Event Title
Evaluating Removal and Mark-Recapture Methods for Estimating Sculpin Abundance in Streams
Presentation Type
Oral and/or Visual Presentation
Presenter Major(s)
Biology
Mentor Information
Carl Ruetz
Department
Annis Water Resource Institute (AWRI)
Location
Kirkhof Center 2201
Start Date
11-4-2012 9:30 AM
Keywords
Environment, Life Science
Abstract
Unbiased estimates of abundance are critical for fisheries management. We evaluated mark-recapture and removal methods for estimating sculpin (Cottus bairdii) abundance. Objectives were to: 1) compare abundance estimates, 2) assess bias of removal methods, and 3) evaluate closed-population model assumption. We sampled 8 streams via electrofishing. On day 1, fish were marked in 3 sections of a 90-m reach. On day 2, fish were captured and temporarily removed from the stream during 4 passes. Removal abundance estimates were significantly lower than mark-recapture estimates and underestimated known abundances. Movement of marked fish was minimal among sections of the 90-m reach in most streams. Survival and mark retention of sculpin held overnight in cages were 100%. Our results suggest the closed-population assumption was valid in most streams and the removal method yielded negatively biased abundance estimates. We recommend using mark-recapture methods to estimate sculpin abundance.
Evaluating Removal and Mark-Recapture Methods for Estimating Sculpin Abundance in Streams
Kirkhof Center 2201
Unbiased estimates of abundance are critical for fisheries management. We evaluated mark-recapture and removal methods for estimating sculpin (Cottus bairdii) abundance. Objectives were to: 1) compare abundance estimates, 2) assess bias of removal methods, and 3) evaluate closed-population model assumption. We sampled 8 streams via electrofishing. On day 1, fish were marked in 3 sections of a 90-m reach. On day 2, fish were captured and temporarily removed from the stream during 4 passes. Removal abundance estimates were significantly lower than mark-recapture estimates and underestimated known abundances. Movement of marked fish was minimal among sections of the 90-m reach in most streams. Survival and mark retention of sculpin held overnight in cages were 100%. Our results suggest the closed-population assumption was valid in most streams and the removal method yielded negatively biased abundance estimates. We recommend using mark-recapture methods to estimate sculpin abundance.