tag, which sends the unique code back to the reader, allowing biologists to identify the individual fish.
The most advanced type of tag in use is a radio or sonic transmitter. Transmitters vary in size, depending on the size of fish they will be used with and the length of time biologists need the tag to transmit the signal. In most cases, the transmitter is surgically implanted into the fish’s body cavity. Each transmitter emits a signal that allows biologists to find and follow an individual fish to determine movement, habitat use and behavior.
Many fisheries projects incorporate the use of visible tags. In these studies, biologists rely on anglers to provide information about the tagged fish when they catch them.
The most commonly used visible tag is the T-bar, or spaghetti tag. This tag is similar to tags used to mark clothing in many stores. A special tagging gun is used to attach the tag near the fish’s dorsal fin. The “T” part of the tag serves as an anchor to hold the tag in place. The visible part of the tag can be a variety of colors and includes a unique number that identifies the fish and contact information for reporting the tag.
Another commonly used visible tag is the dangler tag. Dangler tags are the size of a large medicine capsule and are attached near the fish’s dorsal fin by a pair of thin wires. This type of tag also includes an individual fish number and contact information.
What Do We Learn?
When anglers report catching tagged fish, biologists gain information about those individual fish and the information can be applied to the rest of the population. We learn how fast fish grow, how far they move and how long they live after tagging. Visible tags returned by anglers help us estimate the number of fish that are caught and harvested, allowing us to better manage these populations.
When you report catching tagged fish, we also learn a little about you! We learn what species of fish you like to fish for, where you like to fish and what size of fish you like to keep. The information you report helps us better manage the fish population for the species and size of fish you like to catch.
While we are never surprised to hear that a tagged river or stream fish is no longer in Missouri,