Improving electrofishing catch consistency by standardizing power


Burkhardt, R. W., and S. Gutreuter.  1995.  Improving
electrofishing catch consistency by standardizing power.  North
American Journal of Fisheries Management 15:375-381.   Reprinted
by the National Biological Service, Environmental Management
Technical Center, Onalaska, Wisconsin, May 1996.  LTRMP 96-R004. 
7 pp.  (NTIS #PB96-183355)


ABSTRACT

The electrical output of electrofishing equipment is commonly
standardized by using either constant voltage or constant
amperage.  However, simplified circuit and wave theories of
electricity suggest that standardization of power (wattage)
available for transfer from water to fish may be critical for
effective standardization of electrofishing.  Electrofishing with
standardized power ensures that constant power is transferable to
fish regardless of water conditions.  The in situ performance of
standardized power output is poorly known.  We used data collected
by the interagency Long Term Resource Monitoring Program (LTRMP)
in the upper Mississippi River system to assess the effectiveness
of standardizing power output.  The data consisted of 278
electrofishing collections, comprising 9,282 fishes in eight
species groups, obtained during 1990 from main channel border,
backwater, and tailwater aquatic areas in four reaches of the
upper Mississippi River and one reach of the Illinois River. 
Variation in power output explained an average of 14.9% of catch
variance for night electrofishing and 12.1% for day
electrofishing.  Three patterns in catch per unit effort were
observed for different species:  increasing catch with increasing
power, decreasing catch with increasing power, and no
power-related pattern.  Therefore, in addition to reducing catch
variation, controlling power output may provide some capability to
select particular species.  The LTRMP adopted standardized power
output beginning in 1991; standardized power output is adjusted
for variation in water conductivity and water temperature by
reference to a simple chart.  Our data suggest that by
standardizing electrofishng power output, the LTRMP has eliminated
substantial amounts of catch variation at virtually no additional
cost


KEYWORDS

Electrofishing, fishing methods, management techniques, power
goal, standardization