DRAFT 04/06/05 1 STATUS AND DYNAMICS OF A BURBOT POPULATION ON THE EDGE

• Main Authors: Brian J. Pyper, Michael J. Daigneault, Raymond C. P. Beamesderfer, Vaughn L. Paragamian, Susan C. Ireland
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: 2; Burbot; Lota lota; lota
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.532.8603; http://www.fishsciences.net/reports/2005/status_dyn_burbot_pop_edge.pdf

Abstract: We examined the status and population characteristics of Kootenai River burbot Lota lota using capture-recapture data from 1993-2004. Our objective was to determine the time remaining before this population becomes functionally extinct and to help guide conservation efforts. A total of 403 burbot were captured from 1993 through 2004 (primarily with baited hoop nets), of which 300 were tagged and released, 31 were not tagged, and 72 were recaptures of fish tag up to four years prior. Hoop net catch per unit of effort (CPUE) decline precipitously from 0.054 CPUE in 1996 to 0.008 CPUE in 2004. Mean burbot length increased about 8mm/yr from 516 mm in 1993 to 629 mm in 2004. Two models were developed for capture-recapture analysis, one which included effort data through a series river reaches and one without effort data. The effort model appeared to be more reliable and suggested an average annual mortality of 63%, an average annual recruitment of 77 fish, and an average estimate of 148 burbot in the Kootenai River from 1996 through 2004. Average declines in recruitment and population abundance were estimated to be 21 % and 14 % per year, respectively, resulting in estimates of only 20 recruits and a population size of only 50 burbot in 2004. These data confirm that Kootenai River burbot are in serious decline and may already have passed the point of functional extinction where the population could be expected to recover if favorable habitat conditions were restored.