Contribution of ilatchery and Natural Chinook Salmon to the Upper
St. Mary's River Fishery

Steven M. Diekema
School of Science and Natura1 Resources
Lake Superior State University
Sau1t Ste. Marie MI 49783

Abstract: Chinook Salmon (Oncorhynchous tshawytscha), were sampled from the St.
Mary's River during the fall of 1996 to determine the contribution of hatchery and
naturally reproduced fish. Fish stocked by the Ontario Ministry of Natural Resources
(OMNR) had right ventral fin clips and fish stocked by the Michigan Department of
Natural Resources (MDNR) were marked with oxytetracycline (OTC). Fish were
sampled from the St. Mary's River using two different collection methods: at a salmon
derby and gillnetting. Upon collection, fish were checked for fin clips and tails were
removed from every fish. Tails were frozen until time allowed for two vertebrate to be
extracted from each tail. Vertebrate were placed under a dissecting scope and ultraviolet
light was reflected off the vertebrae to determine the presence of OTC. Of the 123 fish
collected, 39% were stocked by the MDNR 19% were stocked by the OMNR and 42%
were of unknown origin (naturally reproduced or hatchery fish that lost or had no
markings). A total of 58% of all chinook salmon sampled were of hatchery origin. This
assessment is a follow-up assessment to one done in 1995 in which 80% of sampled fish
were of hatchery origin. Chi-square difference in proportions analysis indicated a
significant difference (z=3.80) between the contribution of hatchery-reared fish. With
such high percentages of sampled fish being of hatchery origin the MDNR should
continue stocking chinook salmon into the St. Mary's River to maintain the sportfishery.

Selected References

Weber D. D. and G.J. Ridgway. 1962. The deposition of tetracycline drugs in bones
	and scales of fish and its possible use for marking. The Progressive Fish-Culturist
	24:150-155.

Hesse J. A. 1994. Contribution of hatchery and natural chinook salmon to the eastern
	Lake Michigan sportfisherv. Master's thesis, Michigan State University, East
	Lansing MI.