COMPARISONS OF COVE ROTENONE AND ELECTROFISHING CATCH-DEPLETION ESTIMATES TO DETERMINE ABUNDANCE OF AGE-0 LARGEMOUTH BASS IN UNVEGETATED AND VEGETATED AREAS

We compared cove rotenone sampling and Leslie catch-depletion estimate d of age-0 largemouth bass Micropterus salmoides) abundance in vegetat ed and unvegetated areas of Lake Guntersville, Alabama, in July - Augu st 1992. With the Leslie catch-depletion method, bass abundance was es timated in 0.05 to 0.32-hectare areas enclosed with a block net. A 4.3 -meter direct-current electrofishing boat was able to completely fish each enclosure with five to seven consecutive sampling runs and consta nt effort. Size-selectivity was not evident as no significant correlat ions existed between mean length and mean weight at capture for each s ampling interval. In addition, catchability remained constant over tim e. In a cove that contained Eurasian watermilfoil (Myriophyllum spicat um), we estimated 1,088 age-0 largemouth bass/hectare from the two ele ctrofishing catch-depletion samples compared to 1,386 bass/hectare by subsequent rotenone sampling. Cove rotenone density and biomass estima tes in four unvegetated coves (1.2-hectare each) averaged 86 age-0 lar gemouth bass/hectare and 0.52 kg/hectare and were not significantly di fferent from electrofishing catch-depletion density and biomass estima tes which averaged 104 bass/hectare and 0.78 kg/hectare. This method a ppears to be a reliable and less costly method than cove rotenone samp ling to estimate abundance of age-0 largemouth bass.