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Why Tag Fish?
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.
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