Tagging or marking animals has long been an accepted biological method for monitoring wildlife; birds are banded on their legs, black bears and grizzly bears carry radio transmitters, as do sea turtles. Even monarch butterflies have been banded with delicate mylar patches. The reason for doing this is to tell one creature from another so its daily movements or seasonal migrations can be studied and rates of growth can be learned.
Using various marking methods, scientists have found the wintering grounds of the monarch butterfly in Mexico, pinned down the summer and winter ranges of polar bears, arctic terns, and red knots, and the breeding grounds of some marine turtles. Fish marking or tagging is also an accepted method of study. Sometimes marine biologists clip fins of stocked fish to keep track of them. Shortnosed sturgeon, an endangered species, have swum in their coastal river haunts with radio transmitters telling all. For studying menhaden (pogy), an internal metal tag has been used, to be picked up by a magnet at the processing plant where the fish are ground and cooked.
Tagging is even more important for fishes because, unlike other animals, they spend almost their entire lives out of the sight of the researchers trying to learn about them. For example, biologists may need to find out the movements of striped bass after spawning in the Nanticoke River, a tributary of the Chesapeake. To help find out, they would set nets in the river after spawning and then capture, tag, and release 1000 striped bass, and track returns on these fish during the rest of the season into late fall. Likewise, fisheries biologists on the West Coast would tag salmon from selected streams and watch for those salmon to return to their natal streams to spawn 2-5 years later. With enough tagging data, they could estimate the percentage of fish that returned and gauge a mortality rate for the fish spawned in that stream.
Our tagging program aids scientists, too. All of our tagging data are transferred to the database of the National Marine Fisheries Service Laboratory in Woods Hole, MA. When you tag a fish for the American Littoral Society, you can be sure the information gained is put to good use.
You can learn about specific ways the data our taggers collected is being used to preserve fish and fishing on the following pages.