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Integated approach to the biological basis of age estimation in commercially important fish species


Our objective is to develop a fuller understanding of the environmental influences on otolith growth, leading to a new protocol for estimating fish age. Focussing primarily in gadiform otoliths, we will use known-age material to develop artificial neural network models of age. Otolith growth models will be integrated with results from new laboratory and field investigations to improve the objective basis for interpreting seasonal and non-seasonal growth structures. We will work on hake and cod representing a large proportion of the European fisheries in value and volume. As such, this proposal will improve the confidence and reliability of the scientific data used to underpin management of sustainable fisheries.

This project is a co-operative venture to improve our understanding of the biological basis of age estimation for commercial fish species. Our objective is to integrate modelling, laboratory and field observations to provide an objective basis for interpreting the macrostructure of otoliths used for estimation of fish age. We will take a muIti-disciplinary approach, including mathematical modelling, geochemical analysis of oxygen isotope ratios, experimentation and collection of biological and environmental data, to develop generic models of otolith formation. We will establish a new age estimation protocol, an enable training through a web site accessible by fisheries laboratories and fishermen's organisations.

Description of the work
To achieve a generic understanding of the formation of calcified tissues, we will progress from model development, through new field and laboratory investigations, to the production of a new protocol for age estimation supported by interactive training media. We will begin by developing models of otolith growth and shape. We will evaluate historical collections of otoliths creating a database of this material to model seasonal influences on the formation of these structures. The models will draw on a critical literature review and identify gaps in the data to be filled by new investigations. Additional observations on field samples will include marginal analysis and measurement of otolith oxygen isotope ratios. The effects of temperature and food availability will be investigated through experiments in controlled laboratory conditions to study the formation of otolith macrostructure. Together, the laboratory and field caught fish will be used to test model predictions about seasonality and temperature effects. Because the field and laboratory experiments will be directed at closely related species, we will have a strong data platform for a generic model and age estimation protocol. A new protocol for age estimation will be produced, based on refined models using all available data. Neural network models will be used to classify known and unknown age material to help elucidate the steps necessary in the new protocol. Example images, showing the biological interpretation of features will be assembled and distributed. The efficiency of the new protocol will be tested through a scheduled. age estimation exercise.

We expect to complete and deliver our primary model by the end of the first year. Field observations and laboratory experiments will deliver data for model refinement throughout the first two years of the project. The final year will be dedicated to integrating the new data to refine the model, testing the predictions with artificial neural networks, and delivering an accessible new protocol for fish age estimation. We expect our results to enable more precise and accurate fish age data.




CSC - Cost-sharing contracts


Consejo Superior de Investigaciones Científicas
Serrano, 117
28006 Madrid



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