| 1. |
- Limburg, Karin E., et al.
(författare)
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In search of the dead zone : Use of otoliths for tracking fish exposure to hypoxia
- 2015
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Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963 .- 1879-1573. ; 141, s. 167-178
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Tidskriftsartikel (refereegranskat)abstract
- Otolith chemistry is often useful for tracking provenance of fishes, as well as examining migration histories. Whereas elements such as strontium and barium correlate well with salinity and temperature, experiments that examine manganese uptake as a function of these parameters have found no such correlation. Instead, dissolved manganese is available as a redox product, and as such, is indicative of low-oxygen conditions. Here we present evidence for that mechanism in a range of habitats from marine to freshwater, across species, and also present ancillary proxies that support the mechanism as well. For example, iodine is redox-sensitive and varies inversely with Mn; and sulfur stable isotope ratios provide evidence of anoxic sulfate reduction in some circumstances. Further, S may be incorporated trophically whereas other elements appear to be taken up directly from water. This research suggests a potential means to identify individual fish exposure to hypoxia, over entire lifetimes. With further testing and understanding, in the future fish may be able to be used as "mobile monitors" of hypoxic conditions. (C) 2014 The Authors. Published by Elsevier B.V.
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| 2. |
- Acharya, B. S., et al.
(författare)
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Introducing the CTA concept
- 2013
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 43, s. 3-18
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. (C) 2013 Elsevier B.V. All rights reserved.
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| 3. |
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| 4. |
- Andersson, Jan, et al.
(författare)
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Fisk- och skaldjursbestånd i hav och sötvatten 2015 : Resursöversikt
- 2015
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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 (SLU Aqua) vid Sveriges lantbruksuniversitet (SLU) samt yrkesfiskets rapportering.Rapporten omfattar 40 fiskarter uppdelade i olika bestånd, samt sex skal-och blötdjursarter.Nytt för årets upplaga är en beskrivning av hur de provfisken som ligger till grund för analys och rådgivning utförs.Översikten är utarbetad av Sveriges lantbruksuniversitet (SLU), Institutionen för akvatiska resurser (SLU Aqua), på uppdrag av Havs- och vattenmyndigheten.
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| 5. |
- 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
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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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| 13. |
- Limburg, Karin E., et al.
(författare)
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Tracking Baltic hypoxia and cod migration over millennia with natural tags
- 2011
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:22, s. E177-E182
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Tidskriftsartikel (refereegranskat)abstract
- Growing hypoxic and anoxic areas in coastal environments reduce fish habitat, but the interactions and impact on fish in these areas are poorly understood. Using natural tag properties of otoliths, we found significant correlations between the extent of Baltic Sea hypoxia and Mn/Ca ratios in regions of cod (Gadus morhua) otoliths corresponding to year 1 of life; this is associated with elevated bottom water dissolved manganese that increases with hypoxia. Elevated Mn/Ca ratios were also found in other years of life but with less frequency. We propose that cod exhibiting enhanced Mn/Ca ratios were exposed to dissolved manganese from hypoxia-induced redox dynamics in nursery areas. Neolithic (4500 B. P.) cod otoliths (n = 12) had lowlevels of Mn/Ca ratios, consistent with low hypoxia, but a single otolith dated to the younger Iron Age had a distinct growth band with an elevated Mn/Ca ratio. Sr/Ca patterns reflecting changes in environmental salinity and temperature were similar in both modern and Stone Age otoliths, indicating consistent migration habits across time, and Ba/Sr ratios in modern cod otoliths indicate increasing use of a more saline habitat with age. Using elemental ratios, numerous existing archival collections of otoliths could provide the means to reconstruct hypoxia exposure histories and major patterns of fish movement near dead zones globally.
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| 14. |
- Limburg, Karin, et al.
(författare)
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Prehistoric vs. modern Baltic Sea cod fisheries : selectivity across the millennia
- 2008
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 275:1652, s. 2659-2665
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Tidskriftsartikel (refereegranskat)abstract
- Combining Stone Age and modern data provides unique insights for management, extending beyond contemporary problems and shifting baselines. Using fish chronometric parts, we compared demographic characteristics of exploited cod populations from the Neolithic Period (4500 BP) to the modern highly exploited fishery in the central Baltic Sea. We found that Neolithic cod were larger (mean 56.4 cm, 95% confidence interval (CI)±0.9) than modern fish (weighted mean length in catch =49.5±0.2 cm in 1995, 48.2±0.2 cm in 2003), and older (mean ages =4.7±0.11, 3.1±0.02 and 3.6±0.02 years for Neolithic, 1995, and 2003 fisheries, respectively). Fishery-independent surveys in 1995 and 2003 show that mean sizes in the stock are 16–17 cm smaller than reflected in the fishery, and mean ages approximately 1–1.5 years younger. Modelled von Bertalanffy growth and back-calculated lengths indicated that Neolithic cod grew to smaller asymptotic lengths, but were larger at younger ages, implying rapid early growth. Very small Neolithic cod were absent and large individuals were rare as in modern times. This could be owing to selective harvests, the absence of small and large fish in the area or a combination. Comparing modern and prehistoric times, fishery selection is evident, but apparently not as great as in the North Atlantic proper.
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| 15. |
- Olson, Carina, et al.
(författare)
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Neolithic cod and herring fisheries in the Baltic Sea, in the light of fine-mesh sieving : A comparative study of subfossil fishbone form the late Stone Age sites at Ajvide, Gotland, Sweden and Åland, Finland
- 2007
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Ingår i: Environmental Archaeology. ; 12:2, s. 175-185
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Tidskriftsartikel (refereegranskat)abstract
- During the Late Stone Age, the sites of Ajvide and Jettböle were located on the seashore but in quite different marine environments. Ajvide on Gotland had direct access to the open sea of the central Baltic, while Jettböle in the Åland archipelago was surrounded by islands and skerries in the northern part of the Baltic Sea. Continuous excavations at Ajvide revealed large amounts of Cod (Gadus morhua) while herring (Clupea harengus) was found in small numbers. At Jettböle, as well, cod bones have been observed in large numbers while the skeletal remains of herring were few. In this study, soil samples of fishbone materials from Ajvide and Jettböle were sieved through screens of different mesh-sizes and then osteologically analyzed. The finer screens aided the recovery of small herringbones that usually are lost when sieving through a common standard mesh-size of 4 mm. The results of the study confirmed the importance of fine-mesh sieving for the retrieval of the fishbone materials. Additionally, the achieved osteometric data indicated a difference in cod and herring size between the sites. Other factors that form our base for the understanding of Neolithic fishing strategies are; a general knowledge of the behaviour of the retrieved fish species, a reconstruction of the ancient marine environment and the abundance of fish species at each site.
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| 16. |
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| 17. |
- Sjöberg, Rajlie, et al.
(författare)
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Challenging ICES age estimation protocols: lessons learned from the eastern Baltic cod stock
- 2016
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 73, s. 2138-2149
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Forskningsöversikt (refereegranskat)abstract
- Over the recent decades, the International Council for the Exploration of the Sea (ICES) has set guidelines for best practise quality control of age estimation procedures. The applicability of these guidelines is assessed by reviewing the ageing issues of eastern Baltic cod (EBC) as a case study. Since the implementation of an age-based assessment of EBC in the beginning of the 1970s, the assessment has been hampered by the quality of the age composition data, in recent years to a degree that age-based assessment is no longer used. The reason for the age reading problems is the low visual contrast between growth zones in the otoliths which seems to be the result of complex interactions of the hydrography in the Baltic Sea with the cod's biology and behaviour. Over the last 40 years, various expert groups have struggled to document and improve the agreement of age estimation between national otolith readers, standardize methods and age estimations through repeated exchanges and reference collections as well as an internationally agreed manual. Despite these initiatives the precision of the age estimations based on traditional ageing did not improve, with significant bias persisting between and within readers. Additionally, a wide range of alternative methods for deriving the age information necessary for stock assessment and for validation of the true age have been tested. However, these methods did not produce unbiased age estimates over the entire size and age range of the EBC stock. An age-validation is urgently needed. Deviations from the ICES guidelines identified are as follows: (i) the lack of rigorous quality control, particularly the auditing of national trends in age precision over the years using a reference collection and (ii) the implementation of an age error matrix in the stock assessment.
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| 20. |
- Walther, Yvonne
(författare)
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Bringing integrated ecosystem assessments to real life: a scientific framework for ICES
- 2014
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 71, s. 1183-1186
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Tidskriftsartikel (refereegranskat)abstract
- An ecosystem approach to management (EAM) aims to secure a healthy ecosystem along with sustainable use of its goods and services. Although the main principles of EAM are agreed upon and desirable, wider implementation of EAM is still a challenge. The difficulties stem from unclear definition and communication of the EAM, lack of routines or protocols to develop ecosystem-based advice, inappropriate institutional structures, and communication issues between scientists, advisers, and managers. Integrated ecosystem assessment (IEA) is an instrument that has proven to help in the implementation of EAM. For successful implementation of EAM and IEA in the European regional seas context, an international forum is required that develops tailor-made EAM tools specific to the different regional ecosystems to overcome fragmented national strategies. We describe a multinational peer network of working groups developed within the International Council for the Exploration of the Sea (ICES) under the auspice of Science Steering Group on Regional Sea Programmes. Available is a wealth of data, expertise, scientific methods, and models for each regional sea. This network can be instrumental in advancing IEA for the implementation of EAM in the North Atlantic seas.
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| 21. |
- Walther, Yvonne
(författare)
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Bycathes of cod in Swedish trawl fishery for pelagic species in the Baltic Sea
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Catches were sampled in two fishing methods; industrial fishing for sprat (Sprattus sprattus) using a pelagic trawl, and fishing for herring (Clupea harengus) using a bottomtrawl, to investigate bycatches of cod (Gadus morhua) and other species. Sampling took place in 1993 and 1994 in the Baltic Sea. The industrial fishing was sampled in SD 25-28, and the herring fishing was sampled in SD 25. Bycatches in industrial fishing comprised; herring (17.8 %), cod <33cm (0.06 %), and cod >33 cm (0.15 %). The only discernible bycatches of cod in industrial fishing were in SD 25. Other bycatches in industrial fishing were lumpsucker (Cyclopterus lumpus), three-spined stickleback (Gasterosteus aculeatus), flounder (Platichthys flesus) and salmon (Salmo salar). Catches in herring fishing comprised bycatches of cod <33 cm (0.6%), and cod>33cm (2.7%). Other species occuring as a bycatch in herringfishing were sprat, whiting (Merlangius merlangus), trout (Salmo trutta), and jellyfish (Aurelia aurita)
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