Lord Farday fishing the Macquarie River, NSW with generator cowling removed.

The hull is a 3.4m v-nosed aluminium punt design, custom built by Chris Veal and his team at Baldwin Boats, Mildura, Victoria with input from Clayton Sharpe at the Murray-Darling Freshwater Research Centre. Powered by a 50HP 4-stroke Mercury and featuring the following luxuries, the boat is faster and much more stable (albeit no lighter) than the rather agricultural design of FRV PoleVolt:

• insulated generator shroud;
• side console steering with electric tilt & hydraulic steering;
• electric generator start wired into console;
• integrated live-well with fill-pump, overflow outlet, side-drainage and carpeted cover;
• deck wash;
• navigation, deck & spot lights for night fishing;
• 12V accessory port for charging your 3G iPhone (safety first); and
• an OH&S-lovers bow gate (my personal favourite – so civilised!).

On the plane in the Macquarie River, near Warren, NSW.

Burke O’Neill, director of ETS Electrofishing, supplied the MBS-1DP-COL-SR high-peak current control box, developed by Colton Perna for Australian conditions. This unit is designed for nominal 240 VAC, single phase, 50 Hz operation, from a portable alternator – in this case supplied by a 6.5 KVA Honda from Powerlite – and is capable of delivering 4.8 KVA to the electrode system. Unlike the standard MBS-1D, the safety interlock pad/switch on the COL-SR may be used to directly switch the high voltage output on and off without resetting the front panel START/RESET button. In laymans terms, this combines with the full ETS volt and amp metering to provide more effective and efficient fishing than the 5.0 GPP Smith-Root systems. It’s also about 2/3 the price and user serviceable!

Fishing the Warren Weir pool, Macquarie River, NSW.

Colton Perna completed the wiring of the boat to meet the rigorous Australian standards (which I will post in our resources section the near future), with waterproof safety switches and the ubiquitous quick-release anode fittings. The anode themselves are a relatively new design aimed at eliminating the hassle of setting-up the industry standard Wisconsin arrays – droppers can simply be clipped on and off using the stainless carabiners to change electrode resistance. A new, finger-friendly system of  anode attachment and rotation system, designed by Clayton Sharpe, is also fitted – instead of drop-in holding pins, two frilled circular plates mesh together under a large circular nut which can be adjusted while wearing gloves.

A tagged Murray Cod about to be released.

Our biggest teething problems have been with the trailer. Baldwin Boats supplied a Dunbier trailer, with beefed-up leaf suspension and a third-wheel. This set-up is perfect for launching recreational boats on standard concrete ramps into deep water. However, as any freshwater field technician knows, in the world of research these facilities are available at about 5% of sites visited. On the steep, muddy banks of Western NSW, retrieving Lord Faraday is quite an undertaking, especially if the trailer and boat need to be retrieved from the bottom of a steep bank separately (as is sometimes the case) – the extended corners of the front deck mean that the trailer has to be tilted skyward and the boat scooped onto the trailer, otherwise the deck corners smash into the trailer lights. The deck is also wider than the side skids which hug the hull once the boat is fully retrieved. Lastly, the roller adjustment stems hang down too far, which reduces 4WD clearance dramatically for no reason. We’re currently adjusting the set-up to resolve these issues.

A 3rd wheel winch launch at Warren Weir, Macquarie River, NSW.

Overall, Lord Faraday presents a big step forward in small boat design for Australian river and wetland electrofishing operations. So many great features have been packed on board, while still providing ample space for other gear and a 2- or 3-person crew. Once adjustments to the trailer are complete, I think one would be hard-pressed to find a slicker unit on Australia’s waterways (mind you, I’m slightly biased).

The software is essentially a Microsoft Excel file with a series of macros which enable users to calculate their power outputs given their gear specification and settings. Version 1.41 includes a revolutionary equipment capacity page which begins to answer the question that all electrofishing users should be asking, ‘Can my equipment actually catch the fish that are here?’.

Download the manual.

Download the software.

For many practicioners, however, electrofishing remains very much a dark art. This is understandable given the “very dynamic and complex mix of physics, physiology, and behavior” at play, but we must not fish without thinking. We must not fool ourselves into a false sense of security regarding (a) the scientific validity of our sampling or (b) the potential effects on fish health. Instead we must ask: are we hurting fish; if so, how so; and, if so, is the level of harm justifiable when compared to other gear types and the positive conservation outcomes?

In his 2003 report, Darrel Snyder, Colorado State University, began answering some of these questions, by first detailing the mechanics of electrofishing using field and power transfer theory, together with fish models. He then investigated the evidence relating to fish injuries in two main categories, non-spinal internal injuries and spinal injuries, and reviewed the response thresholds for various North American species, mostly salmonids. He found the latter group to be particularly susceptible to alternating currents. Direct current (DC) and low frequency pulsed DC (<30 Hz, the lower the better), in contrast, caused fewer spinal injuries and hemorrhages (p.98).

Hemorrhages and associated tissue damage in a rainbow trout (source: N. G. Sharber).

Snyder also discussed the relationship between the spatial characteristics of electric fields and fish injuries. He suggested that reducing the area of most intense power (near the anode/s) may not reduce fish injuries, if the threshold for injury is, in fact, occurs at much lower powers (i.e., towards the outside of the field where fish exhibit a twitch response). He concludes:

Except in very severe cases, electrofishing injuries in fish heal and seldom result in immediate or delayed mortality. Instead, most electrofishing mortalities appear to result from asphyxiation due to extended tetany or poor handling. However, electrofishing injuries may significantly reduce subsequent growth, at least until they fully heal. When sufficiently severe, spinal injuries may affect physical appearance or swimming ability. Still, even for highly injury-susceptible species, such as the salmonindae, significant effects at the population level are unlikely except in the case of very small or very extensively and intensively sampled populations, as is sometimes the case for threatened and endangered species.

Electrofishing is a valuable tool for fishery management and research, but when resultant injuries to fish are a problem and cannot be adequately reduced, we must abandon or severely limit its use and seek less harmful alternatives. This is our ethical responsibility to the fish, the populace we serve, and ourselves.

Like the subject matter itself, Snyder’s text is complex. But, for experienced practicioners wanting to be more honest with themselves, this report is a great place to start. Can you address the knowledge gaps identified by Snyder as an add-on to your existing sampling?

Download Snyder’s report here.

The top photo shows a dorsal view X-ray of a rainbow trout revealing spinal fracture caused by electrofishing (source: N. G. Sharber).

Fishing a small waterhole in the Macquarie Marshes, NSW. Note the anode arrays being supported by the safety railing. They're attached with an ingeneous swivel mech.

The hull is a flat-bottom punt, around 4m long. The Smith Root control box is mounted in a rather tall stainless cabinet in front of the driver, who sits on a luxurious padded chair – within easy reach of the 15hp Johnson tiller, generator pull start and choke, and digital sounder unit. The dip-netter stands on the raised foredeck (which provides bonus below-deck storage), protected by a safety railing (which also supports the anode poles via adjustable rope or chain fittings).

The dip-netters view looking aft. Space is at a premium on a craft of this size.

Most of the electics (including two deadman switches) are wired topside for easy access, encased in protective conduit. The generator exhaust is piped outboard to port, away from the crew. Fish are looked after by a large livewell in the centre of the boat, complete with a custom environet and a 12V bildge pump system for easy filling, aeration and drainage.

Livewell detail, showing spray bar and custom net on stainless railing.

On the water PoleVolt handles well, steers predicatbly (if a little slugishly) and is sturdy enough to take hard, consistent abuse (much like her crew). There’s enough room for plenty of gear, although it needs to be suitably protected from the water which sloshes up and down the deck. The railing can be removed to negotiate obstacles, but the complete boat is rather heavy and difficult to maneuver if man-handling is required – portages are out of the question under most circumstances, with frequent re-launches often more efficient.

Launching PoleVole on the Macquarie River, near Warren, NSW. Note the winch cable and 5th wheel in use. Here the outboard is tilted up to avoid bottoming-out and the anode poles are swung back in transport mode. They're made from fiberglass poles, reinforced with steel bars.

One of the best features, however, is the bomb-proof trailer. It has full suspension, with coil springs, rather than flimsy leaves. Reinforcing is everywhere, but the jockey wheel set-up leaves a lot to be desired (especially given the whole set-up is so heavy).

Coupled with a large 4WD, the strong trailer allows for some remote fieldwork. Here we're heading home after a day in the Macquarie Marshes, NSW.

As with any working vessel, PoleVolt is constantly evolving. New Technicians adjust the set-up, making slight improvements every time. I’m sure she’ll continue to perform for the NSW DPI crews for years to come.

An adult golden perch caught in the Macquarie River, tagged and about to be released.

These include:
- backpack units;
- gas-power v. battery power;
- shore-based fishing;
- tow-barges;
- catarafts;
- electric seines;
- pre-positioned area units; and
- diver-operated units.

It doesn’t provide extensive detail on boat mounted units.

Download the Electrofishing Systems Teaching Module (2.9MB)

The aims of the module are to:
- Appreciate need for safe working environment;
- Discuss the value of safety policy documents; and
- Describe approaches to improve safety at electrofishing projects (including an employee safety program).

Download the Electrofishing Safety Teaching Module (1.2MB)

Download the Australian Code of Electrofishing Practice