A Comparison of Electrofishing and Scuba Diving to Sample Black Bass in Western Washington Lakes

Abstract

I examined the use of scuba diving as a nondestructive, cost-effective alternative to sampling black bass with an electrofishing boat, which can injure or kill fish, is not effective in clear water or water of extreme (low or high) conductivity, can be labor intensive, and can be difficult along developed shorelines as well as intrusive to residents. I compared the relative efficiency of nighttime electrofishing and daytime scuba diving for estimating the density and size structure of black bass in three western Washington lakes. Catch per unit effort (number of stock-length fish/400 m shoreline) of electrofishing and scuba diving did not differ significantly for largemouth bass Micropterus salmoides or smallmouth bass M. dolomieu. The length-frequency distributions of sub-stock-length and longer black bass sampled while electrofishing and scuba diving were not significantly different in two of the three lakes surveyed. In some cases, scuba diving may be preferable to electrofishing because of its low impact on the resource, because it does not have the same limitations with respect to water quality, and because it is less labor intensive.