Summary/Research needs
1.7 Review the main results of Working Groups of interest to WGBFAS to WGBFAS
The following sections review, according to the ToRs, the main results from WGIAB, WGSAM, WKMixHer, and PGDATA. They also review briefly the main results from WGBIFS, the progress on mixed fisheries considerations, the working group of WGCHAIRS and finally summarizes a subgroup held at the WGBFAS meeting on means to increase the collaboration between the working group and other ecosystem working groups.
1.7.1 Working group on integrated assessments of the Baltic Sea (WGIAB)
The main working activities of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB) in 2018 were to i) investigate and compare long-term trends in com-munity weighted mean (CWM) traits across subsystems; (ii) discuss and prepare an Ecosystem Overview document for the Baltic Sea; (iii) plan an overall synthesis paper of past and recent ecosystem trends and dynamics across Baltic Sea subsystems, (iv) revisit the Integrated Ecosys-tem Assessment (IEA) cycle and discuss ways to better align our work within this conceptual framework in future. In terms of the first activity, the WG completed preliminary trait-based assessments of CMW traits in the Kattegat, Central Baltic Sea, and Gulf of Riga. These assess-ments demonstrate long-term changes in CWM traits across areas and multiple organism groups (including phytoplankton, zooplankton, benthos, and fish), largely related to changes in temper-ature, salinity, oxygen, and nutrients. Regarding the second activity, the WG provided a quali-tative (expert judgement based) ranking of key stressors and their impacts on ecosystem states, and drafted the ecosystem overview document that was also used as input for the ecosystem considerations in this WGBFAS report (section 1.10). In terms of the third activity, the WG made a work plan outlining what areas, variables and methods to use for a synthesis paper. Due to time constraints, work on this activity will be carried out intersessionally. Under the fourth ac-tivity, the WG discussed the various steps in the IEA cycle, primarily focusing on the first and crucial “scoping” process that aims to identify key ecosystem objectives. Consensus was reached to focus on already available policies (e.g. the Marine Strategy Directive and the Baltic Sea Action Plan) from which key objectives and indicators have been defined and can be used in future efforts to close the IEA loop and make it operational for management.
1.7.2 Working group on integrated assessment methods (WGSAM)
The ICES Working Group on Multispecies Assessment Methods (WGSAM) did in 2018 not work on Baltic Sea multispecies models, however, it is scheduled for the 2019 to prepare new multi-species model runs for Western and Eastern Baltic Sea
1.7.3 Workshop on mixing of western and central Baltic herring stocks (WKMixHER)
WKMixHER was held in Gdynia (Poland) 11–13 September 2018. Different methods for herring stock identification were reviewed at the workshop based on old and ongoing analyses carried on samples from the western and central Baltic Sea. Presented and reviewed methods included the comparison of stocks components based on growth rate (separation function), otolith shape analysis, body morphometry, meristic characters, otolith chemistry, parasitic infection, genetics (microsatellite and SNPs). The suitability of presented methods for stock separation was dis-cussed. At the workshop, it was shown how the central Baltic herring (CBH) actually shares numerous characters with the adjacent western Baltic herring (WBH) stock.
Results presented at the workshop motivated, on the short term, ad hoc preliminary analyses that were performed during the weeks following the workshop. The aim of these analyses was to test the hypothesis that spring-spawning herring from coastal Polish waters represent a population component that is reproductively isolated from both the major WBSSH component (i.e. Rügen) and from the other (northern component) spring-spawning herring from the Central Baltic. The preliminary results from the genetic analyses performed after the workshop supported the hy-pothesis. More work is, however, required to conclude on the issue, and to provide an operative approach to separate herring of different origins in mixed catches from the western and central Baltic Sea for assessment purposes. This motivated the proposal of a long-term plan to collect data for two years, that will then form the basis to (a) identify herring population/stock compo-nents, (b) validate herring assessment units, and (c) find methods for herring separation in mixed samples routinely collected within the data collection. The long-term plan also includes devel-oping operational methods to allocate thousands of herrings sampled currently and (depending on method) historically in catch and survey to their respective spawning components.
1.7.4 Working group on data needs for assessment and advice (PGDATA) and regional coordination groups (RCG)
PGDATA meet in ICES headquarter in February 2019. The aim of PGDATA is to
• Design a Quality Assurance Framework to ensure that information on data quality is adequately documented and applied in assessments;
• Ensure consistency of approach for fishery dependent and fishery-independent data quality framework, and complementarity with approaches developed in other fora such as STECF, EU-MAP;
• Develop and test analytical methods for identifying improvements in data quality, or collections of new data, that have the greatest impacts on the quality of advice;
• Improve or create communication routes between data collectors, data managers and end-users, and advise on new approaches to ease the implementation of the QAF (through publication, RDB-development and cooperation with other WG including shared workshops);
To improve communications between ICES groups and ICES groups and data collectors and to increase the knowledge of the available data and data quality the RCGs and PGDATA are in the process to developed standardized stock and fishery overview maps and tables. These can im-prove the awareness of available data as well as imim-prove the knowledge of data quality for the stock assessment working groups. Some of these overview maps developed from the interna-tional fishery database hosted by ICES RDB was presented during the WGBFAS on Baltic herring and sprat stocks. The maps and tables gave an overview of the reported fishery by ICES square and month as well as maps showing vessel size and flag country. The figures presented was
shown as examples of data already available but currently not very much utilized at the EWG and PGDATA and the RCGs will further develop graphs and plots for the EWG and benchmarks depending on end-user needs.
Figure 1.1. Sprat data from the RDB showing landings by member state and ICES square and by vessel length.
1.7.5 Baltic international fish survey working group (WGBIFS)
The presentation of WGBIFS 2019 was composed from two parts focused on the:
• Baltic acoustic-trawl surveys (BIAS, BASS) in 2018,
• BITS surveys in 2018-Q4 and 2019-Q1,
BIAS
The Baltic International Acoustic Survey (BIAS) in September-October 2018 was completed ac-cording to the plan. However, it did not cover the Russian EEZ, which was not planned either.
The geographical distribution of herring and sprat abundance at age 1+ and age 0, and cod in the Baltic Sea, calculated per the ICES rectangles in 2018 was demonstrated in consecutive graphs.
In September-October 2018, the highest concentrations of herring (age 1+) were detected in the ICES SDs 28, 29, and 32. At the same time, the geographical distribution of age 0 herring abun-dance was limited mainly to the SD 30 and to the ICES Subdivisions 21-24. Sprat (age 1+) dense shoals were mostly distributed in north-eastern part of the Baltic Proper, in the Gulf of Finland (SD 32) and in the Lithuanian EEZ. Total abundance of age 0 sprat was relatively low. Somewhat higher abundances of age 0 sprat were recorded in the ICES Subdivisions 26, 28, and 29. Cod was concentrated mostly in the southwestern part of Baltic Proper. Extremely high concentrations were recorded in the Lithuanian EEZ.
WGBIFS recommended:
The BIAS-dataset, including the valid data from 2018 can be used in the assessment of the CBH (herring) and sprat stocks in the Baltic Sea with the restriction that the years 1993, 1995 and 1997 (when the monitored area coverage was poor) are excluded from the index series. The current BIAS index series can be used in assessment of the Bothnian Sea herring with the restriction that the year 1999 is excluded from the dataset. The abundance indices for age groups 0 and 1 should be handled with caution.
BASS
The Baltic Acoustic Spring Survey (BASS) in May 2017 was also completed according to the plan.
However, it did not cover the Russian EEZ, which was not planned either. In the May survey, the highest concentrations of sprat were distributed in the southern part of the Baltic Proper.
WGBIFS recommended:
The BASS-dataset can be used in the assessment of the sprat stock in the Baltic Sea with re-striction that the year 2016 is excluded from the dataset.
BITS
The realization of valid ground trawl hauls vs. planned during the Baltic International Trawl Survey BITS-Q4/2018 and the BITS-Q1/2019 was on the level of 102 and 97% (by numbers), re-spectively and was considered by the WGBIFS-2019 as appropriate tuning series data for the assessment of Baltic and Kattegat cod and flatfish stocks. Somewhat lower coverage of some depth strata in both BITS surveys has been due to the restrictions enforced by the Swedish mili-tary. There were no trawl hauls performed in the Russian EEZ as Russia did not plan to partici-pate in these surveys.
WGBIFS recommends that the data obtained and uploaded to DATRAS for both the 4th quarter 2018 and the 1st quarter 2019 BITS are used for calculating survey indices for the relevant cod and flatfish stocks.
1.7.6 Progress on mixed fisheries considerations
In 2018, ICES received a special request from the European Commission regarding further de-velopment of mixed fisheries considerations and biological interactions including the Baltic Sea.
The WGBFAS had a Term of Reference in 2018 related to this request;
ToR a) Collate and summarize available information on the pelagic fishery and provide a descrip-tion of the pelagic fisheries in the Baltic Sea including the degree of mixing of herring and sprat by season, area and métier.
The information collated by WGBFAS was incorporated into the fisheries overviews advice (see link http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2018/2018/BalticSeaEcore-gion_FisheriesOverviews_2018_November.pdf) and communicated to the European Commis-sion.
Further work regarding mixed fisheries considerations and biological interactions in the Baltic is currently ongoing and includes;
i. preparation of a scoping meeting (WKBALTIC) in 2019 including stakeholders to iden-tify management needs regarding mixed-fisheries interactions and potentially adapt ex-isting mixed fisheries methodology for application in the Baltic;
ii. further developments of the data call for mixed fisheries data in the Baltic Sea in collab-oration with WGMIXFISH-advice;
iii. assessing other sources of valuable input data such as European Fisheries Control Agency databases.
1.7.7 Annual meeting of expert group chairs (WGCHAIRS)
The WGBFAS chair attended the WGCHAIRS meeting in January 2019. Of the many topics dis-cussed the following where brought up and disdis-cussed at the WGBFAS meeting:
The change of the parentage of ACOM associated expert groups, and that a new steering group called Fisheries Resources will instead parent the majority of ACOM expert groups.
The guidelines for ICES groups, which will be updated twice a year, ones after the ASC and ones after the WGCHAIRS.
The ICES new code of conduct and the importance of identifying, reporting and deal with any potential conflict of interest. This was discussed at the start of the meeting and no conflict of interest was identified. Information about the code can be found in the guidelines for ICES groups.
The new ICES scientific report series and the guidelines for authorship for these reports.
1.7.8 Interactions between WGBFAS and other ICES ecosystem work-ing groups
The group identified several ways to improve the interaction and communication between the WGBFAS and ecosystem working groups. Issue lists were, and will in future, be produced by WGBFAS members for each stock and communicated to the relevant working group for data and information needs/gaps. Such issue lists are one means of communicating the needs of the assessment group to certain groups working on specific issues. WGBFAS will additionally direct recommendations to specific working groups for knowledge gaps or needs.
WGBFAS appointed persons that will specifically identify ICES working groups that may pro-duce knowledge that can feed into the assessment group. Their work can then be summarized at the next WGBFAS meeting.
The subgroup also suggested that it would be beneficial for the communication of WGBFAS and other ecosystem groups, if multiple participants of the assessment group could join for example WGIAB, WGSAM or other relevant groups in order to act as interfaces and to see if WGBFAS can make use of the knowledge produced by these groups. Inviting someone from one of the ecosystem groups to join WGBFAS to learn about our work and future collaborations would likewise be highly beneficial. This will be suggested to ICES.
The subgroup identified that the ICES Annual Science conference in September will provide a good opportunity to gather members from WGBFAS and other ecosystem groups, to discuss how we could improve our communication and interaction. At this meeting, we would discuss our mutual needs and ability to produce eco-system information. WGBFAS will ask ICES to ar-range a meeting during the conference week.
The RCG provides many maps and plots on the data that are used in the assessment and that could be supplementary information for many stocks and for issues of the assessment group.
WGBFAS identified that these maps and plots would be very useful for the WGBFAS report.
Ecosystem overviews should permanently include and annually update sections including com-mercial fish populations. This would include biotic and abiotic components of the ecosystem and their impacts on growth, mortality, spatial distribution or reproduction. Additionally the im-pacts of fisheries on the ecosystem, for example on the food basis for marine mammals and sea-birds, or impacts on the seabed due to trawling should also be considered.