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Alaska
Science Center - Biological Science
Office Lake Clark Fisheries Projects Clove Oil |
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Citation: Woody, C. A., J. Nelson, and K. Ramstad. 2002. Clove oil as an anaesthetic for adult sockeye salmon: field trials. Journal of Fish Biology 60:340-347. http://www.idealibrary.com/servlet/doi/10.1006/jfbi.2001.1842 Abstract: Wild migrating sockeye salmon Oncorhynchus nerka exposed to 20, 50 and 80mgl-1 of clove oil could be handled within 3min, recovered within 10min, and survived 15min exposure trials. Fish tested at 110mgl-1 did not recover from 15min exposure trials. Response curves developed for induction and recovery time considered the following predictors: clove oil concentration, sex, fish length and depth. A significant positive dependence was observed between induction time and fish length for 20, 50 and 80mgl-1 test concentrations; no dependence was observed between induction time and length at 110 and 140mgl-1. Recovery time differed as a function of clove oil concentration, but not fish size. A concentration of 50mgl-1 is recommended for anaesthetizing sockeye salmon ranging in length from 400 to 550mm at water temperatures averaging 9-10°C. Copyright 2002 The Fisheries Society of the British Isles Key Words: clove oil; sockeye salmon; Oncorhynchus nerka; fish anaesthesia Introduction Fish
that are the subject of research studies are often handled, and as
a result may suffer stress.
For example, capture by nets or hook and line, subsequent measuring,
fin clipping, collection of scale samples and insertion of identifying
tags constitutes a level of handling that will stress a fish.
The level of stress a fish undergoes may affect the animal’s
immune response and can make it vulnerable to disease.
To reduce handling stress, biologists use a variety of anaesthetics.
Because we are studying wild salmon that Alaskan Natives may
harvest for subsistence, we must use an anaesthetic that is effective
and will not leave any harmful residues in the meat of treated fish. Two
anaesthetics commonly used on fish are carbon dioxide gas (CO2),
and 3-aminobenzoic acid ethyl ester methanesulphonate (MS-222).
Both substances are generally recognized as safe for human
intake. The problem with
these two substances is that CO2 is considered only partly
effective, while fish treated with MS-222 must be held for 21 days
before release to allow the anaesthetic to leave the fishes body.
Because of these drawbacks, we needed to find an alternative
anaesthetis that was both effective and safe for human consumption. Over the last 5 years, clove oil has been studied to
determine if it is effective as an anaesthetic for fish.
It has been used for centuries as a topical anaesthetic for
humans, particularly for dental problems such as infected teeth.
If you look in your wilderness survival kit, you will likely
find a small bottle. It is recognized as safe by the Food and Drug Administration
and shows great promise in the field of fish research. When we began a study which involved radio tagging fish,
we decided to test the effectiveness of clove oil as an anaesthetic
for sockeye salmon.
Results The graph below indicates the relationship between fish length and induction time. The larger the fish, the longer it took for the anaesthetic to work. However, at anaesthetic concentrations of 110 and 140 mg/liter, fish were immediately knocked out. Recovery times (second graph) were variable among groups but averaged about 6 minutes (black line in box) for the 20-80 mg/L concentrations. Conclusions Clove
oil appears to be an effective anaesthetic for use on migrating adult
sockeye salmon. The test
concentrations that best met our efficacy criteria were 20, 50 and
80 mg/liter. For studies
requiring light anaesthesia we recommend 20 mg/liter and for studies
requiring heavy anaesthesia such as surgery we recommend 80 mg/liter.
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