Tech Talk 79
Fish tags can be useful in fisheries research, as well as broodstock management. When used with proper record keeping, tags can keep track of sex, age, genetic line, year class, dispersal patterns or that the fish's name is "Bob."
Making a good tag consistently can take some practice, but the following general procedure can be followed for most species of fish. The goal is to set the "hook" of the tag into the dorsal fin rays that extend into the musculature of the fish. This means you should actually feel the bone when setting the tag.
- Hold the fish firmly in the swimming position when it is tagged to reduce movement. Anesthetized fish should be held firmly as well. Squirming fish can bend the needle and cause injury.
- Using the needlepoint, lift up a scale on the left side of the fish and insert the needle at the anterior (forward) base of the dorsal fin, forcing it forward through the dorsal rays.
- Once the needle is inserted, hold the gun firmly against the fish's body while compressing the handle firmly.
- Twist the gun slightly and remove the needle. DO NOT RELEASE THE COMPRESSED HANDLE UNTIL THE NEEDLE HAS BEEN WITHDRAWN. Once withdrawn, release the handle slowly to make certain the next tag is fed into position for tagging. Failure to do so may cause feed mechanism to skip.
- Tug the tag lightly to set.
One final note: disease transmission can be a concern when tagging fish. To minimize risk, swab the needle with rubbing alcohol, iodine, etc., after each tag.
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