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Predicting how quickly populations expand their range and whether they will retain genetic diversity when they are introduced to new regions or track environmental conditions suited to their survival is an important applied and theoretical challenge. The literature suggests that long‐distance dispersal, landscape heterogeneity and the evolution of dispersal influence populations' expansion rates and genetic diversity. We used individual‐based spatially explicit simulations to examine these relationships for Tench (Tinca tinca), an invasive fish expanding its geographical range in eastern North America since the 1990s. Simulated populations varied greatly in expansion rates (1.1–28.6 patches year−1) and genetic diversity metrics, including changes in observed heterozygosity (−19 to +0.8%) and effective number of alleles (−0.32 to −0.01). Populations with greater dispersal distances expanded faster than those with smaller dispersal distances but exhibited considerable variation in expansion rate among local populations, implying less predictable expansions. However, they tended to retain genetic diversity as they expanded, suggesting more predictable evolutionary trajectories. In contrast, populations with smaller dispersal distances spread predictably more slowly but exhibited more variability among local populations in genetic diversity losses. Consistent with empirical data, populations spreading in a longer, narrower dispersal corridor lost more neutral genetic variation to the stochastic fixation of alleles. Given the unprecedented pace of anthropogenic environmental change and the increasing need to manage range‐expanding populations, our results have conservation ramifications as they imply that the evolutionary trajectories of populations characterised by shorter dispersal distances spreading in narrower landscapes are more variable and, therefore, less predictable. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) monitoring methods have played a significant role in improving fisheries management decisions. Yet, their impact to date has been rather limited in Canada, where eDNA sampling and analyses are only beginning to be used to inform management and conservation decisions, practices, and policies. Studies investigating hurdles to the incorporation of eDNA evidence into fisheries management decisions generally focus on technical challenges (i.e., risks of false-positive and false-negative detections). We set out to identify challenges that eDNA researchers and conservation practitioners must overcome to fully unlock the benefits of eDNA sampling for fish management in the Canadian context. We discuss aspects of the broad and heterogeneous geography, preponderance of regions located far from densely populated areas, complex political landscape, and cultural diversity of Canada that may complicate the design of reliable eDNA monitoring tools or restrict their use if not adequately addressed. To advocate for the wider use of eDNA sampling, we outline a number of action items that would facilitate the broad adoption of eDNA sampling as a monitoring tool at the Canadian scale. [ABSTRACT FROM AUTHOR]

The coexistence of distinct alternative mating strategies (AMS) is often explained by mechanisms involving trade‐offs between reproductive traits and lifetime fitness; yet their relative importance remains poorly understood. Here, we used an established individual‐based, spatially explicit model to simulate bull trout (Salvelinus confluentus) in the Skagit River (Washington, USA) and investigated the influence of female mating preference, sneaker‐specific mortality, and variation in age‐at‐maturity on AMS persistence using global sensitivity analyses and boosted regression trees. We assumed that two genetically fixed AMS coexisted within the population: sneaker males (characterized by younger age‐at‐maturity, greater AMS‐specific mortality, and lower reproductive fitness) and territorial males. After 300 years, variation in relative sneaker success in the system was explained by sneaker males' reproductive fitness (72%) and, to a lesser extent, the length of their reproductive lifespan (21%) and their proportion in the initial population (8%). However, under a wide range of parameter values, our simulated scenarios predicted the extinction of territorial males or their persistence in small, declining populations. Although these results do not resolve the coexistence of AMS in salmonids, they reinforce the importance of mechanisms reducing sneaker's lifetime reproductive success in favoring AMS coexistence within salmonid populations but also limit the prediction that, without any other selective mechanisms at play, strong female preference for mating with territorial males and differences in reproductive lifespan allow the stable coexistence of distinct AMS. [ABSTRACT FROM AUTHOR]

Introduced and geographically expanding populations experience similar eco‐evolutionary challenges, including founder events, genetic bottlenecks, and novel environments. Theory predicts that reduced genetic diversity resulting from such phenomena limits the success of introduced populations. Using 1900 SNPs obtained from restriction‐site‐associated DNA sequencing, we evaluated hypotheses related to the invasion history and connectivity of an invasive population of Tench (Tinca tinca), a Eurasian freshwater fish that has been expanding geographically in eastern North America for three decades. Consistent with the reported history of a single introduction event, our findings suggest that multiple introductions from distinct genetic sources are unlikely as Tench had a small effective population size (~114 [95% CI = 106–123] individuals), no strong population subdivision across time and space, and evidence of a recent genetic bottleneck. The large genetic neighbourhood size (220 km) and weak within‐population genetic substructure suggested high connectivity across the invaded range, despite the relatively large area occupied. There was some evidence for a small decay in genetic diversity as the species expanded northward, but not southward, into new habitats. As eradicating the species within a ~112 km radius would be necessary to prevent recolonization, eradicating Tench is likely not feasible at watershed—and possibly local—scales. Management should instead focus on reducing abundance in priority conservation areas to mitigate adverse impacts. Our study indicates that introduced populations can thrive and exhibit relatively high levels of genetic diversity despite severe bottlenecks (<1.5% of the ancestral effective population size) and suggests that landscape heterogeneity and population demographics can generate variability in spatial patterns of genetic diversity within a single range expansion. [ABSTRACT FROM AUTHOR]

Local support is critical to the success and longevity of fishery management initiatives. Previous research suggests that how resource users perceive ecological changes, explain them, and cope with them, influences local support. The objectives of this study were two-fold. First, we collated local fishers' knowledge to characterize the long-term socio-ecological dynamics of the small-scale fishery of Sainte-Marie Island, in Madagascar. Second, we empirically assessed the individual- and site-level factors influencing support for fishery restrictions. Our results indicate that fishers observed a decline in fish abundance and catch sizes, especially in nearshore areas; many also perceived a reduction in fish sizes and the local disappearance of species. To maintain their catches, most fishers adapted by fishing harder and further offshore. Accordingly, fishers identified increased fishing effort (number of fishers and gear evolution) as the main cause of fishery changes. Collectively, our results highlight that the transition from a subsistence to commercial fishery, and resulting changes in the relationship between people and the fisheries, was an underlying driver of fishery changes. Additionally, we found that gender, membership to local associations, coping mechanisms, and perceptions of ecological health, were all interlinked and significantly associated with conservation-oriented attitudes. Conservation-oriented attitudes, however, were not associated with fishers' willingness to decrease fishing. In the short-term, area-based restrictions could contribute to building support for conservation. In the long-term, addressing the underlying causes of the decline will necessitate collaborations among the various groups involved to progressively build livelihood flexibility. Collectively, our study provides additional insights on the individual- and site-level factors influencing support for fishery restrictions. It also highlights the importance of dialoguing with fishers to ensure that fishery management plans are adapted to the local context. [ABSTRACT FROM AUTHOR]

Despite the promising applications of genome-wide information to conservation, the field of conservation genomics remains hindered by a research-practice gap. Identifying the benefits from genomics in relation to fish conservation planning and decision-making could contribute to bridging this gap. The goals of our study were twofold. First, we reviewed the fish conservation genomic literature to determine how genomic information has been used to inform conservation decision making; and second, we examined how genomic information can be linked to an existing conservation decision framework. Our review showed that, as fish conservation genomics studies accumulate over time, collaborations between researchers and conservation practitioners are becoming increasingly frequent. While the field is dominated by studies of economically important families (e.g. salmonids, acipenserids) in first-world countries (North America, Europe), it has a broad taxonomic coverage where species of both local and global conservation concern are well represented. We also show that genomic information can readily be harnessed to guide decisions within existing conservation decision frameworks, from the conceptualization (identification of conservation targets and threats) to the implementation and the monitoring of conservation actions. In addition, our review identifies some limitations related to genomic inferences for conservation and proposes solutions to address these uncertainties and improve communication between conservation genomic scientists and practitioners. For genomic researchers, we outline how conservation decisions are made; for practitioners, we illustrate how genomic information can inform decision-making. [ABSTRACT FROM AUTHOR]