Michigan Department of Natural Resources
Research and Development Report No. 182
Institute for Fisheries Research Report No. 1757, 1969
Tests on Trout Mortality from a Battery-powered Stream Shocker
David S. Shetter, Gaylord R. Alexander, and Leonard N. Allison
On 4 June 1969, we tested the latest model of stream electrofishing unit, designed by Mr. Clinton H. Harris. This unit is powered by two 12-volt auto batteries; these plus the control unit can be carried in a light boat. The objective of the test was to determine whether this new unit caused significant mortality of trout when subjected to an amount of current typical of ordinary stream electrofishing.
Mr. Harris gave us further information on the characteristics and capacity of this new shocker, in a letter of 10 August to G. P. Cooper, quoted in part as follows:
The pulses produced by the subject shocker are rectangular in form with a duration of approximately 1.6 milliseconds and a repetition rate of approximately 45 pulses per second.
In the “High” setting, the maximum available voltage is 300 volts and the maximum available current in 4 amperes.
In the “Low” setting, the maximum available voltage is 150 volts and the maximum available current is 4 amperes.
In any given situation, the voltage and current is a function of the resistance across the electrodes. The output is current-limited so that the shocker adjusts itself to the operating situation within the limits of the maximum available voltage and current.
I very much appreciate the work the Messrs. Shetter, Alexander, and Allison did in investigating any possible mortality arising from the use of this type of shocker. We can now go ahead and ask Ed Schultz to build these units for the Department use without fear of mortality resulting from their use in the field.
During tests described below, the control unit was operated at the “Low” setting, with the maximum available voltage of 150 volts and maximum available current of 4 amps (see above).
Other pertinent physical-chemical data on the East Branch are given in a report by Urshel and Hooper (1961). Samples taken by them just above the hatchery ponds, on 2 September 1961, gave the following analyses: on-site temperatures at 2:30 PM, air 68 F, water 54 F; dissolved oxygen 9 ppm; CO2 0 ppm; methyl orange alkalinity 155, Ph-th 6.0 ppm; pH 8.2; conductivity 256 µmho (Micro-ohms) at 18 C.