Salvelinus Alpinus Research Articles

Wild fish consumption and latitude as drivers of vitamin D status among Inuit living in Nunavik, northern Québec.

To measure vitamin D status and estimate factors associated with serum 25-hydroxyvitamin D (25(OH)D) in Nunavimmiut (Inuit living in Nunavik) adults in 2017. Data were from Qanuilirpitaa? 2017 Nunavik Inuit Health Survey, a cross-sectional study conducted in August-October 2017. Participants underwent a questionnaire, including an FFQ, and blood samples were analysed for total serum 25(OH)D. Nunavik, northern Québec, Canada. A stratified proportional model was used to select respondents, including 1,155 who identified as Inuit and had complete data. Geometric mean serum vitamin D levels were 65·2 nmol/l (95 % CI 62·9-67·6 nmol/l) among women and 65·4 nmol/l (95 % CI 62·3-68·7 nmol/l) among men. The weighted prevalence of serum 25(OH)D < 75 nmol/l, <50 nmol/l <30 nmol/l was 61·2 %, 30·3 % and 7·0 %, respectively. Individuals who were older, female, lived in smaller and/or more southerly communities and/or consumed more country (traditional) foods were at a reduced risk of low vitamin D status. Higher consumption of wild fish was specifically associated with increased serum 25(OH)D concentration. It is important that national, regional and local policies and programs are in place to secure harvest, sharing and consumption of nutritious and culturally important country foods like Arctic char and other wild fish species, particularly considering ongoing climate change in the Arctic which impacts the availability, access and quality of fish as food.

Density and biomass of Arctic charr Salvelinus alpinus (L.) complex (Salmoniformes, Salmonidae) from the two oligotrophic lakes at biotopes with different trophic levels

Density and biomass of Arctic charr Salvelinus alpinus (L.) complex (Salmoniformes, Salmonidae) from the two oligotrophic lakes at biotopes with different trophic levels

Assessment of Potential Threats to Arctic Char in Lake Geneva: Bacterial Kidney Disease (BRD)

Evaluating the Impact of Bacterial Kidney Disease on Arctic Char Populations in Lake Geneva: A Critical Analysis – This study investigates a significant ecological concern: the notable reduction in Arctic char harvests from Lake Geneva since 1998. This decline is particularly perplexing given the consistent application of existing fishing regulations and ongoing restocking initiatives. Central to this research is the exploration of the hypothesis that Bacterial Kidney Disease (BKD) plays a pivotal role in escalating mortality rates among these fish populations. Utilizing advanced epistemological methodologies, our investigation rigorously identified the presence of BKD through laboratory analyses. Notably, the incidence of BKD in Lake Geneva’s Arctic char was found to be relatively minimal, with a prevalence of merely 0.6\% in 2004, diminishing to 0\% by 2005. Consequently, this study concludes that the presence of BKD, in isolation, is insufficient to account for the substantial decrease in Arctic char catches observed in the region. These findings prompt further research into alternative factors that might be influencing the decline of the Arctic char in Lake Geneva.

The Guardian of Lake Geneva: From Glacial Epochs to the Era of Global Warming

The manuscript presents an in-depth exploration of the Arctic char, a native species in Lake Geneva, tracing its lineage back to the post-glacial era approximately 13,000 years ago. This study delves into the historical documentation of the species, starting from a notable manuscript in 1150, and continuing through various historical records, including acts and laws. The systematic classification of the Arctic char in Lake Geneva has been a topic of considerable scientific discourse, marked by differing species descriptions over time. Current consensus recognizes Salvelinus alpinus as the sole species inhabiting the lake. The research also examines the socio-economic aspects of Arctic char fishing in the region, highlighting its dual role as both an economic resource and a recreational pursuit. Notably, the manuscript addresses the significant surge in fishing yields during the 1990s, followed by a persistent decline in recent years. This study not only provides a historical perspective on the Arctic char but also underscores the dynamic interplay between environmental changes and fishing activities in Lake Geneva.

Expected Climate Change in the High Arctic—Good or Bad for Arctic Charr?

Lakes in the High Arctic are characterized by their low water temperature, long-term ice cover, low levels of nutrients, and low biodiversity. These conditions mean that minor climatic changes may be of great importance to Arctic freshwater organisms, including fish, by influencing vital life history parameters such as individual growth rates. In this study, Arctic charr sampled from two Svalbard lakes (78–79° N) over the period 1960–2008 provided back-calculated length-at-age information extending over six decades, covering both warm and cold spells. The estimated annual growth in young-of-the-year (YOY) Arctic charr correlated positively with an increasing air temperature in summer. This increase is likely due to the higher water temperature during the ice-free period, and also to some extent, due to the winter air temperature; this is probably due to thinner ice being formed in mild winters and the subsequent earlier ice break-up. However, years with higher snow accumulation correlated with slower growth rates, which may be due to delayed ice break-up and thus a shorter summer growing season. More than 30% of the growth in YOY charr could be explained specifically by air temperature and snow accumulation in the two Arctic charr populations. This indicated that juvenile Svalbard Arctic charr may experience increased growth rates in a future warmer climate, although future increases in precipitation may contradict the positive effects of higher temperatures to some extent. In the longer term, a warmer climate may lead to the complete loss of many glaciers in western Svalbard; therefore, rivers may dry out, thus hindering migration between salt water and fresh water for migratory fish. In the worst-case scenario, the highly valuable and attractive anadromous Arctic charr populations could eventually disappear from the Svalbard lake systems.

Assessment of persistent organic pollutants in killer whales (Orcinus orca) of the Canadian Arctic: Implications for subsistence consumption and conservation strategies

Killer whales (Orcinus orca) historically restricted to certain Arctic regions due to extensive sea ice have recently been documented farther north and for longer durations in the Canadian Arctic. These apex predators accumulate high levels of persistent organic pollutants (POPs). The objective of this study was to evaluate the concentrations and profiles of POPs in killer whales of the Canadian Arctic, thus determining potential risks for Inuit communities if consumed. Biopsies were collected from 33 killer whales across areas of the Canadian Arctic between 2009 and 2021. Significant variability in POP concentrations was observed among whales. The cumulative POP concentrations ranged from 12 to >2270 mg/kg lw, representing ∼200-fold increase from the least to the most contaminated individual. The rank order of concentrations of the top five contaminant classes was ∑DDT, ∑PCB, ∑CHL, ∑Toxaphene, and Dieldrin. Several emerging Arctic contaminants were detected, including chlorpyrifos, endosulfan, pentachloroanisole, and polychlorinated naphthalenes, although at relatively lower concentrations than legacy POPs. Considering the elevated blubber POP levels in killer whales, recommended daily consumption thresholds, established based on human tolerable daily intake (TDI) values, were notably restricted for ∑PCB (<0.14 g), ∑DDT (<6.9 g), ∑CHL (<13 g), dieldrin (<8 g) and heptachlor epoxide (<5 g). Killer whales in the Canadian Arctic exhibited higher POP concentrations than other commonly hunted species such as polar bears, ringed seals, and Arctic char. We acknowledge that a more holistic risk assessment of diet is required to assess the cumulative impacts of contaminant mixtures as well as nutritional quality of tissues commonly consumed by northern communities.

Перспективы создания сети рыбоводных предприятий в российской Арктике

Fostering aquaculture aligns with key priorities for Arctic development in Russia, encompassing ecosystem sustainability, job creation, Northern import reduction, enhanced nutritional value of local products, support for small businesses, and advancement of high-tech industries. This study aims to determine the best configuration for a new network of Arctic fish farms in the Russian Arctic. To comprehend the potential of Arctic fish farming, the study starts from identifying feasible farm locations based on an analysis of demand in key Arctic settlements. Criteria-based assessments identified Pevek, Sabetta, Dudinka, Tiksi, Tazovsky, Yamburg, Kharasavey, and Khatanga as potential locations. A comparative economic analysis evaluates logistic options for networks featuring three to eight fish farms in conditions of limited infrastructure. The study determines the attending vessel location (Novosibirsk) and the genetic breeding center location (Pevek). Transportation schemes for feed, fry, and breeding material are developed in accordance with production process requirements. The study proposes the Arctic char as the focus of commercial cultivation at the simulated facility. Economic and mathematical modeling is employed to forecast the effects of creating networks in two configurations at the business, regional, and national levels. The findings reveal that a network of three facilities is more profitable for investors, while a network of eight facilities yields greater social significance with higher fiscal, social, and ecological effects. The quantitative estimates provided serve as a foundation for investment decisions in the development of fish farming in the Russian Arctic.

Variation in personality shaped by evolutionary history, genotype and developmental plasticity in response to feeding modalities in the Arctic charr

Animal personality has been shown to be influenced by both genetic and environmental factors and shaped by natural selection. Currently, little is known about mechanisms influencing the development of personality traits. This study examines the extent to which personality development is genetically influenced and/or environmentally responsive (plastic). We also investigated the role of evolutionary history, assessing whether personality traits could be canalized along a genetic and ecological divergence gradient. We tested the plastic potential of boldness in juveniles of five Icelandic Arctic charr morphs ( Salvelinus alpinus ), including two pairs of sympatric morphs, displaying various degrees of genetic and ecological divergence from the ancestral anadromous charr, split between treatments mimicking benthic versus pelagic feeding modalities. We show that differences in mean boldness are mostly affected by genetics. While the benthic treatment led to bolder individuals overall, the environmental effect was rather weak, suggesting that boldness lies under strong genetic influence with reduced plastic potential. Finally, we found hints of differences by morphs in boldness canalization through reduced variance and plasticity, and higher consistency in boldness within morphs. These findings provide new insights on how behavioural development may impact adaptive diversification.

Fatty Acid Profile of Juvenile Arctic Char (Salvelinus alpinus Complex) from Natural Ecosystems and Aquaculture.

Significant differences in the fatty acid composition of the muscle tissue of juvenile Arctic char Salvelinus alpinus (Linnaeus, 1758) from the natural habitat (Lake Sobach'e) and aquaculture, as well as juveniles of the anadromous form of char (malma) Salvelinus malma (Walbaum, 1792) from the Avacha River were found. The observed differences between aquaculture and wild juvenile char were associated with different food sources. The muscle tissue of juvenile char from natural habitat was characterized by significantly higher levels of fatty acids-biomarkers of diatoms, as well as biomarkers of marine copepods in the anadromous form. In the fatty acid composition of juvenile char from aquaculture, significantly higher levels of linoleic acid were revealed, as well as long-chain monounsaturated acids, the source of which could be aquaculture feed. The identified differences did not have a significant effect on the content of eicosapentaenoic and docosahexaenoic acids in the muscle tissue of juvenile aquaculture and wild char. The content of biochemically valuable omega 3 polyunsaturated fatty acids in juvenile char from natural ecosystems and aquaculture was similar.

Widespread Deviant Patterns of Heterozygosity in Whole-Genome Sequencing Due to Autopolyploidy, Repeated Elements, and Duplication.

Most population genomic tools rely on accurate single nucleotide polymorphism (SNP) calling and filtering to meet their underlying assumptions. However, genomic complexity, resulting from structural variants, paralogous sequences, and repetitive elements, presents significant challenges in assembling contiguous reference genomes. Consequently, short-read resequencing studies can encounter mismapping issues, leading to SNPs that deviate from Mendelian expected patterns of heterozygosity and allelic ratio. In this study, we employed the ngsParalog software to identify such deviant SNPs in whole-genome sequencing (WGS) data with low (1.5×) to intermediate (4.8×) coverage for four species: Arctic Char (Salvelinus alpinus), Lake Whitefish (Coregonus clupeaformis), Atlantic Salmon (Salmo salar), and the American Eel (Anguilla rostrata). The analyses revealed that deviant SNPs accounted for 22% to 62% of all SNPs in salmonid datasets and approximately 11% in the American Eel dataset. These deviant SNPs were particularly concentrated within repetitive elements and genomic regions that had recently undergone rediploidization in salmonids. Additionally, narrow peaks of elevated coverage were ubiquitous along all four reference genomes, encompassed most deviant SNPs, and could be partially associated with transposons and tandem repeats. Including these deviant SNPs in genomic analyses led to highly distorted site frequency spectra, underestimated pairwise FST values, and overestimated nucleotide diversity. Considering the widespread occurrence of deviant SNPs arising from a variety of sources, their important impact in estimating population parameters, and the availability of effective tools to identify them, we propose that excluding deviant SNPs from WGS datasets is required to improve genomic inferences for a wide range of taxa and sequencing depths.

Comparative characteristics of female Ladoga palia (&lt;i&gt;Salvelinus Alpinus L.&lt;/i&gt;), grown in the conditions of fish farming in the Leningrad region by size, weight and reproductive characteristics

Purpose: to conduct a comparative characterization of females matured for the first time at the age of 4 and 5 years according to the main mass-dimensional and reproductive characteristics.Materials and methods. Experimental studies were carried on the basis of the Federal Fish Breeding Genetic Center (FSGTSR). The object of the study was female Ladoga char (Salvelinu salpinus L.) of the III generation, which reached puberty at 4- (n=50) and 5-year-olds. (n=45) age. Females of the second generation of factory breeding were individually assessed in two stages: during the first spawning at the age of five years (2019) and in the next spawning season at the age of six years (2020). When measuring the body and collecting genital products, clove oil was used as an anesthetic. Anesthesia was performed by placing the fish in an aqueous solution of clove oil at a concentration of 0,15–0,2 ml/l for 2–3 minutes.Results. When evaluating mature females at the age of 4 and 5 years, it was found that with a statistically significant increase in body weight of five-year-olds from 1869.3 ± 57.5 to 2156.6 ± 96.53, the multiplicity between the body weight limits did not change with age and is 3 ,2. For other criteria, there is a tendency to decrease in variability. A statistically significant increase in the average weight of one egg is observed, provided that the average values of other reproductive traits do not differ. At the same time, the variability of these signs in five-year-olds is higher than in four-year-olds. So the working fertility increased from 37,4 to 55,1 %, and relative from 26,8 to 43,7 %. Correlation analysis showed the appearance of a weak negative relationship with age between relative fecundity and most of the weight-size traits, otherwise the general trends were preserved in conjunction with an increase in positive correlation.

Characterization of anadromous Arctic char winter habitat and egg incubation areas in collaboration with Inuit fishers

In Nunavik, anadromous Arctic char spend more than 6 months under ice-covered habitats, mainly in lakes. Their winter habitats in this region have been scarcely studied due to the challenging logistics in the Arctic. In this study, we worked with Inuit fishers to characterize the winter habitat and incubation areas used by Arctic chars in five overwintering lakes and one lentic river reach. The collaborating fishers determined char occupancy of certain areas related to fishing sites (presence, absence, and spawning) and conducted measurements to characterize the sites while performing their fishing activities. The data showed that incubation areas were associated with significantly shallower depths and warmer (albeit not statistically significant) lake bottom temperatures than sites where no spawning occurs, which is beneficial for egg maturation. The productivity of these areas is also beneficial for fry that hatch during winter. Adult and post-smolt habitats tended to be associated with cold littoral zone, but their habitat did not show any other distinct characteristics. This exploratory study adds insights into the cryptic characteristics of the Arctic char winter habitat use, thanks to the Inuit fishers’ knowledge of fish habitats and movements, and the experience and expertise they have acquired working in the local environment.

Peculiarities of Early Ontogeny of Dwarf Forms of Arctic Charr Salvelinus alpinus Сomplex (Salmonidae) from Lakes Tokko and Bol’shoe Leprindo (Transbaikalia). 1. Pure Forms

The results of the study of growth, ossification sequence and peculiarities of the development of skeletal elements, body proportions and meristic characters of laboratory-reared larvae and fry of two dwarf forms of Arctic charr Salvelinus alpinus сomplex spawning at the shore slope (Lake Tokko) and in the profundal zone (Lake Bol’shoe Leprindo) (Transbaikalia) are presented. Charr from Lake Bol’shoe Leprindo demonstrated slower rates of growth and morphogenesis, retardation of the ossification of their predorsal bones series with its displacement from larval to juvenile period of the ontogeny, but the acceleration of the development of the vertebral column. High mortality of pre-larvae of charr from this lake connected with the transfer to exogenous feeding was observed. For the first time the problem of the reorganization of early ontogeny of charr of the genus Salvelinus in connection with the colonization of deepwater habitat is discussed. In larvae of charr from Lake Tokko, the ossification of vertebral centra was often accompanied by the formation of anomalous bony structures in the notochord. The phenomenon of the penetration of skeletogenic cells into the notochord, which has been described in hybrids of sympatric charr forms, was found in a pure charr form for the first time. The development of characteristic morphological features of the two charr forms in the ontogeny was traced. Differences in body proportions between their fry corresponding to those between adult fish were revealed.

Divergent Temporal Trends of Mercury in Arctic Char from Paired Lakes Influenced by Climate-Related Drivers.

Climate-driven changes including rising air temperatures, enhanced permafrost degradation, and altered precipitation patterns can have profound effects on contaminants, such as mercury (Hg), in High Arctic lakes. Two physically similar lakes, East Lake and West Lake at the Cape Bounty Arctic Watershed Observatory on Melville Island, Nunavut, Canada are being affected by climate change differently. Both lakes have experienced permafrost degradation in their catchments; however, West Lake has also undergone multiple underwater Mass Movement Events (MMEs; beginning in fall 2008), leading to a sustained 50-fold increase in turbidity. This provided the unique opportunity to understand the potential impacts of permafrost degradation and other climate-related effects on Hg concentrations and body condition of landlocked Arctic char (Salvelinus alpinus), an important sentinel species across the Circum-Arctic. Our objectives were to assess temporal trends in char Hg concentrations and to determine potential mechanisms driving the trends. There was a significant decrease in Hg concentrations in East Lake char, averaging 6.5%/year and 3.8%/year for length-adjusted and age-adjusted means, respectively, from 2008 to 2019. Conversely, in West Lake there was a significant increase, averaging 7.9%/year and 8.0%/year for length-adjusted and age-adjusted mean Hg concentrations, respectively, for 2009 to 2017 (the last year with sufficient sample size). The best predictors of length-adjusted Hg concentrations in West Lake were carbon and nitrogen stable isotope ratios, indicating a shift in diet including possible dietary starvation brought on by the profound increase in lake turbidity. Our study provides an example of how increasing lake turbidity, a likely consequence of climate warming in Arctic lakes, may influence fish condition and Hg concentrations. Environ Toxicol Chem 2023;42:2712-2725. © 2023 His Majesty the King in Right of Canada and The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

Fishing motives and economic effects of climate change: an application on Arctic char in northern Sweden

Motives for fishing differ among fishers, which may imply different effects of climate change on the net values of fishing. Climate change has impacts on fish population dynamics and on other factors in the fishers’ harvest decision, such as alternative sources of food or income. Here we present a bio-economic model that includes impacts of climate change on fish population and on net values of harvest by fishers with recreational or subsistence fishing motives. The conceptual analysis shows that the economic effects of climate change with simultaneous impacts on fish population growth and harvest values are inconclusive with common fishing access for both fisher types and when there are opposite simultaneous climate effects with exclusive access for one of the fisher types. Numerical results from our model of Arctic char (Salvelinus alpinus) in northern Sweden indicate that climate change, measured as temperature increases, reduces fish population growth but increases net values of fishing for both fisher types. The combined net effect of these counteracting forces is that annual net values can almost cease for the subsistence fisher in the future but increase considerably for the recreational fisher.

Farmed fish welfare during slaughter in Italy: survey on stunning and killing methods and indicators of unconsciousness.

Information on slaughter procedures for farmed fish in aquaculture is limited, both in Europe and in Italy, due to a general lack of field data. The aim of this study was to gather information on the procedures used to slaughter fish in Italy and to discuss them considering the WOAH and EFSA recommendations on fish welfare. Using a questionnaire survey, data were collected by official veterinarians in 64 slaughtering facilities where 20 different species of fish were slaughtered. The main species slaughtered were rainbow trout (Oncorhynchus mykiss; 29/64), followed by European sea bass (Dicentrarchus labrax; 21/64), sea bream (Sparus aurata; 21/64), Arctic char (Salvelinus alpinus; 14/64), European eel (Anguilla anguilla; 11/64), sturgeon (Acipenser spp; 11/64), common carp (Cyprinus carpio; 6/64), and brown trout (Salmo trutta fario L.; 5/64). The most applied stunning/killing methods were "asphyxia in ice/thermal shock" and "electric in water bath," followed by "percussion," "asphyxia in air," and "electric dry system." After the application of the method, the assessment of the fish level of unconsciousness was practiced in 72% of the facilities using more than one indicator, with "breathing" and "coordinated movements" the most practiced. The collected data showed a discrepancy between the available recommendations about the welfare of fish at slaughter and what is practiced in many production sites, but for many species precise recommendations are still not available.

Climate warming accelerates somatic growth of an Arctic fish species in high-latitude lakes

High-latitude aquatic ecosystems are responding to rapid climate warming. A longer ice-free season with higher water temperatures may accelerate somatic growth in lake ectotherms, leading to widespread ecological implications. In fish, rising temperatures are expected to boost rates of food intake and conversion, and predictions based on empirical relationships between temperature and growth suggest a substantial increase in fish growth rates during the last decades. Fish abundance negatively affects growth by limiting food availability. This field study addresses the effects of climate warming on growth of a subarctic population of Arctic charr (Salvelinus alpinus (L.) over nearly 40 years. Juvenile growth of 680 individuals of Arctic charr, was reconstructed by sclerochronological analysis using sagittal otoliths sampled annually from the early 1980s to 2016. Statistical modelling revealed a positive effect of water temperature, and a negative effect of abundance on somatic growth in juvenile individuals. Temperature dependence in growth was significant for average and fast-growing individuals across all investigated age classes. These findings suggest that, as temperatures rise, somatic growth of Arctic charr will increase in high latitude lakes. Climate warming will thus influence cold water fish life history and size-structured interactions, with important consequences for their populations and ecosystems.

Marine diets of anadromous Arctic char (Salvelinus alpinus) and pink salmon (Oncorhynchus gorbuscha) in Svalbard, Norway

During summer, native anadromous Arctic char (Salvelinus alpinus) and the alien species pink salmon (Oncorhynchus gorbuscha) now coexist in marine environments in Svalbard, following the introduction of the latter in the Barents Region. To investigate potential dietary competition between these two salmonid species, stomach contents from Arctic char (n = 301) and pink salmon (n = 28) were sampled from different areas within the archipelago. The most important prey in terms of biomass for both salmonid species were amphipods; Themisto libellula (B = 26.0%) for Arctic char and Onisimus litoralis (B = 35.0%) for pink salmon. Pianka’s niche overlap revealed that dietary overlap between the two species was moderately high (Oobs = 0.59); both species had strong associations with intertidal invertebrates in areas where direct comparisons were possible (Kongsfjorden/Krossfjorden). However, both salmonid species did also eat some fish, with Arctic char consuming more offshore pelagic fish, while the small number of fish eaten by pink salmon were primarily coastal demersal fish species. Arctic char was a more generalist feeder, while pink salmon was more of a dietary specialist. Furthermore, the diet composition of the Arctic char consisted of 32.9% Atlantic prey while the pink salmon, surprisingly, ate only Arctic species, likely due to their tightly coastal feeding habits. Even though the sample size for pink salmon was low, this study contributes new insights into salmonid diets in Svalbard and the potential for introduced species to compete with native Arctic endemics, particularly in the expected warmer Arctic of the future.

Extinction risks and threats facing the freshwater fishes of Britain

Abstract Extinctions occur naturally in all environments, but rates have accelerated rapidly during the Anthropocene, especially in fresh water. Despite supporting many fish species of conservation importance, there has never been a formal assessment of their extinction risks in Britain, which has impeded their inclusion in relevant legislation and policy. This study therefore used the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species™ Categories and Criteria to conduct the first systematic assessment of the extinction risks and threats facing the native freshwater and diadromous fishes of Britain. In addition, national assessments were produced for England, Scotland and Wales, reflecting the level at which environmental policy decisions are taken in Britain. Seven species were categorized as being threatened with extinction at the regional level, with European eel Anguilla anguilla and allis shad Alosa alosa classified as Critically Endangered, Atlantic salmon Salmo salar, vendace Coregonus albula and European whitefish Coregonus lavaretus classified as Endangered, and Arctic charr Salvelinus alpinus and twaite shad Alosa fallax classified as Vulnerable. In addition, burbot Lota lota was classified as Regionally Extinct, ferox trout Salmo ferox was categorized as Data Deficient, and 25 species were categorized as Least Concern. European sturgeon Acipenser sturio and houting Coregonus oxyrinchus, although probably native, qualified as only vagrants in fresh water, so were categorized as Not Applicable. The assessments provide objective baselines against which future changes can be determined, and a key evidence base to support policy and management decisions for the conservation of freshwater and diadromous fish species and their habitats in Britain. It is recommended that the assessments are repeated every 10 years, which would enable changes in conservation status, the effectiveness of policies and where targeted interventions may be required to be examined using the Red List Index.

Mercury at the top of the world: A 31-year record of mercury in Arctic char in the largest High Arctic lake, linked to atmospheric mercury concentrations and climate oscillations

Lake Hazen, the largest lake north of the Arctic circle, is being impacted by mercury (Hg) pollution and climate change. The lake is inhabited by two morphotypes of land-locked Arctic char (Salvelinus alpinus), a sensitive indicator species for pollution and climatic impacts. The objectives of this study were to describe the trends in Hg concentration over time and to determine the relationship of climate to length-at-age and Hg concentrations in each char morphotype, as well as the relationship to atmospheric Hg measurements at a nearby monitoring station. Results for Hg in char muscle were available from 20 sampling years over the period 1990 to 2021. We found significant declines in Hg concentrations for both morphotypes during the 31-year study period. Increased rain and earlier freeze-up of lake ice during the summer growing season was linked to increased length-at-age in both char morphotypes. For the large morphotype, higher total gaseous Hg in the fall and winter seasons was related to higher concentrations of Hg in char, while increased glacial runoff was related to decreases in char Hg. For the small morphotype char, increased snow and snow accumulation in the fall season were linked to declines in char Hg concentration. The Atlantic Multidecadal Oscillation and Arctic Oscillation were positively related to the large char Hg trend and Arctic Oscillation was positively related to the small char Hg trend. Significant trend relationships between atmospheric Hg and Hg in biota in remote regions are rare and uniquely valuable for evaluation of the effectiveness of the Minamata Convention and related monitoring efforts.