Article

Restoring migratory salmonid populations in regulated rivers in the northernmost Baltic Sea area, Northern Finland - biological, technical and social challenges

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Abstract

This paper summarizes the objectives, activities initiated and approaches used in developing Atlantic salmon stock re-building programmes in three large river systems in northern Finland in order to identify the priorities for research and management for further restoration and rehabilitation steps. Until recently, these historically renowned major salmon rivers have been harnessed for hydropower for 40–60 years without provisions for fish passage. Hydropower companies are obliged to compensate for the losses caused by dam construction by annual fish releases, including juveniles of Atlantic salmon and migratory brown trout. Returning fish are harvested in the designated ‘terminal fishery areas’ at river mouths. Recently, activities aimed at restoring salmonid stocks have started in all these rivers. First fishways at the dams closest to the river mouths were constructed on two rivers, and preliminary projects were completed to review the preconditions for restoration, options for bypassing the dams, and to study the performance of these fishways. New projects incorporating further detailed fishway planning are underway. The various projects have proved successful in bringing together authorities, hydropower companies, local organizations, and expertise from various institutions for a joint effort to tackle these multifaceted and multidisciplinary problems.

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... Natural, self-sustaining populations currently exist in less than 30 Baltic rivers (e.g., Ranke et al., 1999). Most of the major Atlantic salmon rivers in Finland were harnessed for hydropower production, mainly in the 1940s and 1950s, (Erkinaro et al., 2011). During that time, production of electricity was seen as an overriding national interest and generally took precedence over other factors, including natural salmon populations. ...
... In recent decades, demands to re-establish natural salmon production in regulated rivers have been significantly increasing. Several restoration projects have been launched, and substantial research activities are ongoing (Erkinaro et al., 2011). ...
... The number of salmon passing the new fishway has been some hundreds of individuals annually. The returning salmon stem from largescale stocking of smolts at the Kemijoki river mouth; the fish mostly originate from salmon stock of the nearby wild salmon Tornionjoki river system, but also include material from the Iijoki river strain (Erkinaro et al., 2011). ...
... This suggests that more FPM populations will become extinct (Bauer, 1983(Bauer, , 1986Beasley et al., 1998;Cosgrove et al., 2000;Geist, 2010;Geist et al., 2006), and that there may be unidentified factors related to reproduction preventing population recovery. Furthermore, many large European river systems were dammed for hydroelectric production during the 20th century, fragmenting them, reducing river connectivity and thereby preventing migrations of anadromous fish, including Atlantic salmon (Bardonnet & Baglini ere, 2000;Erkinaro et al., 2011;Gosselin, 2015;Kallio-Nyberg, Jutila, Koljonen, Koskiniemi, & Saloniemi, 2010;Parrish, Behnke, Gephard, McCormick, & Reeves, 1998). Unfortunately, the salmonid species used for the compensatory salmonid stocking to mitigate dam impacts are not generally required to be the same as the lost species (Erkinaro et al., 2011;Hiltunen, 2010;Marttila et al., 2014) and, in many rivers, Atlantic salmon have been replaced by hatchery-reared brown trout (Hiltunen, 2010;Luhta & Moilanen, 2006). ...
... Furthermore, many large European river systems were dammed for hydroelectric production during the 20th century, fragmenting them, reducing river connectivity and thereby preventing migrations of anadromous fish, including Atlantic salmon (Bardonnet & Baglini ere, 2000;Erkinaro et al., 2011;Gosselin, 2015;Kallio-Nyberg, Jutila, Koljonen, Koskiniemi, & Saloniemi, 2010;Parrish, Behnke, Gephard, McCormick, & Reeves, 1998). Unfortunately, the salmonid species used for the compensatory salmonid stocking to mitigate dam impacts are not generally required to be the same as the lost species (Erkinaro et al., 2011;Hiltunen, 2010;Marttila et al., 2014) and, in many rivers, Atlantic salmon have been replaced by hatchery-reared brown trout (Hiltunen, 2010;Luhta & Moilanen, 2006). Furthermore, building of more hydroelectric dams may be possible in the future (see Erkinaro et al., 2011 and references therein), and thus differences in the potential host suitability between FPM populations require investigation to take it into account both future management plans and fish stockings into FPM rivers. ...
... Field work was conducted in tributaries of the River Iijoki catchment (14,200 km 2 ), and in main channels of the rivers Livojoki (Iijoki catchment), Simojoki (catchment of 3,160 km 2 ) and Luttojoki (Tuloma catchment of 21,500 km 2 ) in Finland, northern Europe ( Figure 1). The rivers Livojoki and Luttojoki were both used by Atlantic salmon as a spawning and nursery area until the mid-1900s, when they were dammed for electricity production (Erkinaro et al., 2011;Karppinen et al., 2002). The undammed River Simojoki still harbours a natural Atlantic salmon population. ...
Article
1. European populations of the freshwater pearl mussel (FPM, Margaritifera margaritifera) have collapsed across much of the species’ geographic range and, despite many types of conservation intervention, the number of successful restoration efforts has been low. The goal of this study was to determine whether there were population-specific differences in the suitability of Atlantic salmon (Salmo salar) and brown trout (S. trutta) as hosts for the parasitic glochidium larvae of FPM. We predicted that such differences would depend on the historical occurrence of these salmonid species in FPM habitats. 2. We studied the potential host specificity both in the field and in laboratory by exposing salmonid fish to FPMglochidia originating from nine populations in different types of streams and rivers within three large river basins in northern Fennoscandia. 3. The exposures showed remarkable population-specific differences in the suitability of host species. In large main channels, previously colonised by Atlantic salmon but mostly now dammed for hydropower production, the occurrence of FPM glochidia was always highest on salmon. Moreover, glochidia on salmon were often larger than the conspecifics on brown trout. Conversely, in small tributaries with no salmon history, brown trout was generally the best, or the only suitable, host for FPM. 4. The adaptation of certain FPM populations to salmon is a highly significant finding, which offers — together with the hydropower dam construction and the salmonid stocking practices that often favour brown trout — an explanation for the collapse of FPM populations living in former Atlantic salmon rivers. 5. This study illustrates the indirect but substantial effects that dams and changes in fish communities may induce, and emphasises the need to determine the most suitable host species for each FPM population in order to inform conservation and management actions.
... Restoration of the complex and dynamic socio-ecological systems of regulated rivers involves several interests and objectives, such as hydropower, fisheries, flood protection, biodiversity and tourism. Trade-offs between sociopolitical, ecological and economic impacts and potential ecosystem services should be taken into consideration (Erkinaro et al., 2011;Karjalainen and Järvikoski, 2010). Integration of conflicting objectives and scientific, in most cases uncertain, information from different disciplines demands a systematic and understandable framework. ...
... In Section 4, we compare the two approaches with focus on the differences in value trees, evaluations of alternatives and the significance of impacts. The comparison is based on the researchers' expert knowledge and their project evaluation as well as the participants' feedback on the assessment process (Karjalainen et al., 2011). ...
... The Atlantic salmon once reproduced in most Baltic rivers, but various human activities have significantly decreased the number of rivers with salmon runs throughout the Baltic area. River fragmentation through damming, deteriorated water quality and overfishing are the most obvious causes of the decline (Erkinaro et al., 2011). In the Baltic Sea area, the salmon is a source of living for a relatively small number of commercial fishers and subsistence fishers (Haapasaari and Karjalainen, 2010). ...
... The parental individuals of our experimental cohorts were selected from first-generation hatchery broodstocks (Neva and Oulu, established in the 1980s), which are maintained by the Natural Resources Institute Finland (LUKE) as a part of a nationally coordinated stock supplementation scheme and for stocking obligations of hydropower companies. Such hatchery broodstocks are necessary as hydropower dams block the migratory routes of the majority of original Atlantic salmon rivers in Finland, and thus there has been little or no natural reproduction in such rivers in many decades (Erkinaro et al., 2011). The Neva stock originates from the river Neva in Russia (Gulf of Finland in the North-Eastern Baltic Sea) and has been used for juvenile salmon releases in the Kymi river in South-Eastern Finland. ...
... In addition, some few individuals from the former, original Oulu river strain were still available and used when this mixed hatchery stock was established (Erkinaro et al., 2011). Every few years, new broodstocks are created from eggs and milt stripped from mature individuals caught in the Kymi (60.48 • N, 26.89 • E) and Oulu (65.01 • N, 25.27 • E) rivers following a successful marine migration. ...
Article
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Age at maturity is a key life history trait involving a trade-off between survival risk and reproductive investment, and is an important factor for population structures. In ectotherms, a warming environment may have a dramatic influence on development and life history, but this influence may differ between populations. While an increasing number of studies have examined population-dependent reactions with temperature, few have investigated this in the context of maturation timing. Atlantic salmon, a species of high conservation relevance, is a good study species for this topic as it displays considerable variation in age at maturity, of which a large proportion has been associated with a genomic region including the strong candidate gene vgll3. Until now, the effect of this gene in the context of different environments and populations has not been studied. Using a large-scale common-garden experiment, we find strong effects of temperature, population-of-origin, and vgll3 genotype on maturation in 2-year-old male Atlantic salmon (Salmo salar). With a temperature difference of 1.8°C, maturation probability was 4.8 times higher in the warm treatment than the cold treatment. This temperature effect was population-specific and was higher in the southern (60.48°N) compared to the northern (65.01°N) population. The early maturation vgll3*E allele was associated with a significantly higher maturation probability, but there was no vgll3 interaction with temperature or population. Both body condition and body mass associated with maturation. The body mass association was only present in the warm treatment. Our findings demonstrate that (i) populations can vary in their response to temperature change in terms of age at maturity, (ii) high intrinsic growth could be associated with higher thermal sensitivity for life history variation and (iii) vgll3 effects on age at maturity might be similar between populations and different thermal environments.
... Papers dealing with effects on population development and not explicitly an ES category are represented in its own category as a (light grey) bar to the right. When papers dealt with multiple categories, those papers were fractionalized between the categories and Europe (Erkinaro et al., 2011;Forseth et al., 2017;Lenders, 2017;Lenders et al., 2016;Limburg & Waldman, 2009;Piccolo et al., 2012;Saltveit, 2006;Soininen et al., 2019). ...
... Therefore, we may have missed some sources of information that discuss the connection between ES from salmon and hydropower, Even if fisheries researchers have thus far been limited in explicitly describing the effects of hydropower on ES delivered by Atlantic salmon, the case is clear that damming and habitat alterations have had far-reaching negative effects on salmon populations (Dymond et al., 2019;Erkinaro et al., 2011;Forseth et al., 2017;Lenders et al., 2016). Thus, river managers are likely to be increasingly called upon to alter hydropower planning and operations (or even to remove dams) to improve fish passage and instream habitat. ...
Article
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Known as the "king of fishes," the Atlantic salmon (Salmo salar, Salmonidae) is an iconic freshwater species whose contribution to human well-being has long been recognized , as have widespread declines in its abundance, partly due to river regulation. To understand how salmon conservation has been addressed within the ecosystem services (ES) framework, we synthesized the peer-reviewed literature on ES provided by salmon in regulated rivers. We developed a search string to capture allusions to provisioning, regulating, supporting and cultural ES and assessed the results to identify knowledge gaps. The effects of hydropower on fisheries catches and on modelled populations were shown in several publications. Overall, few studies focused explicitly on ES from salmon and hydropower; this is surprising given the considerable body of literature on salmon in regulated rivers. Wild salmon as a food source and other provisioning services are less important today than historically. Because predators such as salmon are important for facilitating biodiversity by cycling nutrients and controlling food webs, there is a scope of work for future assessments of these regulating and supporting services. Few papers explicitly addressed cultural ES, despite the salmon's longstanding iconic status; this is a knowledge gap for future ES assessments in relation to hydropower. The influence of ES assessments for policy makers is growing through the Intergovernmental Panel for Biodiversity and Ecosystem Services (IPBES) and the post-2020 biodiversity strategy. Explicitly addressing ES poses an opportunity for river managers to raise awareness of aquatic conservation efforts and well-informed decision-making for sustaining ES.
... The hydromorphological degradation of the river channels resulted in the loss of spawning and nursing habitats for fish. In addition, an increased harvest of sea fishing contributed to the decline of catches of anadromous fish as early as the 1900s [25]. The development of hydropower, in combination with existing pressures, resulted in a complete collapse of the naturally reproducing populations of Atlantic salmon (Salmo salar), Sea trout (Salmo trutta), migratory whitefish (Coregonus lavaretus) and river lamprey (Lampetra fluviatilis). ...
... Previously, these populations supported extensive fisheries in the rivers, estuaries and the nearby coastal areas. The loss of salmon in particular meant a dramatic change for local people in terms of loss of economic revenue as well as the cultural heritage of these iconic species [25]. ...
Article
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Most of Europe’s rivers are highly fragmented by barriers. This study examines legal protection schemes, that specifically aim at preserving the free-flowing character of rivers. Based on national legislation, such schemes are found in seven European countries: Slovenia, Finland, Sweden, France and Spain as well as Norway and Iceland. The study provides an overview of the individual schemes and their respective scope, compares their protection mechanisms and assesses their effectiveness. As Europe’s the remaining free-flowing rivers are threatened by hydropower and other development, the need for effective legal protection, comparable to the designation of Wild and Scenic Rivers in the United States, is urgent. Similarly, any ambitious strategy for the restoration of free-flowing rivers should be complemented with a mechanism for their permanent protection once dams and other barriers are removed. The investigated legal protection schemes constitute a starting point for envisioning a more cohesive European network of strictly protected free-flowing rivers.
... The Salmon Action Plan, introduced by the International Baltic Sea Fisheries Commission (IBSFC) in 1997, implied dealing with the stock declines in selected rivers in different Baltic Sea countries through fishing restrictions, stocking and habitat restoration. Efforts have also been made to restore salmon stocks in former salmon rivers that were dammed for hydroelectric power production in the middle of the 20 th century (Erkinaro et al., 2011). Finland currently has two rivers -Tornionjoki and Simojokiwith naturally reproducing wild salmon stock (International Council for the Exploration of the Sea (ICES, 2017). ...
... The frequent references to tradition and symbolic values among the Finnish but not among the Estonian interviewees may reflect the differing cultural histories related to salmon between these two countries, which are also related to geographical differences between the contexts. In Finland, Baltic salmon was historically abundant until mid-20th century in many big rivers and an important resource, especially in the north (Erkinaro et al., 2011). Salmon also contributed to the development of traditions and local identities in the salmon river areas (Autti and Karjalainen, 2012;Vilkuna, 1975). ...
Article
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The socio-cultural values associated with fish and fisheries affect the utilization and management of fish resources. However, these values often remain implicit in fisheries governance. This paper suggests addressing values explicitly to enhance the legitimacy of governance. We analyzed the values related to Baltic salmon and herring in Finland and Estonia, based on stakeholder interviews. By identifying similarities and differences between the values associated with two species in two countries, this paper demonstrates the multivalued nature of fish and fisheries. Based on our analysis, we recommend explicit and systematic inclusion of values in the early stages of governance processes to ensure morally reasoned management and use of fish resources.
... Despite the urgent need for electricity to fuel economic growth and the consequent prioritization of hydropower over environmental and societal impacts (Erkinaro et al., 2011), the laws at the time did contain provisions limiting construction on Finnish rivers. First of all, the operations were still subject to permitting, and the law required that hydropower-related harms to fisheries must be mitigated, minimized and compensated. ...
... While there is no direct genetic evidence that unintended domestication explains the decreased recapture rates of stocked fish, there is no solid evidence to reject the hypothesis either. Overall, the very low recapture rate and the inadvertent genetic impacts of stocked smolts have challenged the prevailing stocking practices (Erkinaro et al., 2011;Ozerov et al., 2016). Many Finnish salmon and trout broodstocks have now been maintained in hatcheries for 6 to 10 generations. ...
Article
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Historically, Finnish rivers supported vital populations of migratory salmonids. Presently, these species are more or less endangered due to extensive damming and hydropower production. In this article, we study the main legal and scientific drivers for re-evaluating some of the existing hydropower operations in Finland. We argue that there is a need for re-evaluation on the basis of legal obligations stemming largely from EU law and new scientific knowledge. Theoretically, our setting opens up a classical adaptive governance problem in how to address laws and past decisions that are based on outdated assumptions about the functioning of social-ecological systems.
... The Atlantic sturgeon went extinct in five catchments that were freely accessible for more than 40% of their migratory distance, indicating that other environmental conditions probably contributed to its current absence. The Atlantic salmon still occurs in 27 catchments and is presently reintroduced by stocking in 10 rivers, even inaccessible ones (Erkinaro et al., 2010;Östergren, Lundqvist, & Nilsson, 2011). With many reintroductions, the results for sea trout are comparable with the Atlantic salmon. ...
... Reintroduction or stocking of young salmon occurred in many rivers and for many years in high numbers (Erkinaro et al., 2010;HELCOM, 2011;ICPR, 2015;Wolter, 2015). This also took, and sometimes still takes, place in inaccessible rivers where populations did not recover and stocking appeared to be inadequate without other restoration measures. ...
Article
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Fragmentation is one of the major threats to riverine ecosystems and this is most explicitly expressed by the decline in numbers of migratory fish species. Yet each species has different migration requirements and their natural distribution can include several catchments with multiple dams. Hence, to prioritize candidate rivers for improving accessibility, differences between species and between catchments have to be taken into account. The aim of this study was therefore to analyse the species and river specific effects of river fragmentation on migratory fish on a European scale. The effect of river damming on migratory fish was quantified for all 16 European long‐ and mid‐distance anadromous species and for 33 large European rivers. The historical distribution was compared with the current upstream accessibility of the main river and the current distribution and population status of each species. The observed effects of reduced connectivity were further quantified using the Dendritic Connectivity Index for species and the Fragmentation Index for rivers. Our results showed that only very few rivers are still unaffected by dams in the main stem and that the few remaining viable migratory fish populations in Europe occur in these accessible rivers. Barriers were prioritized for making passable based on the potential accessibility gain and the number of benefitting species, showing that the main stems of the rivers Shannon and Nemunas are the best candidates. It was concluded that evaluating species and river specific effects of fragmentation strongly aids in prioritizing rivers for improving upstream accessibility.
... Hydropower dam construction interrupts longitudinal connectivity between spawning and feeding habitats of diadromous fish, and consequently, their natural reproduction is decreased or totally lost (Calles and Greenberg 2009). Increased environmental consciousness and public requests for reducing environmental effects of hydroelectric developments in recent decades have initiated efforts to restore naturally reproducing migratory fish populations in rivers now harnessed for hydropower production (e.g., Erkinaro et al. 2011;Opperman et al. 2011). Moreover, restoration plans for regulated rivers are based on policy initiatives; for example, the European Water Framework Directive (European Parliament 2000) provides guidelines for the Member States to restore the good ecological potential and ecosystem services also in heavily modified watercourses. ...
... A good example for a large-scale need for restoration is the decline of Atlantic salmon (Salmo salar) populations throughout the distribution range of the species that typically has been attributed to inter alia lack of connectivity and degradation of suitable habitat because of hydropower development (Parrish et al. 1998;Saunders et al. 2006;Erkinaro et al. 2011). The anadromous and iteroparous life cycle of Atlantic salmon (e.g., Klemetsen et al. 2003) includes the ascent of returning adult fish up the river for reproduction and the descent of spent individuals (kelts) and migrating juveniles (smolts) towards marine feeding grounds. ...
Article
Connectivity problems in fish migration in regulated rivers have been widely studied, but few studies have rigorously compared parallel migration success between regulated and free-flowing rivers. Here, survival and migration speed of downstream migrating radio-tagged Atlantic salmon (Salmo salar) smolts were studied in two large neighboring rivers in the northern Baltic Sea area: one without and one with dams. Both rivers have a free-flowing upper section, where the survival and migration speed of salmon smolts were similar. Survival along the lower section of the free-flowing river was about six times higher than in the lower part of the regulated river with five hydropower plants. Migration speed of smolts was also significantly faster in the river without dams. These severe problems in downstream connectivity in the regulated river pose challenging tasks for restoration of salmon populations.
... As an extreme case, restoration of the migratory routes in the absence of suitable spawning or nursery habitats may act as ecological traps (Britto and Carvalho 2013). According to several studies, habitat restoration may fail at sites with a high risk of sedimentation, which may reduce egg survival (Erkinaro et al. 2011). ...
... To minimize the negative cumulative effects in a river system consisting of several dams, both the upstream and downstream passage efficiencies should be as high as possible at all dams (Erkinaro et al. 2011). Similar locations of the entrances at each dam minimize migration delays (Laine 2010;Williams et al. 2012). ...
Article
Environmental standards have rarely been applied for promoting the joint production of hydropower and migratory fish. The objective of this study was to review existing research results on the effectiveness and costs of alternative measures improving fish migration, which are necessary for the development of environmental standards. The ranking of alternative measures indicates that cost-effective combinations of measures are case-specific and highly dependent on measure design, implementation and maintenance. In addition to tailored ex ante cost-effectiveness analyses, other preconditions for cost savings include effective and affordable monitoring and enforcement, and cooperation among power companies that share water-use rights within a river basin as well as among other stakeholders, such as the local community, fishermen and recreational users.
... The sea-migrating (anadromous) brown trout and Atlantic salmon strains originating from the River Iijoki were obtained from fish farms where they have been maintained by the Natural Resource Institute Finland (Luke) since damming of the Iijoki main channel for hydropower production in the 1960s (see, e.g., Erkinaro et al., 2011). Before building of the dams, the anadromous Iijoki brown trout also may have migrated to spawn in the smaller streams included in this study, but as it generally, according to local knowledge, preferred the main channel for spawning, this strain also was considered a non-local fish in these stream experiments. ...
Article
The freshwater pearl mussel Margaritifera margaritifera (FPM) is an endangered unionid which has a glochidium larva that attaches to the gills of Atlantic salmon Salmo salar or brown trout S. trutta, although some FPM populations have been shown to exclusively attach to only one of these species. The origin of host fish populations may be crucial for conservation actions for this mussel species, but the relative suitability of local (sympatric) and non‐local (allopatric) salmonid populations as the hosts for FPM has been studied only rarely. We hypothesised that FPM glochidia would show adaptation to local salmonid strains and, therefore, that they would be more successful (abundant, larger) attached to sympatric than to allopatric fish. Here, we investigated the infection success (abundance and growth of encysted larvae in fish) of FPM in local versus non‐local fish by caging different strains of brown trout and Atlantic salmon in rivers where FPM populations are present. Higher abundances of glochidia in local fish were observed in three brown trout streams, and larger glochidia were found in sympatric hosts in one brown trout stream and in one salmon river. Furthermore, non‐local allopatric fish were not better hosts than local fish in any of the FPM populations tested, neither in brown trout or salmon rivers and neither in abundance nor size of larvae. Therefore, the results supported the hypothesis that glochidia show local adaptation by being more successful when attached to local fish strains. Thus, the local, sympatric fish strain should be preferred in FPM conservation programmes that involve captive breeding of juvenile mussels and introduction of host fish, but the regional assessment of local host dependency of FPM also would be important outside the current study area. The results also indicate the importance of restoration of original salmonid populations in FPM rivers to enable the natural, effective reproduction cycle of FPM in their original, sympatric hosts, and thus to promote the recovery of endangered FPM populations.
... Other studies have found that fish growth is negatively affected by hydropower reservoirs because of lowered ecosystem productivity (Milbrink et al., 2011). Habitat for juvenile salmon is often degraded or eliminated as observed for rivers in Finland, and restoration efforts to restore stream substrate quality as well as the installation of fish ladders are applied to increase fish stocks (Erkinaro et al., 2011). As hydropower development increases at high latitudes, it will be necessary to further examine the potential impacts on the ecological function of high latitude rivers. ...
Chapter
Aim The unique aspects of high latitude rivers are discussed including environmental drivers of biotic structure and function, and the effects of development and climate warming on these ecosystems. Ecology of high latitude rivers The physical-chemical environment of these rivers is dominated by cold temperatures and river ice. Spring ice breakup creates intense disturbance that affects the substrate and water chemistry. Nutrient limitation typically limits primary production and heterotrophic processes often dominate ecosystem metabolism, which supports benthic invertebrate and fish production. Diversity of benthos and fish decreases at higher latitudes due to cold temperatures and barriers to colonization. Many fish species are important food sources for Indigenous Peoples. Climate change effects on biodiversity Climate-related increases in water temperature cause changes in diversity as species physiological tolerances are exceeded and other species extend their ranges northward. Permafrost thaw mobilizes nutrients and major ions that can increase ecosystem productivity, while mud slurries from thaw slumps can transport large amounts of terrestrial material into stream systems. Effects of human development High latitude rivers receive contaminants from various sources including atmospheric transport, mineral extraction, landuse change, road development, wastewater discharge, and hydropower generation. Pollutant impacts include biomagnification, acid deposition and altered water chemistry. Conclusion Climate warming will cause substantial change to high latitude river ecosystems and associated flora and fauna. Permafrost thaw mobilizes various nutrients and produces thaw slump sedimentation. The cumulative effects of climate change and pollution will be difficult to predict. Improved baseline knowledge of these ecosystems is needed to advance the ability to model and forecast future ecosystem state.
... Improvements to the quality and quantity of degraded habitat are generally the first and most critical steps to reestablish native fish stocks (Giller, 2005;Einum et al., 2008). Many rivers have therefore undergone extensive work to undo damage resulting from habitat modification, pollution, dam building, and restriction of movement, siltation, eutrophication, channelization, acidification, and other human impacts that have contributed to the collapse or extirpation of fish stocks (Palmer et al., 2005;Erkinaro et al., 2011;Tummers et al., 2016). At some sites, fish and river restoration programmes have been ongoing for decades and new programmes continue to be implemented, as urgency in preserving or restoring species accelerates while stressors multiply. ...
Article
Atlantic salmon is often a focal species of restoration efforts throughout the north Atlantic and it is therefore an excellent case study for how best to design programmes to address and mitigate threats and correct population declines. This perspective is written to promote the work that has been accomplished towards restoration of Atlantic salmon populations and synthesize how we believe the lessons can be used effectively to support efforts by management agencies to restore populations. We reviewed where restoration is needed for Atlantic salmon, agreed on definitions for three levels of successful restoration, and then applied these criteria to 49 published papers focused on Atlantic salmon restoration. We identified 16 successful examples of restoration among 49 papers reviewed and discussed what interventions led to success versus failure. We then addressed key questions about when hatchery stocking should be used as part of a restoration measure and whether local restoration efforts are enough when these wide-ranging species encounter broad-scale changes in the north Atlantic, specifically related to issues of climate change and to marine survival. We advise to avoid restoration as much as possible by protecting and managing existing populations and when restoration is necessary, problems should be identified and addressed in partnership with river users. With appropriate resources and research to resolve ongoing mysteries, restoration of lost Atlantic salmon populations is absolutely feasible.
... In response to anthropogenic stressors, most natural stocks have been extirpated (Pellikka et al. 2015), decreasing the available sea trout that catch and release recreational anglers can target along Finland's coastline. Losses are specifically attributed to decreased available spawning habitat, loss of water quality (in part due to climate change), and overfishing (Koljonen et al. 2014;Erkinaro et al. 2011). Population numbers of fishes in rivers and brooks decreased significantly as a result of partial channelization, and poor water quality (Lähitieto 2017). ...
Article
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Inland recreational fisheries have social, economic, and ecological importance worldwide but these fisheries are increasingly challenged by the diverse effects of climate change. Coupled with other anthropogenic stressors, climate change has contributed to declines in freshwater biodiversity of greater severity than those observed across marine or terrestrial taxa. At a macro level, inland fisheries are experiencing declines. There are, however, a number of success stories, or ‘bright spots,’ in inland recreational fisheries management, where innovative approaches are leading to increases in social and ecological well-being in the face of climate change. Cases such as these are important sources of inspiration and learning about adaptation to climate and environmental change. In this article, we analyze 11 examples of such ‘bright spots’ drawn from multiple jurisdictions around the world from which we extracted lessons that might apply to fisheries management challenges beyond the region and context of each case. Collectively, these bright spots highlight adaptive initiatives that allow for recreational fisheries management to mitigate to stressors associated with current and future climate change. Examples identified include community-based restoration projects, collaborative and adaptive approaches to short-term fisheries closures, transdisciplinary large-scale conservation projects, and conservation-minded efforts by individuals and communities. By highlighting examples of ‘small wins’ within inland recreational fisheries management, this review contributes to the idea that a ‘positive future’ for inland recreational fisheries in the face of climate change is possible and highlights potential strategies to adapt to current and future climate scenarios.
... For anadromous fishes there is evidence to suggest that the costs of migration may be increasing. For anadromous Atlantic salmon Salmo salar, one new cost that has emerged over the last few decades is the reduced freshwater habitat connectivity that results from impoundments of catchments for hydropower or water supply (Erkinaro et al., 2011;Huusko et al., 2017) which has the potential to affect migration success significantly (Gehrke et al., 2011;Marschall et al., 2011). ...
Article
Atlantic salmon (Salmo salar) smolt migration through standing waters is generally known to be associated with slow migration speed and low success. Most previous studies have however been conducted on impounded waters. The bathymetry and specifically the flow dynamics around the outlets differ markedly between impounded lakes and naturally draining lakes. To date no study has attempted to disentangle the effects of the impoundment from that of standing water itself. This question was tested in a single naturally draining standing water and two impounded standing waters within a single catchment using fish tagged with acoustic and PIT tags (in three and two lakes, respectively). Overall migration success (river to estuary) was very low (10%); migration success through the lakes was also very low (total loss rates range: 31 to 55%; 16 to 53%.km⁻¹) compared with migration in the river downstream of the lakes (range: 3.9 to 10.8%.km⁻¹). Migration success was no lower in impounded lakes compared with the naturally draining lake. 49% of directional movements were in a direction opposite to the migration pathway, indicating that a lack of navigational cues may be in-part responsible for low migration success. We tentatively conclude that successful migration through standing waters without strong directional cues may be more stochastic than previously thought. We suggest that at least for some impoundments (as shown here), the impoundment per se may not reduce migration success, its greater effect being the creation of the standing water through which smolts are required to migrate. However, any impoundment effect is likely to be dependent upon a combination of lake basin shape, the exit route from the lake and the navigational cues available to smolts.
... We controlled-crossed eight 2x2 factorial matings of unrelated individuals that each included one vgll3 � EE and one vgll3 � LL male and female (see ref [30] for genotyping details), thereby resulting in 32 families with reciprocal vgll3 genotypes EE, EL, LE and LL (allele order denotes female and male parents of origin respectively, S1 Fig). We used parents from the "Oulujoki" broodstock, which is a mixture of several salmon populations from northern Baltic rivers and is maintained by the Natural Resources Institute Finland (LUKE) [56]. All parents were selected for having a homogenous age-at-maturity-associated haplotype encompassing the vgll3 (chromosome 25 homeolog) coding sequence, the top non-coding association [4], and the coding region of the adjacent akap11 gene (collectively referred to as "vgll3 genotype"). ...
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A major goal in biology is to understand how evolution shapes variation in individual life histories. Genome-wide association studies have been successful in uncovering genome regions linked with traits underlying life history variation in a range of species. However, lack of functional studies of the discovered genotype-phenotype associations severely restrains our understanding how alternative life history traits evolved and are mediated at the molecular level. Here, we report a cis-regulatory mechanism whereby expression of alternative isoforms of the transcription co-factor vestigial-like 3 (vgll3) associate with variation in a key life history trait, age at maturity, in Atlantic salmon (Salmo salar). Using a common-garden experiment, we first show that vgll3 genotype associates with puberty timing in one-year-old salmon males. By way of temporal sampling of vgll3 expression in ten tissues across the first year of salmon development, we identify a pubertal transition in vgll3 expression where maturation coincided with a 66% reduction in testicular vgll3 expression. The late maturation allele was not only associated with a tendency to delay puberty, but also with expression of a rare transcript isoform of vgll3 pre-puberty. By comparing absolute vgll3 mRNA copies in heterozygotes we show that the expression difference between the early and late maturity alleles is largely cis-regulatory. We propose a model whereby expression of a rare isoform from the late allele shifts the liability of its carriers towards delaying puberty. These results exemplify the potential importance of regulatory differences as a mechanism for the evolution of life history traits.
... We controlled-crossed eight 2x2 factorial matings of unrelated individuals that each included one vgll3*EE and one vgll3*LL male and female (see ref 12 for genotyping details), thereby resulting in 32 families with reciprocal vgll3 genotypes EE, EL, LE and LL (allele order denotes female and male parents of origin respectively, Extended Data Fig. 1). We used parents from the "Oulujoki" broodstock, which is a mixture of several salmon populations from northern Baltic rivers and is maintained by the Natural Resources Institute Finland (LUKE) 33 . All parents were selected for having a homogenous age-at-maturity-associated haplotype encompassing the vgll3 (chromosome 25 paralog) coding sequence, the top non-coding association 2 , and the coding region of the adjacent Akap11 gene (collectively referred to as "vgll3 genotype"). ...
Preprint
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A major goal in biology is to understand how evolution shapes variation in individual life histories. Genome-wide association studies have been successful in uncovering genome regions linked with traits underlying life history variation in a range of species. However, lack of functional studies of the discovered genotype-phenotype associations severely restrains our understanding how alternative life history traits evolved and are mediated at the molecular level. Here, we report a cis -regulatory mechanism whereby expression of alternative isoforms of the transcription co-factor vestigial-like 3 ( vgll3 ) associate with variation in a key life history trait, age at maturity, in Atlantic salmon ( Salmo salar ). Using a common-garden experiment, we first show that vgll3 genotype associates with puberty timing in one-year-old salmon males. By way of temporal sampling of vgll3 expression in ten tissues across the first year of salmon development, we identify a pubertal transition in vgll3 expression where maturation coincided with a 66% reduction in testicular vgll3 expression. The late maturation allele was not only associated with a tendency to delay puberty, but also with expression of a rare transcript isoform of vgll3 pre-puberty. By comparing absolute vgll3 mRNA copies in heterozygotes we show that the expression difference between the early and late maturity alleles is largely cis -regulatory. We propose a model whereby expression of a rare isoform from the late allele shifts the liability of its carriers towards delaying puberty. These results reveal how regulatory differences can be a central mechanism for the evolution of life history traits. Author summary Alternative life history strategies are an important source of diversity within populations and promote the maintenance of adaptive capacity and population resilience. However, in many cases the molecular basis of different life history strategies remains elusive. Age at maturity is a key adaptive life history trait in Atlantic salmon and has a relatively simple genetic basis. Using salmon age at maturity as a model, we report a mechanism whereby different transcript isoforms of the key age at maturity gene, vestigial-like 3 ( vgll3 ), associate with variation in the timing of male puberty. Our results show how gene regulatory differences in conjunction with variation in gene transcript structure can encode for complex alternative life histories.
... Now, decades after closing the salmon migration routes, the original salmon stocks have either been lost (as in the River Kemijoki) or maintained by hatcheries (as in the River Iijoki). Both rivers, however, still maintain the potential for salmon reproduction, and an ongoing long-term project to rebuild the salmon stocks has been initiated (summarised in Erkinaro et al., 2011). The task is challenging as there are multiple hydropower dams in both rivers below the remaining spawning and nursery areas upstream. ...
Article
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In hydropeaking rivers, flow regulation typically follows demands in electricity consumption. One hundred and twenty one adult salmon were tagged with radio transmitters to study their spawning run migration patterns in hydropeaking conditions. The fish were released in small groups into the rivers Kemijoki and Iijoki, in Finland. Typically, salmon made subsequent up‐ and downstream movements ascending up‐stream to the tailrace of the power station and then descending again downstream to lower water velocities. The rate of these migration attempts was higher in mid‐summer and at relatively high flows. On an hourly basis, the pattern of migration attempts followed a trend of increasing attempts at dawn and higher discharges and a decreasing trend towards dusk and low flows. It was concluded that day length and discharge were the most important environmental factors, while temperature had less effect on the pattern of migration attempts.
... Similarly, dam-related interruptions to connectivity hinder the ability of migratory fish to complete their life cycles (Limburg and Waldman 2009;Hall et al. 2011;Rolls 2011). Atlantic salmon (Salmo salar) populations have experienced declines across much of the species' range over the last century, particularly in rivers with hydroelectric dams (Parrish et al. 1998;Saunders et al. 2006;Erkinaro et al. 2011). Successful downstream migration of juvenile salmon (smolts) and upstream migration of returning adults are necessary for a complete life cycle (Thorstad et al. 2011a). ...
Article
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Dams challenge Atlantic salmon (Salmo salar) conservation, while hatcheries are a common but poorly evaluated recovery tool. We developed a spatially explicit smolt survival model for the Penobscot River, Maine, USA, population. By partitioning survival through dams (with flow dependency), free-flowing river reaches, and the estuary (with dam dependency), the model quantified how these factors influenced the number of fish entering the ocean. Given historical impounded conditions, 74%–22% of hatchery smolts released entered the ocean annually from 1970 to 2012. Of 19.7 million smolts stocked, 7.7 million entered the ocean (39%). Survival was most variable at dams (range 95% to 63%), followed by in-river (range 98% to 70%) and estuary (range 88% to 82%). Overall, lower-river stocking sites resulted in significantly higher numbers at ocean entry because of fewer dam encounters and shorter migrations. Higher flows also resulted in reduced losses. By reconstructing these freshwater and estuary dynamics, the model provides a more accurate estimate of ocean recruitment annually and can be used for scenario planning of future stocking locations relative to predicted flows while being adaptable to new survival rates.
... At the start of the experiment, on 22 February 2012, six young-of-year Atlantic salmon, originated from captive reared broodstock of the River Oulujoki (Finland) strain (Erkinaro et al. 2011), were randomly selected from the hatchery rearing tank. During the rearing period, the daily photoperiod following local diurnal rhythm was provided by artificial lights. ...
Article
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Visual methods in detecting juvenile Atlantic salmon (Salmo salar L.) in winter were assessed, both in a natural subarctic river in northernmost Finland (70°N) and in an experimental flume, both under ice and in open water. Video surveillance was used under different conditions, and at one field site, data from video cameras and snorkeling were compared with subsequent electrofishing at the same site. In addition, the activity and visibility of juvenile salmon in cold water was studied under controlled experimental conditions using video, PIT tags and a known number of fish present in a laboratory flume. We documented a poor underwater detection rate for juvenile Atlantic salmon by visual observations in wintertime, both in day and night, and both with and without ice cover. Comparison of successively conducted field experiments at the same site resulted in two salmon parr observations by snorkeling, one by video and 63 individuals by electrofishing. In the laboratory experiment the maximum proportion of fish observed was 33 and 50% of those present in the flume by using video-surveillance and PIT tracking, respectively. Both methods indicated that salmon parr were significantly more visible during the darkness compared to the illuminated hours. These results pose critical questions to the traditional visual observation methods used in winter studies on stream salmonids.
... To compensate for the losses of natural salmon production and to maintain salmon fishing, hydropower companies are obliged to release reared smolts (e.g. Erkinaro et al., 2011). Although wild salmon production has recently greatly increased in the northern Baltic Sea rivers (Romakkaniemi et al., 2003;ICES, 2016), large-scale releases of reared smolts are still continuing, totalling 4-5 million individuals annually (ICES, 2016). ...
Article
Atlantic salmon (Salmo salar L.) display significant variation in life history traits, including migration patterns and age at maturity. Hatchery rearing has been shown to affect the life history, and rearing-induced changes may include unfavourable consequences, e.g. shortened sea migration period and smaller size at maturity. We report on a new phenomenon of life history of reared Atlantic salmon in the Baltic Sea area: small-sized salmon returning to freshwater only a few months after release as smolts. These "one-sea-summer (1SS)" salmon were ca. 35 cm in length and weighed ca. 400 g, being clearly larger than smolts, but substantially smaller than one-sea-winter (1SW) salmon from the same cohorts. Almost all 1SS salmon were mature males and, at release, had been longer than the overall mean. Stable isotope analysis suggested that the 1SS salmon had been feeding in different sea areas than 1SW and multi-sea-winter salmon, likely in nearby Bothnian Bay, which is typically not a salmon feeding area. If an increasing proportion of the released salmon are not undertaking a normal marine migration (≥1SW) and are returning to estuaries and rivers as 1SS fish, the success and profitability of the reared salmon releases will decline even more than the reduced post-smolt survival is suggesting. We suggest that alternative rearing practices (e.g. enriched rearing environments and advanced diets) should be considered in hatchery production for shaping the reared smolts towards a closer resemblance to wild smolts. © International Council for the Exploration of the Sea 2017. All rights reserved.
... To compensate for the losses of natural salmon production and to maintain salmon fishing, hydropower companies are obliged to release reared smolts (e.g. Erkinaro et al., 2011). Although wild salmon production has recently greatly increased in the northern Baltic Sea rivers ( Romakkaniemi et al., 2003;ICES, 2016), large-scale releases of reared smolts are still continuing, totalling 4-5 million individuals annually (ICES, 2016). ...
Article
Atlantic salmon (Salmo salar L.) display significant variation in life history traits, including migration patterns and age at maturity. Hatchery rearing has been shown to affect the life history, and rearing-induced changes may include unfavourable consequences, e.g. shortened sea migration period and smaller size at maturity. We report on a new phenomenon of life history of reared Atlantic salmon in the Baltic Sea area: small-sized salmon returning to freshwater only a few months after release as smolts. These "one-sea-summer (1SS)" salmon were ca. 35 cm in length and weighed ca. 400 g, being clearly larger than smolts, but substantially smaller than one-sea-winter (1SW) salmon from the same cohorts. Almost all 1SS salmon were mature males and, at release, had been longer than the overall mean. Stable isotope analysis suggested that the 1SS salmon had been feeding in different sea areas than 1SW and multi-sea-winter salmon, likely in nearby Bothnian Bay, which is typically not a salmon feeding area. If an increasing proportion of the released salmon are not undertaking a normal marine migration (!1SW) and are returning to estuaries and rivers as 1SS fish, the success and profitability of the reared salmon releases will decline even more than the reduced post-smolt survival is suggesting. We suggest that alternative rearing practices (e.g. enriched rearing environments and advanced diets) should be considered in hatchery production for shaping the reared smolts towards a closer resemblance to wild smolts.
... Because salmon from each river over generations have returned to the home river for spawning, the populations have become adapted to the local conditions there (Hansen et al., 1993, Primmer, 2011, Vincent et al., 2013. But the fact that each population is locally adapted makes them vulnerable to anthropogenic habitat changes such as hydropower dams and altered water regimes of rivers (Parrish et al., 1998, Thorstad et al., 2008, Erkinaro et al., 2011. ...
Article
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Upstream migration by adult salmonids is impeded by dams in many regulated rivers, as is the case for landlocked Atlantic salmon, Salmo salar, in the River Klarälven, Sweden. There, the salmon cannot reach the spawning grounds due to the presence of eight dams. Hence, hatchery-reared smolts are released downstream of the dams, and upstream migrating spawners are caught in a trap at the lowermost dam before transported by truck to the spawning grounds past the dams. To identify the spawning grounds and compare the behavior of wild and hatchery-reared Atlantic salmon during upstream migration and spawning, 34 wild and 28 hatchery-reared, radio-tagged Atlantic salmon were followed during their spawning migration from August to October 2011. Half (50%) of the hatchery fish, but only 11,8% of the wild fish ended up as fallbacks, i.e. they migrated past the first downstream power station, and did not spawn. A significantly higher proportion (21.4%) of hatchery- reared salmon moved in an erratic way, with several up and down stream movements, when compared to the wild salmon (5.9%). When looking at the salmon that stayed in the river (exc. fallbacks), wild individuals exhibited a holding behavior (little or no movements before presumed spawning) more often (86.7%) than the reared ones (50%). The wild salmon also held position (and presumably spawned) for longer time (25.4 days) than the reared salmon (16.1 days). Reared salmon held position, on average, 10 km further upstream than wild salmon, passing the presumed best-quality spawning habitat. The migration speed (average 17.4 km/day) between two logger stations did not differ between wild and reared fish or between sexes. Our results suggest that the reproductive success of hatchery-reared Atlantic salmon is relatively low and their capacity as supplementary spawners to the wild population in the Klarälven, is probably small. Copyright © 2015 John Wiley & Sons, Ltd.
... Increasing concern of the declining Baltic S. salar stocks has generated a growing interest to enhance the natural reproduction of S. salar, and several restoration projects have been established to take advance of the potential production areas that exist in the regulated rivers. The project programs include, e.g., habitat evaluation and restoration, stocking of juvenile fish and establishment of fish passes to allow ascending fish to enter the rivers (Erkinaro et al. 2011). One of the recent measures in the rehabilitation of these rivers is the construction of a fish pass in the mouth of River Oulujoki, opening access for ascending fish into the river after almost 60 years of blockade. ...
Article
In this study, 221 two-year-old hatchery-reared salmon, Salmo salar, smolts were tagged with radio transmitters over a period of three consecutive years and released in the river in groups of 20–21 fish in various dates between late April and early June. Tagged smolts were tracked during their downstream migration in the lower 36-km stretch of the regulated River Oulujoki, with the focus on the effects of release date, water temperature and river flow on migration behaviour and survival. The results indicate that release timing and river temperature have profound effects on the initiation of migration, swimming speed and survival of released S. salar smolts. Smolts released early in the spring in cold waters ceased migration after brief downstream movement and were vulnerable to predation, whereas the migration speed and survival rates increased markedly for smolts released later in the spring.
... Second, the River Tornionjoki is unregulated, so migration speed and survival can be investigated in the natural environment of this population and can be compared with migration speed and survival of nature-caught smolts. Third, the present plan is to reintroduce Finnish salmon populations, using the Tornionjoki population as a broodstock for populations that have gone extinct (Erkinaro et al. 2011). This includes opening migration routes for anadromous species by building fish ladders to enable selfsustaining populations. ...
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Low survival of stocked fish has been associated with fitness declines of the captive reared fishes because of genetic domestication and unnatural rearing environments. The effects of broodstock origin (wild or captive) or rearing method (standard or enriched) on survival and migration of hatchery-reared Atlantic salmon smolts (Salmo salar) were investigated in the Tornionjoki River using radiotelemetry. Smolts that were reared with enriched methods had a twofold increase in survival (∼38%) compared with smolts that had been reared in a standard hatchery environment (∼19%). Nature-caught smolts had highest survival (∼57%). Smolts from enriched rearing had a higher initial migration speed than fish from standard rearing. Initial migration speed during the first 3 km was positively correlated to survival probability after 290 km for hatchery fish. There was no clear effect of origin on survival or migration speed. The results of this study show that enriching the rearing environment with methods easily applicable to large-scale production promotes smolt survival and migration speed during river migration, which is imperative for stocking success.
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In this study radio telemetry was used to examine the upstream spawning migration behaviour of anadromous brown trout (sea trout), Salmo trutta L., in a boreal river system, the River Isojoki, Western Finland. The aim was to study the movement activity and migration characteristics of trout during the upstream spawning migration, as well as locate important spawning habitats and study the spawning characteristics. Furthermore, we analysed how flow conditions and a hydropower dam, with adjacent fishways, affected the upstream spawning migration. Tagged trout spawned in both the main stem and in four tributaries, with spawning taking place from early October to November. The movement activity of radio tagged trout was influenced by a hydropower dam (Perus dam), with spring migrators spending prolonged periods at the dam area, postponing the migration upstream. Flow conditions affected total time spent at the dam area, as well as movement activity in the free‐flowing sections above the dam, with increasing flow stimulating activity. Additionally, time of river ascent and location of spawning area had a significant effect on the movement activity of tagged trout. These results are further evidence that synergistic effects of flow and migratory obstacles can negatively influence migrations of anadromous fish, regardless of constructed fishways. Management of flow regimes and efficiency of fishways are vital as climate change will likely influence flow and increase water temperature of boreal river systems, further aggravating issues caused by obstacles.
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Labeobarbus brevicephalus is one of the 17 endemic migratory large African barb species making up a species flock in Lake Tana (Ethiopia). The multiple constructions of dams and irrigation weirs on the tributary rivers of Lake Tana have become detrimental to the upstream spawning migration of these fishes. Considering worst-case scenarios of obstruction of all-natural migratory routes, artificial spawning emulation structures were designed and developed at the Bahir Dar Fisheries and Other Aquatic Life Research Center (BFALRC) to emulate the upstream spawning migration routes and habitats. A pond was constructed to emulate the lake and a canal was connected to the pond emulating tributary rivers. The setups were to enable the fishes to migrate out of the pond and spawn at the upper area (pool) of the canal. At the upstream of the canal, gravel beds were prepared on which the L. brevicephalus could spawn. Running (ready for spawning (stage 5)) male and female L. brevicephalus were placed in the pond. After a day long-acclimatization period lake water was pumped into the canal at a discharge rate of 250–1000 liters/min. Stimulated by the flow, 86 male and 24 female L. brevicephalus moved out of the pond migrated to the upper part of the canal made 16 spawning on the gravel beds, and returned to the pond. The fertilized oocytes (zygotes) were collected and it was possible to hatch them in aquariums in the laboratory.
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Migration behaviour, route selection and mortality of Atlantic salmon, Salmo salar L., smolts were studied at four different hydroelectric facilities in the River Mustionjoki, Finland, in May 2017. Radio-tagged smolts were released upstream of the power stations and tracked by stationary antenna-receiver systems and hand-held receivers. Tracking revealed a general tendency of smolts to move downstream with the main flow, but also variable behaviour and mortality related to diverse conditions characteristic of each power station. Average migration delay at the power stations ranged between 13.8 and 101.1 h (median: 1.7–61.5 h). Estimated mortality ranges were 0%–50% in the forebays, 4%–64% in the power stations and 2–30%/km during river migration after passage of the dam. This study provided essential information on behaviour and mortality in relation to local conditions at each power station required for successful application of fish bypass systems in a salmon restoration project
Technical Report
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Salmon lice are external parasites on salmonids in the marine environment. During recent years, sea lice abundance has been increased due to the presence of salmon farming using on-growing floating seas-cages. Amongst salmonids, sea trout is especially vulnerable to salmon lice infestations, because during their marine residence they typically remain in coastal waters, where open net cage Atlantic salmon farms typically are situated. In this report the existing knowledge about the effects of salmon lice on sea trout populations in the NE Atlantic coastal waters has been reviewed, assessing the current situation of this problematic. Salmon aquaculture increase the salmon lice abundance, which affect negatively on sea trout populations as an increase in marine mortality, changes in migratory behaviour and reduction of marine growth. These conclusions are based on published studies that range from those investigating the effects of salmon lice on individual fish, both in the laboratory and the field, to analyses of their impacts on populations in the wild. In sum, the combined knowledge from the reviewed studies provides evidence of a general and pervasive negative effect of salmon lice on sea trout populations, especially in intensively farmed areas. The effects induced by elevated salmon lice levels inevitably imply a reduction in numbers and body size of sea trout returning to freshwater for spawning, affecting the local population dynamic and recreational and commercial fisheries in the most impacted areas.
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Salmon lice are external parasites on salmonids in the marine environment. During recent years, sea lice abundance has been increased due to the presence of salmon farming using on-growing floating seas-cages. Amongst salmonids, sea trout is especially vulnerable to salmon lice infestations, because during their marine residence they typically remain in coastal waters, where open net cage Atlantic salmon farms typically are situated. In this report the existing knowledge about the effects of salmon lice on sea trout populations in the NE Atlantic coastal waters has been reviewed, assessing the current situation of this problematic. Salmon aquaculture increase the salmon lice abundance, which affect negatively on sea trout populations as an increase in marine mortality, changes in migratory behaviour and reduction of marine growth. These conclusions are based on published studies that range from those investigating the effects of salmon lice on individual fish, both in the laboratory and the field, to analyses of their impacts on populations in the wild. In sum, the combined knowledge from the reviewed studies provides evidence of a general and pervasive negative effect of salmon lice on sea trout populations, especially in intensively farmed areas. The effects induced by elevated salmon lice levels inevitably imply a reduction in numbers and body size of sea trout returning to freshwater for spawning, affecting the local population dynamic and recreational and commercial fisheries in the most impacted areas. (Main Text in Spanish)
Chapter
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Key Message: Baltic salmon (Salmo salar L.) is one of the keystone migratory species in the Baltic Sea. In the past salmon played a central role in the economy and culture of the region. However, salmon population collapsed because of logging, dams for hydropower production, pollution and overfishing. Today salmon is still of great cultural importance as shown for example by estimates of public spending for habitat restoration and WTP by angler. Estimates suggest that the cultural services of salmon are greater than the economic value of commercial salmon landings with a net present value ranging from 6 million EUR to 25 million EUR (ie 0.9–3.6 million EUR / year) in Denmark, Finland, Poland and Sweden for 2009–2015. Baltic salmon plays also an important role in reducing sedimentation, regulating food webs and maintaining the general ecological balance of ecosystems Maintaining and restoring the salmon population requires concerted efforts for habitat restoration and conservation in rivers and the sea.
Chapter
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Key Message: Baltic salmon (Salmo salar L.) is one of the keystone migratory species in the Baltic Sea. In the past salmon played a central role in the economy and culture of the region. However, salmon population collapsed because of logging, dams for hydropower production, pollution and overfishing. Today salmon is still of great cultural importance as shown for example by estimates of public spending for habitat restoration and WTP by angler. Estimates suggest that the cultural services of salmon are greater than the economic value of commercial salmon landings with a net present value ranging from 6 million EUR to 25 million EUR (ie 0.9–3.6 million EUR / year) in Denmark, Finland, Poland and Sweden for 2009–2015. Baltic salmon plays also an important role in reducing sedimentation, regulating food webs and maintaining the general ecological balance of ecosystems Maintaining and restoring the salmon population requires concerted efforts for habitat restoration and conservation in rivers and the sea.
Chapter
Full-text available
Key Message: Baltic salmon (Salmo salar L.) is one of the keystone migratory species in the Baltic Sea. In the past salmon played a central role in the economy and culture of the region. However, salmon population collapsed because of logging, dams for hydropower production, pollution and overfishing. Today salmon is still of great cultural importance as shown for example by estimates of public spending for habitat restoration and WTP by angler. Estimates suggest that the cultural services of salmon are greater than the economic value of commercial salmon landings with a net present value ranging from 6 million EUR to 25 million EUR (ie 0.9–3.6 million EUR / year) in Denmark, Finland, Poland and Sweden for 2009–2015. Baltic salmon plays also an important role in reducing sedimentation, regulating food webs and maintaining the general ecological balance of ecosystems Maintaining and restoring the salmon population requires concerted efforts for habitat restoration and conservation in rivers and the sea.
Chapter
Baltic salmon (Salmo salar L.) is one of the keystone migratory species in the Baltic Sea. In the past salmon played a central role in the economy and culture of the region. However, salmon population collapsed because of logging, dams for hydropower production, pollution and overfishing. Today salmon is still of great cultural importance as shown for example by estimates of public spending for habitat restoration and WTP by angler. Estimates suggest that the cultural services of salmon are greater than the economic value of commercial salmon landings with a net present value ranging from 6 million EUR to 25 million EUR (ie 0.9–3.6 million EUR / year) in Denmark, Finland, Poland and Sweden for 2009–2015. Baltic salmon plays also an important role in reducing sedimentation, regulating food webs and maintaining the general ecological balance of ecosystems Maintaining and restoring the salmon population requires concerted efforts for habitat restoration and conservation in rivers and the sea.
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Nature provides a range of benefits (ecosystem services) that underpin human and socio-economic well-being. Many of these benefits – and the associated economic values – are not acknowledged in decision-making. As a result, nature remains almost invisible in the political and individual choices made. This report presents a synthesis of the socio-economic importance of ecosystem services in the Nordic countries. The study was initiated by the Nordic Council of Ministers (NCM) and the NCM Finnish Presidency in 2011, following in the footsteps of The Economics of Ecosystems and Biodiversity (TEEB) initiative. The study reveals that Nordic ecosystems play an integral role in supporting socio-economic wellbeing. However, a number of gaps in the existing information base still need to be addressed to ensure that these benefits are fully integrated into the Nordic decision-making processes.
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Abstract –  After release to the wild, captive reared salmon have shown lower foraging rates on natural prey and impaired ability to avoid natural predators and thus lower survival compared with wild-born conspecifics. Here, we examine whether captive breeding influences learning of foraging on natural prey and how enriched rearing methods may improve foraging on natural prey by Atlantic salmon (Salmo salar) parr. We reared offspring of hatchery or wild salmon of the same population in either a standard or enriched environment at production-scale densities. The enriched environment featured submerged overhead shelter, varying water current, depth and direction and consequently alterations in food dispersion. Parr reared in the enriched environment expressed higher feeding rates, and parr of wild origin started to forage earlier on natural prey. The enriched method promoted foraging of hatchery reared parr on natural prey and is easily applicable to commercial production of salmonids for reintroduction or stock enhancement purposes.
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Due to hydropower development, the upstream migration of wild anadromous salmon and brown trout is impaired in many European rivers, causing negative effects on the long-term survival of natural salmonid populations. This study identified problems for Atlantic salmon during upstream migration in a regulated river in northern Sweden. Umeälven (mean flow: 430 m3s−1). Tagging from 1995 to 2005 involved radio tags (n=503), PIT tags (n=1574) and Carlin tags (n=573) to study the spawning migration of salmon from the coast past the regulated section of the river to a fish ladder at the dam/spillway 32 km upriver. The results demonstrate that migration success from the coast to the fish ladder varied between 0% and 47% among years, indicating an average loss of 70% of potential spawners. Discharge from the turbines attracted the salmon away from the bypass route. Echo-sounding in the turbine outlet showed that salmon were normally found at 1–4 m depths. They responded with upstream and/or downstream movements depending on flow changes; increased spill in the bypass channel attracted salmon to the bypass. Once in the bypass channel, salmon could be delayed and had difficulties passing the first rapid at high spills. Additional hindrances to upstream migration were found at rapids and the area of the fish ladder, located further upstream in the regulated river section. The average migration duration was 44 days from the estuary to the top of the fish ladder, with large variation among individuals within years. Modelling the salmon population dynamics showed a potential population increase of 500% in 10 years if the overall migration success could be improved from the current 30% to levels near 75%. Consequently improved migration facilities at the regulated river section should be implemented to achieve a long-term sustainability of these threatened anadromous salmonids.
Article
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A Bayesian state-space mark-recapture model is developed to estimate the exploitation rates of fish stocks caught in mixed-stock fisheries. Expert knowledge and published results on biological parameters, reporting rates of tags and other key parameters, are incorporated into the mark-recapture analysis through elaborations in model structure and the use of informative prior probability distributions for model parameters. Information on related stocks is incorporated through the use of hierarchical structures and parameters that represent differences between the stock in question and related stocks. Fishing mortality rates are modelled using fishing effort data as covariates. A state-space formulation is adopted to account for uncertainties in system dynamics and the observation process. The methodology is applied to wild Atlantic salmon (Salmo salar) stocks from rivers located in the northeastern Baltic Sea that are exploited by a sequence of mixed- and single-stock fisheries. Estimated fishing mortality rates for wild salmon are influenced by prior knowledge about tag reporting rates and salmon biology and, to a limited extent, by prior assumptions about exploitation rates.
Article
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The combined model produced a tool for evaluating effects on fish populations from passage through hydropower turbines at dams. Mean blade-strike mortality was higher for adult Atlantic salmon (Salmo salar) and sea-run brown trout (Salmo trutta) (25.2%–45.3%) than for juveniles (5.3%–9.7%). Based on life cycle modeling, salmon populations in two Swedish rivers responded differently to strategies for mitigating mortality caused by fish striking turbine blades. Although population growth rates increased up to 3% and were relatively similar for both rivers, the relative increase in the number of female salmon escaping above a dam annually after 20 years when both juveniles and adults were protected was greater in the River Piteälven (68%) than in the River Vindelälven (46%) and was approximately four times greater in the River Piteälven (38% vs. 10%) when only adults were protected. These population responses were not predicted by estimates of mortality through turbines. They showed the model could be used to evaluate strategies to conserve fish populations affected by dams located in fish migratory corridors and how postspawn adults contributed to population productivity.
Article
Full-text available
Due to hydropower development, the upstream migration of wild anadromous salmon and brown trout is impaired in many European rivers, causing negative effects on the long-term survival of natural salmonid populations. This study identified problems for Atlantic salmon during upstream migration in a regulated river in northern Sweden, Umeälven (mean flow: 430m3s−1). Tagging from 1995 to 2005 involved radio tags (n=503), PIT tags (n=1574) and Carlin tags (n=573) to study the spawning migration of salmon from the coast past the regulated section of the river to a fish ladder at the dam/spillway 32km upriver. The results demonstrate that migration success from the coast to the fish ladder varied between 0% and 47% among years, indicating an average loss of 70% of potential spawners. Discharge from the turbines attracted the salmon away from the bypass route. Echo-sounding in the turbine outlet showed that salmon were normally found at 1–4m depths. They responded with upstream and/or downstream movements depending on flow changes; increased spill in the bypass channel attracted salmon to the bypass. Once in the bypass channel, salmon could be delayed and had difficulties passing the first rapid at high spills. Additional hindrances to upstream migration were found at rapids and the area of the fish ladder, located further upstream in the regulated river section. The average migration duration was 44days from the estuary to the top of the fish ladder, with large variation among individuals within years. Modelling the salmon population dynamics showed a potential population increase of 500% in 10years if the overall migration success could be improved from the current 30% to levels near 75%. Consequently improved migration facilities at the regulated river section should be implemented to achieve a long-term sustainability of these threatened anadromous salmonids.
Article
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Laboratory experiments on brown trout (Salmo trutta) embryos suggest that sublethal stress in the gravel nest such as hypoxia may alter the behaviour and survival of fish during the early juvenile period. Eggs and embryos were incubated at constant temperature (8.2 degrees C +/- 0.6 standard deviation) under nonlethal dissolved oxygen (DO) concentrations (3.0 mg center dot L-1; 26% air saturation level) and normoxia (10.3 mg center dot L-1 DO; 90% air saturation level). The average survival from fertilization to end of embryonic development was 70% and 85% for hypoxic and normoxic groups, respectively. Hypoxic embryos grew slowly compared with their normoxic counterparts, but similar body sizes were observed when yolk-sac absorption was completed. Fish incubated as hypoxic embryos delayed their emergence from the gravel in experimental channels. In presence of freshwater sculpin (Cottus gobio), their swimming activity was reduced by 20%, on average, and predation was enhanced by 14% compared with normoxic groups. Results support the view that subtle events early in a fish's ontogeny can have carry-over effects on later periods of its life cycle, and this phenomenon may be a significant source of variation in salmonid fitness.
Article
Effects of peatland drainage on the incubation success of brown trout (Salmo trutta L.) eggs placed inside gravel-filled boxes were studied in two boreal humic rivers in northern Finland. The survival was 53-84% at the eyed egg stage and as low as 0.2-9.1% at the pre-emergence stage, depending on the site. The lowest survivals were recorded at sites affected by peatland drainage. The survival was inversely related to particulate matter and Fe loading from drained peatlands. The results indicate that the increase in the Fe content of high molecular weight dissolved organic matter transported to rivers followed by its precipitation and sedimentation on the river bed may be a crucial factor in weakening the conditions for salmonid reproduction downstream of peatland drainage areas.
Article
Since 1980, the abundance of wild Atlantic salmon has been monitored by means of catch records, adult counts, electrofishing and smolt trapping in six rivers flowing into the northern Baltic Sea. River abundance (spawners, parr and smolts) was compared with implemented large-scale and river-specific management measures and with natural factors potentially affecting abundance. Since the 1980s, the wild stocks have recovered in a synchronous cyclical pattern. The recovery occurred mainly in two jumps, first a sudden increase dating back to around 1990 and a second sharp rise in the late 1990s. River abundance of young salmon commonly rose about 10-fold and approached the previously estimated production capacity in some of the rivers. This positive development may be explained by a decline in fishing pressure together with covarying natural factors influencing survival and growth. The offshore fishery started to decline at the time of the first increase, while the reduction in the total allowable catches together with seasonal restrictions on the coastal fishery strengthened the second increase. Improved natural conditions seem to have increased both survival and escapement during the first rise. Spawners producing the second rise were the offspring of the spawners of the first rise. The outbreak of the M74 mortality syndrome among alevins reduced the abundance of several year-classes that hatched during the first half of the 1990s. In most rivers, the fraction of older and female fish in the spawning run has increased over the period, thereby increasing the reproductive capacity of the populations. No distinct effects of variations in river-specific management regimes were observed. Instead, the results emphasize the role of fisheries management in the open sea as well as in coastal waters, and also of non-human factors in controlling overall abundance of wild salmon in northern Baltic rivers.
Article
We constructed generalized habitat criteria for juvenile Atlantic salmon (Salmo salar) based on four river-specific suitability indices for depth, water velocity, and substrate to assess whether habitat criteria for juvenile Atlantic salmon are transferable across rivers. We first tested whether salmon are more likely to occupy higher-quality habitats than generally available in a stream reach based on these composite criteria. We then repeated the same procedure using the river-specific criteria of this study and the generalized habitat suitability criteria of Heggenes. As expected, the river-specific criteria were generally the most effective ones in predicting fish habitat use. However, both of the two generalized criteria also transferred fairly well to the test sites. Viewed across salmon size-classes (<9 cm and >9 cm), the river-specific criteria passed the test in ten of eleven cases (91%), and the two generalized criteria passed in nine (82%) of eleven. Thus, it appears that with respect to summertime habitat criteria for juvenile Atlantic salmon, criteria transference is conceivable at least on a regional scale, and perhaps even on a more "universal" scale.
Article
In this paper we discuss how the legitimacy of the impact assessment process is a key issue in conflict mediation in environmental impact assessment. We contrast two EIA cases in hydro-power generation plans made for the Ii River, Finland in different decades, and evaluate how impact assessment in these cases has contributed to the creation, mediation and resolution of conflicts. We focus on the elements of distributional and procedural justice that made the former EIA process more legitimate and consensual and the latter more conflictual. The results indicate that it is crucial for conflict mediation to include all the values and interests of the parties in the goal-setting process and in the definition and assessment of alternatives. The analysis also indicates that procedural justice is the most important to help the people and groups involved to accept the legitimacy of the impact assessment process: how different parties and their values and interests are recognized, and how participation and distribution of power are organized in an impact assessment process. It is confirmed in this article that SIA may act as a mediator or a forum providing a process through which competing knowledge claims, various values and interests can be discussed and linked to the proposed alternatives and interventions.
Article
A fishway (fish pass), consisting of vertical slot and Denil sections, was constructed at the lowest dam on the River Kemijoki, northern Finland, in 1993. The river was one of the best salmon rivers in Europe until 1949, when the dam and the hydropower plant were completed close to the river mouth. From 1993 to 1995, nearly 1000 adult salmonids passed through the fishway despite heavy fishing below the dam. Of environmental variables measured, water temperature, headwater level, and discharge through the power plant in relation to season changes explained most of the variation in Baltic salmon, Salmo salar L., numbers. They had a minor effect on trout, Salmo trutta L. Migratory whitefish, Coregonus lavaretus (L.), entered the fishway but were not observed in its uppermost pool. River lamprey, Lampetra fluviatilis (L.), passed through the vertical slot section of the fishway after plastic bristles were fastened into the bottom of the slots.
Article
Generalized habitat criteria for spawning sites of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) using depth, water velocity and substrate size were created based on published information. In addition, information on critical intragravel conditions for egg development was summarized. Salmon spawned mostly in relatively deep, swift-velocity habitats (20–50 cm, 35–65 cm s−1), whereas trout selected slightly shallower and slower flowing spawning sites (15–45 cm, 20–55 cm s−1). Salmon and trout preferred pebbles (16–64 mm) for spawning. The minimum oxygen concentration for successful incubation of eggs varies with the developmental stage of eggs, and supply of it may be reduced by deposited fine sediment. Habitat criteria for spawning sites are narrower than those for small juveniles; therefore the use of separate criteria is recommended. In addition to the traditional habitat criteria variables (depth, water velocity, substrate), the critical intragravel factors affecting egg survival should be incorporated in biologically meaningful criteria for spawning habitat modelling. Copyright © 2008 John Wiley & Sons, Ltd.
Article
The number and the size of Atlantic salmon, Salmo salar L., using the Isohaara fishway was elevated by increasing the fishway discharge and by changing the type of the pass entrance. The fishway is intended to help fish bypass a hydroelectric station located close to the mouth of the large, regulated River Kemijoki, in northern Finland. Multi-sea-winter (MSW) salmon returned to the river mouth during peak flows in early June but did not use the fishway until 1 month later. Their number in the fishway was positively correlated with the tailwater level. One-sea winter (1-SW) salmon, which arrived approximately one month later, started to enter the fishway without corresponding delays. In autumn, a high tailwater level and a small drop at the fish entrance seemed to be needed for the successful passage of these small-sized salmon and sea trout, Salmo trutta L.
Article
Many ecosystems have been transformed, or degraded by human use, and restoration offers an opportunity to recover services and benefits, not to mention intrinsic values. We assessed whether restoration scientists and practitioners use their projects to demonstrate the benefits restoration can provide in their peer-reviewed publications. We evaluated a sample of the academic literature to determine whether links are made explicit between ecological restoration, society, and public policy related to natural capital. We analyzed 1,582 peer-reviewed papers dealing with ecological restoration published between 1 January 2000 and 30 September 2008 in 13 leading scientific journals. As selection criterion, we considered papers that contained either “restoration” or “rehabilitation” in their title, abstract, or keywords. Furthermore, as one-third of the papers were published in Restoration Ecology, we used that journal as a reference for comparison with all the other journals. We readily acknowledge that aquatic ecosystems are under-represented, and that the largely inaccessible gray literature was ignored. Within these constraints, we found clear evidence that restoration practitioners are failing to signal links between ecological restoration, society, and policy, and are underselling the evidence of benefits of restoration as a worthwhile investment for society. We discuss this assertion and illustrate it with samples of our findings—with regards to (1) the geographical and institutional affiliations of authors; (2) the choice of ecosystems studied, methods employed, monitoring schemes applied, and the spatial scale of studies; and (3) weak links to payments for ecosystem service setups, agriculture, and ramifications for public policy.
Article
Koljonen, M-L. 2006. Annual changes in the proportions of wild and hatchery Atlantic salmon (Salmo salar) caught in the Baltic Sea. e ICES Journal of Marine Science, 63: 1274e1285. DNA-level information from an eight-loci microsatellite baseline database of 32 Atlantic salmon (Salmo salar) stocks was used with a Bayesian estimation method to assess the stock and stock group proportions of Finnish salmon catches in the Baltic Sea area. The proportions of seven stock groups, important to fisheries management, were assessed in catch samples taken between 2000 and 2005. In the Gulf of Bothnia area, the proportion of wild fish in catches showed an increasing trend in all areas until 2003, mainly because of the decrease in total catches caused by the relatively greater mortality of hatchery-reared fish compared with wild fish. In 2004, the total number of wild fish caught had also increased, indicating an increase in the abundance of wild stocks. In catches from the Å land Sea, the proportion of wild fish increased from 44% in 2000 to 70% in 2004, while the catch during the same period increased from 4628 to 7329 fish. In the Gulf of Finland, the local Neva salmon stock, which is released by Estonia, Finland, and Russia, made the largest contribution. In the western part of the Gulf of Finland, fish originating in the Baltic Main Basin also made a substantial contribution to catches. The threatened eastern Estonian and Russian wild stocks were recorded only in the western part of the Gulf of Finland, where the proportion of wild fish increased from 9% in 2003 to 19% in 2004.
Article
The River Rhine has suffered severely from pollution and stream regulation over the last two centuries. Industrial effluents and municipal wastewater have imposed pollutant loads, and major engineering works for drainage and navigation have changed the ecological condition of the river. Only during the last three decades has the rehabilitation of the river system been a topic of concern. The present fish fauna is dominated by eurytopic cyprinids. Rheophilous species have declined in numbers, and anadromous fish have become scarce or extinct. Various forms of ecological rehabilitation in the Dutch Rhine are identified: floodplain development; optimization of migration routes with emphasis on the entrance of migrating species from the sea into the river; and restoration of spawning and nursery areas. Ecological restoration of the Rhine is an international effort. The present socio-economic functions of the river pose serious constraints on the feasibility of ecological targets. Copyright
Article
Despite some highly visible projects that have resulted in environmental benefits, recent efforts to quantify the number and distribution of river restoration projects revealed a paucity of written records documenting restoration outcomes. Improving restoration designs and setting watershed priorities rely on collecting and making accessible this critical information. Information within the unpublished notes of restoration project managers is useful but rarely documents ecological improvements. This special section of Restoration Ecology is devoted to the current state of knowledge on river restoration. We provide an overview of the section’s articles, reflecting on lessons learned, which have implications for the implementation, legal, and financing frameworks for restoration. Our reflections are informed by two databases developed under the auspices of the National River Restoration Science Synthesis project and by extensive interactions with those who fund, implement, and permit restoration. Requiring measurable ecological success criteria, comprehensive watershed plans, and tracking of when and where restoration projects are implemented are critical to improving the health of U.S. waters. Documenting that a project was put in the ground and stayed intact cannot be equated with ecological improvements. However, because significant ecological improvements can come with well-designed and -implemented stream and river restorations, a small investment in documenting the factors contributing to success will lead to very large returns in the health of our nation’s waterways. Even projects that may appear to be failures initially can be turned into success stories by applying the knowledge gained from monitoring the project in an adaptive restoration approach.
Chapter
The Atlantic salmon is an anadromous salmonid native to New England. Populations were decimated mostly due to barrier dams from the late 1700s to the mid-1900s. Government sponsored restoration programs began in the 1960s and continue to the present day, with the challenges and methods evolving considerably during the past 40 years. Although improving fish passage and hatchery production remain important, greater emphasis is now placed on population genetics and natural selection. Restoration programs resulted in increasing population sizes until the early 1990s, when populations uniformly declined. Oceanic conditions are considered to be a primary factor in this downturn, along with other contributing factors such as salmon aquaculture, habitat degradation, increased water temperatures, and endrocrine disruptors. One segment of the species’ U.S. population is now listed as Endangered under the U.S. Endangered Species Act. The programs began as single-species management but are slowly changing to multispecies diadromous fish restoration programs.
Article
Within stream restoration practice there has been little use of formal decision analysis methods for evaluating tradeoffs in selecting restoration sites and design alternatives. Restoration planning suffers from poorly defined objectives, confusion of objectives and means, and a lack of consideration of tradeoffs. Multicriteria decision analysis (MCDA) methods have the potential to improve restoration decision making by quantifying non-economic objectives, communicating tradeoffs, facilitating consistent and explicit valuation, and focusing negotiation on ultimate objectives. To explore the potential usefulness of MCDA, we first review restoration practices and define the characteristics of projects that are good candidates for MCDA. We also present two case studies. The first study is a prioritization of stream reaches for restoration that illustrates how value judgments can affect such decisions. The second study addresses the proposed removal of the Ballville Dam on the Sandusky River in Ohio. An important challenge in the dam removal decision is the linking of habitat improvements to changes in species populations and ecological services that people value. The analysis shows how MCDA can assist decision making by clarifying tradeoffs, in this case by showing that the key issues are conflicts among ecological criteria—not all of which are improved by restoration.
Article
Designing and implementing long-term management plans is difficult both because of the complexity of the fisheries system, and the behaviour of humans. We compared four alternative management plans for the Baltic salmon stocks through approaching experts who interpreted and expressed the views of different stakeholder groups on the options. The focus of the study was on stakeholders’ commitment to the alternative management plans. Committing enhances the probability of achieving the ultimate objective of a plan, while if stakeholders do not commit, the effects of the plan may be less predictable. Thus commitment is an important part of implementation uncertainty in fisheries management. We present how we coupled qualitative analysis with probabilistic Bayesian networks in analysing expert knowledge related to alternative long term management plans in terms of group commitment. Using a Bayesian net provides potential for creating a holistic picture of a fishery by combining the data describing fishers’ commitment with biological data regarding fish stock dynamics and with economic data analyzing economically sound fisheries management.
Article
The distributions and abundances of trout and salmon are strongly influenced by their habitat. The habitat includes both abiotic and biotic factors, which interact in complex webs. Habitat probably has strongest effects during population bottlenecks, when the standing stock approaches the carrying capacity of the environment. Various approaches to modelling interactions between habitat and population density and mean weight have been explored, but further work is needed in this area of investigation. The importance of depth, current, substrate, cover, and to a lesser extent, temperature and oxygen availability to the various stages of the life cycles of salmon and trout are briefly reviewed. By drawing on published data, it is possible to define broad ranges of acceptable conditions for the life stages of each species. However, it is not possible to partition this variation into between-population differences, within-population preferences, within-population tolerances, and effects of interactions between habitat variables. To pursue this important issue further, a structured approach using experimentation both in the field and in suitable laboratory systems is recommended. There is abundant evidence that habitat requirements of salmon and trout overlap. Trout tend to out-compete salmon except often in areas of particularly fast flows and, perhaps, remote from the river bank. The habitat requirements of year classes of salmon and trout overlap and therefore, there is scope for interactions between them depending on the spatial arrangement of habitats and the occurrence of bottlenecks. It is particularly important to understand where the bottlenecks to production lie and to focus on these in the first instance. Otherwise, there is a risk of manipulating habitat that is already in excess, or increasing numbers of a population that will subsequently be constrained, e.g., by over-wintering habitat. For this reason, it is prudent to accept that although manipulations of habitat may appear to be beneficial when considered locally, they should be measured and assessed where possible in terms of the production of returning adults and/or high quality smolts. Because of the complexity of interactions between salmon, trout, and the animals that eat them, it is at present difficult, or impossible, to derive good predictive models of the effects of manipulating habitats under many circumstances.
Article
The “International Principles for Social Impact Assessment” and the “Principles and Guidelines for Social Impact Assessment in the USA”, both developed under the auspices of the International Association for Impact Assessment and published in 2003, are compared. Major differences in the definition and approach to social impact assessment (SIA) are identified. The US Principles and Guidelines is shown to be positivist/technocratic while the International Principles is identified as being democratic, participatory and constructivist. Deficiencies in both documents are identified. The field of SIA is changing to go beyond the prevention of negative impacts, to include issues of building social capital, capacity building, good governance, community engagement and social inclusion.
Article
"Institutions are the mechanisms that integrate the human and ecological spheres. This paper discusses the institutional challenge of integrating salmon (Oncorhynchus spp.) ecosystems and human systems in ways that effectively promote resilience. Salmon recovery in the Columbia River Basin demonstrates the challenge. Despite the comprehensive scope of Basin salmon management, it has a number of problems that illustrate the difficulties of designing institutions for ecosystem and human system resilience. The critical elements of salmon ecosystem management are incentives and transaction costs, and these comprise a large piece of missing institutional infrastructure. Once the focus is placed on incentives and costs, a number of different management strategies emerge as options for salmon ecosystems, including refugia, property rights to ecosystem goods and services, co-management, and markets in ecosystem services."
Article
Dana, ISSN 0106-553X, vol. 10, 61-85 Large-scale releases of hatchery-reared smolts in Baltic rivers were started in regulated Swedish rivers in the 1950s. From 1988 to 1992 the countries around the Baltic released an average of 5.3 million smolts per year in Baltic rivers. The salmon fishery in the Baltic has changed since the 1950s, i.e. the exploitation rate has increased, and a major proportion of the catch is taken in the offshore fishery on mixed stocks in the Baltic Main Basin. Because of the high fishing pressure, many wild stocks have declined to the extent that smolt production is only about 20% of the estimated potential production. This paper discusses the future management of Baltic salmon. A low total allowable catch (TAC) for the offshore fishery combined with a late and variable opening date of the coastal fishery should give wild stocks a chance to proliferate. But in 1992 and 1993 a pathological syndrome, called M74, killed 70-90% of the alevins of reared Swedish Baltic salmon stocks. Recent electrofishing surveys suggest that wild stocks in the Gulf of Bothnia are also affected by the syndrome. If this is true, drastic reductions in fishery exploitation are needed to avoid the depletion, and maybe even extinction, of wild stocks.
Article
There are always conflicting goals in the management of large water courses. However, by involving stakeholders actively in the planning and decision-making processes, it is possible to work together toward commonly acceptable solutions. In this article, we describe how we applied interactive multicriteria decision analysis (MCDA) in a collaborative process which aimed at an ecologically, socially, and economically sustainable water course regulation policy. The stakeholders' opinions about the alternative regulation schemes and the relative importance of their impacts were elicited with the HIPRE software. Altogether, 20 personal interactive decision analysis interviews (DAIs) were carried out with the stakeholders. Our experience suggests that the DAIs can considerably improve the quality and efficiency of the collaborative planning process. By improving communication and understanding of the decision situation in the steering group, the approach helped to develop a consensus solution in a case having strong conflicts of interest. In order to gain the full benefits of the MCDA approach, interactive preference elicitation is vital. It is also essential to integrate the approach tightly into the planning and decision-making process. The project's home pages are available to the public at http://www.paijanne.hut.fi/.
Article
This article analyzes water-related conflicts in Southeast Asia and draws the attention to controversial dam—and hydropower—schemes. It focuses on three dam projects in Thailand, Laos and Burma that are all interwoven by different characteristics of development assistance. But they also slightly differ in terms of the implementation stage, the geopolitical setting, the socio-economical frameworks and the actors involved. Against this analytical background, the approach unveils the complexity of internationalising conflicts that are created under the influence of the ongoing globalisation and by multiple actors involved, their networks, strategies and power relations. “Scarcity of resources—securing energy by development assistance” provides a brief introduction by drawing the main global configurations. “Energy supply and poverty alleviation—new dams in Southeast Asia” zooms in on the specific stage by mirroring dam disputes in Southeast Asia (SEA). Based on these fundamentals, in “Different dams—diverse actors and conflict potentials” the case studies are reconstructed to highlight the multiplicity of dam-projects and inherent controversies. “Conclusion—new conflict frameworks require new instruments of dispute resolution” offers an outlook on conceptual ideas on how to deal with future dam disputes under the auspices of development assistance.
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Restoring the Atlantic salmon stock of the River Tuloma – a pilot experiment using transplanted radio-tagged adult salmon
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The ascent of salmon and sea trout in the Merikoski fishway In: Will salmon return to the River Oulujoki? Final report of Oulu and Lososinka river surveys The Finnish Environment 5
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Telemetry studies on salmon and pike in the lower part of the River Oulujoki In: Will salmon return to the River Oulujoki? Final report of Oulu and Lososinka river surveys The Finnish Environment 5
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Juvenile salmon production areas in the river Oulujoki system. in: Will salmon return to the River Oulujoki? Final report of Oulu and Lososinka river surveys The Finnish Environment 5
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