9346

• UCREFRP Catalog Number: 9346
• Author: Seethaler, K.
• Title: Life History and Ecology of the Colorado Squawfish ‎(Ptychocheilus lucius)‎ in the Upper Colorado River Basin.
• USFW Year: 1978.
• USFW - Doc Type: Utah State University,
• Copyright Material: NO

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"camera lucida." These drawings document the development of young
Colorado squawfish from egg, various larval stages, and juveniles.
Morphometrics and meristics were tabulated for each stage.
Age and growth were similar for fish captured in the Yampa-Green
Rivers and Colorado River at Grand Junction, Colorado, during 1974-76.
Moreover, there was no significant difference between these fish and
those from the upper Green River in 1964-66.
Colorado squawfish became mature when individuals reached a size
of 428-503 mm in total length and an age of 6-8 years. Spawning re-
quirements were speculated from observations in the field and hatchery,
and comparison from related species. Food habits are similarly deduced
from observations and the literature.
Movement of the Colorado squawfish has been difficult to validate,
but seasonal patterns were noted. Two squawfish were tracked briefly
with the use of sonic tags.
The most common parasite of the Colorado squawfish is the copepod,
Lernea sp. Other parasites and diseases include the fungus,
Ichthyophthirius sp., the tapeworm Proteocephalus ambloplites, and the
protozoa Myxosoma sp. and Myxobolus sp.
The decline of the species appears to have resulted from the loss
of habitat due to environmental changes in stream flow and biological
composition. Dewatering, dams and reservoirs, alteration of stream flow
and stream morphology, changes in water quality, and the introduction of
exotic species are discussed as being the principal causal factors.
While additional studies would be useful to management, the urgency
of the situation indicates the need for expeditious efforts at preser-
vation. Artificial propagation is a very important means of buying time

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