Comparison of Electrofishing and Scuba Diving Techniques to Sample Black Bass

Electrofishing can potentially hurt or kill early life stages of fish or fish listed under the Endangered Species Act, is not effective in water of extreme (low or high) conductivity, and when performed at night, can be intrusive to people in residential areas. A non-destructive and less intrusive alternative to nighttime electrofishing is daytime scuba diving. Using a widely accepted length-categorization system to assess fish stocks, I compared the relative efficiency of nighttime electrofishing and daytime scuba diving at estimating the abundance and size structure of black bass in three western Washington lakes. Catch per unit effort and length-frequency distributions of largemouth bass Micropterus salmoides and smallmouth bass M. dolomieu gathered by scuba divers compared favorably with those of electrofishers. In some cases, scuba diving may be preferable to electrofishing because of its low impact on the resource and because it is less labor intensive. Provided the water clarity is sufficient, daytime scuba diving operations can be conducted under all water quality conditions with few concerns from shoreline property owners.