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

Introduction

Artificial propagation is an important tool for recovering endangered razorback s':lcker

Xyrauchen texans and Colorado squawfish Ptychocheilus lucius within their native range in the

Colorado River Basin (Rinne et al, 1986; Johnson and Jensen 1991; Modde et al. 1995), Small

nwnbers of founders in the hatchery stock make the genetic contribution of each individual important

to maintaining genetic diversity, The identification of offspring from each paired mating is

necessary for the maintenance of pedigree records for brood stock development and equalization of

family lots for achieving maximwn effective population size for reintroduction or augmentation of

wild populations (Echelle 1991), Unique marking'offamily lots contributes to the efficiency of the

fish culture facility by allowing the mixing of lots in large growout ponds. Internally implanted

passive integrated transponder (pIT) tags (prentice et al. 1990) are ideal for marking large fish, but

the tags are expensive (approx. $4,00 per tag), the fish must be at least 100 mm totaIlength (TL),

and an electronic scanner is required to read the tag, The use of PIT tags to mark juvenile fish can

add significant costs to propagation, especially when large nwnbers of age-O and age-1 fish may be

excess to the genetic refugia target nwnbers, A simple and inexpensive batch mark that can be

recognized after one or two years would substantially reduce cost and increase pond use efficiency,

Potential marks include freeze branding and elastomer injection, Freeze branding is a widely

used technique for marking small salmonids (Laird et al. 1975; Mighell1969; Fay and Pardue 1985;

Knight 1990), channel catfish Ietalurus punctatus (Brock and Farrell 1977), and walleye Stizostedion

vitreum (LaJeone and Bergerhouse 1991), but it has not been tested for razorback sucker and

Colorado squawfish, A fluorescent elastic polymer (elastomer) was recently developed by

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