Electrofishing is a valuable fish sampling tool that has many benefits over conventional netting methods, including allowing the capture of a range of species that are otherwise often missed or rarely caught. Electrofishing units are either boat-mounted, bank-mounted or carried by an operator as a backpack. Electrofishing involves passing an electrical current through water, stunning fish so that they can be netted and processed. Fish recover quickly, and are released back into their environment. Until now, the use of electrofishing units have been limited to freshwater or areas of lower salinity. As the salinity of the water increases, so does the demand on power needed to maintain a suitable electrical field; it is this power demand that has been the limiting factor in existing electrofishing units.

ARI, working closely with German electrofishing manufacturer Hans Grassl, have developed a prototype boat-mounted electrofishing unit that has the capacity to operate in saline environments such as estuaries. Over the past five years, ARI has tested this prototype electrofishing boat in a range of water salinities to identify and solve any technical problems.

This innovative electrofishing unit will enable more thorough studies of estuaries to be conducted, and will help fill a significant gap in worldwide fish research. It will enhance the collection of ecological information which will provide knowledge to improve biodiversity conservation in high salinity environments. This tool has significant potential to improve environmental monitoring and assessment of environmental flows, connectivity and habitat associations. In particular, it will be a valuable tool for assessing key recreational species such as Black Bream, Estuary perch and Flathead throughout Victorian estuarine systems.

Electrofishing with a backpack unit

he Grassl electrofishing unit in operation in the Nicholson River estuary

For more information contact: jason.lieschke@delwp.vic.gov.au

The following journal article on electrofishing in estuaries is available:

Warry, F.Y., Reich, P., Hindell, J.S., McKenzie, J. and Pickworth, A. (2013) Using new electrofishing technology to amp-up fish sampling in estuarine habitats. Journal of Fish Biology. 82(4): 1119-1137

A short video titled "Grassl Saline Electrofishing Boat" is available on the DELWP YouTube channel, and can also be viewed below: