Electrofishing is a primary sampling method for near-shore fish species in lakes and rivers, and for fish species and assemblages in streams. We must admit, however, that it is a sampling technique with inherent risks. People, water and electricity are in close proximity. This blog describes the potential for human injury or death if someone falls into water having an electrical field. It specifically involves boat electrofishing, but the same idea can be used for tow/push barges, shore-based units and backpack electrofishing.Continue Reading..
Testing equipment, particularly current clamps and scopemeters, have a substantial role to play in electrofishing sampling programs. I was first introduced to this notion years ago by A. Lawrence (“Larry”) Kolz and Jim Reynolds, two people that made substantial advances in the conceptual basis for electrofishing. Since then, Jan Dean and I have used test equipment in a number of situations, built Excel-based programs to utilize collected information, and have worked on identifying inexpensive yet accurate meter alternatives.
In this blog, I will attempt to describe purposes of testing equipment, some approaches and considerations regarding their use, share a few of our test results, and provide a list of suggested models.
Overall resistance of an electrofishing system is determined by the combination of ambient water conductivity and the electrodes. The electrode shape, number, length or size, diameter of stock material, configuration and spacing affect both their overall resistance and the profile of the electrical field in the water around the electrodes. Rarely are there data available for assessing the effects of electrode changes on resistance or on fish catch. This blog presents some empirical results from field measurements of electrode resistance before and after some electrode changes.
Of all the environmental variables which affect electrofishing success, the one for which the most is known, and indeed it has been said is the most important, is water conductivity. This article explores the how and why of conductivity in electrofishing.
Selection of appropriate gear types and models is frequently a difficult task. Often decisions are made with little basis. Here we highlight some factors that we think should be considered when selecting or purchasing electrofishing gear.
Determining water conductivity is critical to improve the efficiency and precision of electrofishing sampling, for electrode design, and even as an input to deciding which control box model to purchase or which equipment type to use. Water conductivity has much more value than simply a number placed in a table for completeness. Reasonably accurate measurement of water conductivity is essential.
Temporary immobilization of fish by electricity (“electroanesthesia” or “electrosedation”) is becoming more common in fisheries work.
Electroanesthesia makes easier handling fish for tag-implantation, spawning, measurement, and other processing tasks.
Dr Alan Temple introduces the key concepts and methods of operating various backpack electrofishing units.
Dr Alan Temple introduces the key concepts and methods of assessing the safety of boat electrofishing units.