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

they were no longer visible (Evenson and Ewing 1985).
Ware's (1968) work with largemouth bass suggested increased
mark loss in fast growing fish; the growth rate of chinook
salmon is faster still, which may contribute to pigment
loss. The greater retention of pigment granules by female
chinook salmon than males corresponds to the findings of
Evenson and Ewing (l985), who attributed this phenomenon to
sexually dimorphic skin characteristics associated with
sexual maturation.
Mortality attributable to initial pigment application
was only 0.5' for the fish used in this study (Bandow
1985), which corresponds to the low initial mortality seen
in other studies when spray pressures were carefully
adjusted (Jackson 1959; Phinney et ale 1967; Hennick and
Tyler 1970). Long term survival (from stocking to sexual
maturity) of our fish was somewhat diminished, however, in
contrast to other studies which report no long-term
mortality effects (Phinney et ale 1969; Phinney 1974;
Hennick and Tyler 1970). The spray-marked fish exhibited
this increased mortality regardless of age at maturity.
Fin-clipping is widely reported to adversely affect
survival of fish (Weber and Wahle 1969; Nicola and Cordone
1973), and it is possible that the cumulative effects of
spray-marking and fin-clipping resulted in some increase in
mortality among those fish. Migratory straying or
misidentification due to fin regeneration may have caused
underestimation of the total number of fish surviving to

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