Setting Doses for Lab Experiments

Experimental set-up for small fish. Picture by Dr. Jan Dean

Lab or tank experiments on fish have been around for decades, beginning with studies of fish behavior in electric fields.  Presently, tank experiments are used for evaluating the effectiveness of candidate waveforms, estimating thresholds for various reactions that assist capture, guidance, and electrosedation, and determining probability of trauma.  While insights gained by lab work, in combination with field trials, can and have improved fisheries sampling and provided insights for risk analysis, there are pitfalls that can sink the ship.  A couple problems that often occur are the rationale for setting dose levels and the actual description of dose levels.  These issues can lead to misinterpretations, inappropriate management decisions, and constrain application of experimental results.  In fact, dose setting is becoming a big issue in electrofishing experimentation.  I have seen studies lately that have used incredibly high doses, in fact extreme overdoses, preventing a connection from the lab to application in the field.  I think the results of those studies are relatively meaningless.  And, most of the disconnect is due to a poor understanding of electric fields generated by common sampling gears and typical exposure times while electrofishing.

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Boat Electrode Changes: Effects on Resistance

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.

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Ambient or specific conductivity?

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.
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Selection of Electrofishing Equipment

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.

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Considerations for Water Conductivity Meters

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.

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Fish Handling Gloves

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.

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PNAMP Electrofishing Method Template

The Pacific Northwest Aquatic Monitoring Partnership (PNAMP) has produced an Electrofishing Method Template to help standardize how sampling is reported across the region. Researchers can use the template to upload information on their sampling and contribute to the project. The template was originally developed to be customizable in, a website designed to provide consistent documentation of protocols and methods used in research and monitoring.

Download the template PDF

Contact Katie Pierson for more information:
Pacific Northwest Aquatic Monitoring Partnership

Free safety presentation

This PowerPoint file contains the information you need to electrofish safely. It is the very first step in starting electrofishing. Developed by Alan Temple, U.S. Fish & Wildlife Service.

Download the file.



Smith-Root training course, Washington, Feb 2016

This is a two-day class being held at Smith-Root headquarters in Vancouver, Washington. Continue Reading..

Australian Code of Electrofishing Practice

The Australian Code of Electrofishing Practice is a non-legally-binding series of guidelines for fisheries researchers and managers. It covers all elements of operating electrofishing equipment under Australia conditions.

Download the Code.

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