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Electrofishing for crappies: Electrical settings influence immobilization efficiency, injury, and mortality

North American Journal of Fisheries Management

By:
, , and
DOI: 10.1577/1548-8675(2002)022<1442:EFCESI>2.0.CO;2

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Abstract

Continuous direct current (DC) and pulsed DC (PDC) of varying frequency and pulse period are commonly used to immobilize and collect crappies Pomoxis spp. in freshwater. However, little information is available about the minimum electrical-setting thresholds required for immobilization or how the settings relate to incidence of injury. We investigated the effect of increasing power densities on the immobilization and injury of black crappies P. nigromaculatus (average total length = 154 mm) treated with DC and various PDC settings. Forced swimming toward the electrodes was observed in black crappies exposed to DC, but that was less apparent for PDC. The minimum peak power densities required to immobilize black crappies ranged from 0.10 to 6.5 mW/cm3 and depended on pulse frequency and period. The incidence of hemorrhaging ranged from 0% to 50% and that of spinal damage from 9% to 45%. However, the severity of injury also depended on pulse frequency and period. No fish suffered mortality at or below the immobilization thresholds, but mortality ranged from 0% to 15% at settings above the thresholds. Mortality was observed with PDC settings of 15 Hz only. Fish that were tetanized following electrical treatment were more prone to injury than those that exhibited narcosis.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Electrofishing for crappies: Electrical settings influence immobilization efficiency, injury, and mortality
Series title:
North American Journal of Fisheries Management
DOI:
10.1577/1548-8675(2002)022<1442:EFCESI>2.0.CO;2
Volume
22
Issue:
4
Year Published:
2002
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
North American Journal of Fisheries Management
First page:
1442
Last page:
1451