Centre Québécois Sur la Santé des Animaux Sauvages/Canadian Wildlife Health Cooperative, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
Electro-immobilization involves the passage of a low-voltage electric current through the body of a fish to induce tonic immobility. Handling glovesa wired to an electric current generator have been developed to facilitate fish handling. Although the use of such gloves has been advocated as a no-residue alternative to chemical immobilization for field studies, the impact of this method on fish welfare remains uncertain. The effect of using electro-immobilization gloves on stress and muscle integrity following a five-minute handling of brook trout (Salvelinus fontinalis) was compared to immersion anesthesia (60 mg/L buffered tricaine methanesulfonateb) and manual restraint using blood markers (six fish per group). Electro-immobilization was associated with an increase in post-procedure plasma lactate and creatine kinase levels compared to immersion anesthesia. Increases in plasma cortisol concentrations were observed in all three groups one hour post-procedure, followed by a return to basal concentrations within two hours in the immersion anesthesia group, but not in the manual restraint and electro-immobilization groups. Respectively one and two individuals from the manual restraint and electro-immobilization groups died or were euthanized due to unresponsiveness or prolonged loss of the righting reflex. This study suggests that five-minute immobilizations of brook trout with electro-immobilization gloves induce a higher stress level and cause more muscular damage than immersion anesthesia. All fish developed secondary cutaneous saprolegniosis most likely due to damages to the mucus layer associated with the absorbent nature of the conductive gloves. These gloves are not recommended for the handling of brook trout in the conditions tested.
a. Electric Fish Handling Gloves, Smith-Root, Vancouver, WA, USA
b. TMS, Syndel, Nanaimo, BC, Canada
Financial support for this project was provided by the Fonds du Centenaire (Université de Montréal). We would like to thank the Station piscicole de Baldwin and Smith-Root for their collaboration with this project.