image science : fish ageing by otolith shape (fabosa)

SUMMARY

For determining the total allowable catch (TAC) of commercially exploited fish species, knowledge of the age distribution of the population is essential. The aim of this project is to develop fast and objective ageing criteria for large-scale routine application.

We intend to develop and validate a non-destructive technique based on measurement of the external shape of otoliths in combination with other directly available data like otolith weight. For validating the methodology we will use otoliths of known-age cod, eel, turbot, sea trout and salmon. Extending the new methodology to other commercially important species like anchovy will be validated by existing ageing techniques.

The shape of the otoliths will be described by their two-dimensional (2-D) contours (e.g. Fourier shape analysis) and by their three-dimensional (3-D) outer surfaces. The 3D approach - novel in the field of otolith analysis - will be used to justify the simpler and faster 2-D technique. 3-D analysis may by itself yield new insights in how age, environmental factors, and genotype influence the growth and the shape of otoliths.

For precisely characterising these factors, a large data base containing contours and 3-D surfaces needs to be collected and processed for each of the species studied. These data bases will form the frame of reference for the novel rapid ageing technology.

The project will be a collaboration between fishery research institutes in Sweden, Italy, and Denmark, and 2-D/3-D data processing groups from Germany, the United Kingdom, and Belgium.

Otolith gallery
Cod otolith scanned with a micro X-ray tomograph and processed with IMAGIC-5

TASKS
Task 1	Otolith data of fish with known age - Cod (Gadus morhua) - Eel (Anguilla anguilla) - Turbot (Psetta maxima) - Sea-trout (Salmo trutta) - Salmon (Salmo salar)
Task 2	Two-dimensional methodology development - Analysis of 2D contours of otoliths - Classification and validation software - Validation and implementation of traditional annulus counting - Design and assembly of an "otolith workstation"
Task 3	Three-dimensional methodology development - Otolith micro X-ray tomography and surface topography - Cross validation of 2D and 3D methodologies - 3D otolith shape modelling
Task 4	Application of the methodology to another economically important species - Anchovy (Engraulis encrasicolus)

PARTNERS

Swedish National Board of Fisheries
Institute of Freshwater Research at Drottningholm

www.fiskeriverket.se

Istituto di Ricerche sulla Pesca Marittima
Consiglio Nazionale delle Ricerche

adria.irpem.an.cnr.it

Image Science
Software GmbH

www.ImageScience.de

Imperial College
of Science, Technology & Medicine

www.bc.ic.ac.uk/research/vanheel/group

SUBCONTRACTORS

Danish Institute for Fisheries Research

www.dfu.min.dk

CO-WORKERS

University of Antwerp
Visielab

www.ruca.ua.ac.be/visielab

University of the Faroes
Fisheries Laboratory

www.frs.fo

MEETINGS

LONDON		October 1997
DROTTNINGHOLM		February 1998
ANCONA		October 1998
DROTTNINGHOLM		February 1999
BERLIN		November 1999
DROTTNINGHOLM		April 2000
ALTEA		May 2000
ÄLVKARLEBY		May 2000
LONDON		November 2000
BERLIN		March 2001
ALTEA		August 2001
ANCONA		November 2001