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

adulthood, but relative numbers of spray-marked and control
fish were assumed constant.
Spray-marking had no obvious effect on growth or
condition. Marginally significant length differences seen
in spray-marked males at age 4 could be related to the
small sample size.
Selective predation upon spray-marked fish was
considered as a possible source for increased mortality.
Immediately following spray-marking the color is very
obvious on the fish in visible light, but most of this
unembedded pigment is sloughed off within a few hours
(Phinney et ale 1967; Sandow 1987), while the fish are
still being maintained in holding tanks. Thereafter,
pigment granules are visible only under ultraviolet light.
While such lighting conditions may exist underwater,
enabling predators to see the pigment, the scarcity of
embedded granules and the presence of other fluorescent
particles in the environment diminish the chance of
selective predation. Phinney (1974) found no selective
predation on spray-marked coho salmon.

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