Abstract

Electric fishing has many advantages in sampling crayfish when compared with the commonly used baited traps. Electric fishing seems to be very little selective and samples of crayfish of all year and size classes, even the smallest juveniles, can be obtained with the method. The number of crayfish and their biomasses can be very accurately evaluated in areas suitable for electric fishing. Crayfish can also be sampled in periods when they are not active and therefore difficult to catch with traps, e.g. during molting, when the females are carrying eggs or juveniles and when the crayfish are diseased or parasited. With electric fishing it is possible to get in suitable areas homogenous, non-selective and comparable samples of a crayfish population. Activity of crayfish, type and mesh size of traps, type of bait, nutritional conditions in the area studied, density or structure of the crayfish population examined or other similar factors, which easily cause differences and selectivity in the samples obtained with traps, do not usually affect the sampling with electricity. The main restrictions of electric fishing are that it can be used only to 0.5 - 0.8 m depths and only in clear waters. The weather must also be calm during fishing. One-summer old juveniles, less than 20 mm in length, are often very difficult to catch and are therefore very easily underestimated even with this method. The methodology and techniques of electric fishing has been discussed.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: