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ABSTRACT The muskrat (Ondatra zibethicus) is an invasive species in Europe. The extensive waterways of the Netherlands provide ideal habitat for muskrats, and a large population established itself after arrival in 1941. A control program was put into effect immediately because muskrat burrowing can compromise the integrity of dikes and, hence, poses a significant public safety risk. The current (2015) annual catch of approximately 89,000 individuals is equivalent to approximately 0.30 muskrats/km of waterway, well above the national objective in spite of decades of effort. The control program is expensive (€35 M annually) and contested by animal rights groups. These factors created the need for a careful evaluation of the full range of control possibilities, from ‘no control’ to ‘extermination.’ As part of this, we experimentally evaluated the validity of a previously published correlation (based on historical data) between catch and effort. We raised or lowered removal effort (2013–2016) in a stratified random sample of 117 5‐km × 5‐km ‘atlas squares’ from the national grid. We found that catch‐per‐unit effort (CPUE) decreased after effort was increased, and rose after effort was decreased, by amounts slightly greater than expected based on the correlational data, though confidence intervals enclose zero. As anticipated, CPUE varied consistently and strongly between seasons. The biggest (and unanticipated) effects were those of the catch in the preceding 3 years (‘history’), and surrounding area (‘neighborhood’). Our experiment confirms estimates of intensity of control required to lower muskrat populations. These results will help with more effective allocation of control effort, and better‐informed evaluation of the economic costs of various control options. © 2020 The Authors. Wildlife Society Bulletin published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

Abstract Secondary contact may have important implications for ecological and evolutionary processes; however, few studies have tracked the outcomes of secondary contact from its onset in natural ecosystems. We evaluated an anadromous alewife (Alosa pseudoharengus) reintroduction project in Rogers Lake (Connecticut, USA), which contains a landlocked alewife population that was isolated as a result of colonial‐era damming. After access to the ocean was restored, adult anadromous alewife were stocked into the lake. We assessed anadromous juvenile production, the magnitude and direction of introgression, and the potential for competition between ecotypes. We obtained fin clips from all adult alewife stocked into the lake during the restoration and a sample of juveniles produced in the lake two years after the stocking began. We assessed the ancestry of juveniles using categorical assignment and pedigree reconstruction with newly developed microhaplotype genetic markers. Anadromous alewives successfully spawned in the lake and hybridized with the landlocked population. Parentage assignments revealed that male and female anadromous fish contributed equally to juvenile F1 hybrids. The presence of landlocked backcrosses shows that some hybrids were produced within the first two years of secondary contact, matured in the lake, and reproduced. Therefore, introgression appears directional, from anadromous into landlocked, in the lake environment. Differences in estimated abundance of juveniles of different ecotypes in different habitats were also detected, which may reduce competition between ecotypes as the restoration continues. Our results illustrate the utility of restoration projects to study the outcomes of secondary contact in real ecosystems.

The muskrat (Ondatra zibethicus) is an invasive species in Europe. The extensive waterways of the Netherlands provide ideal habitat for muskrats, and a large population established itself after arrival in 1941. A control program was put into effect immediately because muskrat burrowing can compromise the integrity of dikes and, hence, poses a significant public safety risk. The current (2015) annual catch of approximately 89,000 individuals is equivalent to approximately 0.30 muskrats/km of waterway, well above the national objective in spite of decades of effort. The control program is expensive (€35 M annually) and contested by animal rights groups. These factors created the need for a careful evaluation of the full range of control possibilities, from 'no control' to 'extermination.' As part of this, we experimentally evaluated the validity of a previously published correlation (based on historical data) between catch and effort. We raised or lowered removal effort (2013–2016) in a stratified random sample of 117 5‐km × 5‐km 'atlas squares' from the national grid. We found that catch‐per‐unit effort (CPUE) decreased after effort was increased, and rose after effort was decreased, by amounts slightly greater than expected based on the correlational data, though confidence intervals enclose zero. As anticipated, CPUE varied consistently and strongly between seasons. The biggest (and unanticipated) effects were those of the catch in the preceding 3 years ('history'), and surrounding area ('neighborhood'). Our experiment confirms estimates of intensity of control required to lower muskrat populations. These results will help with more effective allocation of control effort, and better‐informed evaluation of the economic costs of various control options. © 2020 The Authors. Wildlife Society Bulletin published by Wiley Periodicals, Inc. on behalf of The Wildlife Society. We report on a carefully designed and large management experiment to test hypotheses about the effectiveness of muskrat control by trapping. Muskrat populations can be controlled by trapping, but the spatial scale of implementation appeared to be much more important than anticipated. [ABSTRACT FROM AUTHOR]

Secondary contact may have important implications for ecological and evolutionary processes; however, few studies have tracked the outcomes of secondary contact from its onset in natural ecosystems. We evaluated an anadromous alewife (Alosa pseudoharengus) reintroduction project in Rogers Lake (Connecticut, USA), which contains a landlocked alewife population that was isolated as a result of colonial‐era damming. After access to the ocean was restored, adult anadromous alewife were stocked into the lake. We assessed anadromous juvenile production, the magnitude and direction of introgression, and the potential for competition between ecotypes. We obtained fin clips from all adult alewife stocked into the lake during the restoration and a sample of juveniles produced in the lake two years after the stocking began. We assessed the ancestry of juveniles using categorical assignment and pedigree reconstruction with newly developed microhaplotype genetic markers. Anadromous alewives successfully spawned in the lake and hybridized with the landlocked population. Parentage assignments revealed that male and female anadromous fish contributed equally to juvenile F1 hybrids. The presence of landlocked backcrosses shows that some hybrids were produced within the first two years of secondary contact, matured in the lake, and reproduced. Therefore, introgression appears directional, from anadromous into landlocked, in the lake environment. Differences in estimated abundance of juveniles of different ecotypes in different habitats were also detected, which may reduce competition between ecotypes as the restoration continues. Our results illustrate the utility of restoration projects to study the outcomes of secondary contact in real ecosystems. [ABSTRACT FROM AUTHOR]

The Variable Retention Harvest System (VRHS) is a silvicultural system designed to reduce logging impacts and enhance biodiversity conservation. VRHS has been widely applied worldwide but several important questions remain about its effectiveness for biodiversity conservation. A key issue is whether dispersed or aggregated retention is more effective for conservation, and hence what size of retained patches of forest should be maintained within logged areas. Many studies have indicated that increasing the amount of the original stand retained during harvesting increases the amount of biodiversity conserved. But in a form of the SLOSS (single large or several small areas for conservation) debate, a critical question is: does one large retained island better conserve forest biota than several small islands of the same aggregated area? We addressed this question in an experiment in the Mountain Ash ( Eucalyptus regnans ) forests of the Central Highlands of Victoria, south-eastern Australia. The experiment comprised seven blocks, each with four treatments – an unlogged control, a conventional 15–40 ha clearfelled area, a 15–40 ha harvest unit with a single 1.5 ha retained “island”, and a 15–40 ha harvest unit with three 0.5 ha islands. A subset of the treatment plots and harvest units in our experiment were burned in a major wildfire in 2009. Given this, a subsequent further question we posed was: are there additional effects on birds resulting from logging operations that were followed by wildfires. We identified a significant gradient in species richness across treatments with lowest values in conventional clearfelled areas and highest values in unlogged controls. Unexpectedly, we identified no significant island size effects on bird species richness. We found no individual species that were significantly more likely to occur in a single large island than several small islands. Nonmetric multidimensional scaling revealed significant differences in the composition of the bird community between treatments, consistent with our findings for some of the more common species of birds. Several species were significantly less likely to be recorded in clearfelled areas, although the Flame Robin was more likely to be recorded in them. When we removed clearfelled areas from our analyses, some species were significantly less likely to occur in retained islands than unlogged controls. The application of VRHS did not appear to mediate bird responses to wildfire relative to effects for birds observed in clearfelled harvest units that were subsequently burned in 2009. Our results suggest that VRHS has positive effects on bird biota in Mountain Ash forests. However, this study found no advantage of setting aside a single large island versus several small islands within a given harvest unit for bird species richness nor the occurrence of individual bird species. [ABSTRACT FROM AUTHOR]

In order to overcome the modeling limitations for management experiments, we proposed to integrate the Internet technology with role-playing, and developed a novel modeling method called similarity-extension modeling method. By the novel method, we found a new way to transform an economic experiment into a management one. The basic steps of similarity-extension modeling are presented, and their applications are illustrated by taking Cournot Oligopoly Management Experiment as an example. In the example, the primary Cournot Oligopoly Management Experiment is first established with reference to the basic element model of the Cournot Oligopoly Economic Experiment, and then how to transform the economic experiment into a management one is focused on in detail by introducing management factors. Finally, an improved quantitative process method is delved into for fuzzy management factors based on the Market Quiz Method in psychology. [ABSTRACT FROM AUTHOR]