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Howell, D., Kempf, A., Belgrano, A., Thorpe, R., Vinther, M., Bartolino, V., . . . Urtizberea, A. (2018). Interim Report of the Working Group on Multispecies Assessment Methods (WGSAM). Copenhagen
Open this publication in new window or tab >>Interim Report of the Working Group on Multispecies Assessment Methods (WGSAM)
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2018 (English)Report (Other academic)
Abstract [en]

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).

Place, publisher, year, edition, pages
Copenhagen: , 2018. p. 395
Series
ICES CM 2017/SSGEPI:20 ; 20
National Category
Fish and Aquacultural Science
Research subject
Ecological Modelling Group; INF502 Biomarkers
Identifiers
urn:nbn:se:his:diva-14790 (URN)
Funder
Swedish Research Council Formas, 2012-1330
Available from: 2018-03-05 Created: 2018-03-05 Last updated: 2018-06-08Bibliographically approved
Norrström, N., Casini, M. & Holmgren, N. M. A. (2017). Nash equilibrium can resolve conflicting maximum sustainable yields in multi-species fisheries management. ICES Journal of Marine Science, 74(1), 78-90
Open this publication in new window or tab >>Nash equilibrium can resolve conflicting maximum sustainable yields in multi-species fisheries management
2017 (English)In: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 74, no 1, p. 78-90Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Baltic Sea, multi-species, reference points
National Category
Ecology
Research subject
Ecological Modelling Group; INF502 Biomarkers
Identifiers
urn:nbn:se:his:diva-12862 (URN)10.1093/icesjms/fsw148 (DOI)000397136400008 ()2-s2.0-85020882554 (Scopus ID)
Funder
Swedish Research Council Formas
Available from: 2016-09-02 Created: 2016-09-02 Last updated: 2018-06-08Bibliographically approved
Orio, A., Nielsen, A., Luzenczyk, A., Berg, C., Ustups, D., Artemenkov, D., . . . Mirny, Z. (2017). Report of the Baltic Fisheries AssessmentWorking Group (WGBFAS): 19-26 April 2017, Copenhagen, Denmark. Copenhagen: International Council for the Exploration of the Sea
Open this publication in new window or tab >>Report of the Baltic Fisheries AssessmentWorking Group (WGBFAS): 19-26 April 2017, Copenhagen, Denmark
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2017 (English)Report (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Copenhagen: International Council for the Exploration of the Sea, 2017
Series
ICES CM 2017/ACOM:11
National Category
Fish and Aquacultural Science
Research subject
Ecological Modelling Group; INF502 Biomarkers
Identifiers
urn:nbn:se:his:diva-13959 (URN)
Funder
Swedish Research Council Formas, 2012-1330
Available from: 2017-08-07 Created: 2017-08-07 Last updated: 2018-06-08Bibliographically approved
Howell, D., Kempf, A., Bauer, B., Belgrano, A., Thorpe, R., Vinther, M., . . . Kulatska, N. (2017). Report of the Working Group on Multispecies Assessment Methods (WGSAM), 10-14 October 2016, Reykjavik, Iceland. Copenhagen V, Denmark: International Council for the Exploration of the Sea
Open this publication in new window or tab >>Report of the Working Group on Multispecies Assessment Methods (WGSAM), 10-14 October 2016, Reykjavik, Iceland
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2017 (English)Report (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Copenhagen V, Denmark: International Council for the Exploration of the Sea, 2017. p. 94
Series
ICES CM 2016/SSGEPI ; 21
National Category
Ecology
Research subject
Ecological Modelling Group; INF502 Biomarkers
Identifiers
urn:nbn:se:his:diva-13506 (URN)
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2018-06-08Bibliographically approved
Bergström, L., Blenckner, T., Frelat, R., Grimvall, A., Haapasaari, P., Haas, B., . . . Zagrodzka, Z. (2016). Interim Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB): 18-22 April 2016 Helsinki, Finland. Copenhagen: International Council for the Exploration of the Sea (ICES)
Open this publication in new window or tab >>Interim Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB): 18-22 April 2016 Helsinki, Finland
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2016 (English)Report (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Copenhagen: International Council for the Exploration of the Sea (ICES), 2016. p. 27
National Category
Ecology
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-12863 (URN)
External cooperation:
Note

ICESCM2016/SSGIEA:08

Available from: 2016-09-02 Created: 2016-09-02 Last updated: 2017-11-27Bibliographically approved
Hinrichsen, H.-H., Large, S., Möllmann, C., Müller-Karulis, B., Neuenfeldt, S., Norrström, N., . . . Hamrén, H. (2016). Report of the Workshop on DEveloping Integrated AdviCE for Baltic Sea ecosystem-based fisheries management (WKDEICE): 18-21 April 2016 Helsinki, Finland. Copenhagen: International Council for the Exploration of the Sea (ICES)
Open this publication in new window or tab >>Report of the Workshop on DEveloping Integrated AdviCE for Baltic Sea ecosystem-based fisheries management (WKDEICE): 18-21 April 2016 Helsinki, Finland
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2016 (English)Report (Other academic)
Abstract [en]

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; and

5)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. 

Place, publisher, year, edition, pages
Copenhagen: International Council for the Exploration of the Sea (ICES), 2016. p. 37
Keywords
fisheries, Eastern Baltic cod, Integrated Ecosystem Assessment
National Category
Ecology
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-12866 (URN)
External cooperation:
Note

ICES CM 2016/SSGIEA:13. 4. [Chairs: Maciej Tomczak, Rudi Voss]

Available from: 2016-09-02 Created: 2016-09-02 Last updated: 2017-11-27Bibliographically approved
Bergenius, M., Boje, J., Casini, M., Degel, H., Eero, M., Florin, A.-B., . . . Walther, Y. (2015). Report of the Baltic Fisheries Assessment Working Group (WGBFAS): 14-21 April 2015, ICES HQ, Copenhagen, Denmark. Copenhagen: International Council for the Exploration of the Sea
Open this publication in new window or tab >>Report of the Baltic Fisheries Assessment Working Group (WGBFAS): 14-21 April 2015, ICES HQ, Copenhagen, Denmark
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2015 (English)Report (Refereed)
Abstract [en]

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 20-22

2 ) Cod in Kattegat, Cod in SD 22-24, Cod in SD 25-32

3 ) 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 22-32

5 ) Plaice 21-23, Plaice 2425

6 ) 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.

Place, publisher, year, edition, pages
Copenhagen: International Council for the Exploration of the Sea, 2015. p. 814
Series
ICES CM ; 2015/ACOM:10
National Category
Fish and Aquacultural Science
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-11755 (URN)
Available from: 2015-12-14 Created: 2015-12-14 Last updated: 2017-11-27Bibliographically approved
Almqvist, G., Andersen, M., Willestofte Berg, C., Broadgate, W., Bryan, M., Campana, S., . . . Zimmermann, C. (2015). Report of the Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD). Copenhagen: ICES
Open this publication in new window or tab >>Report of the Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD)
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2015 (English)Report (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Copenhagen: ICES, 2015. p. 172
Series
ICES CM 2015/ACOM ; 35
National Category
Fish and Aquacultural Science
Identifiers
urn:nbn:se:his:diva-11477 (URN)
External cooperation:
Available from: 2015-09-01 Created: 2015-09-01 Last updated: 2017-11-27Bibliographically approved
Bergström, L., Blenckner, T., Grimvall, A., Gårdmark, A., Hamrén, H., Holmgren, N., . . . Wesslander, K. (2015). Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB). Copenhagen: ICES
Open this publication in new window or tab >>Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB)
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2015 (English)Report (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Copenhagen: ICES, 2015
Series
ICES CM 2015/SSGIEA ; 08
National Category
Fish and Aquacultural Science
Identifiers
urn:nbn:se:his:diva-11475 (URN)
Available from: 2015-09-01 Created: 2015-09-01 Last updated: 2017-11-27Bibliographically approved
Holmgren, N., Norrström, N., Aps, R. & Kuikka, S. (2014). A Concept of Bayesian Regulation in Fisheries Management. PLoS ONE, 9(11), Article ID e111614.
Open this publication in new window or tab >>A Concept of Bayesian Regulation in Fisheries Management
2014 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 11, article id e111614Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
PLoS, 2014
National Category
Ecology
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-10449 (URN)10.1371/journal.pone.0111614 (DOI)000345558100088 ()25365071 (PubMedID)2-s2.0-84909619978 (Scopus ID)
External cooperation:
Available from: 2014-12-18 Created: 2014-12-18 Last updated: 2017-12-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2055-4284

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