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Electroshock‐Induced Injury and Mortality in the Spotfin Chub, a Threatened Minnow
Author(s) -
Michael Holliman F.,
Reynolds James B.,
Kwak Thomas J.
Publication year - 2003
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/m02-052
Subject(s) - electrofishing , minnow , zoology , fish <actinopterygii> , biology , threatened species , chemistry , fishery , ecology , habitat
The effects of AC and pulsed DC (PDC) electroshock on mortality and injury (vertebral damage and hemorrhage) of spotfin chub Cyprinella monacha , a threatened minnow, were evaluated in a laboratory experiment. Groups of 18‐20 captive‐reared fish were either designated as a control or exposed for 3 s to one of five electrical treatments (60‐Hz AC at a peak‐to‐peak voltage gradient of 1.7, 2.5, or 3.3 V/cm or 60‐Hz PDC at a peak voltage gradient of 2.5 or 5.0 V/cm). Immobilization, which renders fish susceptible to capture during electrofishing, was the predominant response evoked in the groups exposed to electroshock, with the exception of the 1.7‐V/cm AC group. No injury was detected in any fish in the experiment. Mortality was 10% or less in groups exposed to AC, regardless of voltage gradient. There was no significant variation in mortality among the groups exposed to AC ( P = 0.487‐1.00). Mortality varied significantly in the groups exposed to 60‐Hz PDC (2.5 V/cm (0%) versus 5.0 V/cm (25%); P = 0.047). Our results indicate that electroshocking with 60‐Hz AC and 60‐Hz PDC may be safe for capturing spotfin chub when voltage (thus, voltage gradient) is limited to the immobilization threshold and the exposure period to 3 s. However, AC should be used only in low‐conductivity waters (e.g., <80 μS/cm).