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Annual Variation of Spawning Cutthroat Trout in a Small Western USA Stream: A Case Study with Implications for the Conservation of Potamodromous Trout Life History Diversity
Abstract
Little is known about the variability in the spatial and temporal distribution of spawning potamodromous trout despite decades of research directed at salmonid spawning ecology and the increased awareness that conserving life history diversity should be a focus of management. We monitored a population of fluvial–resident Bonneville Cutthroat Trout Oncorhynchus clarkii utah in a tributary to the Logan River, Utah, from 2006 to 2012 to gain insight into the distribution and timing of spawning and what factors may influence these spawning activities. We monitored Bonneville Cutthroat Trout using redd surveys with multiple observers and georeferenced redd locations. We documented an extended spawning period that lasted from late April to mid-July. The onset, median, and end of spawning was best predicted by the mean maximum water temperature during the first 13 weeks of the year (F = 130. 4, df = 5, R 2 = 0.96, P Castor canadensis. Both dam failure and construction appeared to be responsible for creating new spawning habitat that was quickly occupied, demonstrating rapid temporal response to local habitat changes. Bonneville Cutthroat Trout appeared to establish and defend a redd for up to 2 d, and spawning most often occurred between similar-sized individuals. Spawning surveys for potamodromous trout are an underutilized tool that could be used to better understand the distribution and timing of spawning as well as determine the size and trends of the reproducing portion of populations of management concern. Without efforts to document the diversity of this important aspect of potamodromous trout life history, prioritization of conservation will be problematic.
... For example, in the cutthroat trout (O. clarkii Utah) (Bennett et al., 2014) and in Atlantic salmon (S. salar) (Webb and McLay, 1996), the inter-annual variation in temporal distribution of spawning within populations has been related to water temperature variation. In fact, Table 5 Regression coefficients for the regression of total fecundity, relative fecundity, egg diameter and eyed egg survival on reproductive variables for the naturalized rainbow trout of Calafquén Lake. ...
... Full data set is plotted (n = 133). Bennett et al. (2014) reported that spawning events in cutthroat trout, estimated as mean number of redds recorded weekly, occurred earlier and ended earlier in years that had warmer water temperatures prior to spawning. In addition, reports have indicated that spawning timing in naturalized rainbow trout and native brook trout (Salvelinus fontinalis) is affected by high seasonal precipitation, since this factor influences early life stage survival, affecting population size in subsequent years (Kanno et al., 2017). ...
Naturalized rainbow trout (Oncorhynchus mykiss) populations are an important recreational fishing resource in the Araucanian lakes of southern Chile, but few reproductive studies have been undertaken to assess their sustainability. It is important to address this issue, since this analysis may provide information for improving management activities. In this study we carried out a biometric and reproductive analysis of naturalized rainbow trout breeders to describe their performance and to explore the variables that could determine fecundity, fertilization in addition to egg survival and size. We collected naturalized rainbow trout breeders from six tributaries of Calafquén Lake, during 2006, 2007 and 2012 to record their biometric and reproductive traits. Spawning and incubation were performed under controlled conditions in a hatchery facility to improve the recording process. In each spawning season, total fecundity (TF, No. of eggs/female), relative fecundity (RF, No. of eggs/kg female), fertilization rate (FR, %), egg diameter (ED, mm) and eyed egg survival (EES, %) were modeled as a function of biometric and reproductive parameters, using general linear mixed models. We used this statistical tool to explore the relationships between these reproductive traits and other breeder traits in order to identify all the potential combinations that could be linked to TF, RF, FR, ED and EES. The spawning period ranged from September to November (i.e., spring spawning season), with a clear spawning peak in October in all reproductive seasons. Mean TF (from 2275.9 to 3438.7) and RF (from 1730.5 to 1909.8) fell within the range of, or were close to, data reported for other Araucanian lakes, respectively. Mean values of FR and EES were relatively high, ranging from 88.8% to 93.3% and between 83.4% and 88.8%, respectively. Models indicated that TF is significantly affected by the interaction between female body weight and egg weight, while RF is affected by the combination of female body length and egg weight. In addition, a positive correlation was observed between female body weight and total fecundity, while an inverse association was recorded between relative fecundity and female body length. This trend is in accordance with the trade-off pattern between egg number and fish size described for naturalized populations of rainbow trout from the Northern Hemisphere. However, regression equations output suggests that the reproductive performance of the Calafquén Lake population has a more depleted fecundity in comparison either with naturalized populations from the Northern Hemisphere, or with cultured stocks of this species. Models for ED revealed that this variable is affected by egg weight and also by body length or body weight, all with positive correlations. This result concurs with observations reported for other naturalized populations of rainbow trout from North America, further supporting evidence that larger females of this species produce larger eggs than smaller females. Models for EES revealed the significant positive effect of fertilization rate and relative fecundity, being the latter an unexpected result, given that insignificant correlations between these variables have been found in cultured stocks of this species. Overall, the population analyzed exhibited a regular spawning period, and an optimal reproductive performance in terms of egg survival. To promote the sustainability of the naturalized rainbow trout of Calafquén Lake, we recommend the use of hatchery propagation of wild adults to support the production of fry to be used in subsequent restocking activities. This management effort can benefit because the broodstocks have a short spawning period during their spring run.
... Therefore, in areas where trout are already present, the widespread presence of beaver dam complexes in a watershed would likely have a positive impact on their population dynamics. Specifically in this study area, the high diversity of geomorphic units within beaver dam complexes fosters areas for native cutthroat trout to spawn (Bennett et al., 2014). We anticipate the thermal and hydraulic diversity provided by beaver modification of streams should increase the spawning success, survival, and growth rates of salmonids (Bennett et al., 2014;Brown et al., 2011;Weber et al., 2017). ...
... Specifically in this study area, the high diversity of geomorphic units within beaver dam complexes fosters areas for native cutthroat trout to spawn (Bennett et al., 2014). We anticipate the thermal and hydraulic diversity provided by beaver modification of streams should increase the spawning success, survival, and growth rates of salmonids (Bennett et al., 2014;Brown et al., 2011;Weber et al., 2017). There is also evidence that native Cutthroat Trout move more freely among beaver dams than are nonnative Brown Trout (Lokteff et al., 2013), so thermal diversity is not the only positive effect to aquatic communities. ...
Beaver dams alter channel hydraulics which in turn change the geomorphic templates of streams. Variability in geomorphic units, the building blocks of stream systems, and water temperature, critical to stream ecological function, define habitat heterogeneity and availability. While prior research has shown the impact of beaver dams on stream hydraulics, geomorphic template, or temperature, the connections or feedbacks between these habitat measures are not well understood. This has left questions regarding relationships between temperature variability at different spatial scales to hydraulic properties such as flow depth and velocity that are dependent on the geomorphology. We combine detailed predicted hydraulic properties, field-based maps with an additional classification scheme of geomorphic units, and detailed water temperature observations throughout a study reach to demonstrate the relationship between these factors at different spatial scales (reach, beaver dam complexes, and geomorphic units). Over a three-week, low flow period we found temperature to vary 2 °C between the upstream and downstream extents of the reach with a net warming of 1 °C during the day and a net cooling of 0.5 °C at night. At the beaver dam complex scale, net warming of 1.15 °C occurred during the day with variable cooling at night. Regardless of limited temperature changes at these larger scales, the temperature variability within a beaver dam complex reached up to 10.5 °C due to the diversity of geomorphic units. At the geomorphic unit scale, the highly altered flow velocity and depth distributions within primary geomorphic units provide an explanation of the temperature variability within the dam complex and insight regarding increases in habitat heterogeneity.
... Re-using previously excavated gravels may reduce the energetic costs associated with redd construction (McVeigh et al. 2007), reduce the time exposed to predators, and increasingly remove fine sediment that limits egg-to-fry survival (Jensen et al. 2009). While redd guarding can protect against superimposition (McPhee and Quinn 1998), guarding is uncommon in trout (Bennett et al. 2014). Iteroparous species such as YCT are posed with the tradeoff between current reproductive success and survival among reproductive events (Stearns 1992), and energetic investment in reproduction -including redd guarding -comes at a cost to post spawning survival (Jonsson et al. 1997). ...
Life history diversity is generated and maintained in part by density‐dependent fitness tradeoffs that inhibit a single trait value from reaching fixation. While central to our understanding of evolution, demonstrating density dependence in the strength of fitness tradeoffs is difficult in natural systems. The timing of reproduction is a key life history trait that determines access to breeding habitat and exposure of offspring to competitive interactions and environmental conditions. Understanding the processes underlying diversity in reproductive timing will aid efforts to increase adaptive capacity under global environmental change. Here, we used detailed field studies, genetic parentage assignment, and simulation modeling to evaluate the fitness tradeoffs associated with the timing of reproduction for Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri in groundwater‐dominated tributaries to the upper Snake River, Wyoming, USA. We conducted our study across two years to understand how the strength of tradeoffs changes with population density. We found that early breeders experienced reduced reproductive success relative to later breeders due to the negative impact of nest superimposition (where later breeders construct nests overlapping those constructed previously) on embryo survival. However, as the risk of superimposition declined in the low‐density year and early breeders experienced fewer losses, reproductive success became more similar among individuals breeding at different times. Further, in the spring following the critical period for growth and survival, offspring of early breeders had experienced longer growing seasons, attained larger body sizes, and were equally abundant relative to those of later breeders, suggesting that fitness losses due to superimposition may be offset by size‐dependent competitive ability and overwinter survival. Our results illustrate a mechanism underlying diversity in the timing of reproduction for salmonids. This type of life history diversity will help to ensure the resilience and stability of salmonid populations attempting to adapt to changing local stressors associated with global climate change.
... Bonneville Cutthroat Trout show stress when water temperatures exceed 16°C , but can survive in turbid or degraded streams with temperatures of 22°C or more U.S. Fish and Wildlife Service, 2001). During the snowmelt recession in the spring and summer, Bonneville Cutthroat Trout migrate up to 80 km from mainstem river and lake habitats to spawn in high-elevation headwater tributaries, then return to lower-elevation winter habitat with declining flow (Bennett et al., 2014;. ...
Generalizable methods that identify suitable aquatic habitat across large river basins and regions are needed to inform resource management. Habitat suitability models intersect environmental variables to predict species occurrence, but are often data intensive and thus are typically developed at small spatial scales. This study estimated mean monthly aquatic habitat suitability throughout Utah (USA) for Bonneville Cutthroat Trout (Oncorhynchus clarkii utah) and Bluehead Sucker (Catostomus discobolus) with publicly available, geospatial datasets. We evaluated 15 habitat suitability models using unique combinations of percent of mean annual discharge, velocity, gradient, and stream temperature. Environmental variables were validated with observed conditions and species presence observations to verify habitat suitability estimates. Stream temperature, gradient, and discharge best predicted Bonneville Cutthroat Trout presence, and gradient and discharge best predicted Bluehead Sucker presence. Simple aquatic habitat suitability models outperformed models that used only streamflow to estimate habitat for both species, and are useful for conservation planning and water resources decision‐making. This modeling approach could enable resource managers to prioritize stream restoration across vast regions within their management domain, and is potentially compatible with water management modeling to improve ecological objectives in management models.
... Delayed spawning phenology has been described in salmonids in response to elevated stream temperatures (e.g., brook trout, Warren et al. 2012;brown trout, Riedl and Peter 2013; cutthroat trout, Oncorhynchus clarkii, Bennett et al. 2014). However, when the duration of the period with suitable thermal conditions is shortened, this response can be insufficient to compensate for a warmer thermal regime. ...
Streamflow and temperature regimes are key components of the physical habitats of instream biological communities. Iberian brown trout (Salmo trutta) populations exist in a climatic border where water scarcity and increasing water temperatures during summer could compromise their viability throughout the 21 st century. We predicted climate change-induced modifications in the thermal and hydraulic habitats of both the intragravel (eggs and larvae) and free-swimming (fry, juveniles and adults) stages of brown trout in two mountain streams in central Spain. Spatial-temporal simulations of thermal and hydraulic habitats under two climate change emission scenarios-representative concentration pathway RCP 4.5 (mild scenario) and RCP 8.5 (pessimistic)-were conducted at 1-m altitudinal steps using daily air temperature and streamflow predictions. Increased winter temperatures will reduce embryo and larval development time by 12% (RCP 4.5) and 30% (RCP 8.5) in downstream sites by end of the 21 st century, but this reduction might be insufficient to compensate for the shortening of the period with temperatures below the viability limits for survival of intragravel phase (20% and 54% respectively). Combining streamflow and temperature data for free-swimming stages indicated that the suitable summer habitat will be reduced by between 53-76% (RCP 4.5) and 70-90% (RCP 8.5) by 2099. The predicted effects for all developmental stages are critical for determining population viability at both ends of its altitudinal distribution. However, these responses are river-specific, as limiting factors differ among rivers.
... Although spawning has frequently been observed in the TF and SC sites (e.g., Bennett et al. 2014), the actual number of individuals observed spawning in these tributaries is small when compared to the abundance of the total metapopulation (Mohn 2016). This highlights that, despite being a well-studied system, unknowns remain regarding the spawning locations and behavior of this BCT metapopulation. ...
Abstract Understanding how populations respond to spatially heterogeneous habitat disturbance is as critical to conservation as it is challenging. Here, we present a new, free, and open‐source metapopulation model: Dynamic Habitat Disturbance and Ecological Resilience (DyHDER), which incorporates subpopulation habitat condition and connectivity into a population viability analysis framework. Modeling temporally dynamic and spatially explicit habitat disturbance of varying magnitude and duration is accomplished through the use of habitat time‐series data and a mechanistic approach to adjusting subpopulation vital rates. Additionally, DyHDER uses a probabilistic dispersal model driven by site‐specific habitat suitability, density dependence, and directionally dependent connectivity. In the first application of DyHDER, we explore how fragmentation and projected climate change are predicted to impact a well‐studied Bonneville cutthroat trout metapopulation in the Logan River (Utah, USA). The DyHDER model predicts which subpopulations are most susceptible to disturbance, as well as the potential interactions between stressors. Further, the model predicts how populations may be expected to redistribute following disturbance. This information is valuable to conservationists and managers faced with protecting populations of conservation concern across landscapes undergoing changing disturbance regimes. The DyHDER model provides a valuable and generalizable new tool to explore metapopulation resilience to spatially and temporally dynamic stressors for a diverse range of taxa and ecosystems.
... However, warmer water temperatures would result in earlier reproduction. Earlier reproduction might have a positive impact on survival of the early life history stages of these fishes because it would enable more growth before the onset of winter, a period of high mortality for age-0 fish (Kaeding and Osmundson 1988;Thompson et al. 1991;Coleman and Fausch 2007;Bennett et al. 2014). ...
... However, warmer water temperatures would result in earlier reproduction. Earlier reproduction might have a positive impact on survival of early life history stages of these fishes because it would enable more growth before the onset of winter, a period of high mortality for age-0 fishes (Kaeding and Osmundson 1988;Thompson et al. 1991;Coleman and Fausch 2007;Bennett et al. 2014). ...
Habitat alterations and introduction of non‐native fishes reduced the distributions of the Flannelmouth Sucker Catostomus latipinnis, Bluehead Sucker C. discobolus and Roundtail Chub Gila robusta to less than 50% of their historic ranges. Climate change models generally predict decreased stream flows and increased water temperatures that may further affect these species. Understanding effects of flow and water temperature on their life histories should lead to better assessments of climate change impacts on extant populations and more informed management for species conservation. Basin‐wide larval fish sampling and hatch dates derived from otolith daily increment counts showed water temperature was the dominant environmental factor cueing reproduction. Reproduction for all three species began in spring, first at warmer, lower‐elevation, downstream locations and progressed upriver to higher elevations as water temperatures increased. Warmer water temperatures in tributaries initiated earlier reproductive activity compared to adjacent cooler main‐stem habitat. Presence of larvae in samples and estimated hatch dates demonstrated a distinct, predictable upstream progression of reproduction associated with warming water and clear upstream limits to reproduction for all three species. Larvae presence and hatching dates revealed earlier reproductive activity in 2012 than in 2013, driven by lower flow and earlier stream warming. A regression model predicted stream temperature during fish spawning seasons under different climate change scenarios and showed expanded upstream limits of thermally suitable reproductive habitat and earlier reproduction for our study species. The long‐term implications of climate change are unknown but managers should strive to perpetuate the valuable and relatively pristine native fish community in the upper White River drainage as a vestige of those that formerly existed throughout the Colorado River basin. This article is protected by copyright. All rights reserved.
To mitigate westslope cutthroat trout (WCT; Oncorhynchus clarkii lewisi) declines, Montana Fish, Wildlife, & Parks carries out large scale restorations, including wild-origin stocking efforts from conservation hatcheries. Although hatcheries have made progress in limiting the effects of artificial selection on stocked populations, concerns remain that rearing practices inadvertently reduce the diversity propagated into the wild.
The objective of this research was to identify traits of WCT driving poor survival or reproduction in a hatchery, allowing managers to reduce artificial selection by screening for fish requiring alternative rearing. In Chapter 1, I repeatedly measured 18 behavior, morphology, and health traits from hatchery intake (July 2019) to spawn (June 2021). I identified traits with low within- relative to between-individual variation as traits likely to be indicative of specialization. As specialists tend to maximize performance under a narrow range of conditions, they may be vulnerable to artificial selection within hatcheries. In Chapter 2, I tested whether the specialized traits identified in Chapter 1, growth rate, or age at hatchery intake of individual WCT could predict survival or reproduction.
In Chapter 1, I identified nine specialized (relative condition, weighted health index, health index, body shape, energetic reserves, latency, and upper jaw, lower jaw, and anal fin residual length) traits. I hypothesized these traits would predict later survival or reproductive performance. In Chapter 2, I identified October 2019 daily growth rate in weight and every replicate length measurement after October 2019 to strongly predict total ovulated eggs and total number of hatch embryos produced by females. However, among individual variation in the median percent hatch embryos was not explained by maternal size. Male gamete quality and fertilization success was consistently high, and I found no biologically significant predictors of reproductive performance for males. I also found no predictors of survival for males or females.
Despite high total ovulated eggs and total hatch embryo success for females, variable female median percent hatch embryos suggests that quality of ovulated eggs is driving current limitations to WCT hatchery reproduction. I recommend further investigation into impacts of rearing stressors and post-ovulatory aging on female WCT and their reproductive performance.
Hybridisation with introduced taxa poses a threat to native fish populations. Mechanisms of reproductive isolation can limit or prevent hybridisation between closely related species. Understanding how these mechanisms interact between the same species across geographically distinct occurrences of secondary contact, and how regional factors influence them, can inform our understanding of hybridisation as a threat and management actions to mitigate this threat. We used data collected on adult fish migration timing and approximate emergence timing of subsequent juvenile fish paired with genomic data to assess whether temporal isolation in the timing of spawning exists between Yellowstone cutthroat trout, rainbow trout and hybrids in the North Fork Shoshone River drainage in northwest Wyoming. We found evidence that Yellowstone cutthroat trout spawn, on average, two to four weeks later than rainbow trout and hybrids and two environmental covariates related to water temperature and discharge were associated with differences in spawning migration timing. Despite statistical support for Yellowstone cutthroat trout spawning later, disproportionately high numbers of rainbow trout and hybrids, paired with extended spawning seasons, lead to substantial overlap between all genotypes. Our results provide further evidence of temporal segregation in the timing of spawning as a mechanism of reproductive isolation between closely related species, but substantial spawning overlap suggests temporal segregation alone will not be enough to curtail hybridisation in conservation populations.
Spawning migrants entered Spawn Creek when spring freshets from melting snow increased stream flows and turbidity. Adult cutthroat trout traveled to the Logan River after leaving Spawn Creek. Cutthroat trout fry left Spawn Creek in early fall when dwindling stream flows reduced habitat along stream margins. Trout use Spawn Creek for spawning and the Logan River for growing. Spawn Creek contains extensive spawning habitat with little deep-water habitat while the Logan River is its complement.-from Authors
Male salmon have two life-history tactics: maturing precociously at a small body size, or delaying maturity until a larger body size is reached. Conditional strategies permit rapid responses as alternative life-history and behavioral tactics are expressed. Many human activities in the ocean and salmon breeding environment can be expected to elicit long-term evolutionary changes in the proportion of male coho salmon Oncorhynchus kisutch maturing as jacks. Other activities in freshwater rearing environments will have short-term effects. In some cases, male salmon populations once characterized by fighting hooknose males may instead become characterized by smaller precocious jacks. It is also possible that ocean-caught salmon will someday be females only. -from Author
This book outlines a generic set of procedures, termed the River Styles Framework, which provides a set of tools for interpreting river character, behavior, condition, and recovery potential. Applications of the framework generate a coherent package of geomorphic information, providing a physical template for river rehabilitation activities. management and restoration of rivers is a rapidly growing topic for environmental scientists, geologists and ecologists - this book provides a learning tool with which to approach geomorphic applications to river management describes the essential geomorphological principles underlying river behaviour and evolution demonstrates how the River Styles Framework can turn geomorphic theory into practice, to develop workable strategies for restoration and management based on real case studies and authors extensive experience applicable to river systems worldwide synthesises fluvial geomorphology, ecology and management.
Movements of adfluvial Bull Trout Salvelinus confluentus were evaluated with acoustic telemetry during spawning seasons 2006–2011 in Chester Morse Lake,Washington. Ninety-six percent of the individuals made multiple trips between the lake and river habitat during the spawning season,which lasted from less than 1 day to more than a month. Male Bull Trout took an average 13.2 (± 8.7 SD) trips,while females averaged 18.0 (± 14.0 SD) trips. Directional movement between the lake and a river occurred throughout the day; however,the distribution of movement activity was bimodal,peaking from 0600 to 0900 hours (downstream movement) and from 1700 to 2000 hours (upstream movement). The majority of time spent in the river per trip occurred during nighttime hours for female (mean = 74%) and male Bull Trout (mean = 72%). While spawning activity was not confirmed for each trip,this study illustrates an as-yet unreported movement pattern of adfluvial Bull Trout during the spawning season. These results are relevant to managers considering monitoring population trends by way of redd count surveys because multiple redd sites per spawning season are possible,a situation that could lead to overestimating population numbers. Additional research to determine whether spawning occurs on individual trips would help assess whether population numbers could be overestimated by simply using redd counts in systems similar to the one studied.Received November 14, 2012; accepted January 1, 2013