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Map showing the distribution of Special Areas of Conservation (SACs) for Atlantic salmon in Scotland.

Map showing the distribution of Special Areas of Conservation (SACs) for Atlantic salmon in Scotland.

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Technical Report
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The Scottish Government has ambitious targets for renewable energy production, to which offshore renewables could make a substantial contribution. However, the new marine energy industries must develop on a sustainable basis, ensuring that environmental impacts are assessed, and if necessary, minimised through appropriate mitigation. The likelihood...

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Citations

... Similar to seabirds, any significant changes in the behavior of fish as a result of avoidance or displacement due to FOWT may lead to increased energy expenditure from, for example increased search time for conspecifics or prey items. This behavior could cause alterations to aggregations, spawning events and migration patterns and may also influence the ecological community structure if species of ecological importance avoid impacted areas altogether (Malcolm et al., 2010). Connections between species in ecological communities can be highly complex and impacts on one species in a community can often impact more than one species. ...
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Offshore wind energy is expanding globally and new floating wind turbine technology now allows wind energy developments in areas previously too deep for fixed-platform turbines. Floating offshore wind has the potential to greatly expand our renewable energy portfolio, but with rapid expansion planned globally, concerns exist regarding impacts to marine species and habitats. Floating turbines currently exist in three countries but large-scale and rapid expansion is planned in over a dozen. This technology comes with unique potential ecological impacts. Here, we outline the various floating wind turbine configurations, and consider the potential impacts on marine mammals, seabirds, fishes and benthic ecosystems. We focus on the unique risks floating turbines may pose with respect to: primary and secondary entanglement of marine life in debris ensnared on mooring lines used to stabilize floating turbines or dynamic inter-array cables; behavioral modification and displacement, such as seabird attraction to perching opportunities; turbine and vessel collision; and benthic habitat degradation from turbine infrastructure, for example from scour from anchors and inter-array cables. We highlight mitigation techniques that can be applied by managers or mandated through policy, such as entanglement deterrents or the use of cable and mooring line monitoring technologies to monitor for and reduce entanglement potential, or smart siting to reduce impacts to critical habitats. We recommend turbine configurations that are likely to have the lower ecological impacts, particularly taut or semi-taut mooring configurations, and we recommend studies and technologies still needed that will allow for floating turbines to be applied with limited ecological impacts, for example entanglement monitoring and deterrent technologies. Our review underscores additional research and mitigation techniques are required for floating technology, beyond those needed for pile-driven offshore or inshore turbines, and that understanding and mitigating the unique impacts from this technology is critical to sustainability of marine ecosystems.
... Studies have been carried out on the movements of returning adult salmon in North Sea coastal waters (Hawkins, Urquhart and Shearer, 1979;Smith et al., 1981;Westerberg, 1982, Malcolm et al., 2010, within estuaries (Stasko, 1975;Smith and Hawkins, 1995,) and within rivers (McCleave, Power and Rommel, 1978;Hawkins and Smith 1986). The returning multi-sea-winter adults may arrive at the Scottish coast and enter the estuary of the Dee as early as February and March, and may subsequently be found within the main part of the River Dee throughout the spring, summer and autumn. ...
... The sea stage has been viewed as a feeding migration (Northcote, 1984), with the Atlantic salmon moving into productive marine feeding grounds in the subarctic. There is hardly any information available on the juvenile migratory routes (Malcolm et al., 2010). However, post-smolts of unknown river origin were examined by Shelton et al., (1997), and they migrated northwards off the western coast of Scotland along the continental shelf edge, apparently making use of the dominant ocean currents. ...
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... This knowledge gap is particularly important because these coastal waters are highenergy environments that are increasingly being developed for generation of marine renewable energy via tidal-flow, wind, and wave devices. Numerous productive rivers of high conservation value that also support high-value salmon fisheries discharge into the same coastal waters (Malcolm et al., 2010). There is therefore potential for negative interactions between renewable developments and migrating smolts (Malcolm et al., 2010). ...
... Numerous productive rivers of high conservation value that also support high-value salmon fisheries discharge into the same coastal waters (Malcolm et al., 2010). There is therefore potential for negative interactions between renewable developments and migrating smolts (Malcolm et al., 2010). Potential impacts are physical impact, acoustic, and electromagnetic impacts (Gill et al., 2012, Harding et al. 2016. ...
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... The recruitment of glass eels in the North Sea region has declined more severely than elsewhere in Europe (ICES, 2019b), and the northern North Sea constitutes one of the areas with the lowest number of sampling and monitoring stations (especially in Norway and Scotland) (ICES, 2019b). Specifically, the migratory routes of glass eels through the Shetland Channel into the North Sea have only been inferred, but never directly assessed through sampling programs at sea (Malcolm et al., 2010). Establishing such a sampling program is challenging due to the low abundance of glass eels in shelf water. ...
... This difference in transport, coupled with the westerly winds dominating this area, causes most fish stocks recruiting to the North Sea to pass through the northern passage (Turrell, 1992). This is also considered to be the case for glass eels (Malcolm et al., 2010). ...
... The geographical proximity of the Scottish coast to the NAC and the Shetland Channel, with currents flowing close the Scottish coasts into the North Sea (Figure 2a), is probably a key factor for the high potential recruitment to this area. Currently, no sampling of glass eels off the coast has been conducted in Scotland, and the only evidence of the presence of eels in the country comes from data on yellow eel in freshwater collected by the Scottish Fisheries Coordination Centre (SFCC) (Malcolm et al., 2010). Most of the eel sampling in Scottish freshwaters was conducted by electrofishing, for which eels were not the target species. ...
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The European eel hatches in the Sargasso Sea and migrates across the Atlantic Ocean toward Europe. At the continental shelf, larvae metamorphose into glass eels and then recruit to coastal habitats and estuaries. Among other cues, glass eels orient in situ using lunar cues, but what role this lunar compass plays in their recruitment to the coast is unknown. To assess this, we incorporated empirical in situ observations of glass eel swimming and lunar‐driven orientation into a biophysical advection model. We simulated dispersal of glass eels drifting with the North Atlantic Current to test the hypothesis that lunar‐driven swimming and orientation behavior affects recruitment to North Sea coasts. Particles were released from the continental slope north of Scotland, an obligate passage for migrating eel larvae. Four numerical experiments were conducted: one with passive drift and three including glass eel swimming speeds (ranging from 3 to 12 cm/s) and lunar‐driven orientation. With a speed of 3 cm/s, the lunar compass increased recruitment to the North Sea coasts of Southwestern Norway and Scotland by 34%–40%. Conversely, orientation behavior decreased recruitment to northern areas like Iceland (−46%), the Faroe Islands (−39%) and Northern Norway (−49%). Behavior affected the timing of recruitment to Southwestern Norway, causing peaks of abundance in May–June, but not to other regions. These results show that lunar‐driven orientation and swimming behavior observed in glass eels substantially increases their recruitment to North Sea coasts. Results agree with the distribution of eel in northern Europe, which decreases in abundance with increasing latitude.
... Repeat spawning females were not included in the present analysis because they are considered to represent only a small proportion of spawner abundance in Scotland (Malcolm et al., 2010). However, the proportion of repeat spawners has increased in some areas. ...
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... Certaines études montrent également que la distance parcourue par les truites de mer durant leurs phases migratrices est variable (Malcolm et al. 2010;Degerman et al. 2012;Aldvén et al. 2015). Il semblerait, en effet, que la distance de cette migration puisse être assez courte (<100Km) ou plus longue mais fixe (Malcolm et al. 2010;Degerman et al. 2012;Aldvén et al. 2015). ...
... Certaines études montrent également que la distance parcourue par les truites de mer durant leurs phases migratrices est variable (Malcolm et al. 2010;Degerman et al. 2012;Aldvén et al. 2015). Il semblerait, en effet, que la distance de cette migration puisse être assez courte (<100Km) ou plus longue mais fixe (Malcolm et al. 2010;Degerman et al. 2012;Aldvén et al. 2015). Contrairement au saumon atlantique, qui réalise une longue migration, la truite de mer a tendance à migrer selon une direction qui suivrait les côtes. ...
Thesis
La dispersion, caractérisée par les mouvements d’individus dans l’espace et dans le temps, conduit à la production d’un flux de gènes et permet la connectivité des populations. Comprendre les facteurs qui façonnent les flux de gènes et la structuration des populations est d’une importance capitale pour améliorer les pratiques de gestion et de conservation des espèces. Celles caractérisées par une anadromie facultative, telles que la truite commune (Salmo trutta L.), sont des modèles de choix pour étudier le rôle de la diversité écotypique et comportementale, sous l’effet des activités anthropiques, sur le fonctionnement des populations. En utilisant la génétique des populations cette thèse se propose donc d’analyser la structuration des populations de la truite commune dans le fond du Golfe de Gascogne mais également de déterminer l’influence combinée de la dispersion de la truite de mer, de son comportement reproducteur et des activités anthropiques (repeuplements, transport de reproducteur) sur leur fonctionnement. Cette thèse aborde également la contribution des populations de truites communes (via leur origine natale) au stock de truites de mer capturées par la pêche professionnelle, sur le même site d’étude, en couplant de la génétique des populations et de la microchimie des otolithes. Nos résultats montrent une structuration génétique forte des populations de truite commune avec la présence de sept populations distinctes dans le bassin de l’Adour. Ceci semble être en partie expliqué par un comportement marqué de fidélité au site de naissance des truites de mer, couplé à un mouvement directionnel de celles-ci du sud (Espagne) vers le nord qui ne semble pas résulter en une dispersion effective (i.e. mouvement suivi d’une reproduction). En outre, les repeuplements récents, semblent impacter faiblement la structuration génétique des populations sauvages. Certains flux de gènes détectés localement semblent être dus à d’autres activités anthropiques, telles que le transport de reproducteurs. Les truites de mer capturées par la pêche professionnelle proviennent majoritairement de la population du gave d’Oloron et peu des populations des Nives et du Gave de Pau. La raison pourrait se trouver en premier lieu dans le fait que le Gave de Pau est fortement impacté par la présence de barrières à la migration et en second lieu dans les différences phénotypiques (taille plus petite) présentées par les truites de mer des Nives, par rapport à celle des gaves. Ceci suggère donc une différenciation de cette population et peut expliquer que la pêche professionnelle les capture dans une moindre proportion. Cette thèse a d’autre part pu démontrer les difficultés dans l’assignation d’une origine natale via la génétique lorsque les signatures génétiques sont relativement proches. Elle confirme l’utilité d’un couplage génétique des populations - microchimie des otolithes pour assigner des individus à leur origine natale à une échelle plus fine que le bassin. Les résultats obtenus au cours des trois années de thèse ont permis la détermination de populations génétiquement distinctes dont l’une contribue très largement à l’activité de pêche professionnelle. Ces populations peuvent être considérées comme de potentielles unités de gestion qui pourront servir de base à l‘élaboration de plans de gestion et de conservation. La meilleure compréhension de la biologie et du fonctionnement de la truite commune, et de l’impact des activités anthropiques sur la structuration des populations, acquise lors de cette thèse, pourra également permettre d’améliorer la prise de décisions des gestionnaires locaux pour la conservation et la gestion des populations de truites communes.
... Relatively little is known about the migratory routs of Scottish salmon upon return to the UK coastline. Conventional tagging suggests fish do not migrate directly to their natal rivers, but rather spend a period of time migrating around the coast, with fish tagged in a particular location appearing throughout the country [88]. Again, an ability to utilise all fish as being genetically, rather than physically, tagged has the potential to greatly enhance the ability to better understand coastal migration in the face of continuing development in this area. ...
... The aims of the study presented here were very much to maximise resolution and so aid in managementrelated questions involving determination of the natal origin of salmon around the Scottish coast. For example, the development of marine renewable energy sources around the coast has the potential to impact migratory routes of salmon and understanding migratory patterns has been identified as a research priority [88]. Assignment unit resolution using all markers was sufficient to be able to separate fish from the North & West and East coasts of Scotland whereas this was not able to be achieved when outlier loci had been removed and, as such, would be preferred when maximum levels of resolution are required and assumptions of neutrality can be ignored. ...
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Understanding the habitat use patterns of migratory fish, such as Atlantic salmon (Salmo salar L.), and the natural and anthropogenic impacts on them, is aided by the ability to identify individuals to their stock of origin. Presented here are the results of an analysis of informative single nucleotide polymorphic (SNP) markers for detecting genetic structuring in Atlantic salmon in Scotland and NE England and their ability to allow accurate genetic stock identification. 3,787 fish from 147 sites covering 27 rivers were screened at 5,568 SNP markers. In order to identify a cost-effective subset of SNPs, they were ranked according to their ability to differentiate between fish from different rivers. A panel of 288 SNPs was used to examine both individual assignments and mixed stock fisheries and eighteen assignment units were defined. The results improved greatly on previously available methods and, for the first time, fish caught in the marine environment can be confidently assigned to geographically coherent units within Scotland and NE England, including individual rivers. As such, this SNP panel has the potential to aid understanding of the various influences acting upon Atlantic salmon on their marine migrations, be they natural environmental variations and/or anthropogenic impacts, such as mixed stock fisheries and interactions with marine power generation installations.
... The different sea-age phenotypes of Atlantic salmon are associated with different marine life-histories (see Malcolm et al. 2010 for a review). This contention is supported by stable isotope studies demonstrating differences in the marine diet among groups of Atlantic salmon returning to UK rivers (MacKenzie et al. 2012), differences in the marine growth performance of Atlantic salmon (Bacon et al. 2009) and by observed variations in temporal patterns of Atlantic salmon abundance (Youngson et al. 2002). ...
Technical Report
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Modelling an Atlantic salmon (Salmo salar) population as three phenotypically homogeneous sub-stocks showed different sub-stock dynamics and time-trends, a finding which was robust to three quite extreme variations of marine-mortality scenarios. A process-centred demographic analysis of a phenotypically mixed population (river North Esk, eastern Scotland) separated the life-cycle into two portions: density-dependent (spawner to smolt), represented by a stock-recruitment relationship; density-independent at sea and in both the estuary and river during return to spawning sites. Extensive data spanning three decades was judiciously used to parameterise the model for three phenotypically distinct sub-stocks (early running multi-sea-winter; late-running multi-sea-winter; and one-sea-winter). Quantification of different population parameters was achieved for the putative substocks, illuminating historical population-trends and underlying mechanisms. The approach forms a template for similar model decompositions at other rivers with similar data. Broad implications for salmon management more widely included the enhanced benefits of a process-based life-cycle model that described more phenotypically homogeneous sub-stocks (than a single-stock formulation) for the transport of population parameter values (or derived Biological Reference Points) from well documented (parameter-donor) catchments to data-sparse (parameter recipient) catchments. Full text at: http://www.gov.scot/Publications/2015/10/7173
... However, it is important that these industries are developed sustainably and that potential interactions with wildlife are assessed and mitigated where required. Malcolm et al. (2010Malcolm et al. ( , 2013 scoped the research requirements for diadromous fish in the context of offshore renewables. This identified the need for greater information on the migratory timing and sizes of migrating salmon smolts to identify sensitive periods and locations for development, and to inform future acoustic tagging studies that aim to improve understanding of coastal movements and behaviour. ...
Technical Report
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The Scottish Government has set ambitious targets for renewable power generation. Marine Renewable Energy, including wind, wave and tidal power are expected to contribute significantly to these targets. Information on the timing of Atlantic salmon smolt migrations is required for planning coastal development and the timing of particular activities. Information on smolt sizes is required to plan acoustic tagging studies aiming to improve understanding of fish movement and behaviour in the coastal zone. This report assessed pre-existing information on smolt migration timing and sizes. The commencement of migration was characterised as the day of the year (DoY) on which 25% of smolts had migrated (S25); the end of the migration period was characterised as the DoY on which 75% of smolts had emigrated (S75). The start and end of the migration period varied with elevation and over time, but not as a predictable function of geographical location (latitude and longitude). Thus, a single coastal migration DoY range (S25 to S75) was estimated for the whole of Scotland. By including uncertainty in the predictions it was possible to identify a “sensitive window” for development, where large numbers of migrating salmon smolts could be expected in the coastal zone. This window covers the period DoY 103-145. This envelope does not consider the time that smolts will spend in the coastal zone, so further work is required to adjust this window appropriately. It was not possible to model the spatio-temporal variability in smolt sizes given available data and resources. However, considerable inter-site and inter-annual variability was observed. The data presented here could be used to inform future acoustic tagging studies at existing sites, although it is suggested that pilot data should be obtained where work is to be carried out at new sites.
... Scotland has a target to generate the equivalent of 100% of its electricity needs through renewable sources by 2020 (Anon., 2011), partly from tidal energy, particularly in the Pentland Firth, between Orkney and the mainland (Shields et al., 2009). The potential for these developments to impact on salmon has been raised, in part because the Pentland Firth is regarded as an area through which a large proportion of homing Scottish salmon may pass (Malcolm et al., 2010). In the present study, PSATs were deployed to derive the depth distributions and tag pop-up locations of Atlantic salmon captured, tagged, and released in Northern Scotland, close to the Pentland Firth, on their homeward migration. ...
Article
Knowledge of swimming depths and migration routes of homing Atlantic salmon in open coastal zones is urgently required to inform decisions on managing the species, e.g. for the sustainable development of marine renewable energy. In May–June 2013, pop-up satellite tags programmed to detach from fish after 1–10 d were fitted to 50 adult salmon on the northern coast of Scotland. Most of the tags returned water depth recorded at regular intervals (n ¼ 47) and gave a geographic location following detachment (n ¼ 44). In general, salmonwere found near the surface during the study, with the median number of records at 0–5 m depth ranging from 72 to 85%, depending on the extent of known potential systematic bias. Depth use varied among individuals (8–100% at 0–5 m) and cluster analysis suggested that the sample of fish could be split into two groups, representing different patterns of depth use. These clusters were also associated with pop-up location. There was a small but significant increase in recorded depth at night compared with during the day, contrasting with findings of salmon at sea in other contexts. The mean maximum dive depth was 64 m (range 13–118 m), of similar order to the likely available water column depth. These results suggest that salmon will potentially interact with man-made obstacles, e.g. renewable energy generators, throughout the water column and particularly in surface waters.