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Mark-recapture experiments with baited traps and toxic chemicals
Johnsen SI, Sandodden R, Museth J and Skurdal J 
Published Online: 2/15/2013
Abstract
Norwegian environmental authorities decided to eradicate an introduced signal crayfish, Pacifastacus leniusculus, population using a lethal dose of the pharmaceutical Betamax Vet. Based on the assumption that the Betamax treatment acted as a non-selective sampling method, we conducted a short time experiment investigating selectivity of baited traps as a sampling method in mark-recapture studies. Crayfish were trapped and marked during three consecutive days and Betamax was used after emptying traps the third day. Baited traps were size selective, catching crayfish from 62 – 135 mm. In comparison, the length frequency in the Betamax treatment catch ranged from 24 – 135 mm. However, trap catches reflected the true length frequency for crayfish ? 75 mm. Males predominated in trap catches, whereas no significant differences were found in sex ratio in Betamax treatment catches. It was about six times more likely to catch a marked crayfish in traps when the recovery period increased from one to two days. Due to low catchability of females, we recommend that population estimates be performed on males and doubled assuming a 1:1 sex ratio. A combination of at least a two day recovery period and doubled male estimates from baited traps corresponded fairly well with density estimates based on Betamax treatment catches.
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How to Cite
Johnsen SI, Sandodden R, Museth J and Skurdal J. (2013). Mark-recapture experiments with baited traps and toxic chemicals. Freshwater Crayfish 19(1):63-68. doi: 10.5869/fc.2013.v19.063
Author Information
Stein I. Johnsen,* Human Dimension Department, Norwegian Institute for Nature Research, Fakkelgården, Lillehammer, Oppland County, Norway2624 . E-mail: stein.ivar.johnsen@nina.no
Roar Sandodden, Section for Environmental and Biosecurity Measures, National Veterinary Institute, Tungasletta 2, Trondheim, Sør-Trønderlag County, Norway7485. E-mail: roar.sandodden@vetinst.no
Jon Museth, Human Dimension Department , Norwegian Institute for Nature Research, Fakkelgården, Lillehammer, Oppland county, Norway2624. E-mail: jon.museth@nina.no
Jostein Skurdal, Human Dimension Department, Norwegian Institute for Nature Research, Fakkelgården, Lillehammer, Oppland County, Norway2624. E-mail: jostein.skurdal@nina.no
Corresponding Author indicated by an *.
Publication History
Manuscript Submitted: 10/1/2012
Manuscript Accepted: 1/17/2013
Published Online: 2/15/2013
Published in Print: 2/15/2013
Funding Information
No specific funding statement is available for this article.