Genetic Diversity in Steelhead before and after Conservation Hatchery Operation in a Coastal, Boreal River

Abstract

Allelic variation at 10 DNA microsatellite loci was assayed in scale samples of steelhead Oncorhynchus mykiss (n ϭ 333) collected between 1976 and 2003 from the lower main stem of the Kitimat River, British Columbia. Our objectives were to (1) investigate the genetic diversity of wild steelhead populations in the river before hatchery stocking began in 1984 (baseline samples: 1976-1977, 1983-1984; n ϭ 145) and (2) assess the potential genetic impacts of interbreeding of returning hatchery adult fish with wild spawners over almost 20 years of large-scale hatchery operation (1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003); n ϭ 188). The annual target number of wild broodstock adults used for hatchery production was 40 (20 of each sex) but varied from 9 to 39 among years. The level of population subdivision () among Kitimat River samples was low (0.004) and not significantly different from 0. Tests of between prehatchery and posthatchery operation indicated no significant changes. Similar results were obtained using other measures of genetic differentiation (principal components analysis of microsatellite allele frequencies and Cavalli-Sforza genetic distance). Our data, however, did indicate a slight but significant reduction in allelic richness after hatchery stocking. Pairwise tests for genetic differentiation among samples from different yearclasses were nonsignificant. We conclude that for the current management regime there is little apparent impact of hatchery practices on either the genetic structure or variation within the lower main-stem Kitimat River steelhead, but there may be a reduction in rare alleles. The practice of using substantial numbers of wild fish and multiple year-classes in the hatchery may have minimized genetic changes via genetic drift.

Little impact of hatchery supplementation that uses native broodstock on the genetic structure and diversity of steelhead trout revealed by a large‐scale spatio‐temporal microsatellite survey

“…The Qiagen spin column‐based DNA extraction procedures were used and samples were then stored at −20°C. Genetic variation was assayed at nine microsatellite loci ( Omy77 , Ssa456 , Ssa197 , Oneu14 , Oneu8 , Ots3 , OkiA3 , Ots103 , Ssa85 ) chosen for their utility as population genetic markers for O. mykiss populations within BC (Heggenes et al. 2006; Tamkee et al.…”

“…2010). These loci were amplified from the DNA extractions by polymerase chain reaction (PCR) using flourescently labeled primers outlined in the procedures of Heggenes et al. (2006).…”

“…To ascertain whether or not the results from the Kitimat River study by Heggenes et al. (2006) have any generality that may be used to inform broader management, our study extended this analysis to five other river systems, from southwestern BC.…”

Stocking activities for the Arctic charr in Lake Geneva: Genetic effects in space and time

“…Accordingly, decades of supportive breeding involving local broodstock seem to have had little impact on the genetic composition in other fishes (Eldridge & Killebrew, 2008;Gow et al, 2011;Heggenes et al, 2006;Small, Currens, Johnson, Frye, & Von Bargen, 2009;Stelkens et al, 2012). In contrast, conservation-based strategies, involving supplementation by local fishes are less controversial, as they do not imply genetic pollution by exotic, potentially maladapted, gene pools.…”

“…In contrast, conservation-based strategies, involving supplementation by local fishes are less controversial, as they do not imply genetic pollution by exotic, potentially maladapted, gene pools. In boxplots, bands represent medians; boxes represent interquartile range of data (IQR); whiskers represent minimum and maximum values, or to 1.5 times the IQR, whichever is the smaller; circles represent outliers Many studies have analyzed the genetic changes in restocked fish populations in space and time, exploiting historical samples (e.g., Gow et al, 2011;Gum, Geist, Eckenfels, & Brinker, 2014;Hansen, 2002;Heggenes et al, 2006;Nielsen et al, 1999;Perrier et al, 2013). Accordingly, decades of supportive breeding involving local broodstock seem to have had little impact on the genetic composition in other fishes (Eldridge & Killebrew, 2008;Gow et al, 2011;Heggenes et al, 2006;Small, Currens, Johnson, Frye, & Von Bargen, 2009;Stelkens et al, 2012).…”