Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

2007 ◽  
Keyword(s):  
Deterministic Model ◽  
Adult Population ◽  
Fish Passage ◽  
Adult Longevity ◽  
Bull Trout ◽  
Catastrophic Events ◽  
Mature Adults ◽  
Trout Population ◽  
Lake Washington ◽  
Adult Abundance

ABSTRACT A life cycle model was employed to identify the response of an adfluvial bull trout <em>Salvelinus confluentus</em> population to chronic and catastrophic losses of subadults. The model simulates the bull trout population within Rimrock Lake, Washington, a reservoir on the Tieton River impounded by Tieton Dam. Subadult bull trout are entrained during summer water releases for irrigation, and the dam has no fish passage facilities to enable those fish to return upstream. Suitable spawning and rearing habitat is primarily upstream of the dam. Tagging studies of adult bull trout passing weirs in the two major tributaries to the reservoir were used to estimate model parameters for survival, maturity rates, reproductive capacity, and initial abundance. Sampling data and the deterministic model simulations indicated that the population was capable of rebounding quickly from intermittent catastrophic events. Resilience of the bull trout population resulted from high adult longevity and repeat spawning. The accumulation of mature adults across multiple age-classes led to egg deposition that fully seeded rearing capacity of the natal tributaries, even when several consecutive broods of juveniles exhibited poor survival. Catastrophic events simulated to entrain 50% of the subadults every 15 years caused a 40% reduction in adult abundance within 4 years of the event, followed by a full recovery to maximum production within 9 years. Even during the low point of adult abundance, 15 times more eggs were deposited than were needed to fully seed juvenile tributary habitat. Because the population was already producing juveniles at capacity, simulations for opening fish passage over Rimrock Dam showed that the sustained spawner population would increase by only two adults. However, simulations for expanded juvenile habitat by 14% indicated that the sustainable adult population would increase by 14%. Thus, habitat improvements that target juvenile rearing capacity appear to have the greatest potential to increase population size.

Geographic distribution, species displacement, and niche overlap for lake trout and bull trout in mountain lakes

1993 ◽  
Vol 71 (2) ◽  
pp. 238-247 ◽  
Author(s):  
David B. Donald ◽  
David J. Alger
Keyword(s):  
Trophic Structure ◽  
Lake Trout ◽  
Niche Overlap ◽  
Mountain Lakes ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
East Central ◽  
Allopatric Populations ◽  
Trout Population ◽  
The One

Indigenous lacustrine populations of bull trout (Salvelinus confluentus) and lake trout (S. namaycush) are spatially separated within the southern part of the zone of distributional overlap (northern Montana, southwestern Alberta, and east-central British Columbia). In this area, lake trout occurred primarily in mountain lakes of 1032–1500 m elevation, while bull trout were found primarily in lakes between 1500 and 2200 m. Introductions of lake trout in the twentieth century and data obtained from beyond the study area indicated that both fishes can establish significant allopatric populations (more than 5% of the catch) in large, deep lakes (>8 ha in area and >8 m deep) over a wide elevation range. We tested the hypothesis that lake trout displace or exclude bull trout from lakes by determining the outcome of introductions of lake trout into two lakes that supported indigenous bull trout. Lake trout were introduced into Bow Lake in 1964, and by 1992 the bull trout population was decimated there and in another lake (Hector) situated 15 km downstream. Thus, lake trout can displace bull trout and may prevent bull trout from becoming established in certain low-elevation lakes. Population age-structure analyses also suggest that lake trout adversely affected bull trout. Bull trout populations in sympatry with lake trout, including the one extirpated from Hector Lake, had few old fish (18% were more than 5 years old; N = 40 fish from three lakes) compared with allopatric populations (49% were more than 5 years old; N = 235 fish from seven lakes). Niche overlap and the potential for competition between the two char species were substantial. In lakes with trophic structure ranging from simple to complex, bull trout and lake trout fed on similar foods and had similar ecological efficiencies (growth rates). Predation by lake trout on bull trout was not documented during the study.

Adult population dynamics and reproductive effort of the fishing spider Dolomedes triton (Araneae, Pisauridae) in central Alberta

1992 ◽  
Vol 70 (11) ◽  
pp. 2224-2233 ◽  
Author(s):  
Manfred Zimmermann ◽  
John R. Spence
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Adult Population ◽  
Adult Longevity ◽  
Male Population ◽  
Male Mortality ◽  
Mark Recapture ◽  
Female Population ◽  
Population Size Estimates ◽  
Dolomedes Triton

A combination of simple enumeration and more intensive Jolly–Seber and Manly–Parr mark–recapture estimation was required to give a complete picture of the population dynamics of adult Dolomedes triton on a small pond in central Alberta. The total number of spiders marked was 142 in 1986 and 210 in 1987, and annual adult emergence, using the population size estimates of the two mark–recapture methods, amounted to ca. 150 and 230 individuals in 1986 and 1987, respectively. The sex ratio was not different from 1:1 in 1986, but in 1987 more than twice as many males emerged than females. Males had significantly shorter observed residence times (life-spans) than females. Contrary to longevity estimates based on the survival probabilities given by the Jolly–Seber model, which were close to those based on enumeration, Manly–Parr survival estimates were strongly biased and even yielded impossible estimates of adult longevity. In both years the median date of male emergence preceded that of females by 5–10 days. Male population size decreased dramatically during the interval when the density of the female population increased, supporting the hypothesis that cannibalism by females is a major source of male mortality. Seventy and 55% of marked females produced egg sacs in 1986 and 1987, respectively. First egg sacs contained 472 ± 18.5 (SE) eggs. Four times as many nursery webs were found in 1986 as in 1987, suggesting that significant losses in female reproductive success occur during the period of egg sac care.

Climate change and vulnerability of bull trout (Salvelinus confluentus) in a fire-prone landscape

2015 ◽  
Vol 72 (2) ◽  
pp. 304-318 ◽  
Author(s):  
Jeffrey A. Falke ◽  
Rebecca L. Flitcroft ◽  
Jason B. Dunham ◽  
Kristina M. McNyset ◽  
Paul F. Hessburg ◽  
...  
Keyword(s):  
Climate Change ◽  
Physical Habitat ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
Management Actions ◽  
Trout Population ◽  
Fire Scenarios ◽  
Population Vulnerability ◽  
In Fire ◽  
Future Management

Linked atmospheric and wildfire changes will complicate future management of native coldwater fishes in fire-prone landscapes, and new approaches to management that incorporate uncertainty are needed to address this challenge. We used a Bayesian network (BN) approach to evaluate population vulnerability of bull trout (Salvelinus confluentus) in the Wenatchee River basin, Washington, USA, under current and future climate and fire scenarios. The BN was based on modeled estimates of wildfire, water temperature, and physical habitat prior to, and following, simulated fires throughout the basin. We found that bull trout population vulnerability depended on the extent to which climate effects can be at least partially offset by managing factors such as habitat connectivity and fire size. Moreover, our analysis showed that local management can significantly reduce the vulnerability of bull trout to climate change given appropriate management actions. Tools such as our BN that explicitly integrate the linked nature of climate and wildfire, and incorporate uncertainty in both input data and vulnerability estimates, will be vital in effective future management to conserve native coldwater fishes.

scholarly journals Population status and demographics of Lake Sturgeon in the Bad and White rivers, Wisconsin

2019 ◽  
Vol 10 (2) ◽  
pp. 442-457 ◽  
Author(s):  
Joshua T. Schloesser ◽  
Henry R. Quinlan
Keyword(s):  
Sex Ratio ◽  
Adult Population ◽  
Lake Superior ◽  
Return Time ◽  
Lake Sturgeon ◽  
River Population ◽  
Mature Adults ◽  
Rehabilitation Plan ◽  
Population Trajectory ◽  
Spawning Run

Abstract Lake Sturgeon Acipenser fulvescens rehabilitation efforts in Lake Superior are guided by a rehabilitation plan that sets goals and criteria for a self-sustaining population, including a minimum of 1,500 mature adults, roughly equal sex ratio, and annual exploitation rates &lt; 5%. The Bad and White rivers, Wisconsin host a genetically unique Lake Sturgeon population that is utilized by state-licensed recreational anglers and tribal subsistence fishers. Our objectives were to 1) determine if the Bad River population meets rehabilitation plan targets for a self-sustaining population, 2) assess harvest of Lake Sturgeon by recreational anglers and tribal subsistence fishers for compatibility with rehabilitation goals, 3) determine population trajectory from annual spawning runs, and 4) describe population demographics given the unique physical features of Lake Superior. We sampled Lake Sturgeon in the Bad and White rivers with gill nets over a 17-y period (2001 to 2017). The observed sex ratio in spawning runs was 2.2:1 (male : female), but calculated at 1.6:1 for the entire adult population on the basis of abundance estimates. Weight–length relationships converted to a standardized modified form factor indicated lower condition and possibly lower female fecundity compared with other large North American populations. Annual spawning run size estimates over time indicated that the population trajectory was stable to slightly increasing, and during 2016 was 739 and 241 individuals in the Bad and White rivers, respectively. Total population size (including nonspawners) exceeded 1,500 individuals, which met Lake Superior rehabilitation criteria for a self-sustaining population. Estimates of 1,426 males and 882 females were considered conservative because 472 unknown-sex fish could not be accounted for in return time and abundance models. Spawning return times were 2 or 3 y for males and 4 to 6 y for females, longer than many other populations. Exploitation by recreational anglers and tribal subsistence fishers was 1.3% or lower and met the rehabilitation plan target of &lt; 5%, but we recommend exploitation not exceed 3.1% to maintain a self-sustaining population. These findings help gauge rehabilitation progress in Lake Superior and better describe the demographics of a remnant self-sustaining Lake Sturgeon population in Lake Superior.

scholarly journals Status of the migratory bull trout population in the Jarbidge River drainage /

1996 ◽  
Author(s):  
Bruce W. Zoellick ◽  
Robyn. Armstrong ◽  
James H. Klott
Keyword(s):  
Bull Trout ◽  
River Drainage ◽  
Trout Population

Studies with Ostertagia circumcincta in Sheep. I. The epidemiology of mature adults and arrested larvae

1967 ◽  
Vol 41 (2-3) ◽  
pp. 137-150 ◽  
Author(s):  
P. S. James ◽  
I. L. Johnstone
Keyword(s):  
Adult Population ◽  
Post Mortem ◽  
Fourth Stage ◽  
Mature Adults

By means of egg counts, faecal cultures and post-mortem examinations of sheep the course of an infestation of Ostertagia circumcincta was followed from March until the following January in a flock of 100 twelve-months-old wethers at Wellington, N.S.W. The highest adult infestations and egg counts occurred in March and January, while during the winter months there was a continual accumulation of inhibited fourth stage larvae in the abomasal mucosa. The data suggest that the adult population observed in January arose from the inhibited population observed during the previous winter and that one of the factors controlling the development of the inhibited population was larval intake.

The effect of repeated insecticidal applications on a natural tsetse population.

1960 ◽  
Vol 51 (3) ◽  
pp. 631-637 ◽  
Author(s):  
D. Yeo ◽  
H. R. Simpson
Keyword(s):  
Natural Population ◽  
Deterministic Model ◽  
Theoretical Calculations ◽  
Adult Population ◽  
Residual Effect ◽  
Numerical Work ◽  
Pupal Period ◽  
Tsetse Population ◽  
Repeated Applications

Using a deterministic model of a tsetse population, theoretical calculations have been made of the effect of repeated applications of a non-persistent insecticide upon a natural population. It has been assumed that the insecticidal applications instantaneously reduce the adult population, and that there is no residual effect.For the numerical work it has been assumed a female fly has a pupal period of four weeks and an average expectation of life of six weeks and produces her first larva three weeks after emergence, and subsequent ones at intervals of one-and-a-half weeks.Results have been calculated for kills of females varying from 50 per cent, to 95 per cent, per application, for series of up to eight successive applications, and for intervals between successive applications of from one to six weeks and also for the case when the population is allowed to become stable between applications.

Spatial dynamics of a nonlocal model with periodic delay and competition

2020 ◽  
Vol 31 (6) ◽  
pp. 1070-1100
Author(s):  
L. ZHANG ◽  
K. H. LIU ◽  
Y. J. LOU ◽  
Z. C. WANG
Keyword(s):  
Population Growth ◽  
Basic Reproduction Number ◽  
Deterministic Model ◽  
Reproduction Number ◽  
Abiotic Factors ◽  
Adult Population ◽  
Positive Periodic Solution ◽  
Reaction Diffusion Equations ◽  
Threshold Dynamics ◽  
Uniform Persistence

Each species is subject to various biotic and abiotic factors during growth. This paper formulates a deterministic model with the consideration of various factors regulating population growth such as age-dependent birth and death rates, spatial movements, seasonal variations, intra-specific competition and time-varying maturation simultaneously. The model takes the form of two coupled reaction–diffusion equations with time-dependent delays, which bring novel challenges to the theoretical analysis. Then, the model is analysed when competition among immatures is neglected, in which situation one equation for the adult population density is decoupled. The basic reproduction number $\mathcal{R}_0$ is defined and shown to determine the global attractivity of either the zero equilibrium (when $\mathcal{R}_0\leq 1$ ) or a positive periodic solution ( $\mathcal{R}_0\gt1$ ) by using the dynamical system approach on an appropriate phase space. When the immature intra-specific competition is included and the immature diffusion rate is neglected, the model is neither cooperative nor reducible to a single equation. In this case, the threshold dynamics about the population extinction and uniform persistence are established by using the newly defined basic reproduction number $\widetilde{\mathcal{R}}_0$ as a threshold index. Furthermore, numerical simulations are implemented on the population growth of two different species for two different cases to validate the analytic results.

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