| 1. |
- Bergström, Ulf, et al.
(författare)
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Long-term effects of no-take zones in Swedish waters
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Marine protected areas (MPAs) are increasingly established worldwide to protect and restore degraded ecosystems. However, the level of protection varies among MPAs and has been found to affect the outcome of the closure. In no-take zones (NTZs), no fishing or extraction of marine organisms is allowed. The EU Commission recently committed to protect 30% of European waters by 2030 through the updated Biodiversity Strategy. Importantly, one third of these 30% should be of strict protection. Exactly what is meant by strict protection is not entirely clear, but fishing would likely have to be fully or largely prohibited in these areas. This new target for strictly protected areas highlights the need to evaluate the ecological effects of NTZs, particularly in regions like northern Europe where such evaluations are scarce. The Swedish NTZs made up approximately two thirds of the total areal extent of NTZs in Europe a decade ago. Given that these areas have been closed for at least 10 years and can provide insights into long-term effects of NTZs on fish and ecosystems, they are of broad interest in light of the new 10% strict protection by 2030 commitment by EU member states.In total, eight NTZs in Swedish coastal and offshore waters were evaluated in the current report, with respect to primarily the responses of focal species for the conservation measure, but in some of the areas also ecosystem responses. Five of the NTZs were established in 2009-2011, as part of a government commission, while the other three had been established earlier. The results of the evaluations are presented in a synthesis and also in separate, more detailed chapters for each of the eight NTZs. Overall, the results suggest that NTZs can increase abundances and biomasses of fish and decapod crustaceans, given that the closed areas are strategically placed and of an appropriate size in relation to the life cycle of the focal species. A meta-regression of the effects on focal species of the NTZs showed that CPUE was on average 2.6 times higher after three years of protection, and 3.8 times higher than in the fished reference areas after six years of protection. The proportion of old and large individuals increased in most NTZs, and thereby also the reproductive potential of populations. The increase in abundance of large predatory fish also likely contributed to restoring ecosystem functions, such as top-down control. These effects appeared after a 5-year period and in many cases remained and continued to increase in the longer term (>10 years). In the two areas where cod was the focal species of the NTZs, positive responses were weak, likely as an effect of long-term past, and in the Kattegat still present, recruitment overfishing. In the Baltic Sea, predation by grey seal and cormorant was in some cases so high that it likely counteracted the positive effects of removing fisheries and led to stock declines in the NTZs. In most cases, the introduction of the NTZs has likely decreased the total fishing effort rather than displacing it to adjacent areas. In the Kattegat NTZ, however, the purpose was explicitly to displace an unselective coastal mixed bottom-trawl fishery targeting Norway lobster and flatfish to areas where the bycatches of mature cod were smaller. In two areas that were reopened to fishing after 5 years, the positive effects of the NTZs on fish stocks eroded quickly to pre-closure levels despite that the areas remained closed during the spawning period, highlighting that permanent closures may be necessary to maintain positive effects.We conclude from the Swedish case studies that NTZs may well function as a complement to other fisheries management measures, such as catch, effort and gear regulations. The experiences from the current evaluation show that NTZs can be an important tool for fisheries management especially for local coastal fish populations and areas with mixed fisheries, as well as in cases where there is a need to counteract adverse ecosystem effects of fishing. NTZs are also needed as reference for marine environmental management, and for understanding the effects of fishing on fish populations and other ecosystem components in relation to other pressures. MPAs where the protection of both fish and their habitats is combined may be an important instrument for ecosystembased management, where the recovery of large predatory fish may lead to a restoration of important ecosystem functions and contribute to improving decayed habitats.With the new Biodiversity Strategy, EUs level of ambition for marine conservation increases significantly, with the goal of 30% of coastal and marine waters protected by 2030, and, importantly, one third of these areas being strictly protected. From a conservation perspective, rare, sensitive and/or charismatic species or habitats are often in focus when designating MPAs, and displacement of fisheries is then considered an unwanted side effect. However, if the establishment of strictly protected areas also aims to rebuild fish stocks, these MPAs should be placed in heavily fished areas and designed to protect depleted populations by accounting for their home ranges to generate positive outcomes. Thus, extensive displacement of fisheries is required to reach benefits for depleted populations, and need to be accounted for e.g. by specific regulations outside the strictly protected areas. These new extensive EU goals for MPA establishment pose a challenge for management, but at the same time offer an opportunity to bridge the current gap between conservation and fisheries management.
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| 2. |
- Fredriksson, Susanna, et al.
(författare)
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Inventering och kartläggning av blåmusselbottnar i Blekinge hösten 2015
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- På uppdrag av Länsstyrelsen i Blekinge län inventerades under hösten 2015 förekomst av blåmusslor i tre kustområden i Blekinge. Syftet var att öka kunskapen om skyddsvärda marina miljöers utbredning i utomskärsområden utanför Ronneby, Utklippan och längs Ostkusten inför eventuellt inrättande/utvidgning av områdesskydd. Totalt besöktes 130 nya lokaler vilka filmades med drop-video. Filmerna analyserades med avseende på bottentyp samt förekomst och täckningsgrad av olika arter av växter och djur. Data modellerades därefter tillsammans med resultat från tidigare undersökningar för att få en säkrare prediktion av blåmusslans utbredning i de tre områdena.Resultaten från inventeringen visar att de högsta tätheterna av blåmusslor finns i området runt Utklippan, där musslor täcker i stort sett allt lämpligt bottensubstrat. De tätaste bestånden finns på djup mellan 10 och 20 meter, vilket även stöds av habitatmodelleringen. De faktorer som bidrog mest till modellens förklaringsgrad var djup och vågexponering. I Ronnebyområdet är tätheten av blåmussla inte lika hög, men i den inre delen av det undersökta området, där grovt substrat (häll, block, stor sten) dominerar, identifierades flest arter av rödalger, och även flera arter av fisk, bland annat torsk, flundra, sjustrålig-, svart och svartmunnad smörbult. Längs Ostkusten dominerar sand och grus över stora ytor, redan från 12 m djup, vilket gör att utbredningen av fastsittande organismer är begränsad. På Helcoms rödlista över hotade habitat klassas rev i Östersjön som sårbara. Rev definieras som grundområden med grovt substrat som hyser blåmusslor och fleråriga alger, och omges av djupare bottnar. Detta habitat förekommer utanför Utklippan och i de inre delarna av det undersökta området vid Ronneby, vilket gör att dessa miljöer bedöms vara extra skyddsvärda.
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| 3. |
- Andersson, Jan, et al.
(författare)
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Inventering och modellering av fisk- och kräftdjurssamhället i Stigfjorden sommaren 2012
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Under 31 juli-3 augusti 2012 utförde Kustlaboratoriet vid SLU Aqua ett inventeringsfiske med småryssjor i Stigfjorden mellan Orust och Tjörn med syfte att beskriva fisksamhället i fjorden och att kartlägga viktiga fiskhabitat. Totalt fiskades 80 stationer på djup från ytan ner till 20 m. Området uppvisade ovanligt höga tätheter av juvenil rödspotta, gråsej och torsk. Även fångsterna av stensnultra och tånglake var höga, och bland kräftdjuren dominerade strandkrabban. Resultaten från Stigfjorden jämförs med resultat från tidigare och samtida undersökningar av samma karaktär. Den rumsliga fördelningen av olika arter i förhållande till habitatet beskrevs statistiskt med hjälp av generella additiva modeller, där fångsterna i ryssjorna relateras till data på olika miljövariabler. De statistiska modellerna i kombination med kartor över miljövariabler i området användes sedan för att i GIS producera heltäckande kartor över potentiella habitat för arterna. De arter som modellerades var torsk <18 cm, torsk >18 cm, ål, rödspotta, vitling, stensnultra, tånglake och strandkrabba. Modellernas förklaringsgrad var generellt god, och vattendjup utgjorde den variabel som var viktigast för fördelningen av de flesta arter. Ungtorsk och rödspotta förekom i högst tätheter i de djupare delarna av fjorden, medan gulål, tånglake och strandkrabba, där de två förstnämnda tillsammans med torsken är rödlistade, främst återfanns i de grunda delarna av fjorden. Sammantaget tyder resultaten på att Stigfjorden håller viktiga livsmiljöer för ett flertal fiskarter, framför allt som uppväxtområde för arter som t ex rödspotta och gråsej.
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| 4. |
- Bergström, Lena, et al.
(författare)
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Fish community responses to restoration of a eutrophic coastal bay
- 2024
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 53, s. 109-125
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Tidskriftsartikel (refereegranskat)abstract
- Interest in coastal restoration measures is increasing, but information about subsequent ecosystem recovery processes is limited. In Bjornofjarden on the Baltic Sea coast, Stockholm archipelago, a pioneering case study to reduce coastal eutrophication led to improvements and initially halved phosphorus levels. Here, we evaluate the effects of the restoration on the local fish assemblage over one decade after the measures. The study gives a unique possibility to evaluate responses of coastal fish to nutrient variables and abatement in a controlled natural setting. Cyprinid abundance decreased and perch partially increased with decreasing turbidity levels, while mean trophic level increased over time in the restored area. Responses were overall weak, likely attributed to an attenuation of the eutrophication abatement effect over time. The results suggest that nutrient reduction gives slow responses in fish compared to alternative measures such as fishing closures.
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| 5. |
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| 6. |
- Bergström, Ulf, et al.
(författare)
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Planning the Bothnian Sea : Outcome of Plan Bothnia - a transboundary Maritime Spatial Planning Pilot in the Bothnian Sea
- 2012
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- In all parts of the world the sea is a source of life, of energy, of food, of commerce, of fun. Its water, wind, and waves are all in demand – as a playground for pleasure-seekers and nature-lovers, as a highway for international commerce, as a home for unique communities of wildlife and people. All this is also true for the Bothnian Sea, a part of the northern European Baltic Sea between Finland and Sweden. The Bothnian Sea is used by two neighbouring highly developed societies. There are many demands on its resources, and its open spaces are highly coveted areas for developments such as wind power farms. This relatively sparsely habitated corner of the world is also, at least at times, a place of wild seas and ancient heritage. Like planning on land, maritime spatial planning is a process that has to incorporate ideals of the public good and the various politically-anchored ways to define this, taking in to account private development interests as well as the physical realities of limited natural resources and fragile ecosystems. This book provides an introduction to the Bothnian Sea and the ideas around maritime spatial planning for its offshore areas. We have tried to present a balance between the perspectives of competing interests. As this has been a pilot initiative, we have not aimed to give you ready answers, but instead try to provoke further debate. The Bothnian Sea and its future are in your hands. The editor
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| 7. |
- Bergström, Ulf, et al.
(författare)
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Predation and spatial connectivity interact to shape ecosystem resilience to an ongoing regime shift
- 2024
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Ingår i: Nature Communications. - 2041-1723. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Ecosystem regime shifts can have severe ecological and economic consequences, making it a top priority to understand how to make systems more resilient. Theory predicts that spatial connectivity and the local environment interact to shape resilience, but empirical studies are scarce. Here, we use >7000 fish samplings from the Baltic Sea coast to test this prediction in an ongoing, spatially propagating shift in dominance from predatory fish to an opportunistic mesopredator, with cascading effects throughout the food web. After controlling for the influence of other drivers (including increasing mesopredator densities), we find that predatory fish habitat connectivity increases resilience to the shift, but only when densities of fish-eating top predators (seals, cormorants) are low. Resilience also increases with temperature, likely through boosted predatory fish growth and recruitment. These findings confirm theoretical predictions that spatial connectivity and the local environment can together shape resilience to regime shifts.
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| 8. |
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| 9. |
- Bergström, Ulf, et al.
(författare)
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Stickleback increase in the Baltic Sea - A thorny issue for coastal predatory fish
- 2015
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 163, s. 134-142
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Tidskriftsartikel (refereegranskat)abstract
- In the Baltic Sea, the mesopredator three-spined stickleback (Gasterosteus aculeatus) spends a large part of its life cycle in the open sea, but reproduces in shallow coastal habitats. In coastal waters, it may occur in high abundances, is a potent predator on eggs and larvae of fish, and has been shown to induce trophic cascades with resulting eutrophication symptoms through regulation of invertebrate grazers. Despite its potential significance for the coastal food web, little is known about its life history and population ecology. This paper provides a description of life history traits, migration patterns and spatiotemporal development of the species in the Baltic Sea during the past decades, and tests the hypothesis that stickleback may have a negative impact on populations of coastal predatory fish. Offshore and coastal data during the last 30 years show that stickleback has increased fourfold in the Bothnian Sea, 45-fold in the Central Baltic Sea and sevenfold in the Southern Baltic Sea. The abundances are similar in the two northern basins, and two orders of magnitude lower in the Southern Baltic Sea. The coastward spawning migration of sticklebacks from offshore areas peaks in early May, with most spawners being two years of age at a mean length of 65 mm. The early juvenile stage is spent at the coast, whereafter sticklebacks perform a seaward feeding migration in early autumn at a size of around 35 mm. A negative spatial relation between the abundance of stickleback and early life stages of perch and pike at coastal spawning areas was observed in spatial survey data, indicating strong interactions between the species. A negative temporal relationship was observed also between adult perch and stickleback in coastal fish monitoring programmes supporting the hypothesis that stickleback may have negative population level effects on coastal fish predators. The recent increase in stickleback populations in different basins of the Baltic Sea in combination with negative spatiotemporal patterns and previously observed interactions between stickleback and coastal predatory fish suggests that this species may have gained a key role in the coastal food webs of the Baltic Sea. Through its migrations, stickleback may also constitute an important vector linking coastal and open sea ecosystem dynamics. (c) 2015 Elsevier Ltd. All rights reserved.
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| 10. |
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