DIFFERENTATION OF STOCKED FORM WILD
WALLEYE BASED ON OTOLITH MARKINGS

KURT A. HOFFMAN
SCHOOL OF SCIENCE AND NATURAL RESOURCES
LAKE SUPERIOR STATE UNIVERSITY
SAULT STE. MARIE, MI 49783 U.S.A.

Abstract. -Differentiation of stocked and natural fish is important to
evaluate the success of stocking programs. Usually this is done by tagging
with microtags, floy tags, and fin cups. I looked at otoliths markings as a
possible way to differentiate between stocked and wild walleye. Walleye
from a farm pond were brought into the Lake Superior State University's
Aquatics Lab, simulating there release into the wild. Otoliths were taken
34d and 62d after there introdtiction to the lab. An identifiable mark was
observed on all the otoliths. Next, wallleye were collected from two lakes,
one with no stocking and the other with no natural reproduction . The
walleye were randomly numbered and the otoliths prepared. The walleye
were than identified as stocked or wild based on otolith markings. 33
walleye were identified, 21 wild and 12 stocked. 19 ofthe 21 wild and all
the stocked walleyes were identified correctly. 94% ofthe fish in the
experiment were correctly identified. I conclude that differentiation of
stocked from wild walleye based on otolith markings may provide an
accurate measure of stocking success. However, more research into this
method needs to be done.

SELECTED RFFLRFNCES

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Schmidt, R.F. and Fabrizio. 1980. Daily growth rins on foraging
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