Trout Habitat Research Articles

The relationship between the population characteristics and physical habitat of Manchurian trout (<i>Brachymystax lenok tsinlingensis</i>) in the Geybangcheon stream

The relationship between the population characteristics and physical habitat of Manchurian trout (<i>Brachymystax lenok tsinlingensis</i>) in the Geybangcheon stream

Utilizing classic evolutionary algorithms to assess the Brown trout (Salmo trutta) habitats by ANFIS-based physical habitat model

Present study evaluates the application of coupled evolutionary algorithm- adaptive neuro-fuzzy inference system in the Brown trout riverrine habitats. We implemented the proposed method in the Lar national park as one of the most important Brown trout habitats in the southern Caspian Sea basin. Two classic evolutionary algorithms including the genetic algorithm and the particle swarm optimization were coupled with adaptive neuro-fuzzy inference system. Moreover, two conventional training methods including backpropagation and hybrid algorithm were utilized. Evaluation of developed models was carried out in two stages including assessment of habitat suitability index in observed habitats and using practical hydraulic simulation in a representative reach. Measurement indices consisting of root mean square error, mean absolute error, Nash–Sutcliffe model efficiency coefficient, reliability and vulnerability indices and fuzzy technique of order preference similarity to the ideal solution as decision-making system were used. Results demonstrate the efficiency of the coupled evolutionary algorithm- adaptive neuro-fuzzy inference system to simulate hydraulic habitats of the Brown trout. The first stage of evaluation indicates particle swarm optimization is the best method. However, practical hydraulic simulation corroborates GA is the best method for the training process. Evaluations demonstrate that backpropagation is not an appropriate method for ANFIS-based hydraulic habitat simulation.

Factors affecting seasonal habitat use of native brook trout (Salvelinus fontinalis) in urban headwater streams

AbstractTo better understand the ecology of coldwater fishes in urban‐dominated landscapes, factors influencing seasonal brook trout (Salvelinus fontinalis) habitat use were assessed using backpack electrofishing surveys in three urban groundwater‐fed streams in central Ontario. Generalised additive models revealed that yearling brook trout (<100 mm TL) were primarily influenced by water quality (stream temperature, conductivity), while older brook trout (≥100 mm TL) were primarily influenced by stream morphology (water depth, undercut bank volume). Colder stream temperatures were preferred by yearlings in summer, whereas they occupied the warmest temperatures available in winter and spring. Yearlings were never found in sites with high stream conductivity (≥ 900 µs/cm), regardless of season, which may be attributed to poor water quality in stream sections with stormwater influence. Older brook trout were found mainly at intermediate pool depths in spring and summer, while there was a greater range of depths used during the spawning season. Undercut banks were important for older brook trout occupancy at all times of year. The protection of groundwater aquifers in urban watersheds is recommended to maintain optimal temperature regimes for the persistence and successful recruitment of native brook trout.

The physical and chemical limnology of Yukon’s largest lake, Lhù’ààn Mân’ (Kluane Lake), prior to the 2016 ‘A’ą̈y Chù’ diversion

Despite increasing evidence that large northern lakes are rapidly changing due to climate change, descriptive baseline studies of their physicochemical properties are largely lacking, limiting our ability to detect or predict change. This study represents a comprehensive scientific assessment of the limnology of Yukon’s largest lake: Lhù’ààn Mân’ (Kluane Lake), an important waterbody for local and First Nation communities, and key habitat for trout and salmon. Water sample and instrument data generated throughout 2015 describe distinct regions within the lake and their respective seasonal variability. A deep, glacially-influenced southern basin was characterized by cold, turbid, poorly stratified, unproductive, and nutrient-poor conditions; a shallower northwestern region (Tthe Kaala Daagur (Brooks/Little Arm)) was warmer, fully mixed, and more productive; a northeast region (’Ùha K’ènji (Talbot/Big Arm)) was clear and stratified with intermediate depth, temperature, productivity, and nutrient concentrations; and a central region had intermediate physicochemical conditions relative to the other three. This variability demonstrates the need for adequate spatial (within lake) and temporal (between seasons) monitoring of large northern lakes. In 2016, glacier recession within the watershed resulted in diversion of the lake’s primary inflow (‘A’ą̈y Chù’ (Slims River)). Our results, when used together with Indigenous knowledge, form a historical reference that enables assessments of the potential ecological consequences to Lhù’ààn Mân’.

Ecosystem response to earlier ice break-up date: Climate-driven changes to water temperature, lake-habitat-specific production, and trout habitat and resource use.

Climate warming has yielded earlier ice break-up dates in recent decades for lakes leading to water temperature increases, altered habitat, and both increases and decreases to ecosystem productivity. Within lakes, the effect of climate warming on secondary production in littoral and pelagic habitats remains unclear. The intersection of changing habitat productivity and warming water temperatures on salmonids is important for understanding how climate warming will impact mountain ecosystems. We develop and test a conceptual model that expresses how earlier ice break-up dates influence within lake habitat production, water temperatures and the habitat utilized by, resources obtained and behavior of salmonids in a mountain lake. We measured zoobenthic and zooplankton production from the littoral and pelagic habitats, thermal conditions, and the habitat use, resource use, and fitness of Brook Trout (Salvelinus fontinalis). We show that earlier ice break-up conditions created a "resource-rich" littoral-benthic habitat with increases in zoobenthic production compared to the pelagic habitat which decreased in zooplankton production. Despite the increases in littoral-benthic food resources, trout did not utilize littoral habitat or zoobenthic resources due to longer durations of warm water temperatures in the littoral zone. In addition, 87% of their resources were supported by the pelagic habitat during periods with earlier ice break-up when pelagic resources were least abundant. The decreased reliance on littoral-benthic resources during earlier ice break-up caused reduced fitness (mean reduction of 12g) to trout. Our data show that changes to ice break-up drive multi-directional results for resource production within lake habitats and increase the duration of warmer water temperatures in food-rich littoral habitats. The increased duration of warmer littoral water temperatures reduces the use of energetically efficient habitats culminating in decreased trout fitness.

Salmonid Habitat and Population Capacity Estimates for Steelhead Trout and Chinook Salmon Upstream of Scott Dam in the Eel River, California

Estimating salmonid habitat capacity upstream of a barrier can inform priorities for fisheries conservation. Scott Dam in California's Eel River is an impassable barrier for anadromous salmonids. With Federal dam relicensing underway, we demonstrated recolonization potential for upper Eel River salmonid populations by estimating the potential distribution (stream-km) and habitat capacity (numbers of parr and adults) for winter steelhead trout (Oncorhynchus mykiss) and fall Chinook salmon (O. tshawytscha) upstream of Scott Dam. Removal of Scott Dam would support salmonid recovery by increasing salmonid habitat stream-kms from 2 to 465 stream-km for steelhead trout and 920 to 1,071 stream-km for Chinook salmon in the upper mainstem Eel River population boundaries, whose downstream extents begin near Scott Dam and the confluence of South Fork Eel River, respectively. Upstream of Scott Dam, estimated steelhead trout habitat included up to 463 stream-kms for spawning and 291 stream-kms for summer rearing; estimated Chinook salmon habitat included up to 151 stream-kms for both spawning and rearing. The number of returning adult estimates based on historical count data (1938 to 1975) from the South Fork Eel River produced wide ranges for steelhead trout (3,241 to 26,391) and Chinook salmon (1,057 to 10,117). An approach that first estimated juvenile habitat capacity and then used subsequent life stage survival rates yielded 1,281 (CV 56%) steelhead trout and 4,593 (CV 34%) Chinook salmon returning adults. Variability in estimated fish numbers reflects application of densities and survival rates from other populations, assumptions about salmonid productivity in response to potential spawning habitat capacity, residency and outmigration of early life-stages, summertime water quality conditions, and inter-annual hydrograph, marine, and population variability.

Effect of Beaver on Brook Trout Habitat in North Shore, Lake Superior, Streams

AbstractThe Brook Trout Salvelinus fontinalis is a native salmonid that provides a valued and productive sport fishery in northeastern Minnesota. Revival of North American beaver Castor canadensis (hereafter, “beaver”) populations since their near extermination and concern over their impacts on Brook Trout habitat prompted a reexamination of the complex ecological relationship where the two taxa interact. Suitable Brook Trout habitat is characterized by cold, spring‐fed water with silt‐free rocky substrate and abundant cover, all of which beaver may directly or indirectly affect. Data collection occurred on 79 stream sections (200 m each) and 21 beaver ponds spanning the North Shore of Lake Superior during the summer in 2017 and 2018. Habitat suitability index (HSI) models determined the average HSI and quantity of suitable Brook Trout habitat (m2/100 m2) at stream and beaver pond sites, and a bioenergetics model calculated Brook Trout growth availability (m2/100 m2) and mean growth (g/d) at stream sites. Classification regression trees identified significant thresholds at which beaver activity (e.g., number of dams upstream of sampled sites and beaver pond age) influenced the quantity or quality of Brook Trout habitat and growth. No significant variables were identified as affecting Brook Trout habitat or growth rates in stream sites. Alternatively, the quantity and quality of Brook Trout habitat in this region appeared to be influenced by microhabitat variables (depth, velocity, and temperature) that are eminent at individual stream sites. Brook Trout growth was strongly influenced by velocity (m/s) and mean prey concentration (mg dry mass/m3). Results indicated that 12 of the 21 sampled beaver ponds contained suitable Brook Trout habitat, with dissolved oxygen (mg/L) identified as a threshold. This study recommends focusing on individual stream characteristics and beaver pond dissolved oxygen concentrations to achieve desired Brook Trout habitat and aid in the development of management strategies pertaining to these two taxa in Lake Superior's North Shore streams.

Deciphering lifelong thermal niche using otolith δ18O thermometry within supplemented lake trout (Salvelinus namaycush) populations

Abstract The selection of thermal habitat by fish is strongly regulated by physiology and behaviour. However, delineation of a species lifelong thermal niche remains technically challenging. Lake trout (Salvelinus namaycush) survival and productivity are recognised as being tightly linked to a somewhat restricted thermal habitat. The factors guiding temperature selection during each life stage remain poorly understood. In this study, we tested the significant factors controlling the realised thermal niche of lake trout from two southern Quebec small boreal lakes that experienced supplementation stocking during the last 20 years. We used oxygen stable isotope (δ18O) thermometry of otolith calcium carbonates (aragonite) using secondary‐ion mass spectrometry to estimate experienced lifelong temperatures. We investigated the thermal habitat of lake trout with known genotypes (local, hybrid, and stocked). Ontogeny and genetic origin influenced temperature selection in both studied lake trout populations. Young‐of‐the‐year consistently used warmer, shallower habitats (10.7 ± 2.6°C, 7.5 m depth) prior to a juvenile transition to colder and deeper waters (8.5 ± 3.3°C, 10 m depth). Stocked lake trout, originating from a genetically distinct ecotype, exhibited a more variable thermal niche, with some individuals consistently using warmer habitat (10.4 ± 1°C) than local fish. Their hybrid progeny also occupied a warmer thermal niche, intermediate to the parental strains. We propose that increased fat content and genetic origin are potential explanatory factors for warmer temperature use. This study reiterates that high‐resolution otolith δ18O thermometry is a uniquely well‐suited approach for unravelling the multiple factors that influence lifelong temperature selection in fish. Our results illustrate that the realised thermal niche is influenced by a genetic–environment interaction.

Ecology and movement of juvenile salmonids in beaver‐influenced and beaver‐free tributaries in the Trøndelag province of Norway

AbstractThere is concern that expanding beaver (Castor fiber) populations will negatively impact the important economic, recreational and ecological resources of Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) populations in Europe. We studied how beaver dams influenced habitat, food resources, growth and movement of juvenile Atlantic salmon and trout on three paired beaver‐dammed and beaver‐free (control) tributaries of important salmon rivers in central Norway. Lotic reaches of beaver‐dammed and control sites were similar in habitat and benthic prey abundance, and ponds were small (<3,000 m2). Though few juvenile salmonids were detected in ponds, trout and salmon were present in habitats below and above ponds (comprising 9%–31% and 0%–57% of the fish collected respectively). Trout dominated control sites (79%–99%), but the greatest proportion of Atlantic salmon were upstream of beaver ponds (0%–57%). Growth rates were highly variable, with no differences in growth between lotic reaches of beaver‐dammed and control sites. The condition and densities of juvenile salmon and trout were similar in lotic reaches of beaver‐dammed and control sites, though one beaver‐dammed site with fine sediment had very few juvenile salmonids. Beaver dams did not block the movement of juvenile salmonids or their ability to use upstream habitats. However, the degree of repeated movements and the overall proportion of fish moving varied between beaver‐dammed and control sites. The small scale of habitat alteration and the fact that fish were able to move past dams makes it unlikely that beaver dams negatively impact the juvenile stage of salmon or trout populations.

Impacts of Small-Scale Water Conservation Practices on Summer Streamflow in the Navarro River Watershed, California

The Navarro River watershed in coastal Northern California provides critical habitat for coho salmon and steelhead trout, but low summer streamflow limits habitat quality due to poor hydrologic connectivity, warm water temperatures, and low dissolved oxygen. Strategies to improve salmonid habitat include managing agricultural irrigation and other water use to increase summer streamflow. One such strategy is adding water storage ponds and tanks to replace summer diversions from streams with winter diversions to fill storage. A monthly water budget was developed for the watershed to assess the potential for flow enhancement via such water conservation efforts. Results indicate that adding 12,335 m3 (10 acre-feet) of storage in key tributary sub-watersheds would increase summer streamflows by 0.8 to 1.1 L/s. That represents an up to 12 percent increase in summer streamflow during a moderate drought and up to 100 percent or greater increase during a severe drought. Adding sufficient water storage to eliminate all summer diversions could increase streamflow by up to 21 L/s in tributaries and up to 58 L/s in the mainstem Navarro River. Given the sensitivity of California salmonids to minor changes in summer streamflow, the calculated flow benefits of water conservation would significantly improve salmonid habitat.

Ecological health assessments using fish communities in the habitat of Manchurian trout

Ecological health assessments using fish communities in the habitat of Manchurian trout

Population Assessment and Habitat Use of Brown Trout Following Severe Overwinter Predation from Common Mergansers in a Western New York Stream

Heavy predation by Mergus merganser (Common Merganser) during severe winters of 2013–2014 and 2014–2015 resulted in substantial reductions of wild Salmo trutta (Brown Trout) in open-water, groundwater-fed reaches of Oatka Creek in western New York State. New York State Department of Environmental Conservation considered the need for habitat manipulation to reduce the severity of future overwinter-predation by mergansers in Oatka Creek Park (OCP) but lacked data to make an informed decision. Thus, this study sought to estimate population abundance, density, and year-class distribution of Brown Trout; quantify the availability of cover and habitat; and identify habitat features used by Brown Trout in OCP. We recorded data for 100 Brown Trout (101–512 mm TL) during spring 2016, autumn 2016, winter 2017, and spring 2017. Despite the absence of mergansers in ensuing warmer winters, trout population indices decreased as the study continued, likely affected by high streamflow during sampling events. Year-class distributions typical of a small stream, however, suggest that the population is recovering. Velocity refuges and structural cover were the primary factors determining habitat selection. Large woody debris was the most favored cover type by all Brown Trout; however, boulders were also important, especially during low streamflow. Large trout (>300 mm) showed a strong preference for deepwater habitats with slow currents and high densities of woody debris and boulders, while small trout (<200 mm) preferred shallower complex habitats with slow currents, course substrates, and high cover densities. Quality trout habitat and instream cover is abundant throughout OCP, but the abundance of highly complex overwinter habitats capable of providing protection from mergansers may be limited. Adding complex structural cover to areas favored by smaller trout (<300 mm) could increase habitat complexity and likely reduce the severity of future overwinter predation.

Effects of forestry on summertime low flows and physical fish habitat in snowmelt‐dominant headwater catchments of the Pacific Northwest

AbstractPeriods of summertime low flows are often critical for fish. This study quantified the impacts of forest clear‐cutting on summertime low flows and fish habitat and how they evolved through time in two snowmelt‐dominant headwater catchments in the southern interior of British Columbia, Canada. A paired‐catchment analysis was applied to July–September water yield, the number of days each year with flow less than 10% of mean annual discharge, and daily streamflow for each calendar day. The postharvest time series were divided into treatment periods of approximately 6–10 years, which were analysed independently to evaluate how the effects of forestry changed through time. An instream flow assessment using a physical habitat simulation‐style approach was used to relate streamflow to the availability of physical habitat for resident rainbow trout. About two decades after the onset of logging and as the extent of logging increased to approximately 50% of the catchments, reductions in daily summertime low flows became more significant for the July–September yield (43%) and for the analysis by calendar day (11–68%). Reductions in summertime low flows were most pronounced in the catchment with the longest postharvest time series. On the basis of the temporal patterns of response, we hypothesize that the delayed reductions in late‐summer flow represent the combined effects of a persistent advance in snowmelt timing in combination with at least a partial recovery of transpiration and interception loss from the regenerating forests. These results indicate that asymptotic hydrological recovery as time progresses following logging is not suitable for understanding the impacts of forest harvesting on summertime low flows. Additionally, these reductions in streamflow corresponded to persistent decreases in modelled fish habitat availability that typically ranged from 20% to 50% during the summer low‐flow period in one of the catchments, suggesting that forest harvest may have substantial delayed effects on rearing salmonids in headwater streams.

Projected changes in Brook Trout and Brown Trout distribution in Wisconsin streams in the mid-twenty-first century in response to climate change

Climate warming is a threat to the survival of fishes adapted to cold water. Brook Trout Salvelinus fontinalis and Brown Trout Salmo trutta are two cold-water species occurring in streams in Wisconsin, where climate change may make these species particularly vulnerable. Vulnerable trout populations need to be identified to aid in the development of adaptation strategies. We used web-based stream temperature and fish-distribution models in FishVis to predict current (late twentieth century) and project future (mid-twenty-first century) distributions of Brook Trout and Brown Trout. The models predict the suitability of habitat for trout in individual reaches using environmental variables in a geographic information system, including adjacent and upstream channel characteristics, surficial geology, landcover, and climate. Future projections of air temperature and precipitation were obtained from 13 general circulation models downscaled for Wisconsin. Currently, 34,251 km of streams are suitable for Brook Trout and 20,011 km for Brown Trout. The models project a decline of 68% (10,995 km) in stream habitat for Brook Trout and a decline of 32% (13,668 km) for Brown Trout. These projected declines, while substantial, were lower than earlier estimates because our models account for projected increased precipitation that may enhance groundwater inputs and partially offset higher air temperatures.

Genetic diversity, admixture, and hatchery influence in Brook Trout (Salvelinus fontinalis) throughout western New York State.

Although Brook Trout are distributed across most of eastern North America, population numbers have declined in many regions due to habitat loss, climate change, and competition with non‐native species. In New York State, Brook Trout habitat has been substantially reduced, with many areas showing complete extirpation of Brook Trout populations, predominantly in the western portion of the state. Small, fragmented populations are at risk of genetic diversity loss, inbreeding depression, and reduced fitness, leading to a greater potential for local extirpation. Genetic monitoring is a practical tool that can facilitate further conservation‐decision making regarding small populations. In this study, we used 12 microsatellite loci to examine 3,436 sampled Brook Trout, representing 75 sites from the Allegheny, Erie/Niagara, Genesee, Oswego, Lake Ontario, and Susquehanna drainage basins throughout western New York State. Three Brook Trout hatchery strains were also genetically characterized to evaluate the degree of hatchery introgression between wild populations and hatchery strains stocked in the region. Overall, estimates of genetic diversity varied widely: Allelic richness ranged from 2.23 to 7.485, and expected heterozygosity ranged from 0.402 to 0.766. As observed for Brook Trout in other regions, we found a high degree of genetic differentiation among populations, with all comparisons except one showing significant F ST values. Hatchery introgression was found to be minimal, with estimates ranging from 1.96% to 3.10% of wild individuals exhibiting membership proportions to a hatchery strain cluster exceeding 10% (q ≥ 0.10). Results from this investigation can be used to prioritize management efforts for Brook Trout in western New York State and act as a baseline to monitor future population trends.

Modelling changes in trout habitat following stream restoration

AbstractStream restoration was implemented on the Upper Arkansas River near Leadville, Colorado, to improve brown trout (Salmo trutta) populations. Metals pollution and channel disturbance associated with historic mining, land use, and water development degraded aquatic and riparian habitat. Changes in instream habitat quality following restoration were investigated with a before–after–control–impact study design. Baseline, as‐built, and effectiveness surveys were conducted in 2013, 2014, and 2016, respectively. Two‐dimensional hydrodynamic modelling with River2D was used to estimate weighted usable area (WUA) for adult, juvenile, fry, and spawning brown trout across a range of flows. WUA was calculated from habitat suitability curves for velocity, depth, and channel substrate. Foraging positions (FP) and habitat heterogeneity were also evaluated as indices of habitat quality. All results were analysed with analysis of variance. At impact sites, WUA increased by 12.2% from 2013 to 2014 but decreased by 10.2% from 2014 to 2016, whereas FP increased by 24.8% from 2013 to 2014 but decreased by 26.1% from 2014 to 2016. Spawning habitat increased 53.3% from 2014 to 2016 at impact sites. The 15.4% increase in depth variability from 2013 to 2016 indicates that habitat heterogeneity was enhanced at impact sites. No changes in WUA, FP, or habitat heterogeneity were observed at control sites. Although changes in WUA and FP suggest that initial habitat improvements were not sustained, increased spawning habitat and depth heterogeneity suggest otherwise. Our results highlight the value of monitoring strategies that utilize multiple lines of evidence to evaluate restoration effectiveness, inform adaptive management, and improve restoration practices.

Does habitat occupancy by lake trout and lake whitefish in large lakes match published thermal habitat envelopes?

AbstractHabitat occupancy patterns of lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) in two large Canadian Shield lakes were modelled based on detections of fish from repeated depth‐stratified surveys over several summers. Lake trout and lake whitefish consistently occupied sites outside traditional thermal envelopes and were not detected at some sites within these ranges. This included the metalimnion and shallow epilimnion for lake trout and lake whitefish in Lake Opeongo. Physical habitat covariates were not important in defining lake trout habitat in both lakes. Physical habitat as represented by the hardness/softness gradient based on acoustic substrate surveys was important for lake whitefish in Lake Opeongo but not in Smoke Lake. In addition, thermal envelopes for lake whitefish differed between the lakes possibly because of differences in substrate slope. The wash zone of lakes, where the thermocline contacts the substrate, appears to be a physical habitat feature for lake whitefish in some lakes. Lake whitefish also exhibited diurnal activity behaviour that was reflected through greater detection rates in the morning versus the afternoon. By accounting for imperfect detection, true estimated overall occupancy of lake trout and lake whitefish increased 0.15–0.30 over naïve occupancy. Thermal habitat envelopes for lake trout and lake whitefish are wider than previously thought. Lake trout occupied a consistent thermal habitat envelope while lake whitefish varied between lakes likely because of lake specific differences in basin morphology and wash zone.

Modeling Temperature Regime and Physical Habitat Impacts from Restored Streamflow.

Water infrastructure updates at Grand Canyon National Park (GRCA) provide an opportunity to restore natural flow to Bright Angel Creek, adding an additional ~20% to baseflow. This creek provides habitat for endangered humpback chub (Gila cypha) and invasive brown trout (Salmo trutta). We assess how increased flow may alter habitat and how that change may impact native and nonnative species using physical habitat modeling and statistical analysis of stream temperature data. We used System for Environmental Flow Analysis to calculate the change in habitat area for both species in the lower 2.1 km of the creek before and after the increased flow. Results indicate a slight increase in available habitat for juveniles of both species and a slight decrease for spawning brown trout. We used regression modeling to relate daily average air temperature to stream temperature and periods of increased discharge during water system maintenance were used to model the temperatures during likely future conditions. Both high and low stream temperature were dampened due to the added water resulting in fewer days with suitable spawning temperature and more days with suitable growth temperature for humpback chub. Fewer suitable days for growth upstream but more suitable days downstream, were predicted for brown trout. Compared to other streams that sustain populations of humpback chub, flow conditions for Bright Angel Creek provide fewer days throughout the year with suitable temperatures, particularly during the winter months. Juvenile humpback chub rearing may improve through the restoration of flow however the presence of predatory brown trout complicates the net beneficial impact.

Conservation planning at the intersection of landscape and climate change: brook trout in the Chesapeake Bay watershed

AbstractWe developed a multi‐scale conservation planning framework for brook trout (Salvelinus fontinalis) within the Chesapeake Bay watershed that incorporates both land use and climate stressors. Our specific objectives were to (1) construct a continuous spatial model of brook trout distribution and habitat quality at the stream reach scale; (2) characterize brook trout vulnerability to climate change under a range of future climate scenarios; and (3) identify multi‐scale restoration and protection priorities for brook trout across the Chesapeake Bay watershed. Boosted regression tree analysis predicted brook trout occurrence at the stream reach scale with a high degree of accuracy (CV AUC = 0.92) as a function of both natural (e.g., water temperature and precipitation) and anthropogenic (e.g., agriculture and urban development) landscape and climatic attributes. Current land use activities result in a predicted loss of occurrence in over 11,000 stream segments (40% of suitable habitat) and account for over 15,000 km (45% of current value) of lost functional brook trout fishery value (i.e., length‐weighted occurrence probability) in the Chesapeake Bay watershed. Climate change (increased ambient temperatures and altered precipitation) is projected to result in a loss of occurrence in at least 3000 additional segments (19% of current value) and at least 3000 km of functional fishery value (9% of current value) by 2062. Model outcomes were used to identify low‐ and high‐quality stream segments within relatively intact and degraded sub‐watersheds as restoration and protection priorities, respectively, and conservation priorities were targeted in watersheds with high projected resilience to climate change. Our results suggest that traditional restoration activities, such as habitat enhancement, riparian management, and barrier removal, may be able to recover a substantial amount of brook trout habitat lost to historic landscape change. However, restoration efforts must be designed within the context of expected impacts from climate change or those efforts may not produce long‐term benefits to brook trout in this region.

Seasonal timing of reproductive migrations in adfluvial bull trout: an assessment of sex, spawning experience, population density, and environmental factors

Using individual tags combined with a fish fence operated at the mouth of Smith-Dorrien Creek, the primary spawning habitat for Lower Kananaskis Lake bull trout (Salvelinus confluentus), we approximated a complete census of the spawning population from 1996 to 2000 to assess whether timing of upstream and downstream spawning migrations varied with extrinsic and intrinsic factors. The timing of both upstream and downstream migrations varied with sex, previous spawning experience, density, and temperature. Inferred spawning duration based on the predicted upstream and downstream migration dates indicated that experienced female spawners spent the least amount of time upstream and first-time spawners spent the most time upstream. No consistent differences in upstream migration timing were observed between non-repetitive and repetitive spawners. We suggest that variations in spawning migration timing observed in Lower Kananaskis Lake may be linked to environmental factors that influence upstream swimming ability and acquisition and expenditure of energy with respect to reproduction.