7606

• UCREFRP Catalog Number: 7606
• Author: Negus, M. T., D. A. Belford and S. E. Colvin.
• Title: Long-term Retention of Fluorescent Pigment Marking of Chinook Salmon.
• USFW Year: 1990.
• USFW - Doc Type: St. Paul, MN.
• Copyright Material: NO

INTRODUCTION
Chinook salmon (Oncorhynchus tsha~tscha) comprise
approximately 15% of the angler catch in Minnesota waters
of Lake Superior (D.. Schreiner, MN Dept. Nat. Res.,
personal communication 1990), and Minnesota supplements
that population by annual stocking of 350,000 to 500,000
fingerlings. Assessment of stocked chinook salmon is an
important component of Lake Superior management. Giving
each cohort a unique and readily-identifiable mark would
assist in assessing relative contributions of Minnesota
stocked chinook salmon to the sport fishery, straying and
migration patterns, and relative survival. Identifying
marks must be readily recognizable and retained for the
lifetime of the fish; must be economical; must not
adversely affect survival, growth, or behavior; and must
not increase vulnerability to predators or fishing gear
(Arnold 1966).
Fin-clipping has been the traditional marking method
for chinook salmon, and excision of the posterior portion
of the maxillary bone is becoming more popular. These
techniques require no specialized marking or identification
equipment, but they are labor-intensive when marking large
numbers of small fish. Differential survival and growth of
clipped fish may confound data interpretation (Weber and
Wahle 1969; Nicola and Cordone 1973; Phinney 1974). Fin
regeneration, particularly in fish clipped at a small size,
has also been noted (Shetter 1950; Hale 1954; Mears 1976)

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