Walker, M. K., Yanke, E. A., and Gingerich, W. H., 1994, Use of electronarcosis
to immobilize juvenile and adult northern pike: The Progressive Fish Culturist, v.
56, no. 4, p. 237-243.

Abstract

Electronarcosis, the immobilization of a fish after an electric current has been
applied and discontinued, is a potential alternative to chemical anesthetics.
Successful narcosis was defined as the immobilization of a fish for 1-15 min
without causing physical damage. In the laboratory, AC successfully narcotized
juvenile (13-19-cm standard length, SL) northern pike (Esox lucius) at selected
voltages; however, AC voltages that produced narcosis or resulted in physical
damage were variable and unpredictable. In contrast, 60-90-V pulsed DC (PDC)
for 10-60 s successfully narcotized juvenile pike without inducing physical
damage. Duration of narcosis was directly related to voltage and inversely related
to fish length. In the hatchery, sexually mature northern pike (45-97 cm SL),
collected from the Mississippi River, were successfully narcotized by 60-V PDC
for 10 s. Duration of narcosis was unrelated to fish length or sex, and averaged 58
plus or minus 7 s (mean plus or minus SE). This allowed sufficient time to collect
eggs or milt. All fish were swimming upright within 3 min after treatment, and no
mortalities were observed over the next 24 h. Survival of eggs from fertilization to
eye- up did not significantly differ between eggs collected from electronarcotized
adults and adults anesthetized with MS-222 (tricaine methanesulfonate).
Electronarcosis represents a possible alternative to chemical anesthetics for
immobilizing northern pike broodstock without an apparent impact on egg
survival.

Keywords

anaesthetics-, electrified-gear, stupefying-methods, stocking-organisms,
hatcheries-, freshwater- aquaculture, sublethal-effects, Esox-lucius,
comparative-studies, fish-culture, fish-handling