Standard Methods for Sampling North American Freshwater Fishes

Chapter 8: Coldwater Fish in Wadeable Streams

Jason B. Dunham, Amanda E. Rosenberger, Russell F. Thurow, C. Andrew Dolloff, and Philip J. Howell


Small, wadeable streams comprise the majority of habitats available to fishes in fluvial networks. Wadeable streams are generally less than 1 m deep, and fish can be sampled without the use of water craft. Cold waters are defined as having mean 7-d summer maximum water temperatures of less than 20°C and providing habitat for coldwater fishes.

Fish fauna of small coldwater streams of North America typically include trouts and salmons, sculpins, minnows, sticklebacks, suckers, or lampreys (Hocutt and Wiley 1986). Standard sampling protocols provided herein apply primarily for trouts and salmons because of their sport and commercial values (Johnson et al. 2007). As interest in nonsalmonid species grows, further development of sampling methods for a broader diversity of species is expected. However, many of the following methods can be applied for sampling fish other than trouts and salmons.

The broad taxonomic diversity and size-specific morphological, physiological, and behavioral characteristics within and among salmonid species have led to a diverse array of sampling methods for cold, wadeable streams. While some level of standardization is possible, each method provides complementary information about different species and life stages. The primary elements of standardized sampling programs are based on three of the most common methods for quantitatively sampling fishes in wadeable streams: (1) electrofishing, (2) underwater observation by snorkeling, and (3) nest or redd counts. Methods described herein are intended to provide more specific directions than are found in general references (e.g., Murphy and Willis 1996), and as a complement to a recent volume providing detailed information on salmonid field protocols (Johnson et al. 2007). Our goal is to assist biologists who may be inexperienced in sampling small, wadeable streams, who may be beginning new sampling programs, or who may need information to fine-tune ongoing sampling programs.