AFS: AFS-WWSTC: Fish collection in warmwater streams by electrofishing
|
Official Method Name
|
Warmwater Streams Techniques Manual: Fish |
|---|---|
|
Current Revision
| 1984, revised 1988 |
|
Media
|
WATER |
|
Instrumentation
|
Electrofishing Unit |
|
Method Subcategory
|
Population/Community |
|
Method Source
|
|
|
Citation
|
Bryan, C.F. (Ed.), 1984, Warmwater Streams Techniques Manual: Fish, Southern Division of the American Fisheries Society, LSU Printing Office, Baton Rouge, LA |
|
Brief Method Summary
|
Electrofishing is used in stream sampling to determine species composition, relative abundance, size distribution, and population structure. It is also used to examine aspects of the life histories of individual species (food habits, age and growth, etc.) and to make brood fish collections. Although somewhat selective, it is less biased than many other sampling methods and most fish can be released unharmed. |
|
Scope and Application
|
This manual attempts to: distinguish basic types of electrofishing gear suitable for sampling fish in warmwater streams; suggest stream types for which each is best suited; compare electrofishing with other (similar) methods; and point out safety precautions to be taken when electrofishing. |
|
Applicable Concentration Range
|
|
|
Interferences
|
Many factors (visibility, temperature, etc.) can affect electrofishing efficiency. Fish are more susceptible to capture by electrofishing at night and when they are in shallow water in general. Other factors beyond the biologist's control are species vulnerability, size selectivity, habitat preference, water conductivity, and depth. |
|
Quality Control Requirements
|
Data comparisons are only appropriate for samples gathered during the same season, time of day, sampling gear, etc.
Catch per effort data on the same species of a defined size range may be compared, so long as information on factors that may affect efficiency are recorded. Thus, information on control settings of the electrofishing unit (voltage, amps, ac or dc, pulse frequency and width), water conductivity, visibility, temperature, and time electrofished should be recorded. |
|
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
|
