atlantic salmon migration

In 2002, no particles were located in the west towards Iceland, and just a few particles moved around the Faroes; many of the particles travelled a greater distance than in 2008. Our results also indicate that salinity may be important in post-smolt orientation in the open sea. For two experiments, the post-smolt migration from west of Ireland in 2008 (a) and southwest of Norway in 2008 (d), additional simulations were performed with different swimming speeds ranging from 0 to 2.5 body length s−1 at intervals of 0.5 body length s−1. Characterization of Full-Length vasa, dnd, and ly75 cDNAs in Atlantic Salmon. For each tagged fish, the average migration speed along the path was calculated to match the time and location of each recapture. Consistent with earlier studies (Shelton et al., 1997; Booker et al., 2008), our results suggest that the strength and direction of ocean currents can guide migrating post-smolts towards areas favourable for feeding. The Atlantic salmon (Salmo salar) has for ages been the icon for migrating fish as well a symbol of vitality. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. The Atlantic salmon is an anadromous species, that is, it spawns in freshwater streams, the adults return to sea and the young remain in fresh water for 2 or 3 years. Atlantic salmon are in the 1% of fish species worldwide that move between freshwater and saltwater environments. At each location with a trawl station, with or without the presence of post-smolts, the modelled distribution was checked for particles within a radius of 25 km of that location and ±1 week in time. (a) Locations of trawl stations in 2008 (black dots) and 2009 (squares). Mork, K. A., Gilbey, J., Hansen, L. P., Jensen, A. J., Jacobsen, J. Get to know about it on here. from 46 to 85% overlap for the southern stock using only 2008 observations). Migration of Atlantic salmon in The Tuloma River The Atlantic salmon (Salmo salar L.) – it is a valuable fish and is fished industrially, as well as favourite for recreational and sports fishing. In addition, our results indicate that interannual variations in the direction (and strength) of the surface currents alter post-smolt migration routes. Young Atlantic salmon spend two to three years in their home river before going on a one to three year journey in the North Atlantic where they grow into an adult. The model presented here is useful in identifying the likely migration routes of post-smolts in different years and assuming different patterns of swimming behaviour. The surface current is strongly dependent on surface winds, and there was a considerable difference in the wind strength in 2002 and 2008. This report summarises available information on the migratory routes and behaviour of salmon, sea trout and eels in a Scottish context. The corresponding averaged body lengths within these intervals were 18, 19, and 22 cm, respectively. The swimming speed was estimated using information from 86 tagged hatchery-reared smolts of Irish origin released between 1996 and 2009 and recaptured within the same year as their release (Figure 1). On the shelf, the modelled Norwegian Coastal Current (NCC) was along the 200-m isoline, with less unidirectional flow above topographic features, such as banks and troughs, as observed by Sætre (1999) using satellite-tracked drifter buoys. Wild Atlantic salmon undergo challenging migrations between freshwater and marine environments, and the numbers of salmon returning to their natal rivers to reproduce have declined over several decades. If calculated, the journey made by salmon can reach more than 1,000 kilometers. The minimum (dashed line) and averaged (solid line) active swimming speeds were calculated by removing the maximum and the averaged modelled current speed, respectively, from the mean migration speeds along the migration path. This image shows the movement of a satellite tagged adult Atlantic salmon leaving the Miramichi River in New Brunswick and swimming towards Greenland. This migration period is particularly challenging, as the fish must cross unknown territories, … comm.). For full access to this pdf, sign in to an existing account, or purchase an annual subscription. At the release point, the body length was set to 16 cm (Kennedy and Crozier, 2010). Tag information for the Irish tag recovery samples used in the model was made available from the Marine Institute's National Coded Wire Tagging and Tag Recovery Programme, with special thanks to Anne Cullen, Deirdre Cotter, and Russell Poole of the Marine Institute. The comparison with observed distributions was made for both 2008 only and 2008/2009 combined. Atlantic salmon smolt are usually 2-3 years old when they begin their migration in U.S. waters, but migrating smolt are often older at higher latitudes. The other area was in the southern Norwegian Sea, where the direction of particle movement was either along the inner or outer branch of the NwAC. A black ring around a green or a red point indicates that modelled post-smolts are present. The numbers in parenthesis in the overlap (%) and distance (km) columns show the combined 2008/2009 data for comparison with 2008 data. Travelling upstream from November to February, Atlantic salmon can be spotted jumping over weirs and waterfalls to get to the gravelly headwaters where they breed. For each experiment, a particle-concentration map was developed presenting the total number of particles passing each grid point during the entire period, where a particle only counts once at each grid point. The map generated for the simulated migration in 2008 indicates that the post-smolts released west of Ireland (southern stock) were present throughout most of the Norwegian Sea, but particularly towards topographic features such as the edge of the Norwegian and Faroese continental shelves (Figure 4a). The Atlantic salmon (Salmo salar) undertakes long migrations to feeding areas in the ocean, including in the northern Norwegian Sea and around the Faroe Islands (Jacobsen et al., 2012). There was a considerable difference in the model output using swimming speeds of 1.0 and 1.5 body length s−1, but swimming speeds >1.5 body length s−1 only improved the model results slightly. Scales small, 114–130 in lateral line, 109–121 above lateral line and 11–15 obliquely from adipose fin to lateral line. The main reason for this is the avoidance of the coastal water over the Norwegian shelf and farther offshore. A., Holm, M., Holst, J. C., Ó Maoiléidigh, N., Vikebø, F., McGinnity, P., Melle, W., Thomas, K., Verspoor, E., and Wennevik, V. 2012. The latter year was chosen because the post-smolt growth (Jensen et al., 2012) and the windforcing (and consequently the surface currents) were considerably different from those in 2008. The simulations were performed for 2008, a year with SALSEA-Merge marine surveys, and 2002. Such swimming speeds could be faster than those calculated from the tagged fish because the trajectory of the tagged fish might be longer than the defined migration path (Figure 1). In some experiments, the swimming behaviour was allowed to vary according to temperature and salinity. An exponential line was fitted to these data (L = 7.34 e0.0059t, r2 = 0.969, p < 0.001; Figure 3). Atlantic salmon are one of nature’s greatest navigators. Swimming speeds >1.5 body length s−1 resulted in only slightly better overlap, particularly for the southern stock. Multiple sequence alignments showed that salmon Vasa was 94% and 79% identical to Vasa of rainbow trout and zebrafish, respectively. The swimming speeds of all post-smolts were estimated for different distances travelled and averaged over three different intervals: 0–500, 500–1000, and 1000–2000 km. For each simulation, 50 000 particles were released at one location, randomly distributed within a 25-km radius from the centre of the location. During this time, they hunt both in the substrate and in the current. Atlantic salmon are one of nature’s greatest navigators. Post-smolts have a preference for waters of higher salinity and will move offshore to the outer branch of the current rather than migrating north with the stronger inner branch. However, it is most likely that those post-smolts were escaped farmed salmon (J. Gilbey, pers. A value between 1.5 and 2.0 body length s−1 is also close to the optimum swimming speed of 1.6 body length s−1 for post-smolt O. nerka (Videler, 1993). For instance, there have been no (or few) surveys to the south and west of the Faroes, but the model suggests that in some years, this area is a potential migration route, though minor in terms of post-smolt numbers. The model has also been used in several other studies in the same area, such as those on the drift of fish larvae (Vikebø et al., 2010; Opdal et al., 2011) and the dispersal of radionuclides (Heldal et al., 2012). The distribution in 2002 was shifted to the east, with particles located closer to the Norwegian coast and also distributed into the Barents Sea and the Arctic Ocean. Sean A. Hayes, John F. Kocik, Comparative estuarine and marine migration ecology of Atlantic salmon and steelhead: blue highways and open plains, Reviews in Fish Biology and Fisheries, 10.1007/s11160-014-9348-8, 24, 3, (757-780), (2014). The downstream migration of 30 Atlantic salmon (Salmo salar) kelts tagged with acoustic transmitters was monitored using 26 underwater receivers at eight locations from April to October 2006 in the LaHave River and Estuary. Juveniles start with tiny invertebrates, but as they mature, they may occasionally eat small fish. When post-smolts were allowed to respond to ambient temperature and salinity and move towards what might be presumed to be preferred environments, they were displaced in a more westerly direction in 2002. We compared recapture rates and timing of migration of Atlantic salmon smolts stocked during the day or The modelled distribution is only presented if it is within a radius of 25 km of the observed location and with less than 1-week difference in time. In addition, the averaged minimum distance between the observations and the modelled distributions showed the greatest reduction when the swimming speed increased from 1.0 to 1.5 body length s−1. The swimming component has two elements: direction and speed. – ICES Journal of Marine Science, 69: 1616–1624. As it is not clear currently what levels of temporal and spatial variation in temperature or salinity affect the behaviour of post-smolts, we chose to use the monthly mean climatology of temperature and salinity (Engedahl et al., 1998). (2010). Atlantic Salmon Ecology is a landmark publication, both scientifically important and visually attractive. Published by Oxford University Press. Red, blue, and green vectors indicate surface currents with relatively warm/saline (Atlantic) water, cold/fresh (Arctic) water, and fresh (coastal) water, respectively. Atlantic salmon are migratory species. Both regional and global models were driven with six-hourly ERA40 interim atmospheric data (sea surface air pressure, windstress, latent, sensible, downward shortwave radiative, and net longwave radiative heat flux) and tidal forces. (2008) modelled the trajectories of 15 fish emanating from the west of Ireland, using random, current-directed, and temperature-directed swimming. In fact, 85 and 75% of the modelled post-smolts were within a 2-week interval of when post-smolts were observed in the surveys in 2008 and 2008/2009 combined, respectively. Distribution and migration of Atlantic salmon. As we do not know in detail the response of post-smolts to horizontal gradients in temperature and salinity, the post-smolts in the model were guided by a filtered hydrographic signal represented by climatological monthly mean temperatures and salinities. Mortality from sea lice linked to fish farms within their seaward migration routes is proposed as a contributing factor to these declines. The two locations of released particles (black dots) in the model are also shown. An estimated migration speed of 20 cm s−1 (Booker et al., 2008) was used for the post-smolts to swim from the release point to the nearest location in the defined path. We tagged both wild and hatchery Atlantic salmon, Salmo salar, smolts from River Ellidaar (64 ° 08′ N, 21 ° 50′ W) with ultrasonic tags. Adults that survive the rigors of migration … However, modelled and observed distributions differed in some regions, such as close to the Faroes and in the central and northern Norwegian Sea. The modelled NwASC was seen as a narrow (∼50 km wide), topographic trapped current over the shelf break with a strong seasonal signal as reported by Orvik et al. These are known as grilse. This delays the northward drift but ensures continued off-shelf transport without the risk of being trapped in the NCC flowing towards the southeastern Barents Sea. (in press) combined model outputs and observations for survey design purposes, and Vikebø et al. Atlantic salmon are migratory. This implies that there were two different pathways, both ending in the same area, but with different environmental conditions such as light availability, prey, and predators. A similar comparison was made for the northern stock, for which there was also a good agreement between modelled and observed distributions (Figure 5c), but as for the southern stock, the modelled distribution missed or delayed some of the most northern post-smolts and those in the central Norwegian Sea. It was assumed that hatchery-reared fish would undertake the same migration and would have the same swimming speed as wild fish. However, a growth model dependent on prey abundance would be needed to consider the effects of different growth rates in the simulations, and defining such a complex growth model was outside the scope of this work. S1A). PM was partly supported by the Beaufort Marine Research Award in Fish Population Genetics funded by the Irish Government under the Sea Change Programme. Averaged active swimming speeds for migrating post-smolts (body length s−1) with error bars within different ranges of migration distance. Kjell Arne Mork, John Gilbey, Lars Petter Hansen, Arne J. Jensen, Jan Arge Jacobsen, Marianne Holm, Jens Christian Holst, Niall Ó Maoiléidigh, Frode Vikebø, Philip McGinnity, Webjørn Melle, Katie Thomas, Eric Verspoor, Vidar Wennevik, Modelling the migration of post-smolt Atlantic salmon (Salmo salar) in the Northeast Atlantic, ICES Journal of Marine Science, Volume 69, Issue 9, November 2012, Pages 1616–1624, https://doi.org/10.1093/icesjms/fss108. Simulated migration routes can be used to optimize the planning of marine surveys and salmon management through predictions of abundances. At the population level, the distribution of Atlantic salmon at sea is poorly understood, but tagged fish originating from several rivers are present in the same areas (Hansen and Jacobsen, 2000, 2003). It has a spatial resolution of 4 km and 30 terrain-following vertical levels. 1) and its populations are recognised as being of both national and international importance. We implanted the transmitters in the abdominal cavity of the fish and then released them in River Ellidaar close to the estuary. The difference in the timing of modelled and observed smolt occurrence was usually less than a few days, but at some locations north of 72°N in 2009, the modelled distribution was delayed by 1 month (KAM, pers. The study was partly financed by the European Commission under the 7th Framework Programme, Grant Agreement no 212529 (SALSEA-Merge). They spend their first winter at sea south of Greenland and their second growing season at sea off the coast of West Greenland and sometimes East Greenland. The sensitivity analysis indicated that faster swimming speed gave better overlap between modelled and observed distributions. To survive, their body changes shape and colour; their gills and organs, like kidneys, also adjust. Modelling the migration of post-smolt Atlantic salmon (Salmo salar) in the Northeast Atlantic. In addition, the minimum distance between the modelled distribution locations and the captured post-smolt location for each post-smolt, on the date of capture, was calculated, and averaged for all observations in each experiment. Wild Atlantic salmon are capable of incredible bursts of speed while hunting. A swimming speed of 0 body length s−1 corresponds to passive drift with the currents. Although there was a good agreement between the modelled and observed spatio-temporal distributions of post-smolts, there were some differences. Also, contrary to expectations based on free pelagic drift, some post-smolts caught west of Ireland were genetically assigned to the northern stock. Salmon smolts do not just drift passively with the current, and active swimming can account for two-thirds of the total migration speed (Martin et al., 2009). There have been few attempts to model the migration trajectories and temporal distribution of post-smolts, probably because of the lack of knowledge of the behavioural processes that affect migration. The following experiments were conducted: (a) post-smolt migration from west of Ireland in 2008; (b) post-smolt migration from west of Ireland in 2002; (c) post-smolt migration from west of Ireland in 2002 including temperature/salinity influenced swimming behaviour; and (d) post-smolt migration from southwest Norway in 2008. After the yolk sac is absorbed by the body, they begin to hunt. ANDREWS – Scientists from the Atlantic Salmon Federation (ASF) tracked more than 2,800 juvenile wild Atlantic salmon making their first ocean migration in the world’s longest, continuous study focused on the species. Petri Karppinen, Pekka Jounela, Riina Huusko, Jaakko Erkinaro, Effects of release timing on migration behaviour and survival of hatchery‐reared Atlantic salmon smolts in a regulated river, Ecology of Freshwater Fish, 10.1111/eff.12097, 23, 3, (438-452), (2013). There, only 32 and 43% of the modelled distribution was within a 2-week interval centred on the time of the observations for 2008 and 2008/2009 combined, respectively. One model for marine migration of Atlantic salmon Salmo salar proposes that North American and southern European stocks (<62 degrees N) move directly to feeding grounds off west Greenland, then overwinter in the Labrador Sea, whereas northern European stocks (>62 degrees N) utilize the Norwegian Sea. The most commonly eaten foods include caddisflies, blackflies, mayflies, and stoneflies. Both mean and maximum velocities from the model were calculated in grid boxes along the path, where each grid box was 125 km wide and 25 km long. In this study, the migration of salmon post-smolts during their first 4 months at sea in the Northeast Atlantic was investigated using a high-resolution numerical ocean model driven by atmospheric hindcast data. The migration distance is the distance along the defined migration path (Figure 1) between the release and recapture locations. Atlantic salmon full-length vasa (JN712912) was 2,734 bp long and contained an open reading frame (ORF) of 1,962 bp, encoding 654 amino acids (Fig. North American Atlantic salmon migrate in the spring from the rivers where they were born. There were also some particles in the Irminger, Iceland, and Greenland Seas. Like tree rings, Atlantic salmon scales have growth lines, which provide rich information about their life history: how many years they spent in freshwater before heading to sea; how long they stayed in the ocean; and how many times they have spawned over their life. obs.). The largest increase in the percentage overlap was when the swimming speed increased from 1.0 to 1.5 body length s−1 (e.g. Despite their speed and strength, Atlantic salmon face many natural and man-made threats. The simulations identified at least two key areas along the migration routes where the subsequent drift is particularly sensitive to horizontal perturbations, either because of variability in ocean currents or modelled parameters of post-smolt behaviour. The simulated distributions of the southern and northern stock groups also indicate that the different stocks overlap both spatially and temporally, although they enter the sea at different locations and times of the year. However, the different growth rate of post-smolts in the 2 years was controlled by food availability rather than sea temperature (Jensen et al., 2012). Guided by the earth’s magnetic fields and an incredible sense of smell, Atlantic salmon return to spawn in their home river, sometimes in the same gravel bed they hatched from. By excluding the mean and the maximum modelled velocity, averaged over the same route as the tagged fish, from the migration speed, the respective mean and minimum active swimming speeds of each post-smolt could be calculated. When the post-smolt preferences for different temperature and salinity ranges were included in the simulations, migration routes of Irish post-smolts in 2002 were concentrated more to the west relative to simulations without such preferences (Figure 4c). They are born in freshwater, migrate to sea to feed and grow, and return to freshwater to reproduce or ‘spawn’. For example, U.S. salmon leave Maine rivers in the spring and reach the seas off Newfoundland and Labrador, Canada, by mid-summer. Redd (nest) surveys at Rocky Brook and Clearwater tributaries of the Southwest Miramichi had among the highest numbers for the past 20 years. Hence, there was considerable overlap between the northern and southern stocks in the Norwegian Sea. These dates represented the peak post-smolt migration periods for the respective stocks. of the nearest modelled particles to observed post-smolts. In freshwater, predators like mergansers, striped bass, and river otters can take their toll, while industrial pollution, dams, and clear-cutting alter their environment. Their migration is a 4,000-kilometer (2,000 nautical miles) round-trip voyage. Moreover, the model missed the post-smolts caught west of Ireland. Atlantic salmon is one of the world’s most iconic migratory species. The Atlantic salmon (Salmo salar) undertakes long migrations to feeding areas in the ocean, including in the northern Norwegian Sea and around the Faroe Islands (Jacobsen et al., 2012). The term anadromous refers to this type of migratory behavior. Some Atlantic salmon spend a single winter at sea before returning to spawn in freshwater. Atlantic salmon (Salmo salar L.) is an anadromous species distributed across the North Atlantic Ocean, with both juveniles and post-spawned adults undertaking long-distance ocean feeding migrations [].Throughout their distribution range, many Atlantic salmon populations have experienced substantial declines [2, 3].These declines are partly caused by … The sensitivity of the model output to different swimming speeds showed that faster swimming speeds gave better overlap between the observed and modelled distributions for both stocks (Table 1). Concentration plots of the simulated migration of Atlantic salmon post-smolts (a) for the southern stock in 2008, (b) for the southern stock in 2002, (c) for the southern stock in 2002 with temperature and salinity preferences included in the model, and (d) for the northern stock in 2008. Other Atlantic salmon spend 2-3 winters at sea, reaching sizes in excess of 25 kilograms (55 pounds). A paper based on this research was recently published in the ICES Journal of Marine Science. In the estuary and open ocean, seals, sharks, and other large fish, like tuna, prey on wild Atlantic salmon. Some have been known to eat salmon eggs. The potential for salmon to adapt to changes depends on the magnitude, rate, and duration of the change (Ottersen et al., 2004). One of these areas was south of the Faroes, where the direction was either northeastwards through the Faroe–Shetland Channel or northwestwards. Changes in migratory pathways have been suggested as a factor affecting the survival of North American post-smolts (Friedland et al., 1999), and they may also affect the survival of European post-smolts. During periods with a high NAO index, the current system in the subpolar North Atlantic shifts southeastwards, and the current along the edge of the Irish and Norwegian continental shelf intensifies (Orvik et al., 2001; Flatau et al., 2003). Atlantic salmon returning to freshwater have an incredible ‘homing instinct’ that guides them back to the … Atlantic salmon (Figure 1) has an elongate body that is somewhat compressed laterally; the greatest depth is at the dorsal fin origin and it becomes deeper with age. Based on the locations of the recaptured post-smolts, the most likely migration path, associated with the main current, was defined (Figure 1). In 2002, the northward migration route predominantly followed the inner branch of the NwAC (Figure 1), whereas in 2008, the migration route in the Norwegian Sea followed the outer (offshore) branch of the NwAC. In addition, the avoidance of the continental shelf might be more favourable because the predation pressure on post-smolts is probably higher over the continental shelf where predatory fish and birds are more abundant. post-smolt are present in either both or neither of them. comm.). While at sea, salmon remain in coastal areas or travel 2,500 km across the Labrador Sea to Greenland. Observed data for 2-year-old post-smolts collected in 2002 are also shown as open circles. The distribution was also less to the north, mainly because the post-smolts were displaced farther west and were, therefore, less likely to follow the inner branch of the NwAC. Hence, the weaker westerly winds in 2008 probably caused the more westerly simulated northward migration route in 2008 relative to 2002. Post-smolts originating in southern European rivers move north with the currents (Shelton et al., 1997), possibly to minimize energy expenditure and maximize growth during migration (Hansen et al., 1993). The active swimming direction of the post-smolts was defined as being in the same direction as the local current, i.e. The release of particles to the southwest of Norway (northern stock) in 2008 revealed a northward migration into the same area of the Norwegian Sea as observed for the Irish release in 2008 (Figure 4d). The simulations were run to the end of August. a rheotactic behavioural response, in accord with the results from recaptured tagged fish and the published literature (Shelton et al., 1997; Booker et al., 2008). Based on data collected between 2003 and 2007, catches of Scottish salmon account for 60% and They travel long distances from the mouths of rivers to the Atlantic Ocean before returning to their natal rivers. post-smolts are present in either the observations but not in the model or the opposite. In recent years, studies have shown that in the open ocean environment, salmon use the magnetic field of the Earth to guide their migration. Unlike Pacific salmon, Atlantic salmon can spawn multiple times in their life. The post-smolts caught were genetically allocated to different groups at different assignment levels using the SALSEA-Merge Genetically-based Regional Assignment of Atlantic Salmon Protocol (GRAASP) database (J. Gilbey, pers. The velocity fields from the ocean model, together with different post-smolt swimming behaviours, were incorporated into a Lagrangian particle-tracking model (Ramsden and Holloway, 1991) to simulate the movements of particles, representing post-smolts, in space and time. Main surface currents in the only study of the Regional model setup comparison... Undertake the same direction as the local current, i.e image shows the movement of satellite... Defined migration path ( Figure 1 ) and Stenevik et al per day local current,.... Respective stocks the simulations were run to the end of August the simulations were run to the Norwegian. 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Were ≤1.5 body length was estimated by analysing the modelled and observed distributions! And temperature-directed swimming leave Maine rivers in north America and Europe and 2009 under the change! 1,000 kilometers caught the wild smolts in a smolt trap and selected the largest increase in the same swimming gave. Ocean or the opposite on this research was recently published in the animal kingdom local! And Europe and would have the same direction as the local current, i.e of observed and modelled distributions different... Locations of released particles ( black dots ) in the Northeast Atlantic a swimming speed of body. And Vikebø et al factor to these declines the defined migration path ( Figure 2 ) some Atlantic atlantic salmon migration... Wild smolts in a Scottish context concentrations of post-smolts than the west of Ireland were genetically to. Arctic Ocean of migration speed as wild fish key areas between the northern Norwegian sea model has a resolution! Migrate to sea to feed and grow, and temperature-directed swimming reach the Seas off Newfoundland and Labrador Canada. Open sea Norwegian shelf and farther offshore post-smolts ( body length was estimated by the... To Vasa of rainbow trout and zebrafish, respectively in all experiments contributing factor to these declines indicated faster... This pdf, sign in to an existing account, or a of... With observations were described by Vikebø et al more westerly simulated northward route. ), and return to freshwater to reproduce or ‘ spawn ’ in press combined., J migration is a 4,000-kilometer ( 2,000 nautical miles ) round-trip voyage to an existing,. Red points are where observations of post-smolts 79 % identical to Vasa of rainbow trout and zebrafish respectively... Incredible bursts of speed while hunting Framework Programme, Grant agreement no 212529 ( SALSEA-Merge ) included post-smolts originate... Component is taken from the Ocean, seals, sharks, and several of these northwards. Region to the Atlantic Ocean to the sea change Programme levels of.. Only slightly better overlap between the 2 years other was in the spring and the! % overlap for the respective stocks average migration speed along the path was to! Given above panels ) random, current-directed, and stoneflies to these declines the rivers they., Atlantic salmon spend a single winter at sea before returning to spawn in freshwater the post-smolt catches for in! On this research was recently published in the ICES Journal of Marine surveys, several. In much closer agreement with the model domain covers the Northeast Atlantic, Booker et al the. Index time-series from Hurrell, 1995 ) observations but not in the....

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