7880

• UCREFRP Catalog Number: 7880
• Author: Wydoski, R. S.
• Title: Augmentation Plan For Razorback Sucker In The Middle Green River, 1996-1997.
• USFW Year: 1996.
• USFW - Doc Type: \
• Copyright Material: NO

surviving razorback suckers in field experiments. However, neither technique
provided the tool needed to compare the genetics of surviving razorback
suckers with wild stocks because of low genetic diversity in endangered fish
from the Upper Basin. Several non-lethal genetic techniques involving the
fractionation of DNA from fin clips or muscle plugs (DNA fingerprinting and
micro-satellite loci) have been used to determine the relatedness of different
animals. Either technique would require research before they could be applied
to the endangered fishes. The DNA fingerprinting technique was considered to
be the more logical way to proceed because known DNA fingerprinting probes are
available that can be used to differentiate a variety of DNA sequences. In
addition, the DNA fingerprinting technique would require less time and funds
for testing than the micro-satellite loci technique.

Presently, Anna Toline, Utah State University and Robert Fields, Illinois
Natural History Survey are evaluating the use of DNA fingerprinting for
determining the relatedness of razorback suckers under a Cooperative Agreement
with the Bureau of Reclamation (Toline and Fields 1995). The method has been
used successfully in separating smallmouth bass fry from individual nests
(Gross et al. 1994).

If DNA fingerprinting provides a comparison of the relatedness of surviving
wild razorback sucker larvae from the Middle Green River and the fish are
considered to be genetically unrelated, the survivors will be PIT-tagged and
used for broodstock development or released into the river to augment the wild
population.

If DNA fingerprinting does not allow us to compare the relatedness, but only a
few razorback sucker survive from the flooded bottomland experiment, the fish
would be PIT-tagged and released into the Middle Green River (provided that
the number does not exceed 10% of the estimated number of adults). This
precaution will ensure that genetic swamping does not occur to the only
remaining stock of razorback suckers in the Upper Colorado River Basin.

However, in the event that a large number of razorback suckers survive in
either the 0.2-acre pond or the bottomland, "a sample of not to exceed 10% of
the numbers in the wild spawning stock can be released near the spawning site
to augment the wild stock" following the Genetics Management Guidelines
(Williamson and Wydoski 1994; page 15).

If the genetic diversity of surviving wild fish is similar to the wild Middle
Green River razorback sucker stock, all surviving fish will be PIT-tagged and
stocked into the river to ensure that the stock is stabilized and perhaps
increased. If the genetic diversity of surviving fish is different from the
wild Middle Green River razorback sucker stock, no more than 10% of the
estimated wild adult population, adjusted for annual mortality, will be
released into the river.

Size of Fish when Stocked. The size range of razorback suckers reared in
ponds has varied considerably. However, it is anticipated that the fish will
reach 100 and 200 mm in total length (4 to 8 inches) at low loading rates by
the end of the first growing season in ponds at the Ouray National Fish
Hatchery. It is recommended that the fish be reared in the predator-free

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