| Abstract/Description or Keywords |
The Nechako River supports a small population of white sturgeon genetically distinct from other sturgeon populations within the Fraser River watershed. The Nechako white sturgeon is provincially ranked as a “red-listed” population and is federally designated as an “endangered” species under Schedule 1 of the Species At Risk Act. A comprehensive study of the Nechako white sturgeon suggested that the population exhibits low reproductive success and consequently limited natural recruitment of juveniles which may be insufficient to maintain the population (RL&L, 2000a). The Recovery Plan for Nechako White Sturgeon was published in 2004 by the Nechako River White Sturgeon Recovery Initiative (NWSRI). This plan prioritized a conservation fish culture program to address recruitment failure. The Nechako River pilot broodstock capture program was initiated in 2006 and continued until 2009; the program’s primary objective was to capture pre-spawning sturgeon for use in the fish culture program. This report summarizes the results of the pilot broodstock capture program. The Nechako River was typically sampled for white sturgeon during May of each year. Sampling occurred between river kilometres 110 and 140 and was synoptic in nature. Set-lines and angling were employed as capture techniques resulting in the total capture of 211 sturgeon. Overall, the program was successful in capturing reproductively mature white sturgeon for use in the NWSRI fish culture program. During the 2006 program, 8,320.84 hook-hours of set-line effort and 31.32 rod-hours of angling effort resulted in the capture of 34 sturgeon and three sturgeon, respectively. Of these 37 fish, six sturgeon (2 females, 4 males) were selected as broodstock. 33,294.38 hook-hours and 9.98 rod-hours of effort in 2007 resulted in the capture of 31 sturgeon, 28 on set-lines and 3 on angling gear. Eight sturgeon (4 females and 4 males) were selected as broodstock. In 2008, 64 sturgeon were captured on set-lines (43,018.75 hook-hours) and 10 sturgeon were captured on angling gear (58.67 rod-hours). Nine sturgeon (5 females and 4 males) were selected for broodstock in 2008. In 2009, set-lines captured 67 sturgeon (40,040.6 hook-hours) and angling captured 4 sturgeon (1.33 rod-hours). Three females and two males were selected for broodstock in 2009. All broodstock were transported from Vanderhoof to the Prince George Trout Facility for spawning. White sturgeon captured in 2006 ranged in fork length from 120 to 230 cm. In 2007, fork lengths ranged from 78 to 257cm. Fish captured in 2008 exhibited a range in fork length from 69.5 cm to 241.5cm. White sturgeon captured in 2009 ranged in fork length from 86.5 cm to 258 cm. The length-frequency distributions were similar between each broodstock year and were dominated by sturgeon with fork lengths between 150 cm and 230 cm. The length-frequency distributions of white sturgeon in the study area were similar to previous studies and continued to show a shift towards larger, older individuals. Linear length-weight regressions were also similar between years and were comparable to those documented in previous studies of white sturgeon in the Nechako River. Sex-ratios were skewed towards males in all years, however the ratio of males to females in 2006 was greater than in any other year. A total of 48 radio tags were surgically implanted into mature white sturgeon for use in a telemetry and spawn-monitoring program. |
