| 1. |
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| 2. |
- Ahlbeck Bergendahl, Ida, et al.
(författare)
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Fisk- och skaldjursbestånd i hav och sötvatten 2017 : Resursöversikt
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 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 sju skaldjursarter.Nytt för i år är att vi även beskriver fritidsfisket mer utförligt. Det fisket får allt större betydelse för utvecklingen av många av Sveriges bestånd av fisk- och skaldjur, till exempel sötvattens- och kustlevande arter som abborre, gädda, gös, lax, röding och öring, liksom marina arter som torsk och hummerÖversikten är utarbetad av SLU Aqua på uppdrag av Havs- och vattenmyndigheten.
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| 3. |
- Almqvist, Gustaf, et al.
(författare)
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Report of the Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD)
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ICES Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD), chaired by External Chair Jean-Jacques Maguire, Canada and ICES Chair Marie Storr-Paulsen, Denmark, and attended by two invited external experts Verena Trenkel, France and Meaghan Bryan, USA met in Rostock, Germany, 2–6 March 2015 with 39 participants and six countries represented. The objective of WKBALTCOD was to evaluate the appropriateness of data and methods to determine stock status and investigate meth-ods appropriate to use in the single-stock assessment for the cod stock in SD 22–24 and cod in SD 25–32 in the Baltic. Participants in the workshop were a large group with diverse backgrounds representing the industry, fisheries, NGOs, managers and scientists.The single-stock analytic assessment of the eastern Baltic stock was not accepted by the assessment working group (WGBFAS) in 2014 due to severe problems with the input data. The advice for the eastern Baltic cod was, therefore, based on the ICES approach for data-limited stocks. As an outcome ICES decided to establish a bench-mark for both cod stocks and to scope an integrated assessment for the Baltic cod stocks. The first meeting (WKSIBCA) was therefore meant to introduce the interces-sional work conducted since the assessment working group in April 2014, and to reach some conclusions on how to proceed both in the short term (Benchmark in March 2015) and longer term (2–3 years) and was seen as a data compilation work-shop, there is produced a separate report from this workshop. The WKBALTCOD was the 2nd meeting in the benchmark process and was intended to come up with a final stock assessment method, stock annex and input data for both stocks. As it was not possible to reach conclusive decision on the final model to be used for the east Baltic cod stock during the benchmark meeting and as more work on the preferable models was needed, it was decided by the ACOM leadership to prolong the bench-mark process until the assessment working group meeting in April 2015. This deci-sion has led to a relatively long process partly mixed with the assessment working group WGBFAS.It became clear during the benchmark process that although large effort has been put into explaining the underlying processes leading to the changes in the Baltic ecosys-tem, there is still some lack of understanding of the present situation in the eastern Baltic cod stock. Therefore, it was not possible to reach firm conclusions on the final model to be used and therefore not possible to set reference points. It was decided to continue to explore the most promising models and to continue to improve the input data until the assessment working group started in April.The main challenges still to be solved for the Eastern Baltic cod stock is the quantifi-cation of increased natural mortality and decrease in growth. Through several presentations during the workshop (both WKSIBCA and WKBALTCOD) it became clear that natural mortality very likely has increased in later years, due to decreased condition and increased parasite infection. A decrease in growth also seems plausible duo to a decrease in condition and/or selectivity-induced mortality of the largest in-dividuals. However, as none of these parameters are easily estimated, especially with the severe ageing problems, different model assumptions made the output very shaky.For the western Baltic cod, stock identification issues were examined in area SD 24, the intermediate area: based on otolith characteristics and genetics. Due to the results showing a large proportion of east cod in this area, it was decided to split the catch2 | ICES WKBALTCOD REPORT 2015and survey from SD 24 into either the western or eastern Baltic cod stock. It was pos-sible to derive proportions of eastern and western cod in SD 24 back to the mid-1990s.For the western Baltic cod stock a modelled survey indices was included in the as-sessment covering the western part of SD 24 and Area 22+23 and based on a smoothed ALK.Both cod stocks have in the past used commercial tuning fleet to have a better cov-ered of older age groups. It was decided to abound this time-series duo quality issues such as a limited coverage and problems with technical creeping.WKBALTCOD was not able to explore and define reference points for the Western Baltic cod stock during the meeting due to time constraints, but these were calculated and decided by correspondence after the meeting. The recent protocols on estimation procedures developed by WKMSYREF3 for stocks with a full analytical assessment and for data-limited stocks served as objective guidelines to obtain reference point estimates.
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| 4. |
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| 5. |
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| 6. |
- Belgrano, Andrea, et al.
(författare)
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Överfiske - en miljöfarlig aktivitet : orsaker till fiskbeståndens utarmning och dess konsekvenser i svenska hav
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Bestånden av marina fiskarter har minskat dramatiskt i både Västerhavet och i Östersjön under de senaste 100 åren. Flera olika faktorer påverkar fiskbeståndens storlek, men ett ökande antal studier tyder på att överfiske är en huvudorsak i de flesta fall. Fisket med trål anses också skada många bottenlevande organismer, men det är idag oklart hur omfattande denna miljöpåverkan är. Vidare tyder nya studier på att förlusten av stora rovfiskar kan ge negativa effekter på hela ekosystem genom trofiska kedjereaktioner. Sammantaget anser många forskare idag att fisket utgör ett av de allvarligaste miljöhoten mot svenska hav. Denna rapport sammanställer det vetenskapliga kunskapsläget över orsakerna till nedgången av svenska marina fiskbestånd, samt fiskets roll för minskning av biodiversitet och förändringar i svenska kust- och utsjöekosystem.
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| 7. |
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| 8. |
- Bergenius, Mikaela, et al.
(författare)
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Report of the Baltic Fisheries Assessment Working Group (WGBFAS) : 14-21 April 2015, ICES HQ, Copenhagen, Denmark
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ICES Baltic Fisheries Assessment Working Group (WGBFAS) met 14-21 April 2015 (Chair: Mare Storr-Paulsen, Denmark), with 28 participants and 9 countries represented. The objective of WGBFAS was to assess the status of the following stocks:1 ) Sole in Division IIIa, SDs 20-222 ) Cod in Kattegat, Cod in SD 22-24, Cod in SD 25-323 ) Herring in SD 25-27, 28.2, 29 and 32, Herring in SD 28.1 (Gulf of Riga), Herring in SD 30, Herring SD 31.4 ) Sprat in SD 22-325 ) Plaice 21-23, Plaice 24256 ) Flounder 22-23; 24-25; 26+28 and 27+29-32, Brill 2232, Dab 2232, and Turbot 2232 (survey trends)WGBFAS also identified the data needed, for next year’s data call with some suggestions for improvements in the data call as well as in InterCatch. The report contains an introduction with the summary of other WGs relevant for the WGBFAS, country specific fishery description, the methods used, and ecosystem considerations. The results of the analytical stock assessment or survey trends for the species listed above are then presented with all the stocks with the same species in the same sections. The report ends with references, list of Working Documents, recommendations and Stock Annexes. In first quarter 2015 the Baltic cod stocks and the plaice stocks were benchmarked. As a result the Baltic cod stocks now have to apply a splitting key in SD 24 were both stocks are present. This has changed the assessment from being an area based assessment to now being a stock based assessments and has implications for the advice. The principle analytical models used for the stock assessments were XSA and SAM. For most flatfishes, CPUE trends from bottom trawl surveys were presented (except plaice 2425 and her31 using relative SSB from SAM and XSA, respectively). Ecosystem changes have been analytically considered in the following stock assessments: Herring in SD 25-27, 28.2, 29 and 32, and Sprat in SD 22-32, in form of cod predation mortality. Last year a very large retrospective pattern in the Eastern Baltic cod stock caused that the WG rejected the analytic assessment. Several uncertainties in the data lead to this conclusion i.a age reading problems with large inconsistency between and within nations as well as a change in growth and natural mortality. However, even though a data compilation workshop and a benchmark have been conducted in the intermediate time it was not possible to solve the main issue on growth. The lack of knowledge on growth caused to that even the length based data required in the data call was very uncertain for the models and in the end the WG was not able to produce a better model than was presented last year which is based on survey trends. The Her-30 (Herring in the Botnian Sea) was by the working group down scaled from a category 1 stock to a category 3 stock due to the commercial tuning fleet used in the assessment having very uncertain estimates in the last couples of years. However, during the Baltic ADG an alternative assessment was suggested were the stock is still considered a category 1 stock but the last 8 years of the commercial tuning fleet was terminated. This assessment was conducted after the working group but has been included in the report.
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| 9. |
- Bland, Barbara, et al.
(författare)
-
Expeditionsrapport IBTS, augusti 2016
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Institute of Marine Research is responsible for the trawl survey in the Skagerrak and the Kattegat areas of the North Sea. This survey is conducted twice annually, in quarters 1 and 3. The French bottom trawl GOV is used for sampling demersal species.During this survey a total of 45 valid hauls were towed, 26 hauls in the Skagerrak and 19 in the Kattegat. The catch comprised 57 species of fish. The biological sampling, which includes collection of otoliths for age analysis, was done on the most important commercial species. In total 4 225 otoliths were collected from 11 species.
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| 10. |
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| 11. |
- Bland, Barbara, et al.
(författare)
-
Expeditionsrapport IBTS, augusti 2018
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Havsfiskelaboratoriets trålexpeditioner i Västerhavet (Skagerrak och Kattegatt) genomförs två gånger årligen, i kvartal 1 och 3. Fisket utförs med den franska bottentrålen GOV. Under denna expedition gjordes totalt 45 giltiga tråldrag i hela området, 26 i Skagerrak och 19 i Kattegatt. Som del i IBTS-arbetsgruppens undersökning om ny förkortad standardiserad tråltid och kvantifiering av eventuella fångster under sättning och halning utfördes försök i anslutning till två standardstationer. Totalt fångades 6,9 ton sill, 6,4 ton skarpsill och 160 kg torsk. Viss rekrytering till 0-gruppen i Kattegatt kan ses för sillen; skarpsillen visar en kraftig uppgång vilken domineras av Kattegatts 1-åringar medan torskfångsten var generellt låg med svag rekrytering i både Skagerrak och Kattegatt. Biologiska parametrar på individnivå samlas in på sill- och torskfiskar samt några plattfiskar. Totalt provtogs 3 712 individer från 11 olika arter med avseende på ålder och könsmognad.
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| 12. |
- Bland, Barbara, et al.
(författare)
-
Expeditionsrapport IBTS, augusti 2019
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Havsfiskelaboratoriets trålexpeditioner i Västerhavet (Skagerrak och Kattegatt) genomförs två gånger årligen, i kvartal 1 och 3. Fisket utförs med den franska bottentrålen GOV. Under denna expedition gjordes totalt 45 giltiga tråldrag i hela området, 26 i Skagerrak och 19 i Kattegatt. Totalt fångades 8,4 ton sill, 6,8 ton skarpsill och 69 kg torsk. I Skagerrak visar sillens 0-grupp en markant ökning. Skarpsillen som förra året dominerades av Kattegatts 1-åringar har minskat men 2+-gruppen i både Skagerrak och Kattegatt har ökat. Torsken visar en stark ökning av 0-gruppen, framför allt i Skagerrak men i jämförelse med den starka årsklassen 2011 är siffrorna måttliga. Övriga åldersklasser hos torsken är fortsatt extremt låga. Biologiska parametrar på individnivå samlas in på sill- och torskfiskar samt några plattfiskar. Totalt provtogs 4 191 individer från 11 olika arter med avseende på ålder och könsmognad.
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| 13. |
- Bland, Barbara, et al.
(författare)
-
Expeditionsrapport IBTS, januari 2017
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Havsfiskelaboratoriets trålexpeditioner i Västerhavet (Skagerrak och Kattegatt) genomförs två gånger årligen, i kvartal 1 och 3. Den franska bottentrålen GOV används för provtagningen av demersala arter. Under kvartal 1 används också en MIK-trål nattetid för provtagning av fisklarver. Under denna expedition gjordes totalt 47 giltiga tråldrag i hela området med GOV-trålen, två i Nordsjön, 26 i Skagerrak och 19 i Kattegatt. Eftersom vi i år fiskade två rutor i Nordsjön var vi tvungna att begränsa antalet stationer i Skagerrak, normalt 27 st till 26 st. I år hade Svenska Försvarsmakten tagit bort tillträdesförbudet och de stationer som inte fiskats sedan 2014 kunde nu fiskas. Vädret var under hela expeditionen gynnsamt. Den totala fångsten uppgick till drygt 12 ton och inkluderade 70 fiskarter. Den biologiska provtagningen, som innebär bland annat insamling av otoliter för åldersbestämning, gjordes på de viktigaste kommersiella arterna. Totalt togs 5 223 otoliter från 11 olika arter. MIK-trålningen resulterade i 66 godkända tråldrag med fångst av bland annat 271 sillarver, 4 skarpsillarver och 10 ållarver.
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| 14. |
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| 15. |
- Bland, Barbara, et al.
(författare)
-
Expeditionsrapport IBTS, januari 2019
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Havsfiskelaboratoriets trålexpeditioner i Västerhavet (Skagerrak och Kattegatt) genomförs två gånger årligen, i kvartal 1 och 3. Den franska bottentrålen GOV används för fisket dagtid. Under kvartal 1 används också en mindre finmaskig trål (MIK) nattetid för provtagning av fisklarver. Under expeditionen genomfördes totalt 45 godkända tråldrag med GOV-trålen, tre i Nordsjön, 24 i Skagerrak och 18 i Kattegatt. Svenska Försvarsmakten medgav tillstånd för fiske på 24 stationer istället för de ordinarie 27 stationerna i Skagerrak. Den totala fångsten uppgick till drygt 13,1 ton och inkluderade 70 fiskarter. Den biologiska provtagningen, som inkluderar insamling av otoliter för åldersbestämning, gjordes på de viktigaste kommersiella arterna. Totalt togs 5 555 otoliter från 11 olika arter. MIK-trålningen resulterade i 60 godkända tråldrag med fångst av bland annat 607 sillarver, 2 skarpsillarver och 12 ållarver.
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| 16. |
- Bryhn, Andreas, et al.
(författare)
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Which factors can affect the productivity and dynamics of cod stocks in the Baltic Sea, Kattegat and Skagerrak?
- 2022
-
Ingår i: Ocean and Coastal Management. - : Elsevier BV. - 0964-5691 .- 1873-524X. ; 223
-
Forskningsöversikt (refereegranskat)abstract
- Stocks of Atlantic cod (Gadus morhua) in the Baltic Sea, Kattegat and Skagerrak (N. Europe) have been strongly exploited for decades bringing them into an enduringly depleted status. Scientific cod stock related advice for targeted and mixed fisheries is provided on an annual basis by the International Council for Exploration of the Sea. This advice forms a basis for ministerial decisions on, e.g., the total allowable catch and management plans. Despite measures to reduce fishing-induced mortality of cod, such as catch and effort restrictions, increased gear selectivity, closed areas and seasons, clear signs of recovery are yet to be seen. Thus, traditional advice for the management of these stocks may have to be complemented by advice on supporting measures focusing on other pressures hampering the recovery of cod. The present study elaborates on potential supportive measures for cod stock recovery in the Baltic Sea, Kattegat, and Skagerrak (including local populations where applicable), based on current knowledge. The list of measures presented here is the outcome of in-depth discussions on the state-of-the-art knowledge, among cod experts and further with stakeholders with the aim to follow principles of ecosystem-based fisheries management. Following the identification of different pressures on and prerequisites for the separate stocks, the listed measures differ between stocks and include cod bycatch mortality reduction, alterations in fisheries affecting food sources for cod, restocking, protection of juvenile habitats, and reduced predation. The literature review and the list of measures are intended to provide decision-support for managers and policymakers aiming to provide conditions for the cod stocks to recover.
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| 17. |
- Cardinale, Massimiliano, et al.
(författare)
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Comments on Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak Coast by Svedang et al.
- 2019
-
Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 76, s. 1209-1211
-
Tidskriftsartikel (refereegranskat)abstract
- Svedang et al. (2018) concluded that the occurrence of locally spawned cod eggs suggests that spawning on the Swedish Skagerrak coast takes place, which belong to either a coastal subpopulation that is a remnant stock of a once much larger cod population, or a newly formed subpopulation that is now successfully inhabiting the coastal ecosystems along the Swedish Skagerrak coast. However, after carefully reviewing the results and the data presented by the authors, we were no longer convinced that the information presented provided enough evidence for a local, distinct, coastal cod population in the Swedish Skagerrak. Thus, we requested the original genotype data, which the authors kindly provided to us. This allowed us to explore the substructure of these samples further using STRUCTURE 2.3.2. Re-analysis of the data consistently rejects the existence of an independent coastal Swedish stock in contrast with Svedang et al. (2018) conclusions. We acknowledge the observation of cod spawning in the area but, based on re-analysis of the original genetic data of Svedang et al. (2018), we currently lack the scientific basis to assume the existence of established local stocks, and even less the demographic expansion of an older, relict population in the area.
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| 18. |
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| 19. |
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| 20. |
- Cardinale, Massimiliano, et al.
(författare)
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The "easy restriction" syndrome drive local fish stocks to extinction: The case of the management of Swedish coastal populations
- 2017
-
Ingår i: Marine Policy. - : Elsevier BV. - 0308-597X. ; 83, s. 179-183
-
Tidskriftsartikel (refereegranskat)abstract
- Spatially sensitive management built on detailed biological and socio-economic knowledge is required to establish sound fishing regulations and to avoid extinction of small coastal populations of fish and shellfish. Highly productive isolated populations of several commercial species have historically inhabited the Swedish west coast, but during the past century these populations have been depleted by fisheries and with no sign of recovery. Since 1999 several fisheries regulations and different stakeholder co-management initiatives have flourished along the Swedish coast of the Skagerrak. They aimed to facilitate the recovery of collapsed local stocks but the established regulations failed to identify and restrict the main sources of mortality acting on local stocks and they have thus been ineffective to promote the recovery. Furthermore, regulations have operated on the weakest among stakeholders (e.g.. recreational fishers), which have minor influence over management, and the restrictions have been imposed without providing any data which supported the choice (i.e. the "easy restriction" syndrome). In line with the general "spirit" of recent Swedish fishery management, we conclude that managers, without the disapproval of Swedish scientists, have circumvented limitations which should address the largest mortality factor, i.e. the commercial fishery. The regulations presently in place, have been politically uncontroversial and easy to implement, but have been highly unsuccessful. We therefore suggest that stakeholders, including politicians, should start focusing on more effective and science-based management and less on what is politically attractive if Swedish citizens shall have a chance to witness the recovery of their once flourishing coastal populations.
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| 21. |
- Carlsson, Anders, 1961-, et al.
(författare)
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Sustainability Jam Sessions for vision creation and problem solving
- 2015
-
Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 98, s. 29-35
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents a concept for creating arenas where expertise from certain branches of industry can interact with sustainability professionals and researchers to address and solve sustainability challenges. The concept Sustainability Jam Session (SJS) builds upon the idea of conducting creative meetings between professionals in “jam sessions,” similar to those associated primarily with music and improvisation. Approaches such as these have been used in the IT sector over the past decades, but this is the first attempt to apply it in the area of sustainability. SJS's were tested at the 2012 Greening of Industry Network Conference (GIN2012) and here we report our experiences from arranging six SJS's at the conference.A typical process of an SJS includes a preparatory phase, the actual jam, and documentation and follow up. The preparatory phase mainly involves identifying hosts and topics to be addressed at the SJS, followed by attracting participants. The jam is started by an introduction of the topics, a technical visit (if appropriate), and a problem-solving workshop, ending with a wrap-up reporting. Thorough documentation is necessary for following up the results of the SJS and preparing for implementation of the identified solutions.We conclude that skill, structure, setting, and surrender of control, as well as finding “red and hot” topics for the jams are the key factors for successful SJS's.Based on our experiences from GIN2012, we recommend other research conferences in the sustainability field use SJS's if the intention is to boost the interaction between the conference and the host region or non-academic organizations in general. We also suggest that a similar approach can be used in regional development for creating an infrastructure for learning and transformation towards sustainability and initiatives for open innovation.
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| 22. |
- Casini, Michele, et al.
(författare)
-
Hypoxic areas, density-dependence and food limitation drive the body condition of a heavily exploited marine fish predator
- 2016
-
Ingår i: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- Investigating the factors regulating fish condition is crucial in ecology and the management of exploited fish populations. The body condition of cod (Gadus morhua) in the Baltic Sea has dramatically decreased during the past two decades, with large implications for the fishery relying on this resource. Here, we statistically investigated the potential drivers of the Baltic cod condition during the past 40 years using newly compiled fishery-independent biological data and hydrological observations. We evidenced a combination of different factors operating before and after the ecological regime shift that occurred in the Baltic Sea in the early 1990s. The changes in cod condition related to feeding opportunities, driven either by density-dependence or food limitation, along the whole period investigated and to the fivefold increase in the extent of hypoxic areas in the most recent 20 years. Hypoxic areas can act on cod condition through different mechanisms related directly to species physiology, or indirectly to behaviour and trophic interactions. Our analyses found statistical evidence for an effect of the hypoxia-induced habitat compression on cod condition possibly operating via crowding and density-dependent processes. These results furnish novel insights into the population dynamics of Baltic Sea cod that can aid the management of this currently threatened population.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
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| 28. |
- Eero, Margit, et al.
(författare)
-
Food for Thought Eastern Baltic cod in distress : biological changes and challenges for stock assessment
- 2015
-
Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 72:8, s. 2180-2186
-
Tidskriftsartikel (refereegranskat)abstract
- The eastern Baltic (EB) cod (Gadus morhua) stock was depleted and overexploited for decades until the mid-2000s, when fishing mortality rapidly declined and biomass started to increase, as shown by stock assessments. These positive developments were partly assigned to effective management measures, and the EB cod was considered one of the most successful stock recoveries in recent times. In contrast to this optimistic view, the analytical stock assessment failed in 2014, leaving the present stock status unclear. Deteriorated quality of some basic input data for stock assessment in combination with changes in environmental and ecological conditions has led to an unusual situation for cod in the Baltic Sea, which poses new challenges for stock assessment and management advice. A number of adverse developments such as low nutritional condition and disappearance of larger individuals indicate that the stock is in distress. In this study, we (i) summarize the knowledge of recent changes in cod biology and ecosystem conditions, (ii) describe the subsequent challenges for stock assessment, and (iii) highlight the key questions where answers are urgently needed to understand the present stock status and provide scientifically solid support for cod management in the Baltic Sea.
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| 29. |
- Gårdmark, Anna, et al.
(författare)
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Regime shifts in exploited marine food webs : detecting mechanisms underlying alternative stable states using size-structured community dynamics theory
- 2015
-
Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 370:1659, s. 20130262-
-
Tidskriftsartikel (refereegranskat)abstract
- Many marine ecosystems have undergone 'regime shifts', i.e. abrupt reorganizations across trophic levels. Establishing whether these constitute shifts between alternative stable states is of key importance for the prospects of ecosystem recovery and for management. We show how mechanisms underlying alternative stable states caused by predator-prey interactions can be revealed in field data, using analyses guided by theory on size-structured community dynamics. This is done by combining data on individual performance (such as growth and fecundity) with information on population size and prey availability. We use Atlantic cod (Gadus morhua) and their prey in the Baltic Sea as an example to discuss and distinguish two types of mechanisms, 'cultivation-depensation' and 'overcompensation', that can cause alternative stable states preventing the recovery of overexploited piscivorous fish populations. Importantly, the type of mechanism can be inferred already from changes in the predators' body growth in different life stages. Our approach can thus be readily applied to monitored stocks of piscivorous fish species, for which this information often can be assembled. Using this tool can help resolve the causes of catastrophic collapses in marine predatory-prey systems and guide fisheries managers on how to successfully restore collapsed piscivorous fish stocks.
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| 30. |
- Hentati-Sundberg, Jonas, 1983-, et al.
(författare)
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Can fisheries management be quantified?
- 2014
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Ingår i: Marine Policy. - : Elsevier BV. - 0308-597X .- 1872-9460. ; 48, s. 18-20
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Tidskriftsartikel (refereegranskat)abstract
- Policy efforts to reduce fisheries impact have often created micro-management. Detailed regulations are restricting the fishing industry, and are also acknowledged to limit the progress towards sustainable management. Industry representatives, political bodies and scientists have therefore argued for more simplicity and transparency. Here, fisheries management is quantified in terms of trends in regulations for different Swedish fisheries in the Baltic Sea during the period 1995–2009. The results suggest that many fisheries are suffering from increased micro-management, but interestingly some fisheries showing a different trend.
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| 31. |
- Hentati-Sundberg, Jonas, 1983-, et al.
(författare)
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Does fisheries management incentivize non-compliance? Estimated misreporting in the Swedish Baltic Sea pelagic fishery based on commercial fishing effort
- 2014
-
Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 71:7, s. 1846-1853
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Tidskriftsartikel (refereegranskat)abstract
- Fisheries management agencies and fishing industry representatives depend on reliable estimates of fish biomass and mortality for the determin- ation of sustainable catch levels. Lack of data or misreporting may be reasons for unreliable stock assessment, which, in turn, may result in advice that does not reflect the availability of fisheries resources. It has been suggested that the mixed pelagic trawl fisheries in the Baltic represent a case of biased estimates of fish biomass and mortality resulting from misreporting. Here, we estimate the degree of misreporting in the Swedish pelagic fishery (1996 – 2009) and propose an approach for reconstructing historical catches based on commercial effort data. The analysis suggests that total catches have been underestimated during part of our study period and that systematic misreporting of species composition has taken place over the whole study period. The analysis also suggests that there is overcapacity in the fishery and that such economic incentive could explain the general patterns of misreporting. Applying our method for fisheries with suspected misreporting could significantly improve assessment accuracy, reduce uncertainty and thereby allow for a better link between catches and resource levels.
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| 32. |
- Hentati-Sundberg, Jonas, et al.
(författare)
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FISH AND SEABIRD SPATIAL DISTRIBUTION AND ABUNDANCE AROUND THE LARGEST SEABIRD COLONY IN THE BALTIC SEA
- 2018
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Ingår i: Marine Ornithology. - 1018-3337 .- 2074-1235. ; 46:1, s. 61-68
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Tidskriftsartikel (refereegranskat)abstract
- We studied the at-sea distribution of two auks (Common Murre Uria aalge, Razorbill Alca torda), two gulls (Lesser Black-backed Gull Larus fuscus, Herring Gull Larus argentatus), and Great Cormorant Phalacrocorax carbo during the peak breeding season of 2014 around Stora Karlso, the main Baltic Sea seabird colony. Simultaneously, we quantified forage fish abundance and distribution using hydro-acoustics and pelagic trawling. The auks and gulls had a roughly similar distribution, foraging mainly about 40 km west-northwest from the colony. Great Cormorants were found only in inshore areas, close to the colony. Sprat Sprattus sprattus and herring Clupea harengus biomass was, respectively, 1.38 and 2.68 mt/km(2) averaged over the whole study area. These estimates represent a total biomass for small pelagic fish of 17 900 t in the 4 408 km(2) study area. The estimated prey consumption over the breeding season was 2 310 t for Common Murre and Razorbill combined. Thus, auks may have a non-negligible impact on their prey sources in the region. Common Murres foraged closer to the colony (median 36.3 km) than Razorbills (median 41.1 km), but we found no significant correlation between auk at-sea numbers and fish densities. We discuss how new technology can contribute to detailed monitoring of the interactions between seabirds and fish at different spatial and temporal scales, with the ultimate aim of providing a scientific basis for ecosystem-based management.
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| 33. |
- Hentati Sundberg, Jonas, et al.
(författare)
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Management Forcing Increased Specialization in a Fishery System
- 2015
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Ingår i: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 18:1, s. 45-61
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Tidskriftsartikel (refereegranskat)abstract
- Fisheries systems are shaped by dynamic social-ecological interactions that determine their capacity to provide ecosystem services. Human adaptation is often considered a key uncertainty, and there are few quantitative empirical analyses that address long-term social and ecological change in the analyses of fisheries systems. The aim of this study was twofold: (i) to understand how different drivers influenced the adaptations by fishers, and (ii) to evaluate different consequences of such adaptations, especially with regard to diversity of social and ecological links. We used the Baltic Sea as a case study, a system with different fisheries, largely managed with a single-stock advice, in a top-down basis. The study period 1995-2009 was characterized by profound inter-annual fluctuations in fish stock status and prices, and introduction of new types of management measures. We used multivariate statistical methods to define longitudinal changes in fishing tactics and strategies based on logbook data. Our results indicate that changes in fishing strategies have mainly been driven by regulations, and there were only weak linkages between fishing activities, fish stocks, and price fluctuations. We found contrasting trends between large- and small-scale fishers, where large-scale fishers became more specialized and inflexible, whereas small-scale fishers diversified over time. We conclude that management has had a dominating role in shaping fishing patterns, leading to a reduction of important qualities related to the resilience in this social-ecological system.
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| 34. |
- Hentati-Sundberg, Jonas, 1983-
(författare)
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SEA CHANGE : Social-ecological co-evolution in Baltic Sea fisheries
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sustainable management of natural resources requires an in-depth understanding of the interplay between social and ecological change. Linked social-ecological systems (SES) have been described as complex adaptive systems (CAS), which mean that they are irreducible, exhibit nonlinear dynamics, have interactions across scales and are uncertain and unpredictable. These propositions have however rarely been tested empirically, in part due to a lack of methodological approaches and suitable datasets. In this thesis, I address this methodological and empirical gap in a study of long-term change of Baltic Sea fisheries. In Paper I, we develop the concept of fishing style through integrating multivariate statistical analysis and in-depth interviews. We thereby identify an intermediate level of detail for analyzing social-ecological dynamics, embracing the case specific and context dependent approaches of the social sciences with the generalizable and quantifiable approaches from the natural sciences. In Paper II we ask: How has the Baltic Sea fishery been regulated over time, and can we identify a way to quantify regulations in order to be able to analyze their effects? We analyze all regulatory changes in Sweden since 1995 with a new methodology and conclude that there is a clear trend towards increased micro-management. In Paper III, we use the fishing styles developed in Paper I and examine how they have changed over time. We relate these changes to the dynamics of regulation (Paper II), as well as to the dynamics of fish stocks and prices. We conclude that regulation has been the main driving force for observed changes, but also that regulation has prompted significant specialization and decline in flexibility for fishers over time. These changes are unintended consequences and may represent a looming risk for the long-term sustainability of this social-ecological system. Paper IV zooms in on a particular fishery, the pelagic trawl fishery for sprat Sprattus sprattus and Atlantic herring Clupea harengus, mainly targeted for the production of fishmeal and fish oil. Suspicions of non-compliance in this fishery motivated us to apply a statistical approach where we used socioeconomic data to re-estimate the historical catches in this fishery (a novel approach to catch-reconstruction estimates). We found that catches had been significantly underreported over several years, with consequences for the quality of stock assessments and management. The study underlines the importance of understanding linked social, economic and ecological dynamics for sustainable outcomes. Finally, Paper V takes a longer historical look at the Baltic Sea fishery, using regionally disaggregated data from 1914-2009 (96 years), which were analyzed with a novel type of nonlinear statistical time-series methods (Empirical Dynamical Modeling). Our analysis explicitly recognized the potential nonlinear dynamics of SES and showed high predictability across regions of catches and prices of cod Gadus morhua and herring. The signal was generally nonlinear and predictability decreased strongly with time, suggesting that the dynamics of this SES are ever-changing. To our knowledge, this is the first long-term analysis of a SES using empirical data and methods developed from the CAS field of research. The main contributions of this thesis are the integrated analysis of social and ecological data, the development of novel methods for understanding SES dynamics, insights on the ever-changing nature of CAS and the quantitative analysis of management outcomes. Future work should focus on assessing the generality of these findings across a broad range of SES and evaluate alternative governance approaches given the complexity and uncertainty of SES suggested by this thesis.
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| 35. |
- Hjelm, Hans, 1973-
(författare)
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Cross-language Ontology Learning : Incorporating and Exploiting Cross-language Data in the Ontology Learning Process
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An ontology is a knowledge-representation structure, where words, terms or concepts are defined by their mutual hierarchical relations. Ontologies are becoming ever more prevalent in the world of natural language processing, where we currently see a tendency towards using semantics for solving a variety of tasks, particularly tasks related to information access. Ontologies, taxonomies and thesauri (all related notions) are also used in various variants by humans, to standardize business transactions or for finding conceptual relations between terms in, e.g., the medical domain. The acquisition of machine-readable, domain-specific semantic knowledge is time consuming and prone to inconsistencies. The field of ontology learning therefore provides tools for automating the construction of domain ontologies (ontologies describing the entities and relations within a particular field of interest), by analyzing large quantities of domain-specific texts. This thesis studies three main topics within the field of ontology learning. First, we examine which sources of information are useful within an ontology learning system and how the information sources can be combined effectively. Secondly, we do this with a special focus on cross-language text collections, to see if we can learn more from studying several languages at once, than we can from a single-language text collection. Finally, we investigate new approaches to formal and automatic evaluation of the quality of a learned ontology. We demonstrate how to combine information sources from different languages and use them to train automatic classifiers to recognize lexico-semantic relations. The cross-language data is shown to have a positive effect on the quality of the learned ontologies. We also give theoretical and experimental results, showing that our ontology evaluation method is a good complement to and in some aspects improves on the evaluation measures in use today.
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| 36. |
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| 37. |
- Hjelm, Joakim
(författare)
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Designing spawning closures can be complicated: Experience from cod in the Baltic Sea
- 2019
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Ingår i: Ocean and Coastal Management. - : Elsevier BV. - 0964-5691 .- 1873-524X. ; 169, s. 129-136
-
Tidskriftsartikel (refereegranskat)abstract
- Fisheries management measures often include spatio-temporal closures during the spawning period of the fish with an overarching aim of improving the stock status. The different mechanisms how a spawning closure potentially can influence the stock are often not explicitly considered when designing such closures. In this paper, we review and synthesize the available data and knowledge on potential effects of the implemented spawning closures on cod in the Baltic Sea. The Baltic cod example represents a relatively data rich case, which allows demonstrating how a closure might affect different parameters of stock status via different mechanisms, including potential unintended negative effects. We conclude that designing relatively small area closures appropriately is highly complex and data demanding, and may involve tradeoffs between positive and negative impacts on the stock. Seasonal closures covering most of the stock distribution during the spawning time are more robust to data limitations, and less likely to be counterproductive if suboptimally designed.
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| 38. |
- Hjelm, Joakim, et al.
(författare)
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Expeditionsrapport IBTS, januari 2016
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Havsfiskelaboratoriets trålexpeditioner i Västerhavet (Skagerrak och Kattegatt) genomförs två gånger årligen, i kvartal 1 och 3. Den franska bottentrålen GOV används för provtagningen av demersala arter. Under kvartal 1 används också en MIK-trål nattetid för provtagning av fisklarver. Under denna expedition gjordes totalt 46 giltiga tråldrag i hela området med GOV-trålen, 27 i Skagerrak och 19 i Kattegatt. Även i år var det tre stationer som inte kunde fiskas p.g.a. Svenska Försvarsmaktens tillträdesförbud varvid den värdefulla tidsserien är bruten för dessa stationer. Den totala fångsten uppgick till 18 ton och inkluderade 57 fiskarter. Den biologiska provtagningen, som innebär bland annat insamling av otoliter för åldersanalys, gjordes på de viktigaste kommersiella arterna. Totalt togs 4 943 otoliter från 11 olika arter. MIK-trålningen resulterade i 62 godkända tråldrag med fångst av bland annat 61 sillarver, 4 skarpsillarver och 6 ållarver.
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| 39. |
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Königson, Sara, et al.
(författare)
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Seal exclusion devices in cod pots prevent seal bycatch and affect their catchability of cod
- 2015
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Ingår i: Fisheries Research. - : Elsevier BV. - 0165-7836 .- 1872-6763. ; 167, s. 114-122
-
Tidskriftsartikel (refereegranskat)abstract
- In order to maintain a viable inshore fishing industry, it is important to limit the incidence of seal-inflicted damage to static fishing gear and additional catch losses. Studies in the Baltic Sea have shown that this could be achieved by implementing alternative fishing methods, e.g. by using fish pots instead of lines or gillnets. However, as in net and line fisheries, a pot fishery could also result in bycatch of seals. In order to prevent these bycatches, pot entrances were equipped with seal exclusion devices (SEDs) of various sizes and shapes. A field study was conducted to investigate what effect different types of SEDs had on the bycatch of seals as well as on the pot's catchability. When pots where equipped with SEDs the bycatch of seals was reduced to zero without negatively affecting the pot's catchability. The shape and size of the entrance did have a significant effect on the pot's catchability and the size of the fish. Using symmetrical oval shaped entrances along with larger rectangular entrances divided into two smaller openings increased the pot's catchability. (C) 2015 Elsevier B.V. All rights reserved.
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| 44. |
- Lambertsen, Kate Lykke, et al.
(författare)
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Microglia Protect Neurons against Ischemia by Synthesis of Tumor Necrosis Factor
- 2009
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 29:5, s. 1319-1330
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Tidskriftsartikel (refereegranskat)abstract
- Microglia and infiltrating leukocytes are considered major producers of tumor necrosis factor (TNF), which is a crucial player in cerebral ischemia and brain inflammation. We have identified a neuroprotective role for microglial-derived TNF in cerebral ischemia in mice. We show that cortical infarction and behavioral deficit are significantly exacerbated in TNF-knock-out (KO) mice compared with wild-type mice. By using in situ hybridization, immunohistochemistry, and green fluorescent protein bone marrow (BM)-chimeric mice, TNF was shown to be produced by microglia and infiltrating leukocytes. Additional analysis demonstrating that BM-chimeric TNF-KO mice grafted with wild-type BM cells developed larger infarcts than BM-chimeric wild-type mice grafted with TNF-KO BM cells provided evidence that the neuroprotective effect of TNF was attributable to microglial-not leukocyte-derived TNF. In addition, observation of increased infarction in TNF-p55 receptor (TNF-p55R)-KO mice compared with TNF-p75R and wild-type mice suggested that microglial-derived TNF exerts neuroprotective effects through TNF-p55R. We finally report that TNF deficiency is associated with reduced microglial population size and Toll-like receptor 2 expression in unmanipulated brain, which might also influence the neuronal response to injury. Our results identify microglia and microglial-derived TNF as playing a key role in determining the survival of endangered neurons in cerebral ischemia.
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| 45. |
- Li Zweifel, Ulla, et al.
(författare)
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God havsmiljö 2020 : Marin strategi för Nordsjön och Östersjön Del 2: God miljöstatus och miljökvalitetsnormer
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Havsmiljöförordningens övergripande mål är att upprätthålla eller uppnå en god miljöstatus i de svenska förvaltningsområdena Nordsjön och Östersjön till år 2020. En av uppgifterna i den första förvaltningsperioden är att bestämma vad som kännetecknar god miljöstatus i respektive förvaltningsområde samt att ta fram miljökvalitetsnormer. God miljöstatus baseras på ett ramverk av så kallade deskriptorer som anges i havsmiljödirektivet, det vill säga det EU-direktiv som i Sverige genomförs genom havsmiljöförordningen. Deskriptorerna beskriver god miljöstatus på en övergripande nivå för 11 temaområden. Till varje deskriptor hör en rad kriterier som anger vad som ska ingå i en bedömning av miljöstatus. I Sverige har god miljöstatus formulerats för samtliga 29 kriterier som ska beaktas enligt direktivet. Dessa kvalitativa beskrivningar anger vad som kännetecknar god miljöstatus i Nordsjön och Östersjön. För att praktiskt bedöma om god miljöstatus har uppnåtts föreslås 37 nationella indikatorer. En uppsättning av indikatorer omfattar miljöns tillstånd och avspeglar ekosystemets komponenter i form av nyckelarter, samhällen, och livsmiljöer. En utgångspunkt vid val av indikatorer för miljöns tillstånd har varit koppling till de belastningar som i den inledande bedömningen av miljötillståndet i Nordsjön och Östersjön bedömts ha stor negativ påverkan på ekosystemet. En annan uppsättning indikatorer berör påverkan och belastning på miljön i form av tillförsel av näringsämnen och farliga ämnen, samt biologisk och fysisk störning av miljön. Tillsammans utgör indikatorerna ett verktyg för att följa utvecklingen av miljötillståndet och effekter av åtgärder i havsmiljön. Vid val av indikatorer har arbetet delvis utgått från existerande miljöövervakning och redan utvecklade indikatorer. Med denna utgångspunkt uppfylls en rad av havsmiljödirektivets krav, bland annat en god uppföljning av effekter av tillförsel av näringsämnen. Funktionella indikatorer, det vill säga indikatorer som utvärderats och för vilka god miljöstatus har definierats, saknas dock för tio av havsmiljödirektivets 29 kriterier. För uppföljning av biologisk mångfald saknas bland annat miljöövervakning och metoder för att bedöma livsmiljöers tillstånd. För att kunna bedöma fysiska skador på havsbotten saknas en övergripande sammanställning av information om aktiviteter som påverkar havsbottnar samt metodik för att bedöma effekterna. Det saknas också utvecklade indikatorer för det kriterium som berör uppföljning av storleks- och åldersstruktur hos fiskar. Brist på kunskap gör också att inga förslag på svenska indikatorer kan ges för effekter på levande organismer från marint avfall, undervattensbuller, och främmande arter samt att endast ett begränsat antal indikatorer tagits fram som speglar effekter av farliga ämnen. De indikatorer som fastställs i juli 2012 utgör således inte en slutlig lista för att följa upp havsmiljödirektivet. Bristerna kommer att beaktas i det fortsatta genomförandet av havsmiljöförordningen där nästa steg är att anpassa miljöövervakningsprogrammen till uppföljning av miljötillståndet med valda indikatorer senast år 2014 samt att ta fram åtgärdsprogram till år 2015. God miljöstatus ska uppnås genom tillämpning av miljökvalitetsnormer det vill säga rättsligt bindande regler som avspeglar den lägsta godtagbara miljökvaliteten i Nordsjön och Östersjön. För att nå god miljöstatus har elva svenska miljökvalitetsnormer formulerats. Dessa miljökvalitetsnormer omfattar belastning i form av näringsämnen, farliga ämnen, främmande arter, uttag av arter, fysisk påverkan på havsbottnar och avfall i havsmiljön. Målsättningen har varit att utforma miljökvalitetsnormer som motsvarar alla de belastningar som i den inledande bedömningen har identifierats ha en stor påverkan på miljön.
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| 46. |
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| 47. |
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| 48. |
- Olsson, Jens, et al.
(författare)
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The first large-scale assessment of three-spined stickleback (Gasterosteus aculeatus) biomass and spatial distribution in the Baltic Sea
- 2019
-
Ingår i: ICES Journal of Marine Science. - : Oxford University Press. - 1054-3139 .- 1095-9289. ; 76:6, s. 1653-1665
-
Tidskriftsartikel (refereegranskat)abstract
- Declines in predatory fish in combination with the impact of climate change and eutrophication have caused planktivores, including three-spined stickleback (Gasterosteus aculeatus), to increase dramatically in parts of the Baltic Sea. Resulting impacts of stickleback on coastal and offshore foodwebs have been observed, highlighting the need for increased knowledge on its population characteristics. In this article, we quantify abundance, biomass, size structure, and spatial distribution of stickleback using data from the Swedish and Finnish parts of the Baltic International Acoustic Survey (BIAS) during 2001-2014. Two alternative methods for biomass estimation suggest an increase in biomass of stickleback in the Baltic Proper, stable or increasing mean size over time, and larger individuals toward the north. The highest abundance was found in the central parts of the Baltic Proper and Bothnian Sea. The proportion of stickleback biomass in the total planktivore biomass increased from 4 to 10% in the Baltic Proper and averaged 6% of the total planktivore biomass in the Bothnian Sea. In some years, however, stickleback biomass has ranged from half to almost twice that of sprat (Sprattus sprattus) in both basins. Given the recent population expansion of stickleback and its potential role in the ecosystem, we recommend that stickleback should be considered in future monitoring programmes and in fisheries and environmental management of the Baltic Sea.
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| 49. |
- Orio, Alessandro, et al.
(författare)
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Report of the Baltic Fisheries Assessment Working Group (WGBFAS) : 19-26 April 2017, Copenhagen, Denmark
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ICES Baltic Fisheries Assessment Working Group (WGBFAS) met 19-26 April 2017(Chair: Tomas Gröhsler, Germany and Co-chair: Michele Casini, Sweden), with 41 participants and 9 countries represented. The objective of WGBFAS was to assess the status of the following stocks: Sole in Division 3.a, SDs 20–24; Cod in Kattegat, Cod in SDs 22–24, Cod in SDs 25–32; Herring in SDs 25–27, 28.2, 29 and 32, Herring in SD 28.1 (Gulf of Riga), Herring in SDs 30-31 (Gulf of Bothnia); Sprat in SDs 22–32; Plaice in SDs 21–23, Plaice in SDs 24–25; Flounder in SDs 22–23, in SDs 24–25, in SDs 26+28 and SDs 27+29–32; Brill in SDs 22–32, Dab in SDs 22–32 and Turbot in SDs 22–32. WGBFAS also identified the data needed for next year’s data call with some suggestions for improvements in the data call, and stock-specific research needs.The report contains an introduction with the summary of other WGs relevant for the WGBFAS, the methods used, and ecosystem considerations. The results of the analytical stock assessment or survey trends for the species listed above are then presented with all the stocks with the same species in the same sections. The report ends with references, recommendations, links to Stock Annexes and list of Working Documents.The principle analytical models used for the stock assessments were XSA and SAM. For most flatfishes and cod in SDs 25–32 (data limited stocks), CPUE trends from bottomtrawl surveys were used in the assessment (except plaice in SDs 24–25 for which relative SSB from SAM was used). For the data limited stocks, reference points based on length-based indicators were estimated (except cod in SDs 25-32 for which relative reference points were estimated using the SPiCT model). For cod in SDs 25–32, intersessional work was planned to hopefully allow returning to an analytical stock assessment in the near future. Ecosystem changes have been analytically considered in the following stock assessments: Herring in SD 25–27, 28.2, 29 and 32, and Sprat in SD 22–32, in form of cod predation mortality.
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| 50. |
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