>>schematic

WP1- Tagging and Data Management Programme

Electronic data storage tags will be attached to adult cod (>45cm) to obtain information on the behaviour and environmental experience of free-ranging individuals over the long periods associated with migration and seasonal changes in distribution.

WP2 Geolocation database

In this WP, a comprehensive database for the spatial and temporal development of the relevant environmental conditions in the different ecosystems will be designed and implemented. Data will be gathered from existing and continuously updated databases currently available for all four ecosystems. Temporally and spatially resolved datasets on temperature, salinity, bathymetry, light and productivity in each ecosystem will be integrated in a relational database. An 'expert system' of database queries will be designed in order to return initial possible fish positions from multivariate data recovered from DSTs, a process called geolocation. Geolocation is a technique that can relate the movements of individuals directly to hydrographic parameters such as ambient temperature, bathymetry, salinity, tidal range and time.

WP3- Horizontal migration

In this WP, we will reconstruct the horizontal movements of individuals as accurately as data will allow by using geolocation techniques. Following reconstruction of migratory pathways, the relationship between the timings and durations of spatial movements of cod will be examined with respect to temperature and other important environmental variables. Patterns of behaviour will be classified and any differences in behaviour between areas and ecosystems identified in order to identify common patterns of environmentally driven behaviour that can be used to predict stock responses to environmental change. Once the geographic movements of individuals have been reconstructed, data will be input to a dedicated behaviour based model. This model takes information on the seasonal migrations of individuals at appropriate spatial scales (usually, but not limited to, ICES rectangle) and simulates the spatial dynamics of fish populations on a seasonal basis.

WP4 Vertical movements

The work in this WP will result in a description of the vertical movements of cod in each ecosystem. Such research will provide an understanding of the (mechanisms of) behavioural responses of fish to biological and environmental factors. By studying individual fish rather than parts of the population, the factors that actually affect fish movements and the mechanisms behind them may be revealed, quantified and integrated in a form that will be representative of the whole population and applicable to the design of more effective survey methodologies and management tools.

WP5- Etho-typing and otoliths microstructure analysis

Patterns of behaviour determine the direct environmental experience of an individual as it moves through an annual migratory cycle of between feeding and spawning grounds. One of the key factors likely to influence fish movements is the need to optimise growth during the feeding season, which will result in seasonal changes in temperature and feeding conditions that are reflected in changes in growth dynamics. These changes will be reflected in the structure of otoliths, and by identifying correlations between behavioural activity and environment recorded by DSTs and the microstructures of the otoliths of those fish, a powerful tool for reconstructing behavioural histories of cod from existing otoliths collections will be created.

WP6- Predictive modelling of cod vertical movements

An individually-based model (IBM) will be developed from existing models of vertical migration in marine fish. This model will simulate the behaviour of 'individual' cod, and the effect of these behaviours on their internal state. Internal state will influence 'growth' and 'survival', and in this way, 'good' behaviours i.e. those that increase growth and survival, will be selected for, and 'bad' behaviours i.e. those that decrease growth and survival, will be selected against. Environmental effects e.g. faster growth at higher temperatures, on the internal state of cod will be integrated. By using this approach, behaviour can be simulated as a combined response to environmental factors and to changes in the internal states, such as swimbladder volume and maturity status, of cod. A bioenergetics model developed for cod will be used to simulate growth dynamics.

WP7- Synthesis and case studies

The research in WPs 1-6 will be drawn together in the final, synoptic WP. The ultimate aims of CODYSSEY will be met in this WP i.e. to assess the effectiveness of current management measures for protecting cod stocks and to improve our ability to predict both individual movements and seasonal distributions of cod stocks. The first objective will be to describe, using empirical and modelled data from WP3 and 6, systematic changes in the availability and accessibility of cod to fishing and survey gears, in order to provide advice as to the design, conduct and analysis of stock assessment surveys. The second objective of this WP will be to evaluate critical management hypotheses for each ecosystem using a case study approach. Understanding the horizontal and vertical movement dynamics of cod will then provide a basis for the evaluation of management measures such as closed areas and seasons, which are especially pertinent during Recovery Plans. A third objective is to use the CODYSSEY results to evaluate the validity of the biological assumptions in fisheries models used to provide the basis for fisheries management advice (e.g. MSVPA, Bormicon/Gadget). The fourth and final objective of this WP will be the drawing together of the results of WP3 and WP4 regarding the influence of the environment on the behaviour of cod. The effect of environment on vertical and horizontal movement data will be drawn together to evaluate the effect of environmental/ climate change on cod stocks.

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