole, allowing the angler to sweep the surrounding water and pick out individual targets at ranges up to roughly sixty metres.

The main systems currently available are:

• Garmin Panoptix LiveScope, the platform that brought this technology to the mass market, running through a GLS 10 sonar module paired with a compatible Garmin display. Later generations include LiveScope Plus, LiveScope XR for extended range and open water, and LiveScope 2.19
• Lowrance ActiveTarget and ActiveTarget 2, including the ActiveTarget 2 XL, which offers wide field of view coverage from a single transducer.19
• Humminbird MEGA Live and MEGA Live 2, operating at 1.2 MHz with a range of around 200 feet and connecting directly to compatible displays.19
• Lowrance Eagle Eye 9, an all in one unit released with a starting price of US$999, described by the manufacturer as bringing the same live sonar resolution as ActiveTarget 2 into a single transducer and display package with no separate module required.20

All of these offer forward, down and wide angle modes, marketed variously as perspective, scout or landscape view.

Two points matter for policy. The first is that this is not an incremental improvement on existing sonar. It is a different category of information, and it enables a behaviour, the repeated targeting of a specific identified individual fish, that was simply not possible before. The second is that the cost barrier is collapsing. The Eagle Eye 9 was the first complete forward facing package to come in under one thousand US dollars,20 and the trend is clearly toward cheaper, simpler and more portable units. Any argument that FFS will remain a niche tool used by a small number of dedicated anglers is already out of date.

For the purposes of the policies above, AFET is referring to any sonar system capable of displaying real time imagery of fish and lures at a refresh rate sufficient to observe and track the movement of an individual fish. We are not seeking any restriction on 2D sonar, down imaging, side imaging, chartplotting or mapping.

Appendix: rivers proposed for a complete ban

Avoca River, Balonne River, Barwon River, Beardy River, Bogan River, Broken Creek, Broken River, Campaspe River, Castlereagh River, Chowilla Creek and anabranch system, Condamine River, Darling/Baaka River, Dumaresq River, Edward/Kolety River, Goulburn River, Gunbower Creek, Gwydir River, Kiewa River, King River, Lachlan River, Lindsay River, Loddon River, Macintyre River, Macquarie/Wambuul River, Mitta Mitta River, Moonie River, Mullaroo Creek, Murray River, Murrumbidgee River, Namoi River, Nepean River and Cataract system, Niemur River, Ovens River, Paroo River, Severn River, Wakool River, Wallpolla Creek and connected anabranches, Warrego River, Wimmera River, Yarra River

References

1. Garmin International. LiveScope Ice Fishing Bundle LI — portable Panoptix LiveScope package with swivel pole mount and lithium battery, marketed for kayak and ice use and transferable to a boat. See also the third party kayak transducer pole market, including the RAILBLAZA HEXX Live Pole 60 and comparable telescoping kayak mounts.
2. National Murray Cod Recovery Team (2010). National Recovery Plan for the Murray Cod Maccullochella peelii peelii. Prepared by the Department of Sustainability and Environment, Victoria; adopted by the Commonwealth under the EPBC Act 1999 in October 2010.
3. Department of Climate Change, Energy, the Environment and Water. Draft EPBC Act referral guidelines for the vulnerable Murray cod (Maccullochella peelii). Australian Government.
4. Miles, N.G., Ochwada-Doyle, F., Schilling, H.T. and Crook, D.A. (2023). NSW Stock Status Summary 2023 — Murray cod (Maccullochella peelii). NSW Department of Primary Industries, Fisheries NSW, Port Stephens Fisheries Institute, 16 pp.
5. Rowland, S.J. (1998). Aspects of the reproductive biology of Murray cod, Maccullochella peelii peelii. Proceedings of the Linnean Society of New South Wales 120.
6. Butler, G.L., Davis, T.R., Brooks, S.G., Bowen, C., Cameron, L.M., Rowland, S.J., Smith, D., St Vincent Welch, J. and Carpenter-Bundhoo, L. (2022). Combining bio-telemetry and underwater imagery to elucidate the reproductive behaviour of a large, long-lived Australian freshwater teleost. Journal of Environmental Management 317, 115298.
7. Douglas, J., Brown, P., Hunt, T., Rogers, M. and Allen, M. (2010). Evaluating relative impacts of recreational fishing harvest and discard mortality on Murray cod (Maccullochella peelii peelii). Fisheries Research 106, 18–21.
8. Fisheries Act 1994 (Qld), definition of the precautionary principle.
9. Fisheries Management Act 1994 (NSW), section 3 (Objects of Act).
10. Rogers, M.W., Allen, M.S., Brown, P., Hunt, T., Fulton, W. and Ingram, B.A. (2010). A simulation model to explore the relative value of stock enhancement versus harvest regulations for fishery sustainability. Ecological Modelling 221(6), 919–926.
11. Vertessy, R., Barma, D., Baumgartner, L., Mitrovic, S., Sheldon, F. and Bond, N. (2019). Independent assessment of the 2018-19 fish deaths in the lower Darling. Report to the Australian Government.
12. Sylvia, A. and Weber, M.J. (2019). Use of a mark-recapture model to evaluate largemouth bass delayed tournament mortality. Fisheries Research 219, 105335.
13. Legislative-Citizen Commission on Minnesota Resources (2026). Evaluating impacts of angler technologies on Minnesota fish populations, Draft Workplan 2026-501. Minnesota Environment and Natural Resources Trust Fund.
14. NSW Department of Primary Industries, Fisheries. NSW Recreational Freshwater Fishing Guide — maximum legal length of 75cm for Murray cod.
15. Cooke, S.J., Neely, B.C., Hasler, C.T., Schooley, J.D., Brownscombe, J.W., LaRochelle, L., Danylchuk, A.J., Hunt, T.L. and Norman, J.D. (2025). Emerging live sonar technologies in freshwater recreational fisheries: issues and opportunities. Fisheries 50(2), 66–74.
16. Fisheries Research and Development Corporation (2023). Murray Cod, Status of Australian Fish Stocks Reports, ACT jurisdictional section.
17. Canton of Obwalden (2023). Prohibition on fishing with echo sounders using live sonar technology, extended to Lake Lucerne by agreement of all four bordering cantons.
18. Mississippi Department of Wildlife, Fisheries and Parks (2024). Reduced crappie creel limits on Grenada, Sardis, Enid and Arkabutla reservoirs, effective 24 July 2024, in response to forward facing sonar use.
19. Manufacturer product specifications: Garmin Panoptix LiveScope, LiveScope Plus, LiveScope XR and LiveScope 2; Lowrance ActiveTarget and ActiveTarget 2; Humminbird MEGA Live and MEGA Live 2.
20. Lowrance (2024). Lowrance debuts all-in-one live sonar solution Eagle Eye. Navico Group media release.