Decline of the Migratory Form in Bull Charr, Salvelinus Confluentus, and Implications for Conservation

Nelson, M. Lee; McMahon, Thomas E.; Thurow, Russell F.

doi:10.1023/a:1016062708588

Cited by 62 publications

(14 citation statements)

References 16 publications

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“…In contrast, the migration distances we observed in Mill Creek and the John Day and Umatilla river basins are uniquely short when compared to the published literature on large-bodied (>300 mm FL) fluvial bull trout. In most other instances, the reduction or loss of diversity in migratory behavior has been associated with dam construction, nonnative species or habitat degradation (e.g., Fitch 1997, Swanberg 1997, Jakober et al 1998, Brenkman et al 2001, Nelson et al 2002. The rarity, or lack, of long distance migration among tagged bull trout in three of our study areas suggests that fluvial life history expression has been curtailed; however, there is little information in these study areas about the spatiotemporal distribution of resources critical to bull trout life history expression and the effect of human activities on them.…”

Section: Discussionmentioning

confidence: 99%

Rainbow trout (Oncorhynchus mykiss) habitat overlap with wild Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) in natural streams: do habitat and landscape factors override competitive interactions?

Roloson

Knysh

Coffin

et al. 2018

Can. J. Fish. Aquat. Sci.

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The purpose of this study was to update rainbow trout (Oncorhynchus mykiss) invasion status, delineate factors that increase the invasion probability, and quantify habitat overlap between invasive rainbow trout and native Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) on Prince Edward Island, Canada. Analysis of landscape-level variables in 26 watersheds (14 with and 12 without rainbow trout) demonstrated that watershed slope, percent agricultural land use, and distance to the nearest rainbow trout population significantly increased the probability of rainbow trout establishment. Two independent reach-level fish community surveys were conducted by electrofishing in combination with habitat surveys. Reaches with rainbow trout had higher stream slope, Atlantic salmon were found in wider reaches with larger substrate, and brook trout were typically dominant in headwater reaches with finer substrate. Findings at multiple ecological scales illustrated that rainbow trout invasion success is positively influenced by the presence of high-slope habitat. Habitat separation of the three salmonid species indicates that competition with introduced rainbow trout may not be the most significant threat to native salmonid populations.

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Section: Discussionmentioning

confidence: 99%

Rainbow trout (Oncorhynchus mykiss) habitat overlap with wild Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) in natural streams: do habitat and landscape factors override competitive interactions?

Roloson

Knysh

Coffin

et al. 2018

Can. J. Fish. Aquat. Sci.

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“…In these areas, adults excavate nests within the stream substrates and deposit eggs during the late summer and early fall, the eggs incubate during the winter, and young fish emerge the following spring. At this point, juvenile individuals adopt one of two life histories (Downs et al, 2006;Rieman & McIntyre, 1993), although many populations are thought to support both life history forms (Howell et al, 2016;Nelson et al, 2002). Migratory individuals rear in their natal streams for two or more years, then move downstream to more productive habitats where growth is rapid and eventually return to spawn as relatively large adults (>400 mm total length).…”

Section: Study Areamentioning

confidence: 99%

Do metapopulations and management matter for relict headwater bull trout populations in a warming climate?

Isaak

Young

Horan

et al. 2022

Ecological Applications

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Mountain headwater streams have emerged as important climate refuges for native cold-water species due to their slow climate velocities and extreme physical conditions that inhibit non-native invasions. Species persisting in refuges often do so as fragmented, relict populations from broader historical distributions that are subject to ongoing habitat reductions and increasing isolation as climate change progresses. Key for conservation planning is determining where remaining populations will persist and how habitat restoration strategies can improve biological resilience to enhance the long-term prospects for species of concern. Studying bull trout, a headwater species in the northwestern USA, we developed habitat occupancy models using a data set of population occurrence in 991 natal habitat patches with a suite of novel geospatial covariates derived from high-resolution hydroclimatic scenarios and other sources representing watershed and instream habitat conditions, patch geometry, disturbance, and biological interactions. The best model correctly predicted bull trout occupancy status in 82.6% of the patches and included effects for: patch size estimated as habitat volume, extent of within-patch reaches <9 C mean August temperature, distance to nearest occupied patch, road density, invasive brook trout prevalence, patch slope, and frequency of high winter flows. The model was used to assess 16 scenarios of bull trout occurrence within the study streams that represented a range of restoration strategies under three climatic conditions (baseline, moderate change, and extreme change). Results suggested that regional improvements in bull trout status were difficult to achieve in realistic restoration strategies due to the pervasive nature of climate change and the limited extent of restoration actions given their high costs. However, occurrence probabilities in a subset of patches were highly responsive to restoration actions, suggesting that targeted investments to improve the resilience of some populations may be contextually beneficial. A possible strategy, therefore, is focusing effort on responsive populations near more robust population strongholds, thereby contributing to local enclaves where dispersal among populations further enhances resilience.Equally important, strongholds constituted a small numerical percentage of

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“…Although habitat in lower Big Creek has also been somewhat degraded, upper Big Creek and Meadow Fork likely provide a refuge for bull trout where habitat remains relatively pristine and, unlike upper Lake Creek, few brook trout are present. The persistence of migratory bull trout has also been recognized as an important factor for the persistence of bull trout populations (Northcote 1997;Rieman and Dunham 2000;Nelson et al 2002). Although migratory bull trout spawn in Big Creek and Meadow Fork, they are absent from Lake Creek presumably due to seasonal thermal barriers downstream of spawning habitat.…”

Section: Conservation Implicationsmentioning

confidence: 99%

Spatial patterns of hybridization between bull trout, Salvelinus confluentus, and brook trout, Salvelinus fontinalis in an Oregon stream network

DeHaan

Schwabe²,

Ardren

2009

Conserv Genet

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Hybridization with introduced species represents a serious threat to the persistence of many native fish populations. Brook trout (Salvelinus fontinalis) have been introduced extensively throughout the native range of bull trout (S. confluentus) and hybridization has been documented in several systems where they co-exist and is seen as a significant threat to the persistence of bull trout populations. We identified a group of diagnostic microsatellite loci to differentiate bull trout and brook trout and then used these loci to examine the spatial distribution of hybrids in the Malheur River basin, Oregon USA. In random samples of approximately 100 fish from each of three creeks we identified 181 brook trout, 112 bull trout and 14 hybrids. Although bull trout, brook trout and hybrids were found in all three creeks, they were not evenly distributed; brook trout were primarily found in the lower sections of the creeks, bull trout further upstream, and hybrids in the areas of the greatest overlap. One creek with a population of brook trout in a headwater lake provided an exception to this pattern; brook trout were found distributed throughout the creek downstream of the lake. Several post-F1 hybrids were identified suggesting that hybrids are reproducing in the Malher River Basin. Mitochondrial DNA analysis indicated that both female bull trout and brook trout are involved in hybridization events. Analysis of population structure suggested that brook trout have established multiple spawning populations within the Malheur system. Data presented in this study suggest that relative abundance of brook trout and habitat quality are important factors to consider when evaluating the threat of hybridization to bull trout populations.

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Decline of the Migratory Form in Bull Charr, Salvelinus Confluentus, and Implications for Conservation

Cited by 62 publications

References 16 publications

Rainbow trout (Oncorhynchus mykiss) habitat overlap with wild Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) in natural streams: do habitat and landscape factors override competitive interactions?

Rainbow trout (Oncorhynchus mykiss) habitat overlap with wild Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) in natural streams: do habitat and landscape factors override competitive interactions?

Do metapopulations and management matter for relict headwater bull trout populations in a warming climate?

Spatial patterns of hybridization between bull trout, Salvelinus confluentus, and brook trout, Salvelinus fontinalis in an Oregon stream network

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