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  • 1.
    Bergström, Lena
    et al.
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lagenfelt, Ingvar
    Swedish Agency for Marine and Water Management.
    Sundqvist, Frida
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Andersson, Ingemar
    Swedish Agency for Marine and Water Management.
    Andersson, Mathias H.
    Perfomers of environmental monitoring, Universities, Stockholm University, SU, Department of Zoology. Perfomers of environmental monitoring, Institutes, Swedish Defence Research Agency, FOI.
    Sigray, Peter
    Perfomers of environmental monitoring, Institutes, Swedish Defence Research Agency, FOI.
    Fiskundersökningar vid Lillgrund vindkraftpark: Slutredovisning av kontrollprogram för fisk och fiske 2002–20102013Report (Other academic)
    Abstract [en]

    In 2001, the Government authorised the construction of an offshore wind farm at Lillgrund (48 wind turbines with 2.3 MW generators). The Lillgrund wind farm is located in the Öresund Strait in the southwest Sweden and it connects the brackish Baltic Sea with the Kattegat and North Sea area. In 2002, the Environmental Court defined the final terms and conditions for the wind farm development and the extent of the monitoring programme required. Lillgrund wind farm has been operating since 2008 and is currently the largest investment in offshore wind power that is in operation in Sweden. The National Board of Fisheries conducted a monitoring programme in the area in the years before (2002–2005) and after (2008–2010) the construction of the wind farm; a base line study and a study when the wind farm was operational, respectively. The aim was to investigate the impact of the wind farm, when operating, on the benthic (bottom-living) and pelagic (open-water living) fish as well as on fish migration. These studies have partly been integrated into work conducted as a part of the research project Vindval, funded by the Energy Agency. Throughout the project period, regular contact has been maintained between the National Board of Fisheries and Vattenfall (which owns and operates the wind farm), as well as with the regulatory authority (County Administrative Board of Skåne). The main results can be summarised in a number of points below: 

    Acoustics (sound) 

    • The overall sound energy from the wind farm under water, is mainly generated by vibration from the gearbox.

    • An analysis of the sound pressure level for the wind farm area, showed a correlation between noise level and the number of turbines in the wind farm (the so called park effect), where each individual turbine helps to increase the overall noise level in the area.

    • Sound measurements from Lillgrund wind farm showed that noise levels within a distance of 100 metres from a turbine at high wind speeds are high enough to be a risk for some species of fish to be negatively affected, e.g. in the form of escape behaviour, or masking of vocal communication between individuals.

    • Stress reactions can also occur at distances of more than 100 metres from a turbine. This is due to the fact that the noise from the turbines is continuous and louder than the ambient noise levels within some frequencies.

    Benthic (bottom-living) fish

    • The development of the fish community in Lillgrund was similar to that observed in the reference areas during the study period. For the wind farm as a whole, no effect was observed on the species richness, species composition or quantity of fish.

    • Several species of bottom-living fish showed an increase in abundance close to the individual wind turbines compared with further away, especially eel (yellow eel) (Anguilla anguilla), cod (Gadus morhua), goldsinny wrasse (Ctenolabrus rupestris) and shorthorn sculpin (Myoxocephalus scorpius). The results more likely reflect a redistribution of fish within the wind farm, rather than a change in productivity or migration from surrounding areas. The increase in abundance is probably due to the wind turbine foundations providing an opportunity for protection and improved foraging.

    • The distance within which an increased abundance could be observed was estimated for different species to be between 50–160 metres from a wind turbine.

    Pelagic (open-water living) fish

    • There was a dramatic increase in commercial fishing for herring (Clupea harengus) north of the Öresund bridge, in contrast to the south of this line, where it practically completely stopped during the first years of operation of the wind farm. This change may imply that the Rügen herring migration was affected by the Lillgrund wind farm. Due to the fact that there were other factors in addition to the wind farm contributing to the herring movements, it proved difficult to identify any correlation.  Fish migration

    • According to the study, the wind farm at Lillgrund is not a definitive barrier for the migration of silver eels (Anguilla anguilla) that migrate through and close to the wind farm area. The same proportion of the tagged and released silver eels (approximately one-third), passed the transect line with receivers, both before the wind farm was constructed (the baseline period) and after it was in operation.

    • There was no statistical difference indicating any alterations in the migration period for silver eel, but there was a tendency towards the migration taking longer at higher productivity (>20% of maximum effect) which could indicate that some eels were affected by the wind farm. There was a tendency towards the eels being recorded on fewer occasions than expected within the wind farm when functioning at low productivity (<20 %) and on more occasions than expected when functioning at higher productivity (>20 %), which may indicate that some individuals are less able to navigate past the wind farm at higher production rates.   

    Conclusions

    The study at Lillgrund has resulted in an increase in knowledge of how offshore wind farms can affect fish, which is very valuable. Even within an international perspective, there are very few studies of offshore wind farms in operation.  Three years of monitoring the effects of the wind farm on fish and fisheries is only a relatively short period. Some of the most significant results however, include the fact that some bottom-dwelling fish were attracted to the fundaments of the wind farm and the associated rocky protection layer (reef effect). In addition, an increasing noise level in the Öresund environment was observed and the results of the eel tracking may indicate that the migration pattern of some eels was, to some extent, affected by the wind farm. There is a need for caution however, when applying the results in other marine areas and on a larger scale. Lillgrund wind farm is one of the first large-scale wind farms and is located in an area with frequent and noisy shipping traffic as well as frequent and large fluctuations in external parameters such as salinity and currents. A key gap in our knowledge, despite these studies, is the lack of long term monitoring, to evaluate the long term ecological impacts of the reef effects observed. It would be ideal to re-visit the wind farm after a number of years to see how the fish populations have developed over the longer term, and see whether the observed accumulation of certain fish species near the structures continues, and if quantitative effects on the whole area are also are evident. Studies looking at whether noise as a physiological stress, can affect the fish species that live or pass through the wind farm environment are also required. In addition it would be useful to implement further studies, especially in the Baltic Sea, with regard to the cumulative impacts on migratory fish such as silver eels. The full report is available as a PDF in English.

  • 2.
    Bergström, Lena
    et al.
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lagenfelt, Ingvar
    Swedish Agency for Marine and Water Management.
    Sundqvist, Frida
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Andersson, Ingemar
    Swedish Agency for Marine and Water Management.
    Andersson, Mathias H.
    Perfomers of environmental monitoring, Universities, Stockholm University, SU, Department of Zoology. Perfomers of environmental monitoring, Institutes, Swedish Defence Research Agency, FOI.
    Sigray, Peter
    Perfomers of environmental monitoring, Institutes, Swedish Defence Research Agency, FOI.
    Study of the Fish Communities at Lillgrund Wind Farm: Final Report from the Monitoring Programme for Fish and Fisheries 2002–20102013Report (Other academic)
    Abstract [en]

    In 2001, the Swedish Government authorised the construction of an offshore wind farm at Lillgrund in the Öresund Strait between Denmark and Sweden. In 2002, the Environmental Court defined the final terms and conditions for the wind farm development and the extent of the monitoring programme required.  Lillgrund wind farm came into full operation in 2008, and is currently the largest offshore wind farm in operation in Sweden.  The Swedish National Board of Fisheries conducted a monitoring programme, in the area, in the years before (2002–2005) and after (2008– 2010) the construction of the wind farm; a base line study and a study when the wind farm was operational, respectively. No investigation was conducted during the construction phase. The aim was to investigate the impact of the wind farm during the operational phase on the benthic and pelagic fish as well as on fish migration. These studies have partly been integrated into work conducted as a part of the Vindval Research Programme, funded by the Swedish Energy Agency.

    Acoustics (sound) 

    • The overall sound energy from the wind farm under water is mainly generated by vibration from the gearbox.

    • An analysis of the sound pressure level for the wind farm area, showed a correlation between noise level and the number of turbines in the wind farm (the so called park effect), where each individual turbine helps to increase the overall noise level in the area. 

    • Sound measurements from Lillgrund wind farm showed that noise levels within a distance of 100 metres from a turbine at high wind speeds are high enough to be a risk for some species of fish to be negatively affected, e.g. in the form of direct escape behaviour, or masking of vocal communication between individuals. 

    • Stress reactions can also occur at distances of more than 100 metres from a turbine. This is due to the fact that the noise from the turbines is continuous and louder than the ambient noise levels within some frequencies.   

    Measurements of the underwater noise levels were carried out at varying distances from individual turbines, from longer distances away from the entire wind farm as well as within a reference site (Sjollen) 10 km north of the wind farm. The results show that the wind farm produces a broadband noise below 1 kHz as well as one or two tones where the 127 Hz tone is the most powerful (vibrations from the first stage in the gear box). The majority of the overall underwater sound energy from the wind farm lies around the tone of 127 Hz.  The maximum noise levels, generated by the wind turbine, working at full production (12 m/s), at 1 m were 136 dB re 1µPa(RMS) for the dominant tone of the turbine which was 127 Hz (integrated across 123–132 Hz) and 138 dB re 1µPa(RMS) at the full spectrum (integrated across 52–343 Hz). At a distance of 100 m from the turbine, the noise levels are reduced to 104–106 dB re 1µPa(RMS) across the full spectrum, which is close to the locally measured ambient noise in the Öresund Strait, but the noise level was still around 23 dB above the background level for the 127 Hz tone.

    An analysis of the sound pressure level for the wind farm area showed a correlation between noise level and the number of turbines in the wind farm (called the park effect). Close to the wind farm (<80 m), the noise environment was dominated by the individual wind turbine with a calculated sound propagation loss of 17•log (distance). At greater distances (80 m to 7000 m) the sound propagation loss was non-linear and less than 17•log (distance). This is explained by the fact that the other turbines in the wind farm contributed to the total noise level. At even greater distances (>7 km) the entire wind farm functioned as a point source and the sound propagation loss was once again measured as 17•log (distance). The noise levels equivalent to those recorded and calculated from Lillgrund wind farm have not been shown to cause any physical injury to fish according to the current published scientific literature. It was only within some 100 metres from a turbine at high wind speeds that the noise levels were high enough to result in the risk of negative effects on some species of fish in the form of direct escape behaviour or possible masking of communication. The response depends upon the individual species’ sensitivity to sound. Fish have been shown to become stressed when they find themselves in a consistently noisy environment, which in turn can result in for example, lower growth rates or can have an impact on reproduction. Stress in general can also, in combination with other negative factors, make them more susceptible to disease etc., due to an impaired immune system. Animals can choose however, to remain in an area despite the disturbance, if the area is sufficiently important for their survival or reproduction.  Based on the calculated sound propagation around the wind farm, salmon and eel could theoretically detect the 127 Hz tone at 250 m and 1 km distances respectively at a productivity rate of 60 and 100 %, which is equivalent to a wind speed of approximately 6 and 12 m/s. The calculated distances would be limited by the hearing ability of both fish species and not the background noise levels in the Öresund Strait. For herring and cod, the theoretical detection distance was calculated to be between 13 and 16 km respectively for a production rate of 60 and 100 %. This distance should have been greater, but is limited for these species due to the ambient noise levels in the area. These calculations indicate that fish can potentially detect sound from the wind farm at relatively long distances. Local variations with regard to depth and physical barriers such as peninsulas, e.g. Falsterbonäset in the southern end of the Öresund Strait, can however, have a large impact on the actual sound propagation. 

    Benthic Fish

    • The temporal development of the fish community in Lillgrund was similar to that observed in the reference areas during the study period. For the wind farm as a whole, no effect was observed on species richness, species composition or on the abundance of fish. 

    • Several species of fish however, showed an increase in abundance close to the wind turbines compared with further away, especially eel (yellow eel) (Anguilla anguilla), cod (Gadus morhua), goldsinny wrasse (Ctenolabrus rupestris) and shorthorn sculpin (Myoxocephalus scorpius). The results reflect a redistribution of fish within the wind farm, rather than a change in productivity or migration from surrounding areas. The increase in abundance is probably due to the wind turbine foundations providing an opportunity for protection and improved foraging. The distance within which an increased abundance could be observed was estimated, for different species, to be between 50– 160 metres from a wind turbine. 

    • Fish distribution may to some extent have been influenced by the local acoustic environment, as a lower degree of aggregation close to the wind turbines at higher noise levels. The effect was most obvious for eelpout and eel (yellow eel). No response was seen for cod in relation to sound levels.   

    Changes in the species composition of the fish communities over time were studied in comparison with two reference areas. Of these, the northerly reference area (Sjollen) had a larger marine component than the southern reference area (Bredgrund). The species composition at Lillgrund had similarities with both of the reference areas.  The results from fish sampling with fyke nets and gill net series indicate that there have been no significant changes in the number of species, the species composition or the fish abundance after the wind farm was built, looking at the wind farm as a whole. Some changes have however been noted in relation to individual species. An increased catch of shore crab and eel (yellow eel) was observed during the first two years of production, but not in the third year. The catch of eelpout increased in all areas during the period studied, but to a slightly lesser extent at Lillgrund when compared to the reference areas. For the other species, the changes observed at Lillgrund were similar to at least one of the reference areas. These results suggest that the fish communities within the wind farm were primarily affected by the same general environmental conditions as the fish communities within the reference areas, rather than by the effects of the wind farm.  An analysis of the distribution patterns of fish close to the turbines showed an increased abundance in the immediate vicinity of the wind turbines in four of the eight species of fish studied: specifically shorthorn sculpin, goldsinny wrasse, cod and eel (yellow eel). The effects were seen already after the first year and were similar over all three years studied. An effect was also identified for eelpout, but only in 2010. The aggregation effect was seen within a distance of 50–160 metres from the wind turbines, different for the different species.  A comparison of the relative effect of different factors, based on the data from an extended survey in 2010, showed that the observed distribution pattern could be explained to a larger extent by the presence of the turbines rather than the underwater topography of the area. The analysis also indicated weak effects of the local acoustic environment on fish distribution patterns, with a reduced presence of fish at higher noise levels. The response was strongest for eelpout and eel. No response in relation to noise level was seen for cod. For shorthorn scuplin and common shore crab a response was seen only 11 Swedish Agency for Marine and Water Management Report 2013:19  during the autumn. The magnitude of the effect of noise was, however, lower than the aggregation effect. Hence, fish aggregated close to the wind turbines in all conditions, but the effect was weaker when the noise levels were higher. It is recommended that the the wind farm area is reinvestigated after a number of years to follow the long-term development of the fish populations, and to see if the aggregation effect observed continues and potentially also increases over time. A prerequisite for a long term positive development of fish abundance is that the removal of fish, such as from fishing or predation by marine mammals and fish-eating birds, does not increase in the area. 

    Pelagic Fish

    • There was a dramatic increase in commercial fishing for herring north of the Öresund Link (close to the north of the wind farm) in the first years of operation of the wind farm, in contrast to south of the bridge that forms a part of the Öresund Link, where it virtually completely stopped. This change may imply that the Rügen herring migration was affected by the Lillgrund Wind Farm. Due to the fact that there were other factors in addition to the wind farm contributing to the herring movements, it proved difficult to identify any correlation.   

    The evaluation was based on catch statistics from the commercial fisheries in the Öresund Strait (ICEs subdivision SD 23) and fisheries independent statistics from ICES for adult herring (Rügen herring) (ICES subdivision SD 21–23, western Baltic Sea and southern Kattegatt) and density of juvenile fish (ICES subdivision SD 24). There was a dramatic increase in commercial fishing for herring north of the Öresund Link in the first years of operation of the wind farm, in contrast to south of the bridge where it virtually completely stopped. The reason may be largely explained by the regulations banning drift-net fishing and a favourable market for herring, but potentially also because of the Öresund Link which was completed in 2000.The potential impacts of the wind farm are therefore difficult to distinguish from the impacts of these other factors because detailed resolution in the catch statistics are missing from the years before 1995 prior to the start of the building work on the Öresund Link. The statistics independent of commercial fishing from ICES showed no significant correlation between the density of herring juveniles in the western Baltic Sea and the number of adult herring (3 years old or more) in the following years in the Öresund Strait (ICES SD 21–24). There was however a weak tendency towards a negative development of the fish population over the period 1993 – 2010. The presence of Rügen herring and their migration through the Öresund Strait is likely strongly influenced by the fact that the population shows large fluctuations between the years. In addition, there is a possible overlapping effect on the soundscape from the wind farm and the Öresund Link, which has been in use since 2000.  Overall, the variety of factors together mean that it is difficult to identify any clear results with regard to if the migration of Rűgen herring is influenced by Lillgrund wind farm.

    Fish Migration 

    • According to the results from this work, the wind farm at Lillgrund is not a barrier for the migration of the eels that come into contact with it. An equally large proportion of the tagged and released silver eels (approximately one third) passed the transect line with receivers, at Lillgrund both before the wind farm was constructed (baseline study) and after it was in operation. 

    • There was no statistically significant difference indicating any alteration in the migration speed of eels, but there were occasional longer migration times when the wind farm was working at higher levels of production (>20 % of maximum) which may indicate that some eels are affected by the wind farm. The fact that the eels also showed a tendency towards being noted on fewer occasions than expected within the wind farm at low productivity (<20 %) and on slightly more occasions than expected at higher productivity (>20 %), could indicate that they have greater difficulty in navigating past the wind farm at higher levels of productivity than lower. 

    The impact of the wind farm on migration was studied via tagging of migrating silver eels. In total, 300 acoustically individually tagged eels were included in the study and of these, 100 contributed with useable information. The baseline study period started on a small scale in 2001 and ended in 2005. The majority of the eels were tagged and monitored during the production period (2008– 2010). All tagged silver eels were released south of the wind farm. 

    The results showed that an equally large proportion of the tagged and released silver eels; approximately one third, passed a transect with receivers at Lillgrund wind farm, both during the baseline period 2001–2005, and when it was in production 2008–2009. The greatest proportion of eels passed through the deeper part of the transect by the navigation channel Flintrännan close to the Danish border at Drogden during the production phase (31 %) and baseline period (43 %). A somewhat larger proportion of the eels were registered passing the most easterly part of the transect, close to Klagshamn, during the production phase (14 %) compared with the baseline period (5 %). A behaviour which occurred during the production phase, was that some individuals moved back to the release site, after being in the vicinity of wind farm. The most commonly observed behaviour during the study in 2010 was that an eel was registered moving south of the wind farm in a more or less northerly direction, but without being registered to the north of the wind farm.  The range in the time taken for the movement of the eels from the release site to the transect running through the wind farm was very great, from four to more than 1000 hours. There was no statistically significant difference in the time taken to travel, between periods with low production (<20 % of maximum) and periods with high production (>20 %) or for individuals which passed through or outside of the wind farm.  Even if the eels did not show any statistically significant behaviour, changes in movement patterns may occur for some individuals. The fact that there was a tendency towards longer periods of time taken for movement at higher production levels (not statistically significant) (>20 %) could indicate that some individual eels are influenced by the wind farm. The proportion of eels that took more than a week (168 hours) to make the journey was 48 % during the period with higher production (>20 %) compared with 28 % at lower production. No significant difference in the proportion of passes within or outside of the wind farm respectively could be shown. The eels showed however, – a tendency of being recorded on fewer occasions than expected inside the wind farm at low production levels (<20 %) and on more occasions than expected at higher production levels (>20 %). The irregularities in the proportions, compared with the expected result, could indicate that individual eels stayed longer in the wind farm when it was functioning at higher productivity. If the eels discover the wind turbine only when they are very close and do not change course, then other factors such as the speed of the current across the shallow marine areas become significant and can mean that the time spent in the area is shorter and records fewer. At high productivity, the eels may hesitate and/or divert their course and be recorded from close to or within the area, to then be recorded on the transect outside of the wind farm.  The mechanisms that lie behind the possible impact from the electromagnetic field or the noise pattern are difficult to distinguish, as both can have an impact on the same areas. Travelling speed showed no linear relationship with the level of production in the wind farm. 

    Conclusions

    The study at Lillgrund has resulted in an increase in the understanding of how offshore wind farms can affect fish, which is very valuable. Even within an international context, there are currently very few experience-based studies of offshore wind farms in operation.  The results from three years of monitoring during the operational phase show that the effects of the wind farm on fish populations and fishing were limited. One of the clearest results showed that some benthic fish species were attracted to the foundations of the wind turbines with their associated scour protection (reef effect). In addition, the effect on the local noise environment in the form of increased noise in the Öresund Strait was documented. The results of the eel tracking study may indicate that some eels are influenced by the wind farm on their migration. Some care should be taken however, when applying the results of these studies in other offshore environments and on a larger scale. The monitoring has only been carried out for three years and thus reflects only a short-term perspective. Lillgrund wind farm is also one of the first large-scale wind farms and is situated in an area with regular and noisy shipping traffic and both frequent and large variations in environmental factors such as salinity and currents.  A key knowledge gap that remains after the completion of this work is the lack of studies over a longer period of time, to help identify the long term ecological effects of, for example, the reef effect. Ideally, the wind farm should be re-visited after a number of years to see how the fish populations have developed over the longer term, and see if the observed aggregation of certain fish species close to the wind turbines continues, and to possibly see if any quantitative effects have taken place. Studies are also required in relation to how stress may affect fish species/individuals which choose the reef-like foundations and their noisier environment. Additional studies, primarily for the Baltic Sea, are also required to establish if there are any cumulative effects on migratory fish such as silver eels.

  • 3.
    Bryhn, Andreas
    et al.
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lindegarth, Mats
    Perfomers of environmental monitoring, Institutes, Swedish Institute for the Marine Environment, HMI.
    Bergström, Lena
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Bergström, Ulf
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Ekosystemtjänster från svenska hav: Status och påverkansfaktorer2015Report (Other academic)
    Abstract [en]

    Humans benefit greatly, and in many ways, from marine ecosystems. Marine ecosystems produce oxygen, atmospheric water and food, and they give inspiration, recreational opportunities and much more, often for free. Referring to the benefits for people from marine ecosystems as ecosystem services is a way to make them visible to society. Ecosystem services provide a complementary perspective to the natural scientific aspects, and are used in management, policymaking and the public debate regarding the sea. Valuing ecosystem services can initiate abatement of environmental problems in cases when these have a societal cost which is not reflected in market values. Ecosystem services as a concept has become increasingly influential in the marine environmental policy. Ecosystem services are for instance included in the EU’s Marine Strategy Framework Directive and a number of other international directives and agreements. This report aims to classify the status of marine ecosystem services in Sweden, as well as to evaluate their main anthropogenic pressures. The status classification is made with regard to the three different marine sub-regions of the Swedish economic zone: the Kattegat and Skagerrak, the Baltic Proper, and the Gulf of Bothnia. The three status classes applied are good, moderate and poor. Several of the ecosystem services are classified using indicators or environmental quality norms, and this approach is likely to be central in future assessments of ecosystem services. Other ecosystem services are status classified based on recent literature within the respective fields. Anthropogenic pressures due to human activities such as nutrient overenrichment, climate change, marine litter and extensive fishing, which exert pressure on the environment, are evaluated based on their assessed overall impact on the ecosystem services according to current available knowledge. The overall impacts on the ecosystem services are assessed as small or unlikely negative, moderate negative or large negative. Significant knowledge gaps are highlighted wherever found appropriate. Ecosystem services classified as having bad status (Table i) are maintenance of foodwebs and provision of food (in all Swedish marine sub-regions), maintenance of habitats (in the Kattegat and Skagerrak as well as in the Baltic Proper), and provision of raw material (fodder fish in the Kattegat and Skagerrak). Several ecosystem services were assessed as having good status, e.g. energy provision, provision of genetic resources and cultural inspiration. A number of ecosystem services are, in addition, classified as having moderate status, e.g. natural heritage, recreation, and maintenance of biodiversity. In general, the Gulf of Bothnia has a somewhat better status regarding ecosystem services than the other marine sub-regions, which concurs with a lower level of anthropogenic impact on the marine environment. Comparing the Skagerrak and Kattegat to the Baltic Proper, the ecosystem service provision of raw material differs, with poor status in the Kattegat and Skagerrak and moderate status in the Baltic Proper. Apart from that, their overall patterns regarding status are similar. Among the anthropogenic pressures, nutrient overenrichment has a large negative net impact on maintenance of primary production and habitats. The increasing carbon content in the sea associated with climate change has a large negative net impact on biogeochemical cycles. Extensive fishing has a large negative net impact on maintenance of foodwebs and on provision of food.

  • 4.
    Degerman, Erik
    et al.
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Petersson, Erik
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Bergquist, Björn
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Effekter av kalkning på fisk i rinnande vatten: Resultat från 30 år av elfisken i kalkade vattendrag2015Report (Other academic)
    Abstract [sv]

    I denna rapport har vi utvärderat effekten av kalkning på fisk i vattendrag på nationell nivå med fokus på perioden 1982–2012. Uppgifter om kalkdoser, kalkningsmetoder, vattenkemi och elfiskedata från 609 vattendrag över hela Sverige har använts. Sammanlagt ingick 1029 elfiskelokaler från kalkade vatten och 195 lokaler från okalkade referensvattendrag (totalt 17 492 elfisketillfällen). Referensvattendragen har utgående från pH och alkalinitet indelats i sura, neutrala och kalkrika.   

    Totalt fångades 38 fiskarter, 2 kräftarter och 2 fiskhybrider vid elfiskena. Den vanligaste arten var öring som erhölls vid 90 % av elfisketillfällena, därefter kom elritsa (33 %) och stensimpa (24 %).  Den vattenkemiska effekten har inte utvärderats närmare, men det förelåg en tydlig effekt på pH av kalkning och efter 5-8 års kalkning var lägsta uppmätta pH signifikant över 6,0 som medelvärde för samtliga kalkade vatten. Andelen tillfällen med sura episoder (pH <6,0 respektive pH <5,6) minskade över tid. De vattendrag där det var svårast att upprätthålla pH över 5,6 hade små avrinningsområden (<10 km2), låg andel sjö och en låg kalkdos.   

    Kalkning med doserare uppvisade en högre frekvens av sura episoder jämfört med sjö- och våtmarkskalkning. Efter ett antal år fungerade doserarkalkningen bättre, ofta efter att den kombinerats med våtmarkskalkning.  Resultaten från 30 års elfisken visar att kalkningsverksamheten successivt har nått förväntade resultat. Antalet fångade fiskarter ökade signifikant efter kalkstart och efter 13-16 år hade antalet nått nivån i neutrala referenser. På de kalkade lokalerna ökade 13 av 14 undersökta arter i förekomst och 8 av dessa signifikant: abborre, bergsimpa, braxen, gädda, lake, lax, mört och öring.   

    Andel elfisketillfällen med konstaterad reproduktion, dvs. förekomst av årsungar, ökade signifikant efter kalkning och nådde samma nivåer som i neutrala referenser för öring, lax, stensimpa, elritsa, gädda, lake och mört. För öring tog det över 12 år efter kalkstart innan reproduktionen motsvarade den i neutrala referenser.  Den ekologiska statusen förbättrades signifikant. Sju år efter påbörjad kalkning uppnåddes en signifikant förändring i ekologisk status och efter tolv år visade medelvärdet för lokalerna på god ekologisk status.   

    Sammantaget visade resultaten på en normalisering av fiskfaunan på kalkade lokaler. Genomgående var fiskfaunan signifikant skild från den i sura referenser och blev med tiden alltmer lik den i neutrala referenser, men var fortfarande klart skild från den i kalkrika referenser.  Det var tydligt att återkolonisationen av arter tog lång tid, vilket innebär att kalkningsverksamheten måste vara långsiktig. På lokaler med vattenkemisk provtagning minst fyra gånger under året undersöktes effekten av årets lägsta uppmätta pH på fisk. I neutrala referensvattendrag konstaterades reproduktion av öring vid i medeltal 82,8 % av elfisketillfällena. I kalkade vattendrag ökade andelen tillfällen med öringreproduktion med uppmätt lägsta pH. Ett lägsta pH på 5,6-5,9 låg i underkant för en reproduktion som i neutrala referenser, medan ett lägsta pH på 6,0-6,2 låg i överkant. Även för flera andra arter ökade andelen elfisketillfällen då reproduktion konstaterades med ökat lägsta uppmätta pH, t ex för elritsa, lax och simpor (berg- och stensimpa sammantaget). För elritsa krävdes ett lägsta pH på 6,0-6,2 för att nå reproduktion som i neutrala referenser, för simpor krävdes över 6,2.   

    Ekologisk status är ett index som visar om fiskfaunan liknar den i opåverkade vatten. Medelvärdet för ekologisk status i neutrala referenser var 0,52. På kalkade lokaler där lägsta uppmätta pH under året understeg 6,0 var den ekologiska statusen signifikant lägre än i neutrala referenser. På kalkade lokaler som hade ett uppmätt lägsta pH på minst 6,0 var den ekologiska statusen högre och likvärdig med den i neutrala referenser.  Vår slutsats är att i försurade vattendrag innebär ett mål för lägsta pH på 5,6 en betydande risk att en normaliserad fiskfauna inte uppnås. Vi anser att målet för kalkningsverksamheten ska vara en normalisering av flora och fauna och utgående från fisk bör lägsta tillåtna pH därför sättas till minst 6,0.

  • 5.
    Leonardsson, Kjell
    et al.
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Wildlife, Fish, and Environmental Studies.
    Ericson, Ylva
    Olsson, Jens
    Bergström, Lena
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Optimerad övervakning av fisk i kustvatten2016Report (Other academic)
    Abstract [sv]

    Kustfisk övervakas årligen inom den samordnade nationella och regionala miljöövervakningen, som idag omfattar 16 områden längs Sveriges kust. Provfisken i Östersjön sker med nätfisken och provfisken i Skagerrak, Kattegatt och Öresund med ryssjor. Provfiskena syftar till att beskriva förändringar i fisksamhället när det gäller artsammansättning, relativ förekomst av olika arter och storleksstruktur. Resultaten rapporteras i förhållande till regionala och nationella miljömål, samt internationellt inom havsmiljödirektivet. Därtill används data från kustfiskövervakningen som underlag för fiskerirådgivningen av nationellt förvaltade arter.

    Kustfisk ingår inte som ett obligatoriskt element i vattendirektivet, med undantag för fisk i övergångsvatten som inte finns i Sverige. Det är dock önskvärt att de metoder som används för att bedöma status för kustfisk är harmoniserade med vattendirektivets bedömningsgrunder, så att man så långt som möjligt kan göra helhetsbaserade bedömningar för kustområdet baserat på resultat från bedömningar enligt båda direktiven. 

    De huvudsakliga frågeställningarna för denna utvärdering har varit hur kustfiskövervakningen bäst kan anpassas för att kunna upptäcka förändringar över tiden samt för att få så säkra skattningar som möjligt av de parametrar som undersöks. Utvärderingen har fokuserat på provfisken med Nordiska kustöversiktsnät och ryssjor. I tillägg har provfisken utförda med kustöversiktsnät och nätlänkar enligt äldre standarder analyserats, eftersom dessa är i fortsatt användning i vissa områden. Vid utvärderingen har traditionella metoder för skattning av varianskomponenter, beräkning av statistisk styrka, samt beräkning av den relativa osäkerheten i medelvärdesskattningar använts. Utvärderingen har utförts med avseende på de parametrar som idag används inom rapporteringen av resultat från miljöövervakningen i form av faktablad, och på indikatorer som används eller föreslås för rapportering av god miljöstatus enligt havsmiljödirektivet.   

    Slutsatser från analysen

    1. Merparten av de provtagningsprogram som utvärderats har en relevant precision i årsmedelvärdena för de flesta av de parametrar som utvärderats.

    2. Osäkerheten i områdesmedelvärdena var dock hög för parametrar som syftar mäta abundansen av stor fisk inom enskilda arter, såsom torsk (>38 cm), gös (>40 cm) och skrubbskädda (>30 cm). De nätfisken och ryssjefisken som utvärderats i denna rapport framstår därför som otillräckliga metoder för att mäta dessa.

    3. Mellanårsvariationen var stor för flera av parametrarna i de flesta programmen, vilket innebär att möjligheterna är små att upptäcka en årlig trend på fem procent inom en tioårsperiod. En trend med den storleken överskuggas ofta av den naturliga mellanårsvariationen i provtagningsresultaten. Denna variation kan inte reduceras med ändrad provtagningsdesign eller -frekvens. En möjlighet att minska mellanårsvariansen i samband med utvärderingar är att använda hjälpvariabler, alternativt använda populationsmodeller Ett annat alternativ kunde vara att analysera resultaten sett över större områden eftersom dynamiken var relativt oberoende mellan undersökningsområdena. Man kunde härigenom få en ökad möjlighet att se förändringar över tiden med hjälp av dessa områdens gemensamma årsmedelvärden. I valet av analysmetod måste man dock även beakta vad som är en biologiskt och förvaltningsmässigt relevant skala för rapportering.

    4. Provfisken med Nordiska kustöversiktsnät efter varmvattenarter framstod överlag som väldimensionerade. Det skulle dock gå att förbättra precisionen inom dessa fisken genom att fokusera provtagningen till de djupstrata där mängden och variationen av varmvattenarterna är som störst, det vill säga i djupintervallet 0-10 m.

    5. Provfisken med kustöversiktnät och nätlänkar skulle kunna förbättras för att få ökad precision i medelvärdena genom att allokera om en del av provtagningsresurserna för att utöka antalet stationer. I dessa fisken använder man idag ett fåtal fasta stationer som återbesöks upprepade gånger inom säsong. Dessa upprepade nätfisken visade sig leda till beroende observationer mellan de upprepade fiskena, vilket ger problem med replikathanteringen.

    6. Upprepade provfisken med småryssjor på västkusten var inte behäftade med samma problem med beroende observationer. Ryssjefiskena vid Kullen (Skälderviken), Fjällbacka och Älgöfjorden (Stenungsund) hade en lämplig avvägning mellan antal stationer och replikat. En viss förbättring skulle kunna erhållas för fisket i Fjällbacka genom att omfördela en del resurser från replikat till stationer. Precisionen i resultaten från ryssjefiskena vid Barsebäck och Vendelsö skulle kunna förbättras avsevärt genom att ändra provtagningsdesignen till att bli mer lik den som används vid Kullen och Älgöfjorden.

    7. Provfisken efter kallvattenarter ger i flera fall lägre fångster per ansträngning och sämre precision för kallvattenarterna jämfört med för samma arter i fiskena efter varmvattenarter. Det finns därför ett behov att se över metodiken för fisket efter kallvattenarter för att undersöka om den går att förbättra. 8. Det främsta behovet inom kustfiskövervakningen idag är att öka tätheten av de områden som provfiskas. För en uppföljning av god miljöstatus enligt havsmiljödirektivet behövs en komplettering framför allt med provfiskeområde i Gotlands och västra Bornholmsbassängens kustområden. Ytterligare områden som bör beaktas för att uppnå förtätning kan identifieras på basen av figur 5b-5d i denna rapport.

  • 6.
    Olsson, Jens
    et al.
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Jonsson, Anna-Li
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Duberg, Jon
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lingman, Anna
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Naddafi, Rahmat
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Förlin, Lars
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Parkkonen, Jari
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Larsson, Åke
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Asker, Noomi
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Sturve, Joachim
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Ek, Caroline
    Perfomers of environmental monitoring, Government Agencies, Swedish Museum of Natural History, NRM.
    Faxneld, Suzanne
    Perfomers of environmental monitoring, Government Agencies, Swedish Museum of Natural History, NRM.
    Nyberg, Elisabeth
    Perfomers of environmental monitoring, Government Agencies, Swedish Museum of Natural History, NRM.
    Miljön i Hanöbukten 2015-2017: finns det ett samband mellan tillståndet för fisken, dess hälsa och belastningen av miljöfarliga ämnen?2018Report (Other academic)
    Abstract [sv]

    Under slutet av 2000-talet inkom flertalet rapporter från allmänheten och fiskare i de västra delarna av Hanöbukten om låga förekomster av fisk, förekomst av sårskadad fisk och illaluktande vatten i området. Den här rapporten sammanfattar resultaten och slutsatserna från undersökningar i Västra Hanöbukten utförda under 2015-2017 med syfte att undersöka eventuella samband mellan miljöfarliga ämnen och fiskhälsa, samt orsakerna till uppkomsten av sårskadad fisk i området. Därtill presenteras resultaten från provfisken utförda i syfte att kartlägga bestånden av kustfisk i området. Följande fyra frågeställningar besvaras:  

    Vilka eventuella samband mellan miljöfarliga ämnen och fiskhälsa har framkommit?  

    Vilka orsaker till uppkomst av sårskadad fisk har dokumenterats?  

    Vilka resultat har kartläggningen av kustfiskbestånd, miljöfarliga ämnen respektive fiskhälsa lett till?  

    Vilka slutsatser kan dras gällande vilka arter och storleksklasser som påverkas mest av miljöfarliga ämnen?  

    Resultaten från analyserna av miljöfarliga ämnen i skrubbskädda och torsk visar inte på några generellt förhöjda halter av miljöfarliga ämnen i Västra Hanöbukten under 2015-2016 i jämförelse med referensstationerna Kvädöfjärden och Torhamn (Östra Hanöbukten, skrubbskädda) och sydöstra Gotland (torsk). För några miljögifter såsom DDE och PFOS var halterna hos skrubbskädda något högre i Västra Hanöbukten än i Kvädöfjärden, men halterna ligger under gränsvärden för båda dessa ämnen och inom den naturliga variation som är förväntad med hänsyn till inom- och mellanårsvariation i referensstationer. För torsk visade resultaten att sårskador som antas vara orsakade av nejonöga från Hanöbukten hade högre halter av PCB:er, DDT och dess metaboliter, bromerade flamskyddsmedel och PFAS (poly- och perfluorerade ämnen) jämfört med fiskar utan sårskador i området. Om de högre halterna av miljögifter i sårskadad fisk är ett resultat av lägre kondition och fettvikt hos fisken till följd av sårskadorna eller om gifterna i sig påverkar fisken negativt är idag oklart. För torsk med okända sårskador från Hanöbukten kunde ingen koppling göras mellan uppkomst av sårskador och de analyserade miljögifterna.  

    Undersökningarna av skrubbskäddans hälsa i Västra Hanöbukten visade på tydliga fysiologiska skillnader mellan skrubbskädda som fångats i området jämfört med referenslokalen Kvädöfjärden under 2015. Dessa skillnader kan tyda på påverkan av miljögifter. Men de undersökningar som genomfördes under 2016 och 2017 kunde emellertid inte belägga dessa tydliga skillnader när fisk från Västra Hanöbukten jämfördes med den från referensområdet Torhamn i östra Blekinge. Histopatologiska undersökningar på fisk insamlade 2017 visade även att fiskarna i Västra Hanöbukten är relativt friska. Orsaken till de möjligen episodiskt förekommande förändringarna av fiskens hälsotillstånd i Västra Hanöbukten under 2015 är inte känd, men kan vara ett resultat av variation mellan områden i olika omgivningsfaktorer som födotillgång och/eller vattentemperatur. Det kan dock inte uteslutas att de förändringarna i skrubbskädda som observerats kan vara orsakade av ett eller flera miljöfarliga ämnen som inte ingått i undersökningarna som presenteras i denna rapport.  

    Resultaten från provfiskena visar att fisksamhällets struktur och funktion i de västra delarna av Hanöbukten under 2015-2017 inte avviker i jämförelse med tidigare undersökningar i området och andra kustområden i södra Östersjön. Torsk och skrubbskädda är vanliga arter i fisksamhället i Västra Hanöbukten. Även om fångsterna av arterna generellt var låga i provfiskena under 2015-2017, avviker de inte tydligt från tidigare undersökningar i området och i andra kustområden i södra Östersjön utan speglar sannolikt förändringar under senare år i beståndssituationen för arterna i   Östersjön. Emellertid var också konditionen hos torsk och skrubbskädda låg i de västra delarna av Hanöbukten under 2015-2017, och det finns en antydan till lägre kondition hos båda arterna jämfört med andra kustområden i södra Östersjön som möjligen kan tyda på låg födotillgång i området. Frekvensen av fisk (framförallt torsk och skrubbskädda) med yttre fysiska avvikelser såsom bett, sårskador och deformationer verkar vara något förhöjd i Västra Hanöbukten jämfört med andra områden längs den svenska kusten. De typiska frätskador som allmänheten rapporterat i området kunde inte påvisas i provfiskena, och hudsår delvis sannolikt orsakade av andra djur som säl och nejonöga dominerade de yttre fysiska avvikelserna som noterades. Vad som orsakar övriga avvikelser är idag inte klarlagt, men skulle möjligen kunna kopplas till att fiskens låga kondition gör den mer känslig för yttre påverkan.  Med grund i de utförda undersökningar och erhållna resultat under 2015-2017 har inte några tydliga samband mellan miljöfarliga ämnen, fiskens hälsotillstånd och bestånd dokumenterats i Västra Hanöbukten. Det är därför inte heller möjligt att uttala sig om vilka storleksklasser av fisk som är känsligast för miljöfarliga ämnen. Förutom angrepp av andra djur som säl och nejonöga, har inte orsaken till de okända skador som observerats på fisken kunnat fastställas. Med utgångspunkt i de resultat som idag finns tillgängliga, kan det dock inte uteslutas att den avvikande hälsan hos skrubbskäddan i Västra Hanöbukten under 2015 och vissa av de yttre fysiska avvikelserna som noterades hos fisken under provfiskena kan ha orsakats av miljöfarliga ämnen.   Undersökningarna i Västra Hanöbukten under 2015-2017 har bidragit till en ökad kunskap om tillståndet för fisken i området gällande miljögiftsbelastning, hälsa, samhälle och bestånd, och huruvida det nuvarande tillståndet avviker från andra delar av Östersjön. Systemet i de västra delarna av Hanöbukten är relativt unikt i Sverige, med en öppen kust mot södra Östersjön, och informationen som presenteras i denna rapport bör utgöra en grund för en långsiktig miljöövervakning av fisken i området. En långsiktig miljöövervakning i Västra Hanöbukten medger även en framtida bedömning av miljötillståndet i området, och möjliggör samtidigt upptäckt och dokumentation av episodiska fenomen som påverkar fisksamhällets struktur och funktion, samt fiskens individuella hälsa och belastning av miljöfarliga ämnen.

  • 7.
    Olsson, Jens
    et al.
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lingman, Anna
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Jonsson, Anna-Li
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Förlin, Lars
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Hanson, Niklas
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Larsson, Åke
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Parkkonen, Jari
    Perfomers of environmental monitoring, Universities, University of Gothenburg, GU, Department of Biological & Environmental Sciences.
    Faxneld, Suzanne
    Enheten för miljöforskning och övervakning på Naturhistoriska Riksmuseet.
    Ljunghager, Fredrik
    Swedish Agency for Marine and Water Management.
    Miljöövervakning i Hanöbukten – finns det ett samband mellan tillståndet för fisken, dess hälsa och belastningen av miljöfarliga ämnen?: Delrapport 20162016Report (Other academic)
    Abstract [sv]

    Överlag fanns det inte några övergripande skillnader i de beståndsparametrar som undersökts jämfört med tidigare undersökningar i området. Det fanns heller inga tecken på avvikande fångster utanför Helgeås mynning och endast tecken på syrebrist vid en lokal under den undersökta perioden. Det observerades en något förhöjd sjukdomsfrekvens hos fiskar i Hanöbukten. De bakomliggande orsakerna till den förhöjda sjukdomsfrekvensen i området är inte klarlagd, men pekar på en yttre påverkan på individ-, men inte på bestånds- eller samhällsnivå hos fisken.

    Resultaten från undersökningarna av fiskars hälsotillstånd visar på flera mycket tydliga fysiologiska skillnader hos fiskarna mellan Hanöbukten och referensområdet Kvädöfjärden. Tolkningen kompliceras av det faktum att de två jämförda populationerna av skrubbskädda anses ha olika lekstrategier vilket kan ha påverkat främst fysiologiska mätvariabler som ska spegla fortplantningfunktionen. Det är dock viktigt att betona att det är mycket unikt att två populationer av samma fiskart som fångats vid samma tidpunkt på året uppvisar så stora skillnader i fysiologiska hälsovariabler mellan två områden. Det kan därför inte uteslutas att de observerade skillnaderna för flera hälsovariabler är en indikation på att fiskarna i Hanöbukten är exponerade för något eller några toxiska ämnen. 

    Resultaten från miljögiftsundersökningen visar att det inte är några förhöjda halter av metaller, PCB:er, bromerade flamskyddsmedel och dioxiner i skrubbskäddor från Hanöbukten jämfört med Kvädöfjärden. DDT, kvoten DDT/DDE och PFOS var däremot något högre i Hanöbukten. Resultat från övervakning av sill i Hanöbukten visar också att PFOS och några andra perfluorerade ämnen är förhöjda jämfört med de flesta andra övervakningslokaler i Östersjön. 

    Sammantaget ger inte fiskundersökningarna under 2015 några belägg för effekter på beståndsnivå. Däremot observerades effekter på fisk i Hanöbukten på individnivå, såsom svagt förhöjd sjukdomsfrekvens hos torsk och skrubbskädda samt tecken på hälsoeffekter hos skrubbskädda. Överlag fanns inga förhöjda halter av miljögifter, men det observerades en förhöjd halt av DDT och PFOS och en högre DDT/DDE kvot hos skrubbskädda i området. Fortsatta fiskundersökningar under hösten 2016 syftar till att säkerställa att observerade skillnader/effekter är bestående, samt att försöka belysa vilken betydelse de olika populationernas fortplantningsstrategi respektive rådande miljögiftsbelastning i området har för de observerade hälsoeffekterna hos skrubbskädda i Hanöbukten.

  • 8. Sallmén, Niina
    et al.
    Nathanson, Jan Eric
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Palm, Stefan
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Åtgärdsprogrammet för asp: Aspius aspius2016Report (Other academic)
    Abstract [en]

    This action programme aims to improve the future survival of asp (Aspius aspius) in Sweden. It is to be viewed as a guideline, and is not legally binding. Asp is a nationally red-listed species, categorized as Near Threatened (NT). It is included in Appendix 2 in the EU’s Habitats Directive, which means that the member states are obligated to identify sites of community importance (SCIs), also known as Natura 2000 areas, in order to preserve the species and its habitat. Asp is also listed in Appendix 5, meaning that Sweden must ensure that exploitation is compatible with maintaining the species in a favourable conservation status.  The current distribution of asp is largely limited to Lake Vänern and the river Göta älv, the lakes Hjälmaren and Mälaren and their respective inflowing water sources, and the river system of Motala ström. Small populations are found in the rivers Emån and Dalälven, as well as in the lake Garnsviken, where the species is vulnerable. Individual specimens may be found temporarily along the Baltic Sea coastline.  The decline can be attributed to physical impact on the waterways and the expansion of hydroelectric industry. These interferences have greatly reduced the number of spawning grounds while, simultaneously, migration obstacles have resulted in isolation of populations. Extensive straightening, dredging and modification of natural waterways have destroyed several important spawning grounds and nursery areas. In former times, fishing for migrating and spawning asp was of great importance.  

    The asp usually migrates upstream to areas with turbulent water for spawning, but may also migrate downstream. The spawning mainly occurs for the duration of a little over one week, usually in the second half of April.  During the 21st century, a lot of effort has been put in to mapping the species’ distribution and spawning grounds. In order to ascertain a complete view of the status of the populations, additional inventory in the river systems of e.g. Byälven, Arbogaån and Kolbäcksån is advised. Furthermore, investigation into the extent of spawning in lakes such as Mälaren, Hjälmaren and Vänern should be conducted. The knowledge of nursing areas is inadequate, and it is of great importance that these are recorded.  Since the year 2001 it is forbidden (FIFS 2004:37) to fish for asp between April 1st and May 31st in all watercourses joining with the lakes Vänern, Mälaren and Hjälmaren, as far as the first real migration obstacle. The legislation is in need of revision and updating in order to similarly protect migrating and spawning fish in lakes, fish above the first real migration obstacle, and the weaker populations in rivers Emån and Dalälven.  

    In order to improve compliance with the given restrictions and describe how the species is best handled in bycatch, the information to professional fishermen, sports fishermen and owners of fishing waters should be improved upon.  Havs- och vattenmyndighetens rapport 2016:27  11 Important actions to strengthen the population are: construction of fish passage structures and demolition of obstacles, suitable protocols at hydropower plants and restauration of spawning grounds and nursery areas. In pressing cases where physical action has not provided the desired effect, re-establishment by manual release may be considered.  The cost is estimated to SEK 34 390 000.  

  • 9.
    Sandström, Alfred
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Harr i Bottniska viken: en kunskapssammanställning2017Report (Other academic)
    Abstract [en]

    Coastal populations of European grayling (Thymallus thymallus, L.) are unique to the Bothnian Bay. There are two main population types, one that spawns in the sea and spend the entire life-cycle in brackish water. The other form is anadromous, spawns and recruits in rivers that drain into the sea. The main distribution area at present is in the Swedish northern coastal areas in the Gulf of Bothnia in the counties of Västerbotten and Norrbotten.   

    There are many critical knowledge gaps as concerns coastal grayling populations. There is, nevertheless, a general consensus that the coastal populations have declined markedly over the last 100 years, particularly in Swedish areas south of the Northern Quark and along the Finnish coast. The main knowledge gaps that need to be mitigated have been identified and listed:  

    • grayling population structure

    • ecology and life-history traits

    • influence of fisheries

    • methods for assessing the status of coastal grayling populations

    • distribution and characteristics of grayling essential habitats

    • development of targeted restoration efforts in grayling rivers adapted to the specific needs of grayling  

    The text summarises the available literature on coastal grayling. It also gives examples of methods that can be used for improving the knowledge of coastal grayling, its habitats and the current management of the stocks.

  • 10.
    Sandström, Alfred
    et al.
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Bryhn, Andreas
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Sundelöf, Andreas
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lingman, Anna
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Florin, Ann-Britt
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Petersson, Erik
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Vitale, Francesca
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Sundblad, Göran
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Wickström, Håkan
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Ahlbeck Bergendahl, Ida
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lövgren, Johan
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lundström, Karl
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Edsman, Lennart
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Wennerström, Lovisa
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Ogonowski, Martin
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Ulmestrand, Mats
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Cardinale, Massimiliano
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Lindmark, Max
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Bergenius, Mikaela
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Naddafi, Rahmat
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Fredriksson, Ronny
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Bergek, Sara
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Larsson, Stefan
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Axenrot, Thomas
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Dekker, Willem
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Hekim, Zeynep
    Perfomers of environmental monitoring, Universities, Swedish University of Agricultural Sciences, SLU, Aquatic Resources.
    Fisk- och skaldjursbestånd i hav och sötvatten 2018: Resursöversikt2019Report (Other academic)
    Abstract [sv]

    Den 14:e utgåvan av den samlade resursöversikten av fisk- och kräftdjursbeståndens status i våra vatten.

    I rapporten kan du ta del av bedömningen som görs av situationen för bestånd som regleras inom ramen för EU:s gemensamma fiskeripolitik (GFP). Bedömningarna baseras på det forskningssamarbete och den rådgivning som sker inom det Internationella Havsforskningsrådet (ICES).

    De bestånd som förvaltas nationellt baseras på de biologiska underlagen, och rådgivningen i huvudsak på den forskning och övervakning samt analys som bedrivs av Institutionen för akvatiska resurser vid Sveriges lantbruksuniversitet (SLU Aqua) samt yrkesfiskets rapportering.

    Rapporten omfattar 41 fiskarter och åtta skaldjursarter.

    Nytt för i år är att flodkräftan och signalkräftan har fått egna presentationer. Vi har även ett nytt kapitel "Hållbarhetsbedömning av fisk- och skaldjursbestånd i havsområden runt Sverige”. Det består av en sammanfattning av den årliga bedömningen av hållbarheten i nyttjandet av fisk- och skaldjursbestånd i kust och hav runt Sverige. Bedömningenär baserad på de senaste tre åren vilket möjliggör en jämförelse över tid iantalet hållbart nyttjade bestånd. Jämförelsen visar inga tydliga förändringar över de senaste tre åren.

    Det finns ett nytt avsnitt i kapitlet ”Från biologi till förvaltning” om hur Havs- och vattenmyndighetens tillståndsgivning går till, och hur bedömningen baseras på resursöversikten vid ansökan om fiskelicens eller annan tillståndsgivning. Kapitlet har också utökats med ett avsnitt där SCB:s fritidsfiskeundersökning beskrivs och hur resultatet används i beståndsanalyserna.

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