8008

• UCREFRP Catalog Number: 8008
• Author: Haines, G. B., S. H. Severson and T. Modde.
• Title: Evaluation of Batch Marking Techniques for Culturing the Endangered Razorback Sucker and Colorado Squawfish.
• USFW Year: 1997.
• USFW - Doc Type: \
• Copyright Material: NO

Two-hundred forty razorback sucker (mean TL 127 mm) and 1,015 Colorado squawfish

(mean TL 150 mm), all containing PIT tags for individual identification, were divided into three

groups per species. Each group (hereafter called trial) was assigned a marking date between 6 and

13 June 1995 (Table 1). Each fish had three potential marking locations: the left side for freeze-

branding, the left operculum (razorback sucker) or lower jaw (Colorado squawfish), and the base of

the anal fin for elastomer implant. The treatments were assigned at random to each fish. One-half

of each lot received a freeze brand and one-half no brand (control). One-fifth of each lot received

one of the four colors or no mark (control) on the operculum or lower jaw and base of the anal fin.

For all trials, the same person marked with freeze-brand (Steven Severson) and elastomer (Ronald

Nichols) to reduce variation associated with inconsistencies in application. Prior to marking, the fish

were anesthetized with tricain methanesulfonate (MS-222). After marking, razorback sucker were

placed in a 0.08 hectare pond and Colorado squawfish in two 0.08 hectare ponds. The fish were

harvested, PIT tags read, and marks identified after five and 15 (Colorado squawfish) or 16

(razorback sucker) months. The elastomer marks were observed under an ultraviolet lamp in a

darkened room.

The elastomer data were analyzed using two-way analysis of variance (2 marking locations

X 4 marks) and blocked by trial. There was no replication within blocks; thus, we were unable to

test for interactions between marking locations and marks. Mark retention rates Were log

transformed. The software SYST AT (Wilkinson 1990) was used to compute the statistics.

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