| 1. |
- Almqvist, Gustaf, et al.
(författare)
-
Report of the Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD)
- 2015
-
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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| 2. |
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| 3. |
- Aps, R., et al.
(författare)
-
Central Baltic Sea herring : effect of environmental trends and fishery management
- 2011
-
Ingår i: Ecosystems and Sustainable Development VIII. - Southampton : BioMed Central Ltd.. - 9781845645106 - 9781845645113 ; , s. 69-80
-
Konferensbidrag (refereegranskat)abstract
- Uncertainty is an endemic condition of the Baltic Sea herring (Clupea harengus membras, L) fishery management. It is a condition exacerbated by the fishing fleet overcapacity and consequent exploitation of the herring stock at a level believed to be unsustainable. Some sources of uncertainty are mainly related to biology and fishing technique: the unsolved problem of herring assessment and management units, the recruitment–environment relationship and the reduction in mean weights-at-age, uncertain ageing of fish, the problem of unaccounted fishing mortality caused by the fish selection through the trawl net. Fishing fleet overcapacity is believed to be behind of the regulatory overfishing when setting the Total Allowable Catches (TACs) higher than the scientific advice (decision overfishing) and tolerating the extensive underreporting of catches (implementation overfishing). Two scenarios for the Central Baltic Sea herring fishery management options are constructed and the Bayesian networks are used to represent and update uncertainties encountered in the process of the management related situation assessment. First scenario represents the current status of the fishery management resulting in fishing mortality (F) higher than FMSY – the fishing mortality that corresponds to the Maximum Sustainable Yield (MSY). The second scenario demonstrates the assumed potential impact of economic incentives (e.g.zoning, individual transferable quotas (ITQs), territorial use rights etc.) on the reduction of excessive fishing capacity and bringing actual fishing mortality closer to FMSY.
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| 4. |
- Aps, R., et al.
(författare)
-
Fisheries management : from linear to collaborative science-policy interface
- 2011
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Ingår i: Management of Natural Resources, Sustainable Development and Ecological Hazards III. - : WIT Press. - 9781845645328 - 1845645324 ; , s. 3-14
-
Konferensbidrag (refereegranskat)abstract
- The context of fisheries management, according to recent studies, tends to be complex, uncertain and controversial and it cannot be adequately addressed based on work done within the “linear” science-policy interface (SPI). It is believed that moving towards a more participatory and “collaborative” SPI model would favour implementation of more efficient economic incentives to reduce the fishing fleet capacity and bring the actual fishing mortality closer to the levels considered to be sustainable. Focusing the participatory research basically on fish biology and fish stock assessment seems to be too narrow while, on the other hand, it does not embrace many other important issues of contemporary fisheries management. It is suggested that further involvement of stakeholders into the full-scale bio-economic modelling based participatory research would contribute to better understanding of the dynamics of human natural interface concerned and, consequently, would improve the consensus between different interests.
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| 5. |
- Bergenius, Mikaela, et al.
(författare)
-
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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| 6. |
- Bergström, Lena, et al.
(författare)
-
Interim Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB) : 18-22 April 2016 Helsinki, Finland
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB) meeting was held in Helsinki (Finland), 18-22 April 2016. The meeting was attended by 26 participants from five countries and chaired by Laura Uusitalo, Fin-land, Saskia Otto, Germany, Martin Lindegren, Denmark, and Lena Bergström, Swe-den. This was the first year of the new three-year Terms of Reference (ToR) for WGIAB. The main working activities in 2016 were to A) develop the trait-based ap-proach of understanding the ecosystem function, and B) explore the social-ecological system, including indicator development, revising the conceptual model, and devel-oping case studies. As a primary outcome of the ToR A, we built on our previous work on integrated ecosystem assessments (IEAs) in the Baltic Sea, but extended it beyond considering changes in abundances of a few dominant species, to accounting for community-wide changes in a number of key traits across multiple trophic levels. These traits represent various ecosystem functions upon which we derive important ecosystem services. By investigating temporal changes in the community weighted mean traits of phyto-plankton, zooplankton, zoobenthos, and fish, we demonstrated whether trait reor-ganizations at the level of entire communities occurred in the Central Baltic Sea as a result of the 1980s regime shift. Using in total 29 traits combined for all groups we found indications of two breakpoints across all four taxonomic groups over the last decades, i.e. one around 1990 and one around 2000. Further work will focus on ex-ploring the nature of the changes in trait composition and on standardizing the num-ber of traits and data types (i.e. binary, continuous or categorical) across taxonomic group.In addition, we collected data on key functional groups and abiotic variables in all main sub-basins of the Baltic Sea, setting the stage for a cross-regional comparison of temporal patterns and trends in lower trophic level in the face of recent develop-ments in climate-related drivers.With reference to Tor B, to explore how social indicators could be used in parallel with biological indicators in an integrated assessment framework, we developed a conceptual model of interrelationships between ecosystem and society. We used the model as a basis for mapping factors to be accounted for in the ecosystem-based management using the Baltic salmon and clupeid species as case studies. The models depict 1) the structure of the foodweb relevant to the target species, 2) the key com-munity level and population traits that contribute to the state of the species, 3) main pressures affecting the foodweb and their effects on the species, 4) key management measures, and 5) benefits that the species can produce for society.To support the development of Ecosystem Overview the group members evaluated the probability of occurrence and the magnitude of the effect of 15 pressures occur-ring in the Baltic Sea. The top five pressures identified were input of nutrients, in-creased temperature, decreased salinity, input of hazardous substances, and input or spread of non-indigenous species.The work will continue intersessionally and the next meeting of WGIAB is planned to be held in Lisbon, Portugal, back-to-back with WGCOMEDA and WGEAWESS.
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| 7. |
- Bergström, Lena, et al.
(författare)
-
Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB)
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea(WGIAB) was established in 2007 as a forum for developing and combining ecosystembasedmanagement efforts for the Baltic Sea. The group intends to serve as a scientificcounterpart and support for the ICES Baltic Fisheries Assessment Working Group(WGBFAS) as well as for efforts and projects related to Integrated Ecosystem Assessments(IEA) within ICES and HELCOM. The group works in cooperation with similargroups within the ACOM/SCICOM Steering Group on Integrated Ecosystem Assessments(SSGIEA).The 2015 WGIAB meeting was held in Cádiz, Spain, from 9–13 March, back-to-backwith the meeting of its counterpart in the Working Group on Ecosystem Assessmentof Western European Shelf Seas (WGEAWESS). The meetings had joint sessions as wellas WG specific work, and some participants effectively participated in both meetings.The WGIAB meeting was attended by 27 participants from nine countries. The meetingwas chaired by Christian Möllmann, Germany, Laura Uusitalo, Finland and Lena Bergström,Sweden.This was the last year of the ongoing three-year Terms of Reference (ToR) for WGIAB.The main working activities in 2015 were to i) conduct studies on Baltic Sea ecosystemfunctioning with the goal to publish case studies from different parts of the Baltic Seain peer-reviewed journals, ii) work on the demonstration exercise to develop ecosystem-based assessment and advice for Baltic fish stocks focusing on cod (DEMO) withmultiple approaches, iii) plan further how to integrate the social and economic aspectsmore tightly in the WGIAB work, and iv) discuss the future focus and format of theWGIAB work.The Baltic ecosystem functioning activity focused on identifying and exploring keytrends and linkages in the Baltic Sea foodweb. This was pursued by presentation andfurther discussion of ongoing intersessional work on foodweb modelling and integratedanalyses, and by exercises to develop conceptual models Baltic Sea foodwebsand the links to ecosystem function. Long-term monitoring datasets on the abiotic andbiotic parts of the Baltic Sea Proper ecosystem were updated for use in the continuedwork to develop environmental indicators for fisheries and marine management.The focus of the DEMO 3 (DEMOnstration exercise for Integrated Ecosystem Assessmentand Advice of Baltic Sea cod) was on finding a way to use the results from theDEMO1 and DEMO2 workshops in short and midterm projections/scenarios of Balticcod dynamics based on different types of modelling, as well as designing methodologyand modelling data for practical implementation of Integrated Advice for Baltic cod.The WGIAB was positively inclined towards including social and economic aspectsinto the integrated assessment. Openings to this path were provided by presentationon ongoing project work, and discussing their linkages to ecological aspects. It wasseen as crucial that experts on social and economic analysis should be included andtake an active part in the future work of the group.The group concluded that its upcoming work should focus more closely on functionaldiversity, which was identified as a recurring issue in the Baltic Sea. This approach wasalso identified as a useful connection point between scientific and management aspectsin order for the group to continue serving as a forum for developing ecosystem-basedmanagement efforts in the Baltic Sea. A focus on functional diversity was also seen as2 | ICES WGIAB REPORT 2015a potentially feasible way of bringing together management aspects for different sectors,by linking to ecosystem services concepts.The group proposed Saskia Otto, Germany and Martin Lindegren, Denmark as newincoming Chairs, together with Lena Bergström, Sweden and Laura Uusitalo, Finland.Having four Chairs is justified due to the wide scope of the group's work, as well asthe increased work load due to the planned new foci.
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| 8. |
- Crawford, Elizabeth, et al.
(författare)
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Using Video Footage for Observing Honey Bee Behaviour at Hive Entrances
- 2022
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Ingår i: Bee world. - : Taylor & Francis Group. - 0005-772X .- 2376-7618. ; 99:4, s. 139-142
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Tidskriftsartikel (refereegranskat)abstract
- Video recording is a common method to study animal behaviour. In honey bee studies, short video-recordings are often used to learn more about a behaviour, but rarely used for their quantification. Standard methods for observing bee behaviour involve behavioural assays or direct observation of a limited subset of marked bees within an observation hive. This means that behaviour at the hive entrance may be overlooked. Here we describe a 4-camera set up for the study of behaviour at hive entrances. With minimal disturbance, we were able to record and quantify all previously described behaviours (9 in total - including self-grooming in drones) on and around the hive entrance. We briefly discuss the general feasibility of video footage and the relative frequency of each observed behaviour. Our conclusion is that video footage is a useful and perhaps overlooked method for unbiased quantification and comparisons of bee behaviour at the hive entrance. With this paper we are publishing some example short video-recordings as online supplementary material for educational purposes.
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| 9. |
- Hinrichsen, Hans-Harald, et al.
(författare)
-
Report of the Workshop on DEveloping Integrated AdviCE for Baltic Sea ecosystem-based fisheries management (WKDEICE) : 18-21 April 2016 Helsinki, Finland
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The first ICES Workshop on DEveloping Integrated AdviCE for Baltic Sea ecosystem-based fisheries management (WKDEICE) had the aim to start identifying and devel-oping ways to include environmental and economic considerations into ICES advice on Baltic Sea fish stocks. The WKDEICE meeting was held in Helsinki, Finland, on18–21 April 2016, with 12 participants from three countries and was chaired by Chris-tian Möllmann (Germany), Rudi Voss (Germany), and Maciej T. Tomczak (Sweden). Focusing on Eastern Baltic cod (subdivisions 25-32), WKDEICE addressed five main topics:1)developing a strategy for integrating environmental and economic infor-mation in fish stock advice;2)conducting an integrated environmental assessment;3)conducting a socio-economic assessment;4)conducting short-term projections informed by environmental and economic conditions; and5)communicating the approach and the results.Eastern Baltic cod has been selected as a case study. The exercise will likely be ex-tended to the baltic clupeid stocks of herring and sprat.A central point of the meeting was to discuss and design a concept of operationalized Integrated Ecosystem Assessment (IEA) including short-term predictions, to be used in advice on the main Baltic Sea fish stocks. The group developed an operational strategy, and started to quantify potentially useful environmental indicators, focusing on hydrographic conditions influencing cod recruitment. Economic short-term fore-casts were established to include the human dimension, and to provide additional quantitative information on fishing options. The suggested integrated advice frame-work will be further developed using simulation modelling during a next meeting in 2017. This meeting will be coordinated with the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB) and the Baltic Fisheries Assess-ment Working Group (WGBFAS) to test concepts, apply Management Strategy Eval-uation (MSE) models, and have direct feedback for relevant ICES bodies.
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| 10. |
- Holmgren, Noél, et al.
(författare)
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A Concept of Bayesian Regulation in Fisheries Management
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:11
-
Tidskriftsartikel (refereegranskat)abstract
- Stochastic variability of biological processes and uncertainty of stock properties compel fisheries managers to look for tools to improve control over the stock. Inspired by animals exploiting hidden prey, we have taken a biomimetic approach combining catch and effort in a concept of Bayesian regulation (BR). The BR provides a real-time Bayesian stock estimate, and can operate without separate stock assessment. We compared the performance of BR with catch-only regulation (CR), alternatively operating with N-target (the stock size giving maximum sustainable yield, MSY) and F-target (the fishing mortality giving MSY) on a stock model of Baltic Sea herring. N-targeted BR gave 3% higher yields than F-targeted BR and CR, and 7% higher yields than N-targeted CR. The BRs reduced coefficient of variance (CV) in fishing mortality compared to CR by 99.6% (from 25.2 to 0.1) when operated with F-target, and by about 80% (from 158.4 to 68.4/70.1 depending on how the prior is set) in stock size when operated with N-target. Even though F-targeted fishery reduced CV in pre-harvest stock size by 19–22%, it increased the dominant period length of population fluctuations from 20 to 60–80 years. In contrast, N-targeted BR made the periodic variation more similar to white noise. We discuss the conditions when BRs can be suitable tools to achieve sustainable yields while minimizing undesirable fluctuations in stock size or fishing effort.
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| 11. |
- Holmgren, Noél, et al.
(författare)
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Artificial neural networks in models of specialization, guild evolution and sympatric speciation
- 2007
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 362:1479, s. 431-440
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Tidskriftsartikel (refereegranskat)abstract
- Sympatric speciation can arise as a result of disruptive selection with assortative mating as a pleiotropic by-product. Studies on host choice, employing artificial neural networks as models for the host recognition system in exploiters, illustrate how disruptive selection on host choice coupled with assortative mating can arise as a consequence of selection for specialization. Our studies demonstrate that a generalist exploiter population can evolve into a guild of specialists with an ‘ideal free’ frequency distribution across hosts. The ideal free distribution arises from variability in host suitability and density-dependent exploiter fitness on different host species. Specialists are less subject to inter-phenotypic competition than generalists and to harmful mutations that are common in generalists exploiting multiple hosts.When host signals used as cues by exploiters coevolve with exploiter recognition systems, our studies show that evolutionary changes may be continuous and cyclic. Selection changes back and forth between specialization and generalization in the exploiters, and weak and strong mimicry in the hosts, where non-defended hosts use the host investing in defence as a model. Thus, host signals and exploiter responses are engaged in a red-queen mimicry process that is ultimately cyclic rather then directional. In one phase, evolving signals of exploitable hosts mimic those of hosts less suitable for exploitation (i.e. the model). Signals in the model hosts also evolve through selection to escape the mimic and its exploiters. Response saturation constraints in the model hosts lead to the mimic hosts finally perfecting its mimicry, after which specialization in the exploiter guild is lost. This loss of exploiter specialization provides an opportunity for the model hosts to escape their mimics. Therefore, this cycle then repeats.We suggest that a species can readily evolve sympatrically when disruptive selection for specialization on hosts is the first step. In a sexual reproduction setting, partial reproductive isolation may first evolve by mate choice being confined to individuals on the same host. Secondly, this disruptive selection will favour assortative mate choice on genotype, thereby leading to increased reproductive isolation.
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| 12. |
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| 13. |
- Holmgren, Noél M. A., et al.
(författare)
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MSY-orientated management of Baltic Sea herring (Clupea harengus) during different ecosystem regimes
- 2012
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press. - 1054-3139 .- 1095-9289. ; 69:2, s. 257-266
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Tidskriftsartikel (refereegranskat)abstract
- The Baltic Sea ecosystem has undergone dramatic changes, so-called ecosystem regime shifts, during the past four decades. Baltic Sea herring (Clupea harengus) spawning-stock biomass has declined to a third, and weight-at-age has halved as a result of food shortages and competition with sprat (Sprattus sprattus). The management objective for the herring stock is currently in transition from precautionary to maximum sustainable yield (MSY). The main basin Baltic Sea herring was modelled under the current ecosystem regime and the effect of a recovery of the cod (Gadus morhua) stock and the availability of planktonic food to levels found in the early 1980s analysed. A target of F-MSY = 0.16 for herring, which should decline to F-MSY = 0.10 with recovery of the cod stock, is proposed. An increase in the availability of planktonic food is estimated to more than double the yield at F-MSY = 0.27, overriding the negative effects of cod predation should there be a simultaneous increase in both cod and availability of planktonic food. The estimated net increase in yield is 40% at F-MSY = 0.20. Functions are presented to calculate FMSY and to estimate the expected yield depending on the abundance of cod and food availability. Retrospective application of the functions is indicative of overfishing of herring in the 1990s and early 2000s, and a net loss in yield, with a landing value of some E440 million.
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| 14. |
- Holmgren, Noél M. A., et al.
(författare)
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MSY oriented management of the Baltic Sea herring under regime shifts
- 2011
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Ingår i: ICES report of the Baltic Fisheries Assessment working Group (WGBFAS). - Copenhagen : ICES. ; , s. 752-798
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The ecosystem of the baltic sea has undergone dramatic changes, perhaps a regime-shift, during the last four decades. The Baltic Sea Herring SSB has declined to a third and weight-at-age has halved due to plankton prey deficits. The management objective of the herring is currently in the transition to a cautionary maximum sustainable yield (MSY). We modelled the main basin Baltic Sea herring under the currernt regime, and analysed the effect of a ercovery of the cod stock and the food availability as they were in the early 1980s. We recommend a target F MSY of 0.16, but with a recovery of the cod, recommended target F MSY is is 0.10. A simultaneous increase in both cod and food availability is estimated to increase the yield with 40% at the target F MSY is 0.20. We present functions to calculate F MSY and estimate the expected yield depending on the abundance of cod and food-availability. A retrospective application of our functions indicates over-fishing in the 1990s and early 2000s, and a net loss in yields with a landing value of about E440 Millions.
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| 15. |
- Howell, Daniel, et al.
(författare)
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Interim Report of the Working Group on Multispecies Assessment Methods (WGSAM)
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The pan-regional Working Group on Multispecies Assessment Methods (WGSAM) met in San Sebastian, Spain, 16–20 October 2017. In this eleventh report of the group, work focused on three of the multi-annual ToRs (B, C, D). Based on their knowledge, participants provided an updated inventory of progress of multispecies models in ICES Ecoregions (ToR A), noting those regions where no information was available. A Key Run (ToR B) of the North Sea Stochastic Multispecies Model (SMS) was presented and reviewed in detail by 4 WGSAM experts, and approved by the group following implementation of changes agreed in plenary at the meeting and verified by a subset of experts post-meeting. The Key Run is documented in detail in Annex for ToR B, with key outputs summarised in Section 5 and data files made available on the WGSAM webpage and the ICES expert group Github (https://github.com/iceseg/wg_WGSAM). Since the M2 values are used for the assessment of important North Sea stocks, it is recommended to publish the annex also on the official stock annex website. In addition, WGSAM does not recommend updating existing data series of natural mortality by simply adding the latest three new years. The timeseries as a whole shows patterns which are not retained by this procedure. Multispecies model skill assessment (ToR C) and multi-model ensemble methods (ToR D) were emphasized this year. Considerable progress has been made towards advancing both aspects of multispecies modelling. Investigation of skill assessment and ensemble methods and case studies is critical to ensure that outputs of multispecies assessment models are reliable for use in operational assessment and to inform management decisions. Progress was also made on investigations of top predator impacts on managed fish across several regions (ToR F), including the North Sea where new information was included in the SMS key run. Further progress was also made on multispecies and ecosystem level reference points and harvest control rules in mixed fisheries (ToR G).
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| 16. |
- Howell, Daniel, et al.
(författare)
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Report of the Working Group on Multispecies Assessment Methods (WGSAM), 10-14 October 2016, Reykjavik, Iceland
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Working Group on Multispecies Assessment Methods (WGSAM) met in Reykjavik, Iceland, 10–14 October 2016. In this tenth report of the pan-regional WGSAM, work focused on four (B, E, F, G) of the multi-annual ToRs.Based on their knowledge, participants provided an updated inventory of progress of multispecies models in ICES Ecoregions (ToR A), noting those regions where no information was available. Reporting on ToR A was scarce compared to previous years, partly because recent relevant work was reported against ToR E and G instead.A Key Run (ToR B) of the Baltic Sea Ecopath with Ecosim (NS-EwE) model was presented and reviewed in detail by 4 WGSAM experts, and approved by the group following implementation of changes agreed in plenary at the meeting and verified by the 4 experts in January. The Key Run is documented in a detail in Annex 3, with key outputs summarised in Section 3 and data files made available on the WGSAM webpage). WGSAM also conducted an informal review of the LeMans modelling framework for potential application in the Irish Sea, and recommended adjustments to the framework for further review. Because the LeMans framework is a within-model ensemble addressing parameter uncertainty, this review also related to ToR D.Multispecies model skill assessment (ToR C) and multi-model ensemble methods (ToR D) were not emphasized this year. However, plans were made to coordinate future work for ToR C, and one ToR D presentation reviewed the utility of a dynamic multimodel ensemble for making inferences about the real world. This method can infer results for individual components of aggregate groups; the ensemble model uses correlations in other ecosystem models to determine what the models that group species would have predicted for individual species. A proof of concept for the North Sea was presented.Ecosystem indicator analyses (ToR E) were presented from a wide range of ecosystems. A theoretical analysis comparing results from the Celtic and North Seas with 4 “idealized” fleets was presented to analyse the performance of selected indicators in a multispecies mixed fishery. Four indicators including the Large Fish Indicator (LFI) were examined, and shown to have mixed utility in measuring the impact of different fleet sectors, with the best indicator varying by ecosystem. A multivariate analysis of ecosystem responses to multiple drivers was conducted for four US ecosystems using gradient forest method to identify potential ecosystem thresholds. Other multivariate methods were reviewed that draw on the strengths of multiple indicators for the Northeast US shelf ecosystem. A food web based biodiversity indicator was presented with an application for the Baltic Sea. This could be extended to any ecosystem with an EwE or similar model. A community status indicator relating a species-area relationship to the LFI and mean trophic levels was presented for the Swedish west coast.Impacts of apex predators on fisheries (ToR F) were examined with one presentation and a group discussion planning further work. A multipecies production model was parameterized to simulate interactions between three fish guilds, fisheries, and one marine mammal guild, concluding that fish reference points and trajectories change with marine mammal interactions. Fishery management was also important to reduce vessel interactions with and ensure prey supply to marine mammals. 4 | ICES WGSAM REPORT 2016 Exploration of practical advice for fisheries management incorporating multispecies, mixed fishery, and environmental factors (ToR G) was evident across regions. Two approaches for incorporating species, fleet, environmental, and other interactions are in progress in the Northeast US. One presentation outlined the New England approach, and another outlined the Mid-Atlantic approach. In New England, a management strategy evaluation is in progress to evaluate harvest control rules that consider herring's role as forage in the ecosystem. The modelling framework and stakeholder workshops were discussed. In the Baltic, a Nash Equilibrium optimisation approach incorporating environmental factors was presented for the cod-herring-sprat fishery to attempt to identify a solution that would give good yield for all species simultaneously. In the North Sea a theoretical analysis using 4 “idealized” fleets was presented to analyse the potential implications of "Pretty Good Yield" ranges around MSY. The model examined the likelihood of the fishery being precautionary for the different species given the uncertainties involved, and concluded that the upper ends of MSY ranges would not guarantee precautionarity.
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Leidenberger, Sonja, et al.
(författare)
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Vetenskapliga studier av honungsbin
- 2022
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Ingår i: Fauna och flora. - : Naturcentrum AB. - 0014-8903. ; 117:2, s. 28-32
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 21. |
- Niklasson, Mats, et al.
(författare)
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Free-living colonies of native honey bees (Apis mellifera mellifera) in 19th and early 20th century Sweden
- 2023
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Ingår i: Journal of Insect Conservation. - : Springer Nature. - 1366-638X .- 1572-9753.
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Tidskriftsartikel (refereegranskat)abstract
- Little information exists on the history and ecology of free-living colonies of European honey bees (Apis mellifera L.) in Europe, including its dark north-western subspecies (Apis mellifera mellifera). Our aim was to investigate the presence of colonies of free-living, native honey bees (A. m. mellifera) during the last two centuries in Sweden. For this we examined systematic interviews of beekeepers (176 answers from 158 questionnaires) performed in the years 1928–1981, with information dating back to the early 1800s. An overwhelming majority of answers (96%) confirmed the past presence of free-living colonies of honey bees in Sweden. While some stated that free-living colonies were simply absconded swarms from managed hives, the majority of interviewees (69%) believed that free-living colonies were of a truly wild origin. A decreasing trend in first-hand accounts of free-living colonies suggests that free-living populations underwent a dramatic decline at the end of the 19th century. This was also expressed in words by many interviewees, who in 14 cases stated that the loss of old forests and tree-cavity nest sites at the end of the 1800s was the primary cause of the decline. Direct accounts of perennial, free-living colonies, combined with detailed descriptions of the collection of large free-living colonies and/or wild honey, is strong evidence of free-living honey bees being well adapted to winter survival. These accounts contradict the officially supported view that the honey bee is a recently imported, domesticated, non-native species in Sweden. The results give a scientific underpinning and provide inspiration for the restoration of native forests which could facilitate populations of free-living colonies of A. m. mellifera exposed to natural selection. This could potentially lead to its return as a fully wild species. In an uncertain future, allowing for a natural lifestyle could increase resilience and reinstate characteristics that are otherwise lost in honey bees due to the increasing effects of artificial trait selection.
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| 22. |
- Niklasson, Mats, et al.
(författare)
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Vårt inhemska honungsbi
- 2024
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Ingår i: Bitidningen. - : Sveriges Biodlares Riksförbund. - 0006-3886 .- 2002-8202. ; :3, s. 22-23
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Honungsbiets naturliga hemvist är framförallt det ihåliga trädet, det känner nog nästan alla till, kanske också av egen erfarenhet.
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| 23. |
- Norrström, Niclas
(författare)
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Artificial neural networks in models of specialization and sympatric speciation
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with specialization and how it is linked to sympatric speciation. The trait driving specialization is a cue recognition trait modelled with artificial neural networks that exploiters use to discriminate beneficial resources from detrimental resources based on the signals of the resources. Paper I investigates how haploid exploiters and the resources coevolve when the signals of the resources can evolve through mutations. We find that this coevolution can be a cyclic process with saltational changes between different stages and that evolution is only directional and the exploiters are only specialists in parts of this cycle. In simulations underlying Paper II the signals of the resources can not mutate but the exploiters have a diploid genome and the organisms reproduce sexually. We show that the disruptive selection stemming from exploiters specializing on different resources can overcome the homogenizing effect of sexual recombination when exploiters mate randomly and produce a functional genetic polymorphism with specialized exploiters. A functional genetic polymorphism removes the force of reinforcement but we run simulations where the exploiters have a mating gene determining if mating is random or if exploiters should mate assortatively in Paper III. We find that assortative invades the exploiter population and homozygote specialists evolve because the genetic polymorphism pays a cost by having some alleles being silenced (that is they do not contribute to the complete phenotype) in certain genotypes so a mutation in these silenced alleles is not selected against, which cause these alleles to accumulate deleterious mutations. The homozygote specialists, mating assortatively, are much more efficiently removing deleterious mutations from the population and hence can invade the population. Finally, in Paper IV we investigate the effects of resource and resource signal arrangements in the environment. We show that the environment can influence the evolution of specialization and sympatric speciation. By modelling a resource discrimination trait based on the interaction of epistatic genes we find a novel force promoting sympatric speciation over genetic polymorphisms.
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| 24. |
- Norrström, Niclas, et al.
(författare)
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Coevolution of exploiter specialization and victim mimicry can be cyclic and saltational
- 2007
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Ingår i: Evolutionary Bioinformatics. - : Libertas Academica. - 1176-9343. ; 2, s. 35-43
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Tidskriftsartikel (refereegranskat)abstract
- Darwin’s Principle of Divergence explains sympatric speciation as gradual and directional. Contradicting evidence suggests that species’ traits evolve saltationally. Here, we model coevolution in exploiter-victim systems. Victims (resource population) have heritable, mutable cue phenotypes with different levels of defense. Exploiters have heritable, mutable perceptual phenotypes. Our simulations reveal coevolution of victim mimicry and exploiter spe-cialization in a saltational and reversible cycle. Evolution is gradual and directional only in the specialization phase of the cycle. Once linked to assortative mating, exploiter specialization provides conditions for speciation.
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| 25. |
- Norrström, Niclas, et al.
(författare)
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Nash equilibrium can resolve conflicting maximum sustainable yields in multi-species fisheries management
- 2017
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press. - 1054-3139 .- 1095-9289. ; 74:1, s. 78-90
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Tidskriftsartikel (refereegranskat)abstract
- The current fisheries management goals set by the European Commission states that fish stocks should be harvested to deliver maximum sustainable yields (MSY) and simultaneously, management should take ecosystem considerations into account. This creates unsolved trade-offs for the management of the stocks. We suggest a definition of a multi-species-MSY (MS-MSY) where no alternative fishing mortality (F) can increase yield (long term) for any ecologically interacting stock, given that the other stocks are fished at constant efforts (Fs). Such a MS-MSY can be solved through the game theoretic concept of a Nash equilibrium and here we explore two solutions to this conflict in the Baltic Sea. We maximize the sustainable yield of each stock under two constraints: first, we harvest the other stocks at a fixed F (FNE); second, we keep the spawning stock biomasses of the other stocks fixed [biomass Nash equilibrium (BNE)]. As a case study, we have developed a multi-species interaction stochastic operative model (MSI-SOM), which contains a SOM for each of the three dominant species of the Baltic Sea, the predator cod (Gadus morhua), and its prey herring (Clupea harengus), and sprat (Sprattus sprattus). For our Baltic Sea case, MS-MSYs exist under both the FNE and the BNE, but there is no guarantee that point solutions exists. We found that the prey species’ spawning stock biomasses are additive in the cod growth function, which allowed for a point solution in BNE. In the FNE, the herring MSY was found to be relatively insensitive to the other species’ fishing mortalities (F), which facilitated a point solution. The MSY targets of the BNE and the FNE differ slightly where the BNE gives higher predator yields and lower prey yields.
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| 26. |
- Norrström, Niclas, et al.
(författare)
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Selection against Accumulating Mutations in Niche-Preference Genes Can Drive Speciation
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 6:12, s. 29487-
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Tidskriftsartikel (refereegranskat)abstract
- Our current understanding of sympatric speciation is that it occurs primarily through disruptive selection on ecological genes driven by competition, followed by reproductive isolation through reinforcement-like selection against inferior intermediates/heterozygotes. Our evolutionary model of selection on resource recognition and preference traits suggests a new mechanism for sympatric speciation. We find speciation can occur in three phases. First a polymorphism of functionally different phenotypes is established through evolution of specialization. On the gene level, regulatory functions have evolved in which some alleles are conditionally switched off (i.e. are silent). These alleles accumulate harmful mutations that potentially may be expressed in offspring through recombination. Second mating associated with resource preference invades because harmful mutations in parents are not expressed in the offspring when mating assortatively, thereby dividing the population into two pre-zygotically isolated resource-specialist lineages. Third, silent alleles that evolved in phase one now accumulate deleterious mutations over the following generations in a Bateson-Dobzhansky-Muller fashion, establishing a post-zygotic barrier to hybridization.
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| 27. |
- Norrström, Niclas, et al.
(författare)
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Winter weight loss of different subspecies of honey bee Apis mellifera colonies (Linnaeus, 1758) in southwestern Sweden
- 2021
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Ingår i: PLOS ONE. - : PLoS. - 1932-6203. ; 16:10
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Tidskriftsartikel (refereegranskat)abstract
- Honey bees are currently facing mounting pressures that have resulted in population declines in many parts of the world. In northern climates winter is a bottleneck for honey bees and a thorough understanding of the colonies’ ability to withstand the winter is needed in order to protect the bees from further decline. In this study the influence of weather variables on colony weight loss was studied over one winter (2019–2020) in two apiaries (32 colonies in total) in southwestern Sweden with weather stations recording wind and temperature at 5-min intervals. Three subspecies of honey bees and one hybrid were studied: the native Apis mellifera mellifera, the Italian A. m. ligustica, the Carniolan A. m. carnica and the hybrid Buckfast. Additionally, we recorded Varroa mite infestation. To analyze factors involved in resource consumption, three modelling approaches using weather and weight data were developed: the first links daily consumption rates with environmental variables, the second modelled the cumulative weight change over time, and the third estimated weight change over time taking light intensity and temperature into account. Weight losses were in general low (0.039 ± 0.013kg/day and colony) and comparable to southern locations, likely due to an exceptionally warm winter (average temperature 3.5°C). Weight losses differed only marginally between subspecies with indications that A. m. mellifera was having a more conservative resource consumption, but more studies are needed to confirm this. We did not find any effect of Varroa mite numbers on weight loss. Increased light intensity and temperature both triggered the resource consumption in honey bees. The temperature effect on resource consumption is in accordance with the metabolic theory of ecology. The consequences of these findings on honey bee survival under predicted climate changes, is still an open question that needs further analysis.
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| 28. |
- 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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| 29. |
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