9492

• UCREFRP Catalog Number: 9492
• Author: Snyder, D. E.
• Title: Computer-Interactive Key to Sucker Larvae and Early Juveniles of the Upper Colorado River Basin with Description of Longnose Sucker.
• USFW Year: 2003.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

fishes in the region. This was to be accomplished by preparation of a manuscript (this [mal
report) for subsequent publication as a supplement to the 1990 guide. The supplement would
include updated descriptive information for the species covered in that guide, a comparable
descriptive species account for longnose sucker, an updated and expanded comparative
summary, and a new computer-interactive key or keys (program and files on diskette or compact
disk) to correct, update, and expand upon the existing printed keys. A secondary objective of the
project was to provide proof-of-concept for the effective application of a relatively new
taxonomic tool to larval-fish identification, the computer-interactive key.

Methods

Specimens Examined

Description of the larvae and early juveniles of longnose sucker was based on specially
assembled developmental series that were laboratory-reared in 1979 and 2001 from eastern-
slope, north-central Colorado populations and selected collections of wild early juveniles
(young-of-the-year) from the lower Gunnison River in 1993 and 1995. Ninety-eight (98)
specimens were examined and analyzed in detail, 57 specimens were cleared and stained with
alizarin red for examination of skeletal features, and still others were cursorily examined for
extremes in developmental state or pigmentation. Specimens were either fixed in 10% formalin
and subsequently preserved in phosphate-buffered 3% formalin or preserved directly in 95%
ethanol without formalin fixation. All specimens are maintained as part of the LFL Collection.
Specimens analyzed, examined, or illustrated in detail were individually cataloged as:
LFL# 6690 (1 specimen; 37.0 m.m TL, total length) - Collected 7 September 1993 from
Gunnison River kIn 96.1, Delta County, CO, by USFWS; formalin.
LFL# 6837 (1 specimen; 38.5 m.m TL) - Collected 7 September 1993 from Gunnison River km
83.7 by USFWS; formalin.
LFL# 26446 (1 specimen; 34.7 mm TL) - Collected 19 September 1995 from Gunnison River
kIn 55.7 by USFWS; formalin.
LFL# 67261-67263, 67265, 67274-67275, 67277-67278 (8 of 166 specimens from LFL#
26647; 21.1-38.0 m.m TL) - Collected 21 September 1995 from Gunnison River kIn
94.0 by USFWS; formalin.
LFL# 67264, 67273, 67276 (3 of 10 specimens from LFL# 26520; 25.1-30.6 mm TL)-
Collected 19 September 1995 from Gunnison River km 80.0 by USFWS; formalin.
LFL# 67266-67267 (2 of7 specimens from LFL# 6799; 42.5-46.0 mm TL) - Collected 7
September 1993 from Gunnison River kIn 84.0 by USFWS; formalin.
LFL# 67268, 67272 (2 of 4 specimens from LFL# 6703; 32.8-48.8 mm TL) - Collected 7
September 1993 from Gunnison River kIn 95.5 by USFWS; formalin.
LFL# 67269-67270 (2 of39 specimens from LFL# 6758; 46.2-50.2 mm TL) - Collected 7
September 1993 from Gunnison River km 89.5 by USFWS; formalin.
LFL# 67271 (1 of 10 specimens from LFL# 6899; 42.8 mm TL) - Collected 7 September 1993
from Gunnison River km 83.1 by USFWS; formalin.
LFL# 67220-67260 (41 specimens, 7.6-19.9 mm TL) - From developmental series that was
laboratory-reared in 1979 by LFL from Parvin Lake stock, Larimer County, CO;
formalin.

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