9444

• UCREFRP Catalog Number: 9444
• Author: Hawkins, J. A.
• Title: X-ray Assessment of Electrofishing Injury of Colorado Pikeminnow.
• USFW Year: 2002.
• USFW - Doc Type: Recovery Program Project 64,
• Copyright Material: NO

INTRODUCTION

The eolorado pikeminnow Pfychocheilus lucius is a federally listed, endangered
species that occupies rivers in the Upper Colorado River Basin. Status and trends of
their populations are currently monitored by annual abundance estimates (Osmundson
and Burnham 1998; Osmundson 2002; T. ezapla, personal communication), and from
1986 to 2000 populations were monitored by an Interagency Standardized Monitoring
Program (ISMP; USFWS 1987, McAda 2002). Both programs use boat electrofishing
to capture adult Colorado pikeminnow. Although electrofishing is widely used to
capture many species of fish, studies have demonstrated that electrofishing can reduce
performance, injure, or kill some fish (Fredenberg 1992, Snyder 1992, Sharber et al.
1994; Dalbey et al. 1996; Thompson et al. 1997). Because of the unknown effects of
electrofishing on individual animals and their populations, some researchers suggest
that electrofishing be limited or eliminated in studies of rare species (Snyder 1995;
Nielsen 1998). For rare species such as the Colorado pikeminnow it is important that
negative effects on both individuals and the population are understood so that the
benefits of electrofishing can be weighed against the potential costs (Carlson and Muth
1993). This is especially critical for eolorado pikeminnow that reside in large, turbid
rivers where electrofishing is one of the most effective techniques for collecting fish.
The Recovery Implementation Program responsible for monitoring Colorado
pikeminnow populations identified the need to assess electrofishing effects on
endangered fishes. This study was a preliminary assessment of electrofishing injury of
Colorado pikeminnow caught during ISMP sampling with the goal of determining if