AFS: AFS SD Trout:  Trout collection in wadeable trout streams by backpack electrofishing

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Official Method Name
 Standardized Sampling Guidelines for Wadeable Trout Streams
Current Revision
August 1992
Media
 WATER  (Waterbody type - Wadeable stream)
Instrumentation
 Backpack Electrofishing Unit
Method Subcategory
 Population/Community
Method Source
  AFS
Citation
 American Fisheries Society - Southern Division: Trout Committe. 1992. Standardized Sampling Guidelines for Wadeable Trout Streams
Brief Method Summary
 These guidelines constitute an attempt to standardize trout stream sampling procedures and promote data exchange among the various natural resource management agencies represented by members of the American Fisheries Society, Southern Division Trout Committee. Compliance with these guidelines is strictly voluntary, although it is anticipated that widespread acceptance of the concept of standardized trout stream sampling procedures will provide the basis for a sound regional coldwater fisheries database.
Scope and Application
 The following guidelines for standardized sampling methods in wadeable trout streams are based on the recommendations of the Standardized Trout Stream Sampling sub-committee of the American Fisheries Society, Southern Division Trout Committee. Wadeable trout streams, exclusive of tailwaters, are defined as those that can be waded and sampled with backpack electrofishing gear. Southeastern trout streams are the primary focus of these guidelines, although they may be used (with or without modification) in other geographical regions.The objectives of these guidelines are:
  1. Establishment of standardized sampling procedures that will provide a mechanism by which data can be more readily compared among various streams
  2. Provision of standardized trend data on population changes (e.g., density, standing crop, species composition, size and age structure, etc.) through time as they relate to various abiotic effects (e.g., droughts, floods, regulation differences or changes, etc.)
Applicable Concentration Range
Interferences
 Stream flow rates have a marked effect on electrofishing efficiency; therefore, avoid sampling during high flow conditions (e.g., those typically occurring in the winter and early spring or after storm events). Disadvantages associated with winter and early spring sampling, notwithstanding high stream flows, may include safety hazards (e.g., anchor ice) and lowered fish catchability related to extremely cold water and the tendency for trout to enter the substrate and not float well when stunned (Armour 1983). Sampling during the period of peak leaf fall may present problems with keeping block nets in place and with seeing and retrieving stunned fish.
Quality Control Requirements
  1. Since complete electrofishing surveys of even the smallest streams are usually impractical, fish stock assessments must be based on a sample of stream reaches (Bohlin et al. 1982). The recommended procedure for selecting these sampling sections (also referred to as stations or sites) for monitoring purposes is to use "representative" stream reaches that contain the major habitat types or units present, such as pools, riffles, runs, etc. If possible, streams should be traversed prior to station selection to ensure that major habitat types are included in proportion to their occurrence. Representative reaches can be chosen randomly or sited using specific criteria as project needs dictate. Bovee (1982) and Hamilton and Bergersen (1984) provide additional information regarding habitat-based site selection. Non-contiguous habitat units may also be sampled if "representative" reaches are unavailable or lack the desired level of precision for specific studies. Representative reaches are, however, recommended for long-term monitoring stations.
  2. Minimum recommended station length is 100 m in streams =10 m in mean width as this length typically provides for the inclusion of at least one cycle of the basic stream habitat units present. The recommended station length in streams with mean widths exceeding 10 m is 200 m since it is difficult to include all major habitat types in 100-m stations in these larger streams. In practice, these station length recommendations should be used as points of reference since actual station lengths will often require adjustment to avoid habitat unit fragmentation and to make use of any fish passage obstructions present.
Sample Handling
 All sampling must follow procedures to protect held fish. Air pumps and water transfers should be used as necessary to maintain safe conditions. Large fish should be kept separate from smaller prey-size fish to avoid predation during containment.
Maximum Holding Time
 Fish should be processed as soon as possible after capture to minimize stress.
Relative Cost
 3 - 6 hrs. per site/sample
Sample Preparation Methods
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