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CS 3: Baltic Sea

Description of work

To overall goal of the Baltic case study is to understand the mechanisms which (i) support or counteract recovery of the cod stock, and (ii) are necessary to develop reliable long-term management plans for sprat. According to the structure of the project a broad range of analyses will be conducted to meet this goal.
The various results which are the expected outcomes of the case study work and the corresponding participation of the different partners are listed in Table 1. According to the overall setup of UNCOVER, WPs 1-3 investigate the effect of different production regimes (i.e. changes in the environment) and fisheries on the individual and stock biology, reproductive potential, recruitment and trophic interactions of the target species. These WPs thus deliver new knowledge (i) on spatio-temporal patterns of stock structure and distribution, (ii) reproduction and recruitment processes, and (iii) the relative importance of trophic interactions and bottom-up forces on stock trajectories. These analyses will be largely based on results and extensive databases derived in former EU-projects dealing with Baltic fish stocks (e.g. BASYS, CORE, STORE, BECAUSE) as well as national initiatives (e.g. GLOBEC-GERMANY). In addition process knowledge on hydrographic and trophodynamic processes affecting survival of cod larvae using direct field manipulation from a national danish project will be used.
Based on above analyses, models will be developed for identified key processes to be used in the various model studies in WP2 and 3:
1.    Process-models on growth and survival of cod and sprat early-life-stages will be included in existing coupled individual-based biological-physical oceanographic models (WP2) to investigate the effect of various environmental drivers on recruitment success and to generate proxies to be used in recruitment modelling. The coupled models will further be used in predicting recruitment success under varying environmental conditions.
2.    Process models on e.g. growth, maturation, fecundity, food consumption and energy allocation of cod and sprat developed under WPs 1 and 3 will be used to enhance and improve existing multispecies models (4M, SMS), which allow to study the effect of predation on prey stock sizes, the hind- and forecasting of the three major Baltic fish stocks, i.e. beside cod and sprat, also herring. In addition past changes in the Baltic ecosystem will be reconstructed using dynamic mass-balance models (ECOSIM) which also use process models and recruitment- as well as growth-environment relationships. After a successful reconstruction of the ecosystem history these models will be used for simulations on the impact of both the environment and the fishery on the dynamics of the cod and sprat stocks.
Beside providing knowledge on how environmental and anthropogenic influences affect the stock dynamics and thus the recovery potential of the two Baltic fish stocks (WPs1-3), the Baltic case study will use results out of the environmental process analyses in the “Framework for the evaluation of Management Strategies (FEMS)??? (WP4). A sub-group out of participants of the Baltic case study together with the WP 4 lead team will use identified candidate biological process models, enhanced multispecies inetraction models (M4, SMS) and management control strategies to test the effect of (i) contrasting formulations of different ecological processes and (ii) the efficacy of alternative management options. Input to the latter will come from reviews on existing recovery plans and socio-economic investigations (WP5).
All ecological (WPs1-3), evaluation of strategies (WP4) and socio-economic investigations (WP5) conducted will be synthesized to achieve rebuilding/management strategies for Baltic cod and sprat and contribute to the generic work on recovery strategies performed within UNCOVER (WP6).
Stakeholder links
Liaison will be established to incorporate stakeholders. A stakeholder meeting will be arranged shortly after the kick off meeting of the project and throughout the project in connection to planned meetings with the broader group of stakeholders.

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