Determining electrofishing response thresholds of smallmouth bass (micropterus dolomieu), flathead catfish (pylodictus olivaris), and blue catfish (ictalurus furcatus)
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We examined the response to electrofishing of three Missouri sportfish: Smallmouth Bass, Blue Catfish, and Flathead Catfish. We had three objectives for this research effort: 1) determine the effective conductivity of each species and whether this value differs from recommended values; 2) determine the effect of waveform, fish size, and water temperature on capture-prone response thresholds of each species; and 3) develop power goals and sampling recommendations for each species. We found that the effective conductivity of Smallmouth Bass was 123μS/cm, which is near the previously used estimate (115μS/cm), so existing goals may be adequate. For Flathead Catfish, we estimated an effective conductivity of 69μS/cm. For Blue Catfish, we estimated an effective conductivity of 94μS/cm. We recommend using the average of these two estimates to develop power goals. We tested 12 waveforms for each species, using a different set of waveforms for Smallmouth Bass than for catfish. For Smallmouth Bass, waveform had little effect on response thresholds and suggest that current methods using a waveform of 60/25 are appropriate for sampling, assuming the response thresholds are related to conductivity. For catfish, although differences among waveforms were present, we were unable to identify a particular waveform that was more effective, so more research is needed. However, we recommend the use of the current standard waveform, 15/30, as this tended to have a reduced length effect relative to other waveforms.