scholarly journals Beaver activity increases habitat complexity and spatial partitioning by steelhead trout

2019 ◽  
Vol 76 (7) ◽  
pp. 1086-1095 ◽  
Author(s):  
Gus Wathen ◽  
Jacob E. Allgeier ◽  
Nicolaas Bouwes ◽  
Michael M. Pollock ◽  
Daniel E. Schindler ◽  
...  
Keyword(s):  
Habitat Complexity ◽  
Habitat Restoration ◽  
Fish Habitat ◽  
Castor Canadensis ◽  
Small Scale ◽  
Microhabitat Use ◽  
Spatial Partitioning ◽  
Management Actions ◽  
Microhabitat Heterogeneity ◽  
Positive Correlations

Freshwater habitat restoration is a major conservation objective, motivating efforts to restore habitat complexity and quality for fishes. Restoration based on the engineering activities of beavers (Castor canadensis) increases fish habitat complexity, but how this affects fish habitat use and movement behaviours is not well known. We used a network of passive integrated transponder antennas to quantify small-scale movement and microhabitat use of 175 individual juvenile steelhead (Oncorhynchus mykiss) in a stream channel with a complex bathymetric profile resulting from a beaver impoundment and in a simplified channel devoid of beaver activity. Our results show that juvenile steelhead exploit microhabitat heterogeneity by employing a range of behaviours that maximizes available habitat via spatial and temporal partitioning among individuals. These results suggest spatial resource partitioning as a potential mechanism for the previously established positive correlations among steelhead density, survival, and production with beaver-based restoration within the study watershed. More broadly, our findings provide insight as to how populations can exploit habitat complexity through spatial partitioning that can be informative for planning restoration and management actions.

Using confidence intervals to estimate the response of salmon populations (Oncorhynchus spp.) to experimental habitat alterations

2005 ◽  
Vol 62 (12) ◽  
pp. 2716-2726 ◽  
Author(s):  
Michael J Bradford ◽  
Josh Korman ◽  
Paul S Higgins
Keyword(s):  
Confidence Intervals ◽  
Effect Size ◽  
Null Hypothesis ◽  
Statistical Power ◽  
Habitat Restoration ◽  
Coho Salmon ◽  
Fish Habitat ◽  
Monitoring Program ◽  
Considerable Uncertainty ◽  
Monitoring Programs

There is considerable uncertainty about the effectiveness of fish habitat restoration programs, and reliable monitoring programs are needed to evaluate them. Statistical power analysis based on traditional hypothesis tests are usually used for monitoring program design, but here we argue that effect size estimates and their associated confidence intervals are more informative because results can be compared with both the null hypothesis of no effect and effect sizes of interest, such as restoration goals. We used a stochastic simulation model to compare alternative monitoring strategies for a habitat alteration that would change the productivity and capacity of a coho salmon (Oncorhynchus kisutch) producing stream. Estimates of the effect size using a freshwater stock–recruit model were more precise than those from monitoring the abundance of either spawners or smolts. Less than ideal monitoring programs can produce ambiguous results, which are cases in which the confidence interval includes both the null hypothesis and the effect size of interest. Our model is a useful planning tool because it allows the evaluation of the utility of different types of monitoring data, which should stimulate discussion on how the results will ultimately inform decision-making.

scholarly journals Habitat affinity and density-dependent movement as indicators of fish habitat restoration efficacy

2019 ◽  
Author(s):  
Carlos M. Polivka
Keyword(s):  
Behavioral Ecology ◽  
Habitat Restoration ◽  
Pacific Salmon ◽  
Fish Habitat ◽  
Explanatory Power ◽  
Habitat Characteristics ◽  
Density Data ◽  
Trade Offs ◽  
Effectiveness Studies ◽  
Habitat Affinity

AbstractConceptual and methodological tools from behavioral ecology can inform studies of habitat quality and their potential for evaluating habitat restoration in conservation efforts is explored here. Such approaches provide mechanistic detail in understanding the relationship between organisms and their habitats and are thus more informative than correlations between density and habitat characteristics. Several Pacific salmon species have been the target of habitat restoration efforts for the past 2-3 decades, but most post-restoration effectiveness studies have been limited to correlative data described above. In mark-recapture assays from four different study years, the affinity of sub-yearling Chinook salmon (Oncorhynchus tschawytscha) and steelhead (O. mykiss) for stream pools restored with or created by engineered log structures was greater than that for pools without restoration, though with high interannual variability. From corresponding distribution and density data, it was clear that habitat affinity data are not always concordant with single observations of density. The same was true of the correlation between either affinity or density and physical characteristics of pools, although depth and current velocity had some explanatory power for both responses in Chinook. Movement into pools by Chinook during the assays indicated that restored pools can support more immigrants at a given density than can unrestored pools; however no such pattern emerged for steelhead. Variation among individuals in body condition has implications for population-wide fitness, and such low variation was correlated with stronger affinity for pools in Chinook regardless of restoration status. This suggests that pools may mediate habitat-related trade-offs and that restoring them might have a positive effect on fitness. Thus affinity, immigration, and condition data give much-needed mechanistic indication of habitat selection for restored habitat via an apparent capacity increase and those potential fitness benefits. This is stronger support for restoration effectiveness than density differences alone because density data 1) may simply indicate redistribution of fish from poor to good habitats and 2) are not adequate to show correlations between restoration and positive change in traits correlated with fitness.

scholarly journals Increasing habitat complexity on seawalls: Investigating large- and small-scale effects on fish assemblages

2017 ◽  
Vol 7 (22) ◽  
pp. 9567-9579 ◽  
Author(s):  
Rebecca L. Morris ◽  
M. Gee Chapman ◽  
Louise B. Firth ◽  
Ross A. Coleman
Keyword(s):  
Habitat Complexity ◽  
Fish Assemblages ◽  
Scale Effects ◽  
Small Scale

Are vegetation interfaces important to foraging insectivorous bats in endangered coastal saltmarsh on the Central Coast of New South Wales?

2012 ◽  
Vol 18 (4) ◽  
pp. 282 ◽  
Author(s):  
Leroy Gonsalves ◽  
Bradley Law ◽  
Cameron Webb ◽  
Vaughan Monamy
Keyword(s):  
New South ◽  
Individual Species ◽  
Microhabitat Use ◽  
Central Coast ◽  
Insectivorous Bats ◽  
Insect Abundance ◽  
Bat Activity ◽  
Management Actions ◽  
South Wales ◽  
Linear Elements

Conservation of insectivorous bats and their habitats is of increasing concern in Australia and linear elements in the landscape form important foraging habitats for many species. Only recently has use of endangered coastal saltmarsh habitat by bats been documented. Vegetation adjoining saltmarsh provides echolocating bats with linear elements that may be used while foraging and commuting to patches of high insect abundance. We used acoustic detectors to investigate whether individual species and total bat activity along seaward and landward saltmarsh edges was different to the interior of the saltmarsh. Four taxa accounted for greater than 80 % of all bat activity in each zone with similar taxa recorded in both edge and interior zones. However, significantly more bat activity was recorded in edge zones. While differences in microhabitat use by individual species were also found, bat morphology did not account for the observed differences. Conservation managers of saltmarsh and adjoining habitats should consider potential impacts of management actions on foraging bats and their prey. Retention of strips of edge vegetation may help to balance the conservation requirements of endangered coastal saltmarsh habitats and the foraging insectivorous bat populations they sustain.

Potential benefits of a conservation hatchery program for supplementing Oregon coast coho salmon (Oncorhynchus kisutch) populations: a stochastic model investigation

2005 ◽  
Vol 62 (8) ◽  
pp. 1920-1935 ◽  
Author(s):  
Gretchen R Oosterhout ◽  
Charles W Huntington ◽  
Thomas E Nickelson ◽  
Peter W Lawson
Keyword(s):  
Habitat Restoration ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Solution Space ◽  
Oregon Coast ◽  
Hatchery Fish ◽  
Natural Production ◽  
Management Actions ◽  
Genetic Risks ◽  
Hatchery Program

This study developed a stochastic life cycle model to simulate idealized supplementation strategies to investigate the following question: under what circumstances could hatchery fish stocking contribute to the recovery of Oregon coast coho salmon (Oncorhynchus kisutch)? Simulations were used to find a solution space, defined by the attributes of wild and hatchery-bred salmon, their offspring, and their environments, where hatchery fish could supplement natural production without further depressing it until natural or human factors restricting production were relieved. These simulations suggest that short-duration, tightly controlled, low-intensity conservation hatchery programs designed to minimize genetic and ecological risks may yield minor short-term increases in adult coho salmon abundance while posing significant ecological and genetic risks. No solution space was found that indicated clear long-term benefits from such a supplementation program. Of all the management actions modeled, habitat restoration offered by far the largest and only permanent gains in coho salmon abundance while posing no genetic or ecological risk to the fish. The modeled benefits of habitat restoration were significant regardless of assumptions made about the fitness of hatchery fish and their offspring.

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