Cameron Freshwater, Charles Parken, Strahan Tucker, Antonio Velez-Espino, and Jackie King
The abundance of many Chinook salmon stocks has declined despite reductions in harvest. We used state-space models parameterized with data from 57 Chinook salmon indicator stocks to quantify long-term (since 1972 release year) changes in juvenile marine survival rate and mean age-at-maturity, as well as identify stock groupings with coherent dynamics. We found that juvenile marine distribution–rather than freshwater life history, run timing, or adult marine distribution–was the best predictor of trends in both survival and age. Only subyearling stocks that enter the Strait of Georgia showed evidence of transitioning to a low juvenile survival regime, other groupings exhibited low and stable or cyclical patterns in survival. Conversely, declines in mean age-at-maturity were widespread and do not appear to have stabilized, suggesting future declines in Chinook salmon population productivity may be influenced by earlier maturation or increased adult mortality, rather than further reductions in juvenile marine survival.
Neala Kendall, Benjamin W. Nelson, Mike Haggerty, Mike Crewson, Dave Beauchamp, Diego Holmgren, Sandra O’Neill, and Casey Ruff
What ecosystem variables have been associated with Salish Sea (Washington State, USA and British Columbia, Canada) and coastal Washington Chinook and coho salmon marine survival trends? Have these relationships varied over time? Scientists and managers seek to use these relationships to predict salmon abundance, but changing relationships over time can make this a challenging endeavor. I will discuss our work relating Chinook salmon marine survival to the presence and abundance of pink salmon in the Salish Sea and evaluating stanzas in this relationship. Inclusion of other ecosystem variables paints a more complete picture of factors related to coho and Chinook salmon marine survival.
Kjetil Hindar, J. Henrik H. Berntsen, Odd Terje Sandlund, Eva B. Thorstad, and Kyrre Kausrud
Pink salmon (Oncorhynchus gorbuscha) were for many years transplanted from the Pacific to the Barents and White Sea for increasing opportunities for local fisheries. Transplanted fish survived but did at first not establish. After choosing a donor stock further north in the Pacific Magadan Oblast from 1985 onwards, transplants were successful and soon thereafter established self-sustaining populations in Northwest Russia. Pink salmon were also found in North Norwegian rivers and may have established populations there around 2007. In 2017, an unprecedented expansion of pink salmon was seen in the Atlantic Ocean, including all of Norway, Scotland, Denmark and Sweden, Scotland and elsewhere in the UK, Ireland, Germany, and France. Some pink salmon were observed even further west in Iceland, Greenland, and eastern Canada. In Norway, this was followed by a doubling of catches in 2019 and on top of that, a 10X-increase in 2021. Pink salmon is now the most common anadromous salmonid in Norwegian rivers, and in the northernmost counties, they outnumber the sum of all other anadromous salmonids: Atlantic salmon (Salmo salar), anadromous brown trout (S. trutta) and anadromous Arctic charr (Salvelinus alpinus). Effects on native salmonids include aggressions towards upmigrating individuals, blocking and possibly displacing them from some spawning areas, and competition for food and space among juveniles during early life in the river. Pink salmon may also act as vectors for fish diseases, potentially harmful to both wild and farmed salmon, and they enforce ecosystem effects by transporting nutrients from the ocean to formerly nutrient-poor rivers. Modeling indicates that increasing water temperatures in the north in spring and early summer favor pink salmon survival and increase spawning population size. Climate predictions from current scenarios suggest larger pink salmon populations in the future, and we speculate that warming of Arctic waters can lead to pink salmon establishing as a circumpolar species.
Marisa N. C. Litz and Mickey Agha
Effective management of coho salmon begins with accurate annual forecasts of adult abundance. In western Washington, resource management decisions have benefited from a life cycle monitoring program where a full census juvenile and adult trap has operated since 1982. Annually at the trap, all juveniles were marked with a coded wire tag and released. Returns of marked precocious males (jacks) and recoveries of tagged adults in fisheries and at the trap were used to estimate marine survival. Over time, there has been considerable variation in juvenile production, jack rates, and adult returns. Variation in marine survival and life history diversity were evaluated with respect to environmental conditions experienced during both freshwater and marine life history phases using generalized additive mixed models. Results were used to identify limiting life history stages. Juvenile outmigration timing and size did not vary through time, although earlier migrating smolts had higher overall jack and adult survival rates. Notably, the expression of jack life history increased through time, especially following a breakpoint in 2005, a year characterized by delayed upwelling in nearshore habitats. Instream conditions experienced during the juvenile rearing period had minimal effect on life history expression and smolt survival compared to nearshore oceanographic conditions immediately following freshwater emigration, supporting the idea that jack rate and recruitment strength is mostly determined during the early marine period. Forecast models also identified differences in marine survival associated with ecological climate regimes related to El Niño Southern Oscillation. Coho management tools such as forecasting benefit from a holistic perspective that considers environmental variation throughout the entire life history.
Jean-Michel O. Matte, Guillaume J.R. Dauphin, Cindy Breau, Carole-Anne Gillis, André St-Hilaire, Normand E. Bergeron
Abundances of Atlantic salmon have steadily declined from exposure to various stressors, including increasing thermal stress events with warming water temperatures in freshwater habitats. Temperature is a strong driver of somatic growth, and can induce cascading effects on foraging behavior, competition, and ultimately, population dynamics of salmon. Furthermore, the effect of temperature on growth is often context-dependent and variable among populations, compromising our ability to forecast the potential effects of climate change. Using monitoring data from two Atlantic salmon populations from Eastern Canada (Margaree and Miramichi rivers), we show that incorporating hierarchical structure (in space and in time) can help quantify variability in growth patterns and how they relate to temperature. This flexible and promising approach also allows data-rich sites to inform relationships in data-poor sites.
Kentaro Honda, Koh Hasegawa, Ikuo Ono, and Kazushi Miyashita
Mobile predators head for denser prey patches in general. For stock enhancement purposes, chum salmon (Oncorhynchus keta) fry are frequently released from hatcheries. Therefore, the effects of feeding by riverine predators cannot be disregarded. In the Chitose River, northern Japan, it was believed that a number of exotic piscivorous brown trout (Salmo trutta) aggregate near the hatchery to prey on fry during the period when around 30 million fry are released (>1 million at a time). This study investigated the validity of this belief. None of 27 brown trout tracked by acoustic telemetry appeared near the hatchery during the release period. Underwater visual censuses showed that the number of brown trout near the hatchery did not increase during the release period. Dietary analysis showed that brown trout captured both near the hatchery and about 10 km downstream had preyed on >100 fry released the day before their capture. Our results suggest that the lack of aggregation near the hatchery resulted from the rapidly dispersing, large masses of fry provided easy prey for brown trout regardless of proximity to the hatchery.
Megan E. Moore, Austen C. Thomas, Michael J. Malick, Matthew M. Klungle, and Barry A. Berejikian
Predation by harbor seals may be threatening the recovery of ESA-listed steelhead. After freshwater rearing, steelhead smolts experience high mortality during their rapid migration from river mouth to the Pacific Ocean. Previous work indicates that harbor seal predation is a primary source of early marine mortality, but the level of impact exerted by harbor seals on steelhead has not been quantitatively assessed. We estimated the percentage of Nisqually steelhead migrants consumed by harbor seals in 2016, 2017, and 2018 from estimates of (1) the proportion of harbor seal diet comprised of steelhead, (2) the number of smolt outmigrants in the Nisqually River, (3) the downstream survival of smolts to the estuary, and (4) the number of harbor seals residing in South Puget Sound (SPS). Metabarcoding of DNA in harbor seal fecal samples collected in SPS identified small fractions of harbor seal diet comprised of steelhead smolts. Those small fractions, however, translated into substantial mortality on Nisqually River steelhead cohorts when multiplied by the estimated energetic demand of the SPS harbor seal population. Model results indicate that between 9% (2017) and 33% (2018) of outmigrating steelhead were eaten by harbor seals during the 24-kilometer migration through SPS, and that harbor seal predation accounted for 26% (2017) to 70% (2018) of the total mortality incurred over that same distance. Independent estimates of harbor-seal consumption of steelhead during the same years (7-17%), quantified using behavioral metrics of acoustic tagged Nisqually smolts, are comparable to consumption model estimates and indicate that most South Puget Sound mortality takes place in or near the estuary. This study demonstrates the capacity of marine mammal predators to measurably impact survival and potential productivity of small prey populations, and provides information to managers tasked with balancing the impacts of one protected species with the recovery of another.
Hem Nalini Morzaria-Luna, Isaac C. Kaplan, Chris J. Harvey, Michael Schmidt, Elizabeth A. Fulton, Raphael Girardin, and Parker MacCready
Cumulative human impacts in Puget Sound have likely contributed to declining trends in juvenile marine survival of Chinook and coho salmon. We use an Atlantis ecosystem model for Puget Sound (AMPS) to identify drivers that most strongly affect Chinook and coho salmon survival. Atlantis is an ‘end-to-end’ modeling framework for marine ecosystems that integrates oceanographic, geochemical, ecological, and anthropogenic processes in a three-dimensional, spatially explicit domain. The AMPS is initialized to represent recent conditions (c. 2011) and simulates food web dynamics using 73 functional groups, including 21 salmon groups. Hydrodynamics in the AMPS are driven by outputs from a Regional Ocean Modeling System model for Puget Sound. We use the AMPS to test two categories of impacts (1) bottom-up processes including competition with hatchery salmon and with wild pink and chum salmon, increase in gelatinous zooplankton, declines in herring biomass and availability as forage, declining availability of crab larvae in salmon diets, and the shift in release timing of hatchery Chinook; and (2) top-down processes, increased predation by pinnipeds, increased predation by Harbor porpoise, seabirds, dogfish, and predation by and competition from resident Chinook. Over a 30-year simulation, salmon responded strongly in scenarios related to herring, gelatinous zooplankton, and residency (e.g. the proportion of salmon that migrate to the ocean). Forcing the model with declining trends in herring led to 5-10 % declines in most salmon groups, except Chum, while increasing trends in gelatinous zooplankton led to 12-53% percent declines of Chinook and coho salmon groups. Our scenario approach allowed us to rank past drivers of salmon declines, and to identify management actions that are likely to produce improvements in salmon survival. Our results contribute to management of Puget Sound via the Salish Sea Marine Survival Project.
Elliott L. Price, Evgeny A. Pakhomov, and Brian P. V. Hunt
In the North Pacific, zooplankton are critical for understanding the status of salmon populations as they constitute a major proportion of their diet. Salmon, among other marine organisms, structure part of their life histories around food availability, including migrating to food sources in the marine environment, and timing of spawning to coincide with high food availability. Therefore, understanding how food sources are structured across the North Pacific is critical in developing management strategies for salmon. Our aim is therefore to identify the composition and structure of zooplankton communities in the North Pacific and determine how the communities relate to the physical and chemical environment. Zooplankton specimens were collected from stations in during the IYS Gulf of Alaska expeditions in 2019 and 2020 using bongo nets and Juday nets, and CTD casts were used to define water column characteristics. Size fractionated zooplankton biomass was measured, and all species present were identified, staged and sexed to define the community composition. We present the spatial distribution of zooplankton by defining distinct communities across the North-eastern Pacific using hierarchal clustering and show the environmental associations of these communities using an ordination method. In addition, we show how the zooplankton community composition differed between the 2019 and 2020 expeditions, highlighting the impact of year to year variability in zooplankton biomass as a result of basin top town pressures from planktivores and basin scale climate variability.
Olivia Simmons, J.Robert Britton, Phillipa Gillingham, Marie Nevoux, Etienne Rivot, John Armstrong, Mathieu Buoro, Patrick Gargan, Tormod Haraldstad, Michael Millane, Thilo Reich, William Riley, Øystein Skaala, and Stephen Gregory
Populations of anadromous Atlantic salmon Salmo salar (‘salmon’) have decreased
dramatically across much of their geographic range in recent decades. It is posited this is being driven by low marine survival, resulting in reduced adult return rates to natal rivers. We hypothesised that marine return rates of adult salmon are positively influenced by their body lengths as seaward-migrating juveniles (‘smolts’), so larger smolts will be more likely to survive at sea and return as spawning adults to the natal river. We also suggest that the magnitude of this effect decreases with latitude, with its effect being weaker in more northerly populations. These were tested using individual capture-mark-recapture data from seven salmon populations in Western Europe spanning 13 degrees of latitude and 12 years of smolt cohorts. We used a multi-state state-space model to test whether marine return rates were influenced by smolt body length andlatitude, and their interaction. Across the seven populations, smolt length had a significant positive effect on the probability of adult return, which was stronger in southern versus northern populations. Atlantic salmon smolt body length is thus an important indicator of their marine return rates, especially among populations in the warmer, southern part of their geographic range, with this having important implications for conserving declining salmon stocks. It suggests that management in their freshwater juvenile stages can increase MRR and should focus not only on the numbers of seaward-migrating juveniles, but also their individual quality, as indicated by their body length.
Shigehiko Urawa and Shinya Mizuno
The year class strength of salmon population is largely determined during early marine residence. Pathogens may occasionally play a significant role in regulating salmon populations. Several hundred species of parasites have been recorded from anadromous salmon within their native range in the North Pacific and Atlantic oceans, and some cause growth reduction and mortalities of hatchery-reared juveniles. However, our knowledge is limited for the impact of parasites on the survival and fitness of wild salmon in the ocean. The aim of this paper will review case studies to imply possible marine mortalities of Pacific (Oncorhynchus spp.) and Atlantic salmon (Salmon salar) caused by different parasites such as the ectoparasitic protozoan (Ichthyobodo salmonis), digenean trematode (Nanophyetus salmincola), and sea lice (Lepeophtheirus salmonis and Caligus spp.). The euryhaline flagellate I. salmonis is distributed in the North Pacific and Atlantic coasts, infecting the skin and gills of specific anadromous hosts: chum (O. keta) and Atlantic salmon. The heavy parasite infection destructs the skin epidermis of juvenile chum salmon, which causes a breakdown in the osmoregulation. These juveniles result in significant mortalities when they migrate into the coastal ocean, mainly due to a failure in seawater adaptation. The parasite remains infecting the survivors throughout the freshwater and ocean life of anadromous host for reproduction. The metacercarial stage of digenean N. salmincola is primarily found in the kidney and muscle of freshwater fishes including Chinook (O. tshawytscha) and coho salmon (O. kisutch) in coastal rivers of the Pacific Northwest. The parasite has negative effects on the swimming performance, growth, osmoregulation, immune function, and disease resistance of juvenile salmon, and parasite-associated host mortalities occur during early marine residence. Like I. salmonis, the salmon louse L. salmonis is found both from the Pacific and Atlantic oceans. The parasite has a major risk for sustainable aquaculture production of Atlantic salmon, but the impact of sea lice on wild salmon populations is debated. Multiple factors affect parasite-infected salmon in the ocean. Field and laboratory experiments are essential to quantify the impact of parasites in natural environments.
Samantha M. Wilson and Jonathan W. Moore
Climate change may be shifting the timing of animal migrations and their prey availability at different rates and it is unclear how this may impact survival (i.e., the match/mismatch hypothesis). For example, juvenile salmon migrate from freshwater to the ocean and rely upon seasonally abundant marine prey. Yet climate change may be altering juvenile salmon migration timing, possibly increasing the frequency of mismatches with prey. Here we address two key questions: 1) is the timing of juvenile salmon migration shifting and could this lead to mismatches with prey? 2) How do mismatches between juvenile salmon and their prey in the early marine environment influence marine survival? We collated a dataset on smolt outmigration timing of 66 populations of at least 20 years in length for six species of Pacific salmon ranging from Oregon to Alaska. We found that the magnitude of shifts in outmigration timing varied between species and across populations. Key freshwater variables (e.g., temperature, latitude) were not predictive of rates of shifts in outmigration timing suggesting local response diversity may complicate prediction of shifts in outmigration timing under climate change. We then examined how timing of marine prey availability relative to migration timing of juvenile steelhead trout influenced ocean survival in a focal population. We found that larger steelhead trout always had higher marine survival and when prey availability peaked earlier, survival was higher. Differing rates of phenological change across species and populations may result in more phenological mismatches which could impact salmon survival. Importantly this body of work shows that traits determined in freshwater (e.g., size, migration timing) can impact survival in the marine environment (i.e., carryover effects).
Sabrina Garcia, Cindy A. Tribuzio, Andrew C. Seitz, Michael B. Courtney, Julie K. Nielsen, Jim M. Murphy, and Dion S. Oxman
The role of predation on Pacific salmon (Oncorhynchus spp.) during their marine life stage is part of the “black box” in understanding salmon life history. Salmon sharks (Lamna ditropis) have been identified as a major salmon consumer with the potential to impact both population abundance and demographics, such as age at return. Salmon sharks are a widely distributed apex predator in the North Pacific Ocean and known to feed on salmon in summer months when they are concentrated in coastal areas during their return migration to natal spawning streams. However, the importance of salmon in salmon shark diets throughout the year is unknown. To assess the potential impact of salmon shark predation on salmon, information on salmon shark migration and distribution is needed to assess the degree of overlap between predator and prey. Salmon sharks in the eastern North Pacific Ocean, specifically Prince William Sound, Alaska, have been satellite-tagged and tracked for many years. These sharks, all female, tend to make repeat migrations between coastal Alaska and the California Current ecosystem. To date, only four salmon sharks, all males, have been satellite-tagged and tracked outside of the eastern North Pacific Ocean. Three of these tagged sharks migrated between the central Pacific Ocean and the Bering Sea. Although the satellite-tagging technology employed here cannot determine feeding habits of salmon sharks, information on salmon distribution and tracks from satellite-tagged sharks may be used to assess potential predator-prey spatio-temporal overlap. Winter research cruises in the high seas, like the 2022 Pan-Pacific expedition, are important as they provide a platform to opportunistically satellite tag salmon sharks. The broad geographic areas sampled during these surveys, which overlap with potential salmon shark habitat, provide information on prey density that can be used alongside satellite tag data to understand salmon shark movements. If salmon shark predation on Pacific salmon is to be quantified, additional movement information is needed for salmon sharks from the Bering Sea and western North Pacific along with region- and species-specific migration patterns of salmon during their marine residence. Additionally, diet studies conducted outside summer months, from salmon sharks across their geographic range, and of varying sizes are needed to determine diet composition. Finally, estimates of salmon shark abundance would help determine if salmon shark predation on salmon has increased in concert with decreasing salmon abundance, but abundance estimates are currently not available for salmon sharks in the North Pacific Ocean.
Jessica R. Rodger, Jessie Lilly, Hannele H. Honkanen, Amy Green, Diego del Villar, Lorna Wilkie, Richard Kennedy, Andrea Barkley, Robert Rosell, William Roche, Ross McGill, Samantha Beck, Jim Henderson, Debbie Parke, Alan Kettle-White, Lucy Ballantyne, Shona Marshall, Paul Hopper, James Thorburn, Fred Whoriskey, Niall Ó Maoiléidigh, Ken Whelan, Angus Lothian, and Colin Adams
The evidence suggests that the decline in Atlantic salmon populations from across Europe are, at least in part, due to increasing losses occurring during the marine phase of migration. Emerging data suggests that migration success of out-migrating fish may be poor, particularly in the earliest stages of their migration when they may be in close proximity to human activity. Yet this stage of the migration remains very poorly understood.
In this study we aimed to determine the migration pathways of Atlantic salmon post-smolts during the early phase of their marine migration through the waters surrounding the western British Isles and Ireland. 1649 salmon smolts migrating from 20 rivers in Scotland, England and Northern Ireland were tagged with acoustic transmitters during spring 2021. 457 receivers were deployed in curtain arrays in the seas of the North Channel between Ireland and Scotland, off the Hebrides and mainland Scotland. Our results show that Atlantic salmon post-smolts migrated in multiple directions and in complex patterns during the early phase of their marine migration. There were significant between-river differences in the pathways adopted by post-smolts from different regions. The timing of passage and migration speed of post-smolts through coastal marine waters also varied markedly, with mean movement rates ranging between 4.32 and 39.94 km/day. This study is the first to establish a wider picture of the migration pathways of Atlantic salmon post-smolts during the early coastal phase of their marine migration in the western British Isles and Ireland. The results show complex patterns of Atlantic salmon post-smolt migration, with multiple pathways and waters utilised during the early phase of their marine migration. This study has significant consequences for our understanding of the potential conflict between migrating salmon and human activities in coastal zones.
Line E. Sundt-Hansen, Julien Cucherousset, Mathieu Buoro, Libor Závorka, Knut A.E. Bækkelie, August E. Høyland, Grethe Robertsen, Eli Kvingedal, and Kjetil Hindar
Humans have a long history in manipulating growth in animals for our advantage, through selective breeding for rapid growth in farmed salmon and developing genetically modified salmon reaching a larger size faster than wild fish. Breeding programs for many salmonids have focused on developing more extreme phenotypes (e.g. faster growth rate, and/or larger size at reproduction), which may disproportionally impact wild salmonids if they are released or escape into the wild.
Impact of escaped farmed salmon into the wild have often focused on interactions between wild and farmed salmon, at the individual or population level. However, there is a lack of knowledge considering the impact of escaped farmed salmon on aquatic ecosystems and ecosystems functions.
In a series of experiments in semi-natural facilities at NINAs research station at Ims, we have tested how rapid growth (potential) of farmed Atlantic salmon affects their behaviour and competition and interaction with wild Atlantic salmon. Further, we have tested how this competition is influenced by population density, food abundance and predation. Moving from the individual to an ecosystem approach, we have tested how Atlantic salmon with a rapid growth potential, impact the ecosystem and ecosystem function. Our results show that not only does rapid growth impact the individuals and other conspecifics, but also other organisms in the ecosystem and their functions.
Raphaël Bouchard, Kyle Wellband, Laurie Lecomte, Louis Bernatchez, and Julien April
Captive-breeding programs are among the most adopted conservation practices to mitigate loss of biodiversity, including genetic diversity. However, both genetic and nongenetic changes occurring in captivity can reduce fitness of supplemented individuals which complicate rehabilitation efforts. In the case of Atlantic Salmon, the intensity of changes that occur in captivity and their impact on fitness will vary with the stocking practice adopted. In this study, we test whether salmon stocked at the parr stage have reduced reproductive success compared to their wild conspecifics and if they contribute to increase genetic diversity in the targeted population. To do so, we use high-throughput microsatellite sequencing of 38 loci to accurately assign 2381 offspring to a comprehensive set of possible parents from a supplemented Atlantic salmon population in Québec, Canada. Captive-bred salmon stocked at the parr stage had fewer mates than their wild conspecifics as well as a reduced relative reproductive success compared to their wild counterparts. Nonetheless, in comparison with previous studies, stocking at the parr stage significantly improved relative reproductive success compared to salmon stocked as smolts and they displayed a reduction of reproductive success similar to salmon stocked as fry which spend less time in captivity than parr. Moreover, supplementation of captive-bred salmon significantly contributed to increasing genetic diversity. These results should contribute to informing resource managers in determining the best stocking practice to enhance Atlantic salmon populations.
Vladimir Radchenko
The role of Pacific salmon in freshwater ecosystems is mainly assessed on observations of their spawning run attracting attention by high spawner biomass. The role played by juvenile salmon in freshwater ecosystems has received less attention, and limited research is conducted in a wide network of spawning streams. Meanwhile, migration of juvenile pink salmon Oncorhynchus gorbuscha, one of the most abundant species of Pacific salmon, is a significant event in small water bodies within this salmon range that determines the functioning of freshwater ecosystems and trends in biomass and abundance of many ecologically related species. This report is based on observations of the food composition in stomachs of mass fish species caught during recreational fishing in the small lake (about 60,000 m2) in the Harrison lake-river system in southern British Columbia: cutthroat trout Oncorhynchus clarkii, lake whitefish Coregonus clupeaformis, and northern pikeminnow Ptychocheilus oregonensis. Tiny (tenths of a gram) schooling, inactively swimming pink salmon outmigrants are easy prey for those fish in stream estuaries. Up to 164, 126, and 28 pink salmon fry, respectively, were found in the stomachs of the listed fish specimens during the season of downstream migration of pink salmon (April – early May). Since fry were poorly digested, almost intact, we consider this amount as close to the maximum daily intake by piscivorous fish. Pink salmon downstream migration lasts there about a month as well as a time of cutthroat and whitefish occurrence. For later migrating pikeminnow, time of co-dwelling with juvenile pink salmon in that small lake is estimated as two weeks. During this time, three listed species can consume a significant part of their annual diet, especially in terms of energy. This is especially important for whitefish and pikeminnow, which usually feed upon low calorie benthic food during the rest of year. In one small lake under consideration, three piscivorous species can eliminate a number of pink salmon fry from spawning of 2,500 – 3,000 pink salmon in the small inflowing creek. In addition to these species, coho salmon O. kisutch, Dolly Varden Salvelinus malma, bull trout Salvelinus confluentus, longnose sucker Catostomus catostomus, and piscivorous birds also prey upon salmon fry there. Since only odd-year pink salmon broodline reproduces in the southern British Columbia, this creates a significant difference in forage conditions for the listed fish species in even and odd years.
David C. Scott, Misty MacDuffee, Lia Chalifour, and Scott G. Hinch
| Juvenile Pacific salmon must grow quickly to obtain a size at ocean entry that will result in a higher probability of early marine survival. Juvenile Chinook salmon with ocean type life histories migrate to the ocean after a brief freshwater or estuary rearing stage during which they must grow quickly to access preferred prey resources, and there are many factors which can influence growth rates during this period. We studied juvenile Chinook salmon in the lower Fraser River and estuary over six years (2016-2021) to understand variation in estuary use between two major populations of ocean type Chinook which differ in their early life history. We collected 3,244 genetic samples from individual Chinook over six years and found that the timing of migration to the estuary did not significantly vary across years despite significant variation in climatic conditions in each year. However, we found significant variation in relative fork lengths between years, which followed the same overall trends across years with the smallest individuals occurring in 2017 and 2020 in both populations and the largest fish in 2019 in both populations. These differences were shown to be statistically significant with larger fish in 2019 and statistically smaller fish in 2017 and 2020. We found the largest individuals in 2019 and 2016, both years which experienced relatively warm and dry winter and spring conditions, and the smallest individuals in both populations in 2017, a year with a particularly cold and snowy winter and average spawner abundance. As climate change is predicted to result in warmer and milder winters it may result in increased early growth for these individuals which could result in increased early survival for sub-yearling migrants and potentially explain increases in productivity of the South Thomspon population in recent decades. However, these effects are likely counteracted but negative changes to upwelling and marine productivity associated with the same climate trends therefore, it will be important to understand how these various factors interact to determine overall marine survival. |
Momoka Arimoto, Kentaro Honda, Ayaka Izutsu, Shigehiko Urawa, Christoph M. Deeg, and Munetaka Shimizu
Evaluating growth status in salmon at high seas is important for better understanding their survival and age of maturation. A growth-promoting hormone insulin-like growth factor (IGF)-1 is emerging as an index of growth in salmonids. Under laboratory settings, circulating IGF-1 level reflects recent (past one to two weeks) growth rate, which makes it a good complement with growth estimation using the scale and otolith. The objectives of the present study were to observe spatial variations in circulating IGF-1 levels in high-seas chum salmon in the summer and winter and search for its possible link with environmental variables such as surface seawater temperature (SST). Blood of chum salmon were collected during surveys by the R/V Hokkou maru in the summer 2021 and from the IYS expedition by the R/V Professor Kaganovskiy in the winter 2019. One hundred and seventy plasma samples were obtained from 17 stations (SST: 8.9–10.8 ºC) in the Bering Sea and 84 samples were obtained from 31 stations (SST: 5.0–7.7 ºC) in the Gulf of Alaska. IGF-1 levels in plasma were quantified by time-resolved fluoroimmunoassay. Plasma IGF-1 levels in chum salmon in the Bering Sea in summer were ranging from 80 to 220 ng/ml, being relatively higher than those of juveniles on the Hokkaido coast in spring (10–120 ng/ml). There was a spatial variation in plasma IGF-1 levels in fish in the Bering Sea although its link to STT was not clear. Plasma IGF-1 levels exhibited a larger variation in fish in the Gulf of Alaska in winter, ranging from 50 ng/ml to 400 ng/ml, possibly due to a mixture of different ages, nutritional status or/and maturation stages. With some exceptions, plasma IGF-1 levels in fish in cold area were rather high. The reason for this is not known at preset but we suspect that the high IGF-1 levels might be due to reduced binding to the receptor in poor growing fish in cold seawater. We are currently re-establishing immunoassays for IGF-binding proteins (IGFBPs) which respond to metabolic conditions, and negatively or positively affect the availability of circulating IGF-1 to the receptor. The ratio of IGF-1 to these IGFBPs should inform us catabolic and anabolic status of the fish more precisely and reveal relationships among IGF-1, fish condition and environmental variables.
Kazuya Fujii, Takashi Kanbe, Shouko Inoue, and Hitoshi Araki
Knowledge of the downstream migration of salmon juveniles is limited, and even less is known about their behaviors immediately after release. To elucidate the downstream migration of 27000 juveniles of chum salmon released into the Makomanai River, a tributary of the Toyohira River in Hokkaido, Japan, water samples were collected multiple times at multiple points for three days after the release of the salmon juveniles for an environmental DNA (eDNA) survey. Using a semi-quantitative eDNA detection method, we estimated the concentration of salmon-derived eDNA, and clarify the spatiotemporal distribution of salmon juveniles after release.
As a result of the analysis, eDNA presumably derived from released salmon juveniles was detected. Peak of the salmon eDNA concentration was detected on the first day of release and shifted downstream over time. Our results suggest that it is possible to estimate the downstream migration of released salmon juveniles using eDNA, at least for a day or two within c.a. 10km below the release point in the river.
Yuya Kogame, Hirokazu Urabe, and Takafumi Fujimoto
Hatchery-reared fish differ from wild fish in phenotypic traits that are related to fitness. This is thought to be related to changes in DNA methylation due to rearing in hatcheries. DNA methylation is a mechanism that regulates gene expression, tends to occur during early life, and is persistent. Therefore, the DNA methylation that occurs during adaptation to hatchery environment may adversely affect the adaptation of juveniles to wild environment after release. In the chum salmon hatchery program in Hokkaido, juveniles are reared in hatchery environment until they attain release size (1 g), and it is possible that their DNA methylation may differ from that of wild fish. In this study, we compared hatchery-reared and wild adults to investigate whether hatchery environment affects DNA methylation of fish.
Hatchery-reared adults (n = 8) were caught from the Chitose River and wild adults (n = 10) were caught from the Izari River. Liver tissue and sperm samples were collected from the fish. DNA was extracted from each sample, and the percentage of methylated DNA was measured. Otolith were checked to determine whether the fish originated from the hatchery or wild.
No significant difference was observed between hatchery and wild fish (p = 0.41); the mean percentage of methylated DNA in the liver of hatchery fish and wild fish was 0.92 ± 0.05% and 0.86 ± 0.28% (mean ± SDs), respectively. The mean percentage of methylated DNA of sperm was 0.45 ± 0.08% for hatchery fish and 0.46 ± 0.07% for wild fish, with no significant difference between them (p = 0.70). There was no difference between the mean percentage of methylated DNA of hatchery and wild fish for both liver and sperm; however, variations in the methylated DNA of liver of wild fish (0.35 – 1.35%) was greater than that of hatchery fish (0.90 – 1.03%).
Emma Lunzmann-Cooke, Stephen Johnston, Brian Hendriks, Aswea Porter, David Welch, D.W., Erin Rechisky, and Scott Hinch
Although many recreationally caught Pacific salmon are harvested in British Columbia, a substantial number of fish are released after capture. Released fish are often assumed to survive; however, actual catch-and-release mortality rates are largely unknown for Pacific salmon. This study examines the factors influencing post-release mortality of coho salmon (Oncorhynchus kisutch) in a marine recreational fishery in British Columbia. Coho were angled in the marine environment, affixed with acoustic transmitters, and tracked using an existing network of acoustic receivers located at multiple locations frequented by coho including the Salish Sea, Puget Sound, and the Fraser River. We found survival to the first point of detection was 61%, and survival was lower among coho with injuries such as scale loss, eye damage, and bleeding. Quantifying post-release survival rates and understanding how capture and handling factors influence behaviour and survival will provide information vital to developing management tools and fishing best practices to increase survival of wild fish.
Jason Daniels, Diane Lavoie, Joël Chassé, Martin Castonguay, and Jonathan Carr
Atlantic salmon are a long-distance migratory species which has experienced dramatic population declines in the last several decades. There is increasing evidence that high mortality during the post-smolt period may be bottlenecking recovery efforts. Unfortunately, there is little information known about how post-smolts are distributed within the ocean environment and what orientation mechanisms are utilized to undertake these long-distance migrations. Large scale telemetry projects are beginning to provide valuable information with respect to migration timing and early at sea survival for some populations of Atlantic salmon. One such project has been using acoustic telemetry to describe migration survival and timing of Atlantic salmon smolts and post-smolts from several Southern Gulf of St. Lawrence (GoSL) rivers since 2003. Since 2007 an acoustic telemetry receiver line has been installed seasonally across the Strait of Belle Isle (SoBI), the preferred exit from the GoSL for post-smolts migrating to the Labrador Sea. Entry of these fish into the GoSL generally occurs asynchronously between populations from early May to mid June. Interestingly, however, populations exit the GoSL with a surprising temporal overlap. The slope of the relationship between entry and exit of these populations is generally consistent between years, however, some interannual variation exists in the intercept. Furthermore, the interannual variation corelates well with variation of GoSL sea surface temperature. We used an individual based model (IBM) to track simulated particles through an ocean circulation model to refine and/or define potential theories regarding orientation mechanisms of migrating post-smolt. These particles represent acoustically tagged post-smolt observed entering and exiting the GoSL from 2007 to 2018. Contrary to previous studies employing IBM’s in relation to Atlantic salmon, we found that neither thermotaxis nor positive/negative rheotaxis alone permit the simulated particles to exit the GoSL through the SoBI. Preliminary analysis suggests that post-smolts are influenced by the 10 ºC isocline in addition to what we interpret as a magnetic attractant towards the Labrador Sea. Recent studies suggest this magnetic orientation mechanism is utilized by several species of salmonids among many other long-distance migratory species. Migration timing does appear to be linked to near surface ocean temperatures with the rate of warming leading to quicker transit times across the GoSL. This could lead to potentially smaller and less fit individuals arriving into the Labrador Sea before the first winter sea.
Nadezhda K. Khristoforova and Anna V. Litvinenko
The trace element composition of salmon (Salmo salar L.), as the most valuable salmon grown in the cages of North European sea waters, as well as whitefish (Coregonus lavaretus L.) inhabiting fresh water bodies of the Kola Peninsula, has been studied relatively well. However, the content of trace elements in pink salmon (Oncorhynchus gorbuscha W.), introduced from the Russian Far East to the Euro-Arctic region in the second half of the last century by the Soviet Union, has remained unexplored to date, despite its significant spawning approaches in the last decade.
In this study, the content of essential and nonessential trace elements Pb, Cd, Ni, Cu, Zn and Fe was evaluated in the organs and tissues of pink salmon that came to spawn in July 2019 in the watercourses of the Kola Peninsula – the Kola and Tuloma rivers flowing into the Barents Sea and pink salmon within the natural range, previously selected in two Sakhalin-Kuril region rivers – Firsovka and Reidovaya. Pink salmon, going out to feed within the natural range in the Pacific Ocean and returning back to spawn, passes a highly nourished and at the same time geochemically impacted natural zone formed in the Kuril Islands area by high volcanic activity, supplying a variety of chemical elements to surface waters due to upwelling and hydrodynamic processes. For Sakhalin-Kuril pink salmon, the concentration of Pb in organs and tissues is most noticeably increased. The sea waters of the extreme north-west of Russia are experiencing a powerful anthropogenic and technogenic impact formed by the Gulf Stream collecting household and industrial effluents of the American coast and Northern European countries and unloading in the form of the North Atlantic Current in the Barents Sea. In addition, surface runoff and aerotechnogenic transfers from the industrially saturated Kola Peninsula, which is determined by the extraction, processing and smelting of a number of metals, primarily Ni and Cu, as well as Zn and Fe, “enrich” the marine environment and affect the trace element composition of introduced pink salmon.
Micah J. Quindazzi and Francis Juanes
During their marine life stage, Chinook (Oncorhynchus tshawytscha) and Coho Salmon (Oncorhynchus kisutch) from watersheds connected to the Salish Sea display two distinct migration phenotypes; Salish Sea resident and out-migrant. Knowledge of Chinook and Coho marine migrations has been limited to tagged individuals caught by anglers and researchers. It is unclear how fishing effort and angler compliance, as well as other factors influence the proposed migration pathways undertaken by different stocks. Amongst the migrant phenotype, these salmon may only move as far as the continental shelf just off the coast of Washington and Vancouver Island, or they may migrate offshore into the Gulf of Alaska. It is unknown how environmental and genetic factors cause some salmon to remain resident in the Salish Sea and others to out-migrate. These different migration pathways influence contaminant burden of these salmon and the degree to which they are exposed to local versus global sources. It is currently unknown which migration paths would lead to increased contaminant burdens as it has not been feasible to track the individual movement of salmon. Microchemical techniques, specifically trace element and stable isotope analyses, can be used to identify the marine migration life history of Chinook and Coho that return to their natal watersheds. Initial results on 2018 Coho samples indicate that otolith trace elements can be used to determine differences between marine regions with a 100% classification success rate. ~40% of Coho from a few Southern BC river systems remained as residents within the Salish Sea, which is consistent with other models. Contaminants of concern, such as mercury (Hg) and polychlorinated biphenyls (PCBs) as well as dietary tracers (stable isotopes of C, N, S) are assessed in conjunction with marine migration information to determine differences in contamination between marine regions across the Northeast Pacific.
Kristin Bøe, Bjørn Bjøru, Steffen Wolla, and Arne Sivertsen
Atlantic salmon populations in Norway are facing a gradual deterioration in genetic diversity due to population losses and declines, as well as introgression by farmed Atlantic salmon. In order to ensure that Atlantic salmon populations have the best chances of adapting to a changing environment, preserving genetic diversity in the wild is imperative. Cryopreservation of Atlantic salmon sperm is a method that allows for a long-term repository of important genetic material, and is a valuable tool in preserving the genetic resources of wild salmonid populations. When used in combination with live brood-stock, cryopreserved sperm may enable the restoration of genetic diversity lost in the wild. The current presentation describes The Norwegian Gene Bank program for Atlantic salmon, which involves live gene bank facilities as well as a ‘frozen gene bank’ where paternal germplasm from 180 Norwegian Atlantic salmon populations have been stored. Although in situ conservation efforts should always be the preferred means to conserve biodiversity, ex situ measures such as cryopreservation may act as an important ‘failsafe’ or as a complementary measure.
Eric Danner, Miles Daniels, and James Gilbert
Water in California’s Central Valley is highly regulated by state and federal water projects, and salmonid freshwater habitats are highly impacted by how the system is managed. Water temperatures are a key factor, as these habitats are at the southern end of the range for Chinook salmon. We developed a temperature dependent mortality model to quantify the impacts of water management scenarios on developing salmon eggs. We then linked a comprehensive suite of models to forecast how operations interact with key inputs, including reservoir inflow, agricultural demand, valley floor hydrology, meteorology, reservoir and conveyance facility operations, and salmon spawning distributions. The resulting decision support tool has a number of properties that make it highly applicable to salmon management. (1) The framework has the capacity efficiently to evaluate thousands of combinations of inputs (hydrology, meteorology, operations, etc.). As a result, instead of evaluating a limited number of operational scenarios (which are highly dependent on the dynamic hydrological and meteorological conditions), this tool can be used to explore the sample space and determine if there are efficiencies that would otherwise be unknown. (2) The framework can incorporate a wide range of objectives, including environmental (other managed species), and economic (costs associated with altering water deliveries). (3) The framework is linked to a full life cycle model of endangered Sacramento winter-run Chinook salmon, which allows for the evaluation of long-term population dynamics associated with all of the above factors, including climate change.
Katrina Connors, Eric Hertz, and Katy Kellock
Salmon play a key role in the culture, ecology and economy of British Columbia. However, the lack of centralized, standardized, and easily accessible data on the state of Pacific salmon, and threats to them, impedes efforts to make evidence-based management decisions. In an effort to create broader public understanding of salmon status and trends in British Columbia, the Pacific Salmon Foundation is leading a major initiative to synthesize, and make openly accessible, the best available information on salmon and their freshwater habitats in British Columbia. We have developed an interactive data visualization platform, the Pacific Salmon Explorer (www.salmonexplorer.ca), to provide standardized, reproducible, and open-access information on a suite of indicators of salmon population condition. This biological information is coupled with habitat assessments that quantify pressures on freshwater salmon habitats. Our novel approach provides a synoptic overview of the current status of salmon populations and their habitats in British Columbia, while highlighting areas where data gaps exist and where more research is needed. The Pacific Salmon Explorer provides a relevant example for demonstrating how the synthesis, analysis, and communication of decision-relevant information can be brought to managers, scientists and the general public on complex environmental problems.
Brittany Jenewein, Mike Hawkshaw
The challenges each of these factors present have been documented in fisheries management for decades, but improvements in managements systems to gather the right information, lower the risk of decisions, and resolve conflicting objectives have been somewhat limited and slowly implemented. Recent research in project management suggests it is possible to balance all aspects of the iron triangle with new approaches and efficiencies (e.g. lean, agile, Scrum, Kanban), and we argue that can also be the case in fisheries management. Effective fisheries management plays a critical role in ensuring fish recovery and survival, especially in light of unknown effects of environmental change, and can be achieved by understanding how the pillars interact and optimizing them simultaneously. One example of an effective management system that optimizes each of the three pillars comes out of the Pacific Salmon Treaty’s Chum Technical Committee: In 2012 they developed a Strategic Plan to identify priorities and gaps in information needed to support the requirements of the Pacific Salmon Treaty (Knowledge), the Treaty language was not prescriptive in how these requirements should be achieved (Strategy), and they directed efforts into these priority research areas and into developing a multi-component model to incorporate this information into management (Decision). This work has led to significant improvements in the understanding of and ability to effectively manage Chum Salmon in the South Coast of British Columbia and Puget Sound. There is still work required to determine whether Chum Salmon will be positively or negatively affected as changes continue in their environment, but this approach of building up each pillar simultaneously is putting the tools in place to ensure management can adaptively respond to either scenario.
Stephen D. Johnston, Brian J. L. Hendriks, Emma L. Cooke, Kaitlyn R. Zinn, Aswea D. Porter, Erin L. Rechisky, David W. Welch, and Scott G. Hinch
Chinook salmon (Oncorhynchus tshawytscha) population productivity has generally declined coast-wide, and one approach that has been adopted to help conserve populations is an increased reliance on catch-and-release regulations. Fisheries managers have employed these regulations that aim to maintain the socioeconomic benefits of these fisheries and reduce the exploitation on stocks of concern. Incidental mortality of these discard events remains largely unquantified and may be relatively large, thus, undermining the conservation goals. Using acoustic telemetry and a large-scale receiver network we have tracked the fate of 379 Chinook post-release within the Salish Sea in 2020 and 2021. We have found eye injuries and notable bleeds sustained during fishery interactions caused decreases in survival probability in successful migration through the Discovery Islands and northern Strait of Georgia by 20% and 14%, respectively. Chinook that were captured with relatively larger, “Commercial” style hooks were 4.9 times more likely to sustain and eye injury and 2.2 times more likely have notable blood loss. Further, presence of scale loss was associated with a 15% reduction in survival probability and was 3.7 times more likely when fish were netted, and 14 times more likely if fish were netted and placed on the deck of the boat. The use of in-line attractors, or “flashers”, were shown to reduce immediate survival from 98% to 85%, suggesting that escape behaviours associated with this gear type may elicit a more acute anaerobic response. We provide evidence that specific injuries and angler gear choice and handling behaviour alter survival outcomes for Chinook salmon post-release.
Grethe Robertsen, Ola Ugedal, Eva Marita Ulvan1, Peder Fiske, Sten Karlsson, Bjørn Florø-Larsen, Merethe Hagen Spets, and Øyvind Solem
To ensure recruitment levels that are sufficient to maintain Atlantic salmon populations over time, spawning targets are set for many Norwegian rivers. Spawning targets includes calculating a desired minimum biomass of spawning females in individual rivers. One measure to increase the probability that spawning targets are reached is to protect female salmon from being harvested in sports fisheries by setting rules that they should be released if caught. For this measure to be effective the fishermen have to respect the rules and be able to recognize females based on morphological appearance. We do an assessment of this by comparing the gender of salmon caught and reported by sportfishermen with the gender determined genetically from scales that the fishermen collect and submit together with each catch report. In analyses of salmon that were caught and reported by sport fishermen in one river with no female protection (River Namsen) and three rivers with female protection (River Surna, River Orkla and River Gaula), we find that females are generally reported as males (25-45%) more frequently than males are reported as females (10-17%). Furthermore, the proportion of females that are reported with the wrong gender was lowest in the river where there were no specific protection of female salmon. Finally, the probability that a caught fish is reported with the correct gender increases with body size for females and decreases with body size for males.
Zachary Sherker, Patrick Zubick, Nicholas Lapointe, Pat Matthew, David Maloney, and Scott Hinch
Pacific salmon cannot access thousands of kilometers of spawning and rearing habitat in B.C. because of culvert barriers. Tens of millions of dollars have been spent to remediate these barriers by either retrofitting culverts with baffles and weirs, or replacing them with bridges. Very little monitoring has been done to assess the effectiveness and longevity of these remediations. We are assessing fish passage at 20 bridge replacement and 20 culvert retrofit sites (aged 10-15 years) by comparing fish community structure and abundance upstream and downstream of remediated sites. We collected data for 14 retrofit sites in 2021, and found that over a third of these had no anadromous salmonids upstream, and two thirds had lower species richness above the culvert, suggesting that these sites were again barriers. Structural assessments of the remediated culverts indicated that failed rock weirs and unresolved stream constriction issues were the biggest inhibitors to fish passage.
Kate Morse, Jennifer Hodges and Tommy Sheridan
Building off the success of the International Year of the Salmon’s 2022 Pan-Pacific Winter High Seas Expedition, this presentation seeks to highlight the integration of the Expedition’s outreach program(s) into Copper River Watershed Project’s (CRWP) salmon-themed education programs. Since 2010, the CRWP and the Prince William Sound Science Center have partnered together to help Cordova’s elementary-aged students raise salmon from eggs to fry in a tank in their school as part of a broader salmon-centric curriculum. In 2019 this program expanded to include the five additional schools in the Copper River Watershed. The overall goals of these education programs are to help students learn about and connect with salmon, the natural resource at the core of their cultures, communities, and way of life. Tying learning to real-world experiences brings classroom lessons to life, and students learn about local jobs and salmon economics through field trips and connecting with salmon scientists, harvesters, and resource managers. As part of the 2022 International Year of the Salmon research expedition, North Pacific Anadromous Fish Commission Commissioner Tommy Sheridan crewed the F/V Northwest Explorer as part of the Expedition’s broad ecosystem survey, pelagic trawling, and detailed sampling of marine life in the upper ocean. Throughout the Northwest Explorer’s 20 days at sea, expedition scientists, including Sheridan, were able to provide frequent updates to the public via the Expedition website, including journal entries, and occasional videos as bandwidth allowed. As Program Director for Copper River Watershed Project, Morse led shoreside lessons with her team of collaborators as students tracked the expedition and expanded their understandings of the Salmonsphere to include open ocean research. This presentation will provide examples of innovative ways to connect salmon scientists and salmon science to youth so they grow to become inspired, informed salmon advocates.
Katharine N. Shelledy and Ken Currens
This presentation characterizes the ecosystem services of salmon and salmon hatcheries, as described in published literature, for socio- and eco- logical systems. Hatcheries produce over 80% of salmon in Washington. Ecosystem services provided by salmon and by extension salmon hatcheries have yet to be described in a way that considers both Western and Indigenous frameworks. We relied on two existing frameworks 1) Common International Classification of Ecosystem Services (CICES) and 2) Earth Economics’ Sociocultural Framework on the Significance of Salmon for Tribes and First Nations to organize ecosystem services of a) salmon in general and b) salmon specified as originating from hatcheries. We identified 159 papers that met our criteria based on a rigorous, systematic review of 685 published papers found through Web of Science. Authors frequently described how salmon provide nutrients and energy to various systems and organisms, provision profit (especially to fisheries), regulate freshwater chemistry, and have significance for culture or heritage, all falling within the CICES framework. Some of these same services were applicable to Earth Economics’ Sociocultural Framework, although far fewer services could be mapped onto this framework compared to CICES. The importance of salmon as food was most frequently described, followed by the significance of salmon for indigenous management systems. Notably, the majority of services described overall were ecological rather than sociocultural, and authors focused on services of naturally produced salmon and not hatchery salmon. These results reflect a research emphasis on the ecological effects of ‘wild’ salmon; we recommend broadening research scope in the future to reflect the influence of the total salmon production system – hatcheries included – on local ecosystems, tribes, and communities.
Stine Rybråten, Camilla Brattland, Niklas Högstedt, and Tomas Sandnes
The world’s population of wild Atlantic salmon is in severe decline. As Norway is among the species’ main living areas, Norwegian authorities have taken a particular responsibility to protect wild Atlantic salmon as a measure of biodiversity conservation in a global context. Current conservation measures are however subject to conflict. The authorities strive to balance the salmon stock situation with Norway’s accession to international initiatives like UNDRIP and IPBES, calling for the inclusion of Indigenous and local knowledges (ILK) in sustainable management of biocultural diversity. Still, guidelines and practices for bringing together different knowledge types as a basis for decision-making is lacking in the Norwegian natural management system. Furthermore, the country’s strong sector division limits the Norwegian Environment Agency’s salmon management tool to regulating fishing rules. Locally, increasingly strict fishing restrictions make fishers call for salmon conservation solutions compatible to maintaining and developing local and indigenous fishing traditions and knowledges.
This presentation, addresses common and distinctive features of the Deatnu-Tana River in Sápmi, Northern Norway/Finland, and the Namsen River in Trøndelag, Central Norway, as well as these rivers’ adjacent fjords. In both areas, salmon is highly valued, forming a central part of the communities’ culture, identity, diet, economy, social relations and/or spiritual practices. Both areas furthermore experience a decline in their returning salmon stocks, causing national authorities to question the adequacy of local management measures. In 2021, for the first time in history, the salmon fisheries in Deatnu-Tana were closed by Norwegian authorities, as a measure of salmon protection. Based on participatory research, interviews, and local meetings, we present and discuss the complexities of Indigenous and local involvement in salmon management and knowledge production, intersecting local, national and international scales.