7019

• UCREFRP Catalog Number: 7019
• Author: Hawkins, J. A.
• Title: Age and Growth Of Colorado Squawfish From the Upper Colorado River Basin, 1978-1990.
• USFW Year: 1991.
• USFW - Doc Type: Fort Collins, CO.
• Copyright Material: NO

50

Records were checked for errors by sorting the fields numerically or alphabetically and
looking for unusual entries or obvious mistakes. If different sources reported the same capture
record, then the most accurate record was retained. Questionable records were verined with
original field notes. Changes and inconsistencies were recorded in a logbook to provide a
chronology of database changes

RESULTS

The database currently contains 3740 records. These numbers will change as more
obscure records are added and inconsistences are corrected. The total number of fish tagged for
each species or hybrid were summarized (Table 5). The number of capture records were
summarized by year and river for Colorado squawfish, (Table 6) humpback chub (Table 7), and
razorback sucker (Table 8).

For some fish captures there were often duplicate records from different agencies. Some
fish were collected during cooperative studies between agencies and each agency would log the
capture in its own database. Unfortunately data in these "identical" records often differed.
Determining the most correct record was very time consuming and difficult. The most accurate
and complete record was retained.

Because tag number was crucial for identifying a record, emphasis was placed on its
correctness. Some tag numbers had been transposed (402-G incorrectly reported as 420-G).
Forty-two were truncated (e.g. 2067-G and 38049-G were reported as 206-G and 8049-G).
These problems were difficult to find and caused the same capture record to exist under two
different tag numbers. The correction of these and other problems to date is documented in
Table 9. '

Identical tag numbers were identified as problems when tag size or type was not reported
(Table 10). In the consolidated database, these records were tentatively made unique by a
different letter (A, B, C) in the capture-number field. Records with unresolved probleDlSwere
identified (Table 11).

Another problem was length of recaptured fish. Many recaptured lengths were the same
as length at first capture. This usually occurred if the time interval between captures was less
than one week. In some cases, the fish might not have been measured at recapture and the initial
capture measure was repeated. Researchers often do not measure the length of fish when
recaptured a short time after initial tagging. An excuse may be that it decreases handling time
and injury and avoids potential discrepancies in measurements. In regard to measurement
discrepancies, differences in lengths at capture and recapture within a short period would allow
the calculation of variability of our field measurements. One source adjusted for shrinking
lengths of recaptured fish by averaging lengths that varied between initial capture and recapture.
These cecords were often averaged several years after their entry into the database. Lengths and
weights that were found to be averaged were replaced with original measurements in the
consolidated database (Table 12).

RECOMMENDATIONS

Tagging is a valuable tool that will aid in understanding and recovering endangered fishes
of the Upper Basin. Continued tagging of adult fish will build on our existing knowledge of life
history patterns and support information obtained from other methods like radio-telemetry.
Tagging should be extended to juveniles to help document their cecruitment into upstream
reaches of the basin. Their movement patterns and growth cates are also important.

Carlin tags are being phased out because of their apparently harmful affects on growth
and possibly behavior. Passive Integrator Transponder (PIT) tags will probably be used in the
near future. This transition period is an ideal time to review our past tagging accomplishments
and weaknesses.