7937

• UCREFRP Catalog Number: 7937
• Author: Chart, T. E. and E. P. Bergerson.
• Title: Methods for Long-term Identification of Salmonids
• USFW Year: 1988.
• USFW - Doc Type: A Review.
• Copyright Material: NO

OR (Evenson and Ewing 1985). Retention of the mark
varies greatly in small fish, 50 mm long (Phinney 1966;
Phinney et al. 1967; Hennick and Tyler 1970; White
1976; Strange and Kennedy 1982; Bax 1983).
Evenson and Ewing (1985) reported that the
transparent tissue around (but not in) the eye was one
of the most common and visible areas of pigment
retention - an observation that corroborates the
findings of Andrews (1972) in his work with fathead
minnows (Pimephales promelas). The caudal peduncle
is also a likely location for pigment retention, as
evidenced in tagging work in largemouth bass,
Micropterus salmoides (Englehardt 1977) and in
Chinook salmon and steelhead (Evenson and Ewing
1985).
Moring and Fay (1984) summarized the efficiency of
this tagging method for various species and life stages.
Initial mortality was reportedly low, accounting for
losses of only 0.4% (Strange and Kennedy 1982) and
3.8% (Phinney 1974) in two studies.
There appears to be a sexual difference in mark
retention in Chinook salmon and steelhead, the males of
both species retaining the pigment for the shorter
periods (Evenson and Ewing 1985). These researchers
reviewed possible explanations for this anomaly and
warned prospective users of this tagging method of the
potential shortcoming. Advantages and disadvantages
listed by Moring and Fay (1984) follow.
Advantages
1. Efficient mass marking (Phinney et a1.1967; Mattson
and Bailey 1969; Andrews 1972; Phinney and Mathews
1973).
2. No anesthesia required and low cost (Phinney et al.
1967; Pribble 1967).
3. Low mark-related mortality (Phinney et al. 1967;
Andrews 1972; Phinney 1974; Strange and Kennedy
1982).
4. Ease of use of marking equipment, limited training
required, and simple detection with portable equipment
(R.einjtes 1963; Pribble 1976; McAfee 1980; Bax 1983).
Disadvantages
1. Lack of permutations, which must be considered the
main deterrent associated with this marking ;method;
lack of an external identifier, and need for special
(allthough relatively inexpensive) detection equipment.
2. Less efficient with smaller fish (Mattson and Bailey
1969; White 1976; Strange and Kennedy 1982; Bax
1983).
Dyes and Microtaggants
Subcutaneous injections of dyes and liquid latex were
first tested as a tagging method by Wigley (1952} and
Davis (1955). Microtaggants (color-coded plastic
particles) were originally manufactured by the 3M
Company to identify explosives, tools, and other
equipment. Johns (unpublished manuscript) suggested
using the microtaggants to mark wild animals. In 1985,
Mi:crotrace Incorporated, Minneapolis, MN, began
mainufacturing Microtaggants brand particles (Klan and
Parker 1986), which are small laminated colored plastic
chips up to seven layers thick. The tags are now also
av,Wable with fluorescent or magnetic layers to aid
detection. Smith Root Inc. also manufactures
Collor-coded wire tags that are made with a stainless steel
alloy (magnetically detectable). These tags are
cylindrical (0.25 mm in diameter and 1 mm long) and
were advertised as being compatible with all tag
injection systems.
A variety of chemical compounds and commercial
dyE;s have been injected as fish identifiers (see Moring
and Fay 1984 for details). Short-term retention of some
of these compounds has been excellent (Chapman 1957;
Kelly and Loeb 1964; Lotrich and Meredith 1974; Fay
and Pardue 1985). Moser et al. (1986) also

Species Age or length
(years) (cm) Retention
(%,) Term
(months)
Reference
Coho salmon 0 97-99 12-24 Phinney and
Mathews 1973
Coho salmon 0 9'7 12 Phinney 1974
Brown trout 0 100 20 Strange and
Kennedy 1982
Atlantic salmon 0 100 7
Coho salmon 1 100 29 Duncan and
Donaldson 1968
Chinook salmon 16.6-18.7 95-60 12-54 Evenson and
Ewing 1985
steelhead 21.7 82-80 24-46
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