Predation by Eurasian otters on adult Atlantic salmon

The return of the Eurasian otter to western Norway has sparked human-predator conflicts as otters prey on vulnerable Atlantic salmon populations. Although predation may not be the direct cause of salmon population declines, otters that kill salmon in rivers before they spawn may impact the salmon spawning stock, with potential consequences for stock recruitment. Concerns of local people and stakeholders suggest that otter predation inhibits recovery of salmon populations. However, there is limited information on mortality caused by otter predation on adult salmon. To gain insight into impacts of otter predation on salmon populations, I quantified the predation by otters on adult salmon in two rivers in Western Norway using a novel combination of radiotelemetry and temperature loggers. I tagged 45 salmon in Aureelva and 30 salmon in Søre Vartdalselva and tracked the salmon until they died or left the river. This method identified the fates of 95 % of tagged salmon. Otters killed 9 tagged salmon in Aureelva and 20 tagged salmon in Søre Vartdalselva. I found no evidence that otters selectively killed salmon based on sex, length, health status or activity level, which suggests that predation mortality on pre-spawners was additive. Otter predation contributed in reducing both salmon populations below their spawning targets, and without otter predation both populations would have been closer to reaching their spawning targets. However, the magnitude of predation differed greatly between rivers. Salmon in Søre Vartdalselva had greater predation risk compared to salmon in Aureelva, possibly due to differences in the number of holding pools between the two rivers. The findings from this study emphasise that management decisions should be guided by river-specific evaluations of impacts of otter predation on salmon, for which the combination of radiotelemetry and temperature loggers can provide a valuable tool.Predation by Eurasian otters on adult Atlantic salmonpublishedVersio

Predation research with electronic tagging

Predation is a fundamental aspect of ecology that drives ecosystem structure and function. A better understanding of predation can be facilitated by using electronic tags that log or transmit positions of predator or prey species in natural settings, however, there are special considerations that must be made to avoid biased estimates. We provide an overview of the tools available for studying predation with electronic tags including the tag types and analytical tools that can be used to identify where, when and how prey are killed by predators. We also discuss considerations for experimental design when studying predation using electronic tags, including how to minimize effects of capture and tagging procedures. Ongoing innovation and integration of sensors for tags will provide more detailed data about the performance of tagged predators and the fate of tagged prey. Where analysts can effectively resolve the timing of predation using state-of-the-art tags and analytical tools, we foresee exciting advances in our understanding of animal demographics, evolutionary trajectories and management systems. Prospects to develop new tools and approaches for tracking predation while designing studies to more effectively limit bias are an important frontier for understanding ecosystems and addressing human–wildlife conflicts. Given great uncertainties about environmen-tal change and intensifying conflicts between humans and predators, effective study designs integrating electronic tagging to study predation have a promising future in fundamental and applied ecologypublishedVersio

Tunprojektet fik royalt besøg af H.K.H. Kronprins Frederik

Tunmærkningen har igen haft besøg af H.K.H. Kronprins Frederik, som i går kom og hjalp med mærkningen og fik lejlighed til at høre om resultaterne fra netop den tun, han selv var med til at mærke i projektet i 2021

Digital fisheries data in the Internet age: Emerging tools for research and monitoring using online data in recreational fisheries

Recreational fisheries are diverse in scale, scope, and participation worldwide, constituting an important ecosystem service of marine and freshwater ecosystems. Management of these socio-ecological systems is challenged by monitoring gaps, stemming from difficulties engaging with participants, biased sampling, and insufficient resources to conduct biological or social surveys of fish and human populations. In the Internet age, online data have great potential to make a meaningful contribution to recreational fisheries research, monitoring, and management. Recreational fishers in some countries increasingly use social and other digital media to share their experiences with followers, with most data freely available to web scrapers that compile databases of text (e.g. tweets, status updates, comments), photos, videos and other media that contain information about spatiotemporal activity, sentiments towards catches/experiences, targeted and bycatch species, effort levels, and more. Although the future of recreational fisheries research, monitoring and management will likely involve more digital scraping, uptake is only just beginning and there are several challenges including tool availability/accessibility, sampling biases, and making findings relevant and usable to practitioners. Despite these challenges, we envision fisheries managers will increasingly turn towards online sources of fisheries data to supplement conventional methods. We challenge scientists to work towards continued method development and validation of various digital fisheries data tools and emphasize how biases from the online behaviour of users may complicate interpretations of these data for fisheries management.publishedVersio

Digital fisheries data in the Internet age: Emerging tools for research and monitoring using online data in recreational fisheries

Recreational fisheries are diverse in scale, scope, and participation worldwide, constituting an important ecosystem service of marine and freshwater ecosystems. Management of these socio-ecological systems is challenged by monitoring gaps, stemming from difficulties engaging with participants, biased sampling, and insufficient resources to conduct biological or social surveys of fish and human populations. In the Internet age, online data have great potential to make a meaningful contribution to recreational fisheries research, monitoring, and management. Recreational fishers in some countries increasingly use social and other digital media to share their experiences with followers, with most data freely available to web scrapers that compile databases of text (e.g. tweets, status updates, comments), photos, videos and other media that contain information about spatiotemporal activity, sentiments towards catches/experiences, targeted and bycatch species, effort levels, and more. Although the future of recreational fisheries research, monitoring and management will likely involve more digital scraping, uptake is only just beginning and there are several challenges including tool availability/accessibility, sampling biases, and making findings relevant and usable to practitioners. Despite these challenges, we envision fisheries managers will increasingly turn towards online sources of fisheries data to supplement conventional methods. We challenge scientists to work towards continued method development and validation of various digital fisheries data tools and emphasize how biases from the online behaviour of users may complicate interpretations of these data for fisheries management

Digital fisheries data in the Internet age: Emerging tools for research and monitoring using online data in recreational fisheries

Recreational fisheries are diverse in scale, scope, and participation worldwide, constituting an important ecosystem service of marine and freshwater ecosystems. Management of these socio-ecological systems is challenged by monitoring gaps, stemming from difficulties engaging with participants, biased sampling, and insufficient resources to conduct biological or social surveys of fish and human populations. In the Internet age, online data have great potential to make a meaningful contribution to recreational fisheries research, monitoring, and management. Recreational fishers in some countries increasingly use social and other digital media to share their experiences with followers, with most data freely available to web scrapers that compile databases of text (e.g. tweets, status updates, comments), photos, videos and other media that contain information about spatiotemporal activity, sentiments towards catches/experiences, targeted and bycatch species, effort levels, and more. Although the future of recreational fisheries research, monitoring and management will likely involve more digital scraping, uptake is only just beginning and there are several challenges including tool availability/accessibility, sampling biases, and making findings relevant and usable to practitioners. Despite these challenges, we envision fisheries managers will increasingly turn towards online sources of fisheries data to supplement conventional methods. We challenge scientists to work towards continued method development and validation of various digital fisheries data tools and emphasize how biases from the online behaviour of users may complicate interpretations of these data for fisheries management

Digital fisheries data in the Internet age: Emerging tools for research and monitoring using online data in recreational fisheries

Recreational fisheries are diverse in scale, scope, and participation worldwide, constituting an important ecosystem service of marine and freshwater ecosystems. Management of these socio-ecological systems is challenged by monitoring gaps, stemming from difficulties engaging with participants, biased sampling, and insufficient resources to conduct biological or social surveys of fish and human populations. In the Internet age, online data have great potential to make a meaningful contribution to recreational fisheries research, monitoring, and management. Recreational fishers in some countries increasingly use social and other digital media to share their experiences with followers, with most data freely available to web scrapers that compile databases of text (e.g. tweets, status updates, comments), photos, videos and other media that contain information about spatiotemporal activity, sentiments towards catches/experiences, targeted and bycatch species, effort levels, and more. Although the future of recreational fisheries research, monitoring and management will likely involve more digital scraping, uptake is only just beginning and there are several challenges including tool availability/accessibility, sampling biases, and making findings relevant and usable to practitioners. Despite these challenges, we envision fisheries managers will increasingly turn towards online sources of fisheries data to supplement conventional methods. We challenge scientists to work towards continued method development and validation of various digital fisheries data tools and emphasize how biases from the online behaviour of users may complicate interpretations of these data for fisheries management

Tracking aquatic animals to understand a world increasingly shaped by a changing climate and extreme weather events

Despite great promise for understanding the impacts and extent of climate change on aquatic animals, their species, and ecological communities, it is surprising that tracking tools, like biotelemetry and biologging devices, have not been extensively used to understand climate change or develop and evaluate potential interventions that may forestall or mitigate its effects. In this review, we provide an overview of methodologies and study designs that leverage available tracking tools to investigate aspects of climate change on aquatic ecosystems. Key interventions to protect aquatic life from the impacts of climate change, including habitat restoration, protected areas, conservation translocations, mitigations against interactive effects of climate change, and simulation of future scenarios can all be greatly facilitated by using electronic tagging and tracking. We anticipate that adapting study designs (e.g. use of replicated ponds, randomized control trials, physiologging) to effectively use tracking will greatly enhance our understanding of climate change and its impacts on aquatic ecosystems, hopefully also facilitating research into effective solutions and interventions against the most extreme and acute impacts

Electronic tagging and tracking aquatic animals to understand a world increasingly shaped by a changing climate and extreme weather events

Despite great promise for understanding the impacts and extent of climate change and extreme weather events on aquatic animals, their species, and ecological communities, it is surprising that electronic tagging and tracking tools, like biotelemetry and biologging, have not been extensively used to understand climate change or develop and evaluate potential interventions that may help adapt to its impacts. In this review, we provide an overview of methodologies and study designs that leverage available electronic tracking tools to investigate aspects of climate change and extreme weather events in aquatic ecosystems. Key interventions to protect aquatic life from the impacts of climate change, including habitat restoration, protected areas, conservation translocations, mitigations against interactive effects of climate change, and simulation of future scenarios, can all be greatly facilitated by using electronic tagging and tracking. We anticipate that adopting animal tracking to identify phenotypes, species, or ecosystems that are vulnerable or resilient to climate change will help in applying management interventions such as fisheries management, habitat restoration, invasive species control, or enhancement measures that prevent extinction and strengthen the resilience of communities against the most damaging effects of climate change. Given the scal-ability and increasing accessibility of animal tracking tools for researchers, tracking individual organisms will hopefully also facilitate research into effective solutions and interventions against the most extreme and acute impacts on species, popula-tions, and ecosystems