| 1. |
- Ahlbeck Bergendahl, Ida, et al.
(author)
-
Fisk- och skaldjursbestånd i hav och sötvatten 2016 : Resursöversikt
- 2016
-
Reports (other academic/artistic)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 uppdelade i olika bestånd, samt sju skal- och blötdjursarter.Nytt för årets upplaga är kapitlet om ekosystemtjänster. Avsnittet beskriver de fördelar människan får genom ekosystemen, till exempel hur fisk och skaldjur kommer till nytta för människan genom föda, rekreation och biologisk mångfald. Nytt för i år är också att rapportens diagram och figurer anpassats för läsare med defekt färgseende.Översikten är utarbetad av SLU Aqua på uppdrag av Havs- och vattenmyndigheten.
|
|
| 2. |
|
|
| 3. |
- Ahlbeck Bergendahl, Ida, et al.
(author)
-
Fisk- och skaldjursbestånd i hav och sötvatten 2017 : Resursöversikt
- 2017
-
Reports (other academic/artistic)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.
|
|
| 4. |
|
|
| 5. |
- Almqvist, Gustaf, et al.
(author)
-
Report of the Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD)
- 2015
-
Reports (other academic/artistic)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.
|
|
| 6. |
|
|
| 7. |
- Andersson, Magnus, et al.
(author)
-
Fiskbestånd och miljö i hav och sötvatten : Resurs- och miljööversikt 2012
- 2012
-
Reports (other academic/artistic)abstract
- Detta är den nionde utgåvan av den samlade översikten över fisk- och kräftdjursbeståndens status i våra vatten. Kunskap om fiskbestånden och miljön är en förutsättning för att utnyttjandet av fiskresurserna skall bli bärkraftigt. För svenska vattenområden beskrivs miljöutvecklingen i ett ekosystemsperspektiv, dels för att tydliggöra fiskens ekologiska roll och beskriva yttre miljöfaktorer som påverkar fiskbestånden, dels för att belysa fiskets effekter på miljön.Fiskbestånd och miljö i hav och sötvatten är utarbetad av Sveriges lantbruksuniversitet (SLU), Institutionen för akvatiska resurser (SLU Aqua), på uppdrag av Havs- och vattenmyndigheten. Rapporten sammanfattar utveckling och beståndsstatus för de kommersiellt viktigaste fisk- och kräftdjursarterna i våra vatten. Bedömningar och förvaltningsråd är baserade på Internationella Havsforskningsrådets (ICES) rådgivning, SLU Aquas nationella och regionala provfiskedata, samt yrkesfiskets rapportering.
|
|
| 8. |
- Andersson, Magnus, et al.
(author)
-
Short-term tagging mortality of Baltic cod (Gadus morhua)
- 2021
-
In: Fisheries Research. - : Elsevier BV. - 0165-7836 .- 1872-6763. ; 234
-
Journal article (peer-reviewed)abstract
- Tagging-induced mortality experiments are an important component of mark-recapture studies, as they can be used to assess the appropriateness of the tagging methodology, and to improve the reliability of estimates of recapture rates used for calculations of mortality rates and population size. Here, short-term tagging mortality of Baltic cod was estimated through containment experiments in the southern Baltic Sea. Experimental cod were selected from trawl catches, and approximately half were tagged externally with T-bar tags and received an intraperitoneal injection of tetracycline-hydrochloride. The rest of the experimental cod formed the control group, and received neither tag nor injection. The tagged and control cod were mixed evenly within submersible cages, and held for 5-8 days. The experiments were conducted in different regions and during different months by different tagging teams. Overall mortality rate was 16 % (n = 324), with the mortality rate of the tagged group 19 %, and the mortality rate of the control group 13 %. A general linear mixed model was fit to assess the effect of tagging, month, experiment duration, fish length and tagging site (i.e. the combined effect of region and tagging team) on mortality. Tagging had no effect on mortality, indicating that mortality can be attributed mainly to the capture and handling procedure. There was a significantly negative relationship between fish length (range: 20-55 cm) and mortality. Mortality did not differ between the months tested, but there was a significant effect of tagging site on mortality. Tagging-related mortality should be accounted for in analyses of data from mark-recapture studies of Baltic cod, and some variability in mortality between tagging sites can be expected.
|
|
| 9. |
|
|
| 10. |
- Bartolino, Valerio, et al.
(author)
-
Forecasting fish stock dynamics under climate change: Baltic herring (Clupea harengus) as a case study
- 2014
-
In: Fisheries Oceanography. - : Wiley. - 1054-6006 .- 1365-2419. ; 23:3, s. 258-269
-
Journal article (peer-reviewed)abstract
- Climate change and anthropogenic disturbances may affect marine populations and ecosystems through multiple pathways. In this study we present a framework in which we integrate existing models and knowledge on basic regulatory processes to investigate the potential impact of future scenarios of fisheries exploitation and climate change on the temporal dynamics of the central Baltic herring stock. Alternative scenarios of increasing sea surface temperature and decreasing salinity of the Baltic Sea from a global climate model were combined with two alternative fishing scenarios, and their direct and ecosystem-mediated effects (i.e., through predation by cod and competition with sprat) on the herring population were evaluated for the period 2010-2050. Gradual increase in temperature has a positive impact on the long-term productivity of the herring stock, but it has the potential to enhance the recovery of the herring stock only in combination with sustainable fisheries management (i.e., F-msy). Conversely, projections of herring spawning stock biomass (SSB) were generally low under elevated fishing mortality levels (F-high), comparable with those experienced by the stock during the 1990s. Under the combined effects of long-term warming and high fishing mortality uncertainty in herring SSB projections was higher and increasing for the duration of the forecasts, suggesting a synergistic effect of fishery exploitation and climate forcing on fish populations dynamics. Our study shows that simulations of long-term fish dynamics can be an informative tool to derive expectations of the potential long-term impact of alternative future scenarios of exploitation and climate change.
|
|
| 11. |
- Bartolino, Valerio, 1979, et al.
(author)
-
Historical spatiotemporal dynamics of eastern North Sea cod
- 2012
-
In: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 69:5, s. 833-841
-
Journal article (peer-reviewed)abstract
- Recent analyses of historical data of fish abundance and distribution have shown the importance of a long temporal perspective in the evaluation of the current status of fish populations, but pose numerous difficulties such as fragmentation and inhomogeneities in the amount of available information in space and time. Using mixed-effects models in a multiscale analysis, we identified an appropriate spatiotemporal scale of investigation of a high-quality, spatially explicit historical data set, and we reconstructed the long-term spatial dynamics of Atlantic cod (Gadus morhua) in the Kattegat– Skagerrak along the 20th century. We identified a northern and southern main aggregation of adult cod in the study area, corresponding to the Skagerrak portion of the North Sea and the Kattegat cod stocks, respectively. The stocks showed specificities in their spatial dynamics, but common extensive loss of coastal aggregations during the last decades when only 13% (Kattegat) and 35% (Skagerrak) of the estimated early century cod biomass was left. Our reconstruction showed that the collapse of the cod stocks in the area followed the peak in landings in the 1960s–1970s, suggesting that the postwar development of the industrial fisheries played a major role in the decrease of local abundances and disappearance of local adult cod aggregations.
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Bartolino, Valerio, et al.
(author)
-
Spatio-temporal dynamics of a fish predator: Density-dependent and hydrographic effects on Baltic Sea cod population
- 2017
-
In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12
-
Journal article (peer-reviewed)abstract
- Understanding the mechanisms of spatial population dynamics is crucial for the successful management of exploited species and ecosystems. However, the underlying mechanisms of spatial distribution are generally complex due to the concurrent forcing of both density-dependent species interactions and density-independent environmental factors. Despite the high economic value and central ecological importance of cod in the Baltic Sea, the drivers of its spatio-temporal population dynamics have not been analytically investigated so far. In this paper, we used an extensive trawl survey dataset in combination with environmental data to investigate the spatial dynamics of the distribution of the Eastern Baltic cod during the past three decades using Generalized Additive Models. The results showed that adult cod distribution was mainly affected by cod population size, and to a minor degree by small-scale hydrological factors and the extent of suitable reproductive areas. As population size decreases, the cod population concentrates to the southern part of the Baltic Sea, where the preferred more marine environment conditions are encountered. Using the fitted models, we predicted the Baltic cod distribution back to the 1970s and a temporal index of cod spatial occupation was developed. Our study will contribute to the management and conservation of this important resource and of the ecosystem where it occurs, by showing the forces shaping its spatial distribution and therefore the potential response of the population to future exploitation and environmental changes.
|
|
| 15. |
- Bartolino, Valerio, et al.
(author)
-
Sprat (Sprattus sprattus)
- 2023
-
In: Climate effects on fish in Sweden – Species-Climate Information Sheets for 32 key taxa in marine and coastal waters. - 9789180468961 ; :2023:17, s. 155-156
-
Book chapter (other academic/artistic)
|
|
| 16. |
- Bauer, Barbara, et al.
(author)
-
Reducing eutrophication increases spatial extent of communities supporting commercial fisheries : a model case study
- 2018
-
In: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 75:4, s. 1306-1317
-
Journal article (peer-reviewed)abstract
- In this study we investigate if eutrophication management has the potential to substantially affect which areas are going to be most suitable for commercial fishing in the future. We use a spatial ecosystem model, forced by a coupled physical-biogeochemical model, to simulate the spatial distribution of functional groups within a marine ecosystem, which depends on their respective tolerances to abiotic factors, trophic interactions, and fishing. We simulate the future long-term spatial developments of the community composition and their potential implications for fisheries under three different nutrient management scenarios and changing climate. The three nutrient management scenarios result in contrasting developments of bottom oxygen concentrations and phytoplankton abundance, with substantial effects on fish production. Nutrient load reduction increases the spatial extent of the areas suitable for the commercially most valuable demersal fish predator and all types of fisheries. This suggests that strategic planning of fishery management strategies could benefit from considering future changes in species distributions due to changes in eutrophication. We show that combining approaches from climate research, physical oceanography, biogeochemistry, biogeography, and trophic ecology with economical information provides a strong foundation to produce scientific knowledge that can support a multisectoral management of ecosystems.
|
|
| 17. |
|
|
| 18. |
- Belgrano, Andrea, et al.
(author)
-
Överfiske - en miljöfarlig aktivitet : orsaker till fiskbeståndens utarmning och dess konsekvenser i svenska hav
- 2011
-
Reports (other academic/artistic)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.
|
|
| 19. |
|
|
| 20. |
- Bergenius, Mikaela, et al.
(author)
-
Report of the Baltic Fisheries Assessment Working Group (WGBFAS) : 14-21 April 2015, ICES HQ, Copenhagen, Denmark
- 2015
-
Reports (other academic/artistic)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.
|
|
| 21. |
- Bergström, Lena, et al.
(author)
-
Klimatförändringar och biologisk mångfald : Slutsatser från IPCC och IPBES i ett svenskt perspektiv.
- 2020
-
Reports (other academic/artistic)abstract
- De stora miljö- och samhällsproblemen kommer inte ensamma. De är sammankopplade på olika sätt. Detta innebär utmaningar men ger också möjligheter att utveckla åtgärder och lösningar. Det gäller både för klimatfrågan och frågan om att motverka förlusten av biologisk mångfald och ekosystem. Kunskapens betydelse för att hantera dessa och andra aspekter är ovärderlig, såväl kring specifika frågeställningar som kring omständigheter och förutsättningar för åtgärdsarbetet.Den här kunskapssammanställningen har gjorts av forskare från Lunds universitet och Sveriges lantbruksuniversitet på uppdrag av Naturvårdsverket och SMHI. Forskarna har tagit avstamp i de omfattande kunskapsutvärderingar som gjorts av den mellanstatliga klimatpanelen (IPCC) och den mellanstatliga plattformen för biologisk mångfald (IPBES). Slutsatserna från IPCC och IPBES sätts i ett svenskt perspektiv, bland annat genom utvalda exempel vilka fungerar som aktuella illustrationer av hur klimatförändringar påverkar biologisk mångfald och ekosystem i Sverige.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Bergström, Ulf, et al.
(author)
-
Stickleback increase in the Baltic Sea - A thorny issue for coastal predatory fish
- 2015
-
In: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 163, s. 134-142
-
Journal article (peer-reviewed)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.
|
|
| 25. |
- Bertos-Fortis, Mireia, et al.
(author)
-
Unscrambling Cyanobacteria Community Dynamics Related to Environmental Factors
- 2016
-
In: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 7
-
Journal article (peer-reviewed)abstract
- Future climate scenarios in the Baltic Sea project an increase of cyanobacterial bloom frequency and duration, attributed to eutrophication and climate change. Some cyanobacteria can be toxic and their impact on ecosystem services is relevant for a sustainable sea. Yet, there is limited understanding of the mechanisms regulating cyanobacterial diversity and biogeography. Here we unravel successional patterns and changes in cyanobacterial community structure using a 2-year monthly time series during the productive season in a 100 km coastal-offshore transect using microscopy and high-throughput sequencing of 16S rRNA gene fragments. A total of 565 cyanobacterial OTUs were found, of which 231 where filamentous/colonial and 334 picocyanobacterial. Spatial differences in community structure between coastal and offshore waters were minor. An "epidemic population structure" (dominance of a single cluster) was found for Aphanizomenon/Dolichospermum within the filamentous/colonial cyanobacterial community. In summer, this cluster simultaneously occurred with opportunistic clusters/OTUs, e.g., Nodulana spumigena and Pseudanabaena. Picocyanobacteria, Synechococcus/Cyanobium, formed a consistent but highly diverse group. Overall, the potential drivers structuring summer cyanobacterial communities were temperature and salinity. However, the different responses to environmental factors among and within genera suggest high niche specificity for individual OTUs. The recruitment and occurrence of potentially toxic filamentous/colonial clusters was likely related to disturbance such as mixing events and short-term shifts in salinity, and not solely dependent on increasing temperature and nitrogen-limiting conditions. Nutrients did not explain further the changes in cyanobacterial community composition. Novel occurrence patterns were identified as a strong seasonal succession revealing a tight coupling between the emergence of opportunistic picocyanobacteria and the bloom of filamentous/colonial clusters. These findings highlight that if environmental conditions can partially explain the presence of opportunistic picocyanobacteria, microbial and trophic interactions with filamentous/colonial cyanobacteria should also be considered as potential shaping factors for single-celled communities. Regional climate change scenarios in the Baltic Sea predict environmental shifts leading to higher temperature and lower salinity; conditions identified here as favorable for opportunistic filamentous/colonial cyanobacteria. Altogether, the diversity and complexity of cyanobacterial communities reported here is far greater than previously known, emphasizing the importance of microbial interactions between filamentous and picocyanobacteria in the context of environmental disturbances.
|
|
| 26. |
- Blenckner, Thorsten, et al.
(author)
-
Climate and fishing steer ecosystem regeneration to uncertain economic futures
- 2015
-
In: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 282:1803
-
Journal article (peer-reviewed)abstract
- Overfishing of large predatory fish populations has resulted in lasting restructurings of entire marine food webs worldwide, with serious socioeconomic consequences. Fortunately, some degraded ecosystems show signs of recovery. A key challenge for ecosystem management is to anticipate the degree to which recovery is possible. By applying a statistical food-web model, using the Baltic Sea as a case study, we show that under current temperature and salinity conditions, complete recovery of this heavily altered ecosystem will be impossible. Instead, the ecosystem regenerates towards a new ecological baseline. This new baseline is characterized by lower and more variable biomass of cod, the commercially most important fish stock in the Baltic Sea, even under very low exploitation pressure. Furthermore, a socio-economic assessment shows that this signal is amplified at the level of societal costs, owing to increased uncertainty in biomass and reduced consumer surplus. Specifically, the combined economic losses amount to approximately 120 million E per year, which equals half of today's maximum economic yield for the Baltic cod fishery. Our analyses suggest that shifts in ecological and economic baselines can lead to higher economic uncertainty and costs for exploited ecosystems, in particular, under climate change.
|
|
| 27. |
- Bryhn, Andreas, et al.
(author)
-
Which factors can affect the productivity and dynamics of cod stocks in the Baltic Sea, Kattegat and Skagerrak?
- 2022
-
In: Ocean and Coastal Management. - : Elsevier BV. - 0964-5691 .- 1873-524X. ; 223
-
Research review (peer-reviewed)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.
|
|
| 28. |
- Cardinale, Massimiliano, et al.
(author)
-
A centurial development of the North Sea fish megafauna as reflected by the historical Swedish longlining fisheries
- 2015
-
In: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 16:3, s. 522-533
-
Journal article (peer-reviewed)abstract
- Historically, to compensate for declining catches, fishers have usually shifted from species characterized by high catch rate onto less easily caught species or have moved into new fishing grounds. Such shifts are poorly documented for areas with a long history of exploitation (i.e. North Sea) as they occurred long time before the start of the regular assessments of the marine resources. The Swedish longline fisheries in the Kattegat-Skagerrak and North Sea have a long history that spans over several centuries. These fisheries have historically targeted large demersal predator fish as ling (Molva molva), cod (Gadus morhua), Atlantic halibut (Hippoglossus hippoglossus) and skates (mainly Dipturus spp.). In this study, data from the Swedish longline fisheries from 1859 to 1960 have been collated. The data show that the geographical expansion of the fishery was extensive. At the turn of the 20th century, offshore longlining became concentrated north and west of the Shetlands and Hebrides, and after the WWII, the fishery expanded to Iceland and Rockall. In the offshore fishery, CPUE for the main target species, ling, remained stable, whereas for the other species, with the exception of tusk (Brosme brosme), CPUE showed a dramatic decline over time. In contrast, in the coastal longlining fishery, severe declines were revealed for all major target species except cod. We argue that the constant search for new fishing grounds in the Northeast Atlantic reflects a dwindling resource, where the fishermen kept the catch rates of ling high by travelling to more and more distant fishing grounds. © 2014 John Wiley & Sons Ltd.
|
|
| 29. |
|
|
| 30. |
- Cardinale, Massimiliano, et al.
(author)
-
CPUE trends of Hilsa kelee and Thryssa vitrirostris exploited by the artisanal finfish fisheries in Mozambique derived from an on-shore sampling of catches by trip
- 2014
-
In: Scientia Marina. - 0214-8358. ; 78, s. 55-64
-
Journal article (peer-reviewed)abstract
- Artisanal fisheries are often overlooked by fisheries management agencies despite their great importance for food security and livelihoods. The assessment and management of those fisheries is often rare, especially in developing countries. In Mozambique, a probability-based survey for the monitoring of the small-scale fisheries has been conducted in several coastal provinces since the late 1990's. Here we used the Mozambican on-shore data collection programme to illustrate both the difficulties and possibilities of estimating trends in catch per unit of effort (CPUE in kg day(-1)) for stocks when data is limited in both quantity and quality, as is often the case for artisanal fisheries. Data on catch and effort collected between 1998 and 2009 from four regions along the Mozambican coast and two different gears were used to assess the status of two species (Hilsa kelee and Thryssa vitrirostris) exploited by the artisanal fisheries. The results showed that standardized CPUE have declined for some of the regions and gears analysed, whereas for others the trend has been stable or has even increased during the last 12 years. However, when CPUE is scaled for the increase in net length, most of the times series show a declining trend.
|
|
| 31. |
|
|
| 32. |
|
|
| 33. |
- Cardinale, Massimiliano, et al.
(author)
-
Spatial and temporal depletion of haddock and pollack during the last century in the Kattegat-Skagerrak
- 2012
-
In: Journal of Applied Ichthyology. - : Hindawi Limited. - 0175-8659 .- 1439-0426. ; 28:2, s. 200-208
-
Journal article (peer-reviewed)abstract
- By reconstructing a centennial time-series of stock spatio-temporal dynamics and commercial landings, the long-term erosion is shown of the spatial structure of haddock and pollack in the Skagerrak and Kattegat that resulted in their regional depletion in the area. The erosion occurred in parallel with the development of the industrial fisheries and the peak in landings was followed by a decline in adult biomass and individual size. Also found was that pollack adult biomass was significantly lower for elevated water temperatures, while the response for haddock was less clear. However the main decline of both stocks and the disappearance of their adult aggregations occurred several decades before the unprecedented warming trend, which started in the Skagerrak and Kattegat only in the mid-1980s. These findings also suggest that haddock in the study area is not responding to the scale on which the management of the neighbouring North Sea haddock stock is currently performed. These results illustrate the hazardous consequences of prolonged overfishing on the population structure of commercially exploited stocks and the lack of knowledge which ultimately leads to spurious assumptions on the recovery potential of many fish stocks. Also argued is that the continuation of commercial fishery at sustainable levels adjusted to the present stock productivity might hinder the recovery of these depleted stocks for a long period of time.
|
|
| 34. |
- Cardinale, Massimiliano, et al.
(author)
-
The community structure of over-wintering larval and small juvenile fish in a large estuary
- 2014
-
In: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 139, s. 27-39
-
Journal article (peer-reviewed)abstract
- The Skagerrak and Kattegat are estuarine straits of high hydrographical and ecological diversity, situated between the saline waters of the North Sea and the brackish waters of the Baltic Sea. These sustain important nursery grounds of many fish species, of which several oveminter during the larval and early juvenile stages. In order to give more insight into the communities of the overwintering ichthyoplankton in estuarine areas, we examine an annual series of observations from a standard survey carried out 1992 -2010. Species differences and annual variability in distributions and abundances are described, and linkages between ichthyoplankton abundances and corresponding hydrographical information are analysed by GAM methods. Communities were dominated by herring, gobies, butterfish, sprat, pipe-fishes, lemon sole and European eel (i.e. glass eel), and all the sampled species showed large annual fluctuations in abundances. The species showed quite specific patterns of distribution although species assemblages with common distributional characteristics were identified. Within these assemblages, the ichthyoplankton abundances showed linkage to environmental characteristics described by bottom-depth and surface temperature and salinity. Hence the study points to a significant structuring of overwintering ichthyoplankton communities in large estuaries, based on the species habitat choice and its response to physical gradients. (C) 2014 Elsevier Ltd. All rights reserved.
|
|
| 35. |
- Carlos, Diaz-Gil, et al.
(author)
-
Spatio-temporal composition and dynamics of zooplankton in the Kalmar Sound (western Baltic Sea) in 2009-2010
- 2014
-
In: Boreal Environment Research. - 1239-6095 .- 1797-2469. ; 19:4, s. 323-335
-
Journal article (peer-reviewed)abstract
- In pelagic food webs, zooplankton is the link between lower and higher trophic levels. It is thus essential to know how the zooplankton community structure varies with its environment. We investigated the seasonal and spatial variation in the zooplankton diversity and community structure during two consecutive years in the Kalmar Sound, along the Swedish east coast, an area with a strong bathymetric gradient and of high ecological importance for e.g. commercial fish species. Two zooplankton communities were identified in the area: a coastal/estuarine community in the south and an open-water community in the north. They were separated mainly by differing salinity and temperature conditions. Biodiversity increased from spring to autumn and was higher in the open waters.
|
|
| 36. |
- Casini, Michele
(author)
-
A metacommunity perspective on source-sink dynamics and management: the Baltic Sea as a case study
- 2014
-
In: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 24, s. 1820-1832
-
Journal article (peer-reviewed)abstract
- The degree to which metapopulation processes influence fish stock dynamics is a largely unresolved issue in marine science and management, especially for highly mobile species such as Atlantic cod (Gadus morhua) and herring (Clupea harengus). The Baltic Sea comprises a heterogeneous oceanographic environment that structures the spatial and temporal distribution of the dominant species cod, herring, and sprat (Sprattus sprattus). Despite local differences, the stocks are traditionally managed as homogeneous units. Here, we present a metacommunity-perspective on source sink dynamics of Baltic Sea fish stocks by using a spatially disaggregated statistical food web model. The model is fitted to area-specific time series of multiple abiotic and biotic variables using state-space methods. Our analysis reveals pronounced net fluxes between areas, indicative of source sink dynamics, as well as area-specific differences in species interactions (i.e., density dependence, competition, and predator prey) and the degree of fishing and climate impact on survival and recruitment. Furthermore, model simulations show that decreasing exploitation pressure in the source area for cod (without reallocating fishing effort) produces an increase in neighboring sink habitats, but a decline of prey species in response to increased predation. Our approach provides valuable insight concerning metacommunity-structuring of marine fish and may serve as an important tool for implementing sustainable management strategies under the ecosystem approach to marine and fisheries management.
|
|
| 37. |
- Casini, Michele, et al.
(author)
-
Assessing the overlap between fishing activities and chondrichthyans distribution exposes high-risk areas for bycatch of threatened species
- 2023
-
Other publication (other academic/artistic)abstract
- Sharks, rays, and chimaeras (chondrichthyans) play a crucial role in marine ecosystem functioning but are highly vulnerable to fishing. Hence, understanding the spatial overlap between chondrichthyans and fishing effort is essential for effective conservation and management. Here, we propose an integrated approach that combines Vessel Monitoring System data with geostatistical species distribution models to assess the potential impact of fishing on chondrichthyan populations in the western Adriatic Sea. By mapping the overlap between model-based chondrichthyan distribution, species richness, and the proportion of threathened species with bottom trawl fishing activities, we identify areas at high risk for chondrichthyan bycatch. Our findings show that many of these species are at risk across a large part of their distribution within the study area. Notably, there is a substantial spatial overlap between regions where threatened chondrichthyans are found and species-rich areas with locations of intensive bottom trawl fishing in the northern and central offshore regions of the western Adriatic, emphasizing the vulnerability of these species to fishing pressure. Furthermore, differences in overlap between distinct fishing gears highlight the importance of considering specific fishing practices when formulating management strategies. While our work provides novel insights to potential bycatch hotspots, limitations related to data sources, spatial resolution, and the inability to directly quantify fishing impacts should be considered. Nonetheless, our findings contribute to the development of targeted conservation and spatial management measures, offering a general approach to study model-based spatial hotspots aimed at protecting and sustaining chondrichthyan populations in the heavily exploited Adriatic Sea.
|
|
| 38. |
- Casini, Michele, et al.
(author)
-
Changes in population depth distribution and oxygen stratification are involved in the current low condition of the eastern Baltic Sea cod (Gadus morhua)
- 2021
-
In: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 18, s. 1321-1331
-
Journal article (peer-reviewed)abstract
- During the past 20 years, hypoxic areas have expanded rapidly in the Baltic Sea, which has become one of the largest marine "dead zones" in the world. At the same time, the most important commercial fish population of the region, the eastern Baltic cod, has experienced a drastic reduction in mean body condition, but the processes behind the relation between deoxygenation and condition remain elusive. Here we use extensive long-term monitoring data on cod biology and distribution as well as on hydrological variations to investigate the processes that relate deoxygenation and cod condition during the autumn season. Our results show that the depth distribution of cod has increased during the past 4 decades at the same time of the expansion, and shallowing, of waters with oxygen concentrations detrimental to cod performance. This has resulted in a progressively increasing spatial overlap between the cod population and low-oxygenated waters after the mid-1990s. This spatial overlap and the actual oxygen concentration experienced by cod therein statistically explained a large proportion of the changes in cod condition over the years. These results complement previous analyses on fish otolith microchemistry that also revealed that since the mid-1990s, cod individuals with low condition were exposed to low-oxygen waters during their life. This study helps to shed light on the processes that have led to a decline of the eastern Baltic cod body condition, which can aid the management of this population currently in distress. Further studies should focus on understanding why the cod population has moved to deeper waters in autumn and on analyzing the overlap with low-oxygen waters in other seasons to quantify the potential effects of the variations in physical properties on cod biology throughout the year.
|
|
| 39. |
- Casini, Michele
(author)
-
Climate variability drives anchovies and sardines into the North and Baltic Seas
- 2012
-
In: Progress in Oceanography. - : Elsevier BV. - 0079-6611. ; 96, s. 128-139
-
Journal article (peer-reviewed)abstract
- European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) are southern, warm water species that prefer temperatures warmer than those found in boreal waters. After about 40 years of absence, they were again observed in the 1990s in increasing quantities in the North Sea and the Baltic Sea. Whereas global warming probably played a role in these northward migrations, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the contraction of the subpolar gyre were important influences. Sardine re-invaded the North Sea around 1990, probably mainly as a response to warmer temperatures associated with the strengthening of the NAO in the late 1980s. However, increasing numbers of anchovy eggs, larvae, juveniles and adults have been recorded only since the mid-1990s, when, particularly, summer temperatures started to increase. This is probably a result of the complex dynamics of ocean-atmosphere coupling involving changes in North Atlantic current structures, such as the contraction of the subpolar gyre, and dynamics of AMO. Apparently, climate variability drives anchovies and sardines into the North and Baltic Seas. Here, we elucidate the climatic background of the return of anchovies and sardines to the northern European shelf seas and the changes in the North Sea fish community in the mid-1990s in response to climate variability. (C) 2011 Elsevier Ltd. All rights reserved.
|
|
| 40. |
- Casini, Michele, et al.
(author)
-
Density-dependence in space and time: Opposite synchronous variations in population distribution and body condition in the baltic sea sprat (Sprattus sprattus) over three decades
- 2014
-
In: PLoS ONE. - : Public Library of Science. - 1932-6203. ; 9:4
-
Journal article (peer-reviewed)abstract
- Spatio-temporal density-dependent processes are crucial regulatory factors for natural populations. However, there is a lack of studies addressing spatial density-dependence in fish growth. A previous investigation has suggested spatio-temporal density-dependence in body condition of Baltic sprat. Here, we used different techniques, such as centre of gravity, distance, and homogeneity indices, to better characterize the spatial and temporal variations in sprat density and body condition in the Baltic Proper. Our results evidenced a negative spatio-temporal co-variation between the centres of gravity of density and maximum condition. In the 1980s-early 1990s both centres were located in the middle of the Baltic Proper. From the mid 1990s the centres progressively separated in space, as the sprat population moved towards the north-eastern Baltic Proper, and the centre of maximum condition towards the south-western areas. Moreover, at low abundances, sprat density and condition were homogeneously distributed in space, whereas at high abundances both density and condition showed pronounced geographical gradients. The ecological processes potentially explaining the observed patterns were discussed in the light of the Ideal Free Distribution theory. We provide evidence that the shift in the spatial distribution of cod, the main predator of sprat, has been the main factor triggering the overall spatial changes in sprat density, and thus condition, during the past thirty years. The spatial indices shown here, synthesizing the spatio-temporal patterns of fish distribution, can support the implementation of the EU Marine Strategy Framework Directive. © 2014 Casini et al.
|
|
| 41. |
- Casini, Michele
(author)
-
Eaten by a cormorant: unexpected return of a tagged Baltic cod
- 2021
-
Conference paper (peer-reviewed)abstract
- Temperature-depth data storage tags (DSTs) continuously store individual measurements of water depth and water temperature of the habitat used by free-ranging fish. To analyse the data, the DSTs need to be returned. Usually they are returned by fishers whereas returns of fish tagged with DSTs that died due to natural causes are rare. During an international tagging project, one DST was returned by an ornithologist which found the data logger in a pellet in a cormorant colony. Although the cod itself was not available since it was already digested, the DST provided 90 days of data prior to the predation event. The cod mostly remained in waters shallower than 40 m and conducted daily in- and offshore movements covering the whole water column, leading to daily temperature differences of up to 8.8°C. In May, during one trip where the cod used very shallow waters (1.5m water depth) in the morning (09:00 h), it was taken by a cormorant. Digestion, indicated by temperatures of 39.3°C to 41.2°C, took 31 hours. This returned DST emphasizes that large-scale tagging projects should not only raise awareness in the fisheries sector but also among ornithologists when avian predators target the tagged fish species.
|
|
| 42. |
- Casini, Michele, et al.
(author)
-
Expeditionsrapport BITS, februari 2016
- 2016
-
Reports (other academic/artistic)abstract
- Expeditionen genomfördes med hjälp av TV3L bottentrål enligt Baltic International Trawl Survey (BITS) manual (Anon., 2014a). Sverige tilldelades 50 slumpvis utvalda stationer. 47 giltiga hal utfördes. Tre stationer kunde inte fiskas p.g.a. tillträdesförbud utfärdat av Svenska Försvarsmakten (tabell 3). Sammantaget genomfördes 47 drag med TV3L bottentrål inklusive 10 fiktiva drag som inte trålades eftersom syrekoncentrationen nära botten var <1,5 ml/l (de inkluderas i beståndsuppskattningen som 0-fångst) och täckte delar av områdena SD 25, 26, 27 och 28 i år. Under hela undersökningen registrerades akustiska data kontinuerligt. Under denna undersökning fångades 20 fiskarter. Totalfångsten i vikt dominerades av sill, skarpsill, torsk, skrubbskädda, rötsimpa och rödspätta. Hydrografiparametrar, bl. a. salthalt, temperatur och syrekoncentration, observerades och mättes på de flesta trålstationerna. I denna rapport visas enbart syrekoncentrationen vid botten.
|
|
| 43. |
|
|
| 44. |
|
|
| 45. |
- Casini, Michele, et al.
(author)
-
Hypoxic areas, density-dependence and food limitation drive the body condition of a heavily exploited marine fish predator
- 2016
-
In: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 3
-
Journal article (peer-reviewed)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.
|
|
| 46. |
|
|
| 47. |
|
|
| 48. |
|
|
| 49. |
|
|
| 50. |
- Casini, Michele
(author)
-
Lägesrapport TABACOD
- 2019
-
In: Svensk fisknäring. - 2002-9845 .- 2003-1556. ; 3, s. 14-15
-
Journal article (pop. science, debate, etc.)
|
|
