Salmonid Field Protocols Handbook: Techniques for Assessing Status and Trends in Salmon and Trout

The Role of Sample Surveys: Why Should Practitioners Consider Using a Statistical Sampling Design?

Donald L. Stevens, Jr., David P. Larsen, and Anthony R. Olsen

doi: https://doi.org/10.47886/9781888569926.ch3

The primary purpose of this book is to describe the great variety of field sampling protocols for determining the abundance, distribution, and productivity of salmonid populations, especially in stream and river networks. These protocols guide the field practitioner in the selection of appropriate methods to collect fish once the sampling locations have been determined. Equally important is the selection of the locations where fish are to be collected, especially when it is impractical to conduct a census by which all the fish are counted or when information is required for all locations on the stream network. Statisticians sometimes distinguish these two aspects as the sampling or survey design (Where should I collect the fish?) and the response design (How should I collect the fish?) (Stevens and Urquhart 2000).

This chapter provides a small amount of balance across these two critical parts of developing a program to monitor salmonid populations by describing some important components of survey designs relevant to the estimation of the abundance, distribution, and productivity of salmonid populations. A variety of statistical books (e.g., Särndal 1978; Cochran 1987; Thompson 1992; Lohr 1999) cover many of the aspects of survey designs in great detail. Some information on environmental sampling is provided by Gilbert (1987), Olsen et al. (1999), and Stehman and Overton (1994). Stevens and Urquhart (2000) discuss technical issues that arise with response designs when conducting a survey in environmental settings. Two recent books provide some insights useful to fisheries workers; chapter 7 of Thompson et al. (1998) is devoted to statistical sampling of fishes, and Thompson (2004) focuses on the topic of sampling for rare or elusive species. Finally, a forthcoming American Fisheries Society book, Analysis and Interpretation of Freshwater Fisheries Data, edited by Michael Brown and Christopher Guy, will greatly aid fisheries workers in freshwater systems of North America.