A: Jason Barnucz, aquatic science biologist with Fisheries and Oceans Canada, responds: there are several ways to dispatch fish that are accepted in the scientific community. In today’s fisheries, professionals follow strict animal-use protocols to ensure specimens are handled properly at all stages of fisheries surveys. A lot of fisheries research/monitoring involves the release of live animals after being caught and measured, but euthanasia is still, however, part of fisheries research.
The American Fisheries Society recommends cold shock and electrical
shock. These are commonly used for preparing fishes for processing. Small numbers of fish can also be euthanized by exposure to relatively
high concentrations of anaesthetics such as MS222; however, the use of MS222 and other chemical anaesthetics as euthanizing agents has not
been approved officially by the FDA or Health Canada. This is a concern,
as some fish (i.e. game fish) may be caught and consumed after release by
anglers and we don’t want anglers to be exposed to fish anaesthetics.
We regularly use a clove oil bath to anaesthetize fish and this same
bath can also be used to euthanize fish, if fish are left long enough.
In all of these processes careful monitoring always takes place.
Spinal cord dislocation or decapitation are also generally acceptable
methods, provided the procedure is performed quickly and accurately.
For anglers, I would recommend a cold shock bath to euthanize fish, as
mentioned above. The bath is prepared quickly by an angler before a trip,
while keeping fish fresh and easy to prepare at the end of one. The
use of a “preacher” or “fish bonker” may be used to dispatch fish quickly
as well. A swift blow to the head/top of spine on most game fish species
is furthermore effective.
Originally published in the 2019 Fishing Annual (March) edition of Ontario OUT of DOORS magazine