WP 4: Evaluation of strategies for rebuilding

Description of work

As a result of several existing FP5 and FP6 projects (including MATES, MATACS, EFIMAS and COMMIT) a generic 'Framework for the Evaluation of Management Strategies' (FEMS) has been developed. This tool has been further developed and is now  called FLR - Fisheries Libraries in R. FLR will be utilised within UNCOVER to quantify and compare impacts of different management strategies and biological/ecological processes impacting stock recovery.

The simulation framework applied in this WP enables the modelling of both “real??? and “perceived??? systems using two stages. In stage 1, the “real??? system (i.e., the fish stock or ecosystem) is represented within an operating model from which simulated data are sampled. In stage 2, sampled data are used within a management framework incorporating a stock-assessment model as well as various management options. Depending on the perception of the stock that emerges, management controls are applied to the fishery and, fishing impacts are subsequently fed back into the “real??? biological system (for an example see Figure 1). Using a range of performance measures it is therefore possible to assess the implications of management actions or contrasting model formulations for “true / real??? or “perceived??? stock recovery. Both stages of the “generic evaluation??? incorporate uncertainty (process errors, measurement errors, estimation errors, model mis-specification, and implementation errors) in model input and output.

The 'operating model' attempts to represent all biological and ecological processes that have a significant impact on population or ecosystem dynamics, as well as the 'true' removals and changes in stock structure due to fishing. WP4 will construct a range of 'operating models' for selected stocks on the basis of outputs from other WPs. Each operating model will represent a set of alternative, plausible hypotheses (e.g, contrasting model formulations of growth, recruitment, natural mortality or fishery selectivity-at-age). Available fishery and fishery-independent data will be utilized in order to parameterize process models within FEMS, and to formulate probability distributions. Biological process-models developed in other WPs for selected species (e.g., cod, herring) will be incorporated (e.g., spatial movement parameters from WP1, environmentally sensitive recruitment models from WP2, predator-prey models from WP3 and multi-fleet models from WP5)
In addition, results from FEMS will be assessed in light of socio-economic parameters emerging from WP5. This will form part of an iterative feed-back cycle within WP6 in conjunction with WP 1-3 and 5. The overall objective will be to develop 'relevant' management options that will be more likely to achieve the overall objective of stock recovery, based on our current understanding of biological and fishing processes against a backdrop of socio-economic constraints.

Two levels of questions will be investigated using FEMS. Level 1 questions relate to identifying how potential changes in generic biological features of stocks affect recovery strategies in general. For example, Level 1 questions can explore how alternative indices of reproductive potential (WP1), variable growth/maturation/fecundity (WP1), different S/R relationships (WP2), and/or different species interactions (WP3) will influence stock recovery strategies. The answers to Level 1 questions will form the basis of general policy recommendations provided to WP6. Simulations addressing Level 1 questions will be undertaken by the WP4-lead team (task coordinators and related key personnel) in conjunction with coordinators of the other WPs. In addition, this group will review the insights and experience of other EU projects (e.g., EFIMAS and COMMIT) to refine both strategic questions and ensure coherence in the technical aspects of running FEMS.
Level 2 questions address stock-specific issues that are relevant to each of the four Case Studies.  For example, exploring recovery strategies for Baltic cod under different hydrographic scenarios (habitat qualities) and/or populations sizes of sprat (both a predator of cod eggs and an important prey resource for cod adults).

WP 4 is organised into two separate tasks (WP4.1 and WP4.2) that, because of the highly iterative nature of the program, are operating in parallel with a high degree of collaboration:
(to read more about the tasks, click on their titles below)

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