Concerted Action "Improvements of Tagging Methods for Stock Assessment and Research in Fisheries" (CATAG)
FINAL REPORT May 1999 (DRAFT)
2 RATIONALE AND OBJECTIVES
Scientific assessments form the basis of fish stock management for the major commercial stocks of European fresh and saline waters. Many different tools are used and amongst them are tagging - recapture programmes. Although the motivation for such programmes is often to obtain quantitative measures for use in monitoring and management of commercially-exploited fish populations, there have been few good examples of this in practice. A major problem has been disagreement among scientists concerning the reliability of recapture results and the validity of the models used to handle the tagging data collected. Therefore, a thorough review is needed of the limitations and problems associated with existing techniques and methodology.
Rapidly-developing microelectronic technology has stimulated the design and development of new electronic ‘smart’ fish tags and many new instruments are already on the market. This situation poses questions and challenges. To what extent can these new approaches be used to solve specific problems and overcome limitation inherent in present methodology? Furthermore, are there new technological approaches in sight, which can form the basis for new approaches and cost-efficient solutions to problems within quantitative fisheries’ biology?
Stock enhancement programmes have become an integral part of present approaches to both population conservation and compensatory releases to maintain fisheries. An important European issue in this context is the impact of salmonid aquaculture on wild populations. Tagging techniques in general, and the application of new technology in particular, may provide useful tools for the evaluation of the benefits of stocking exercises.
The CATAG concerted action (CA) had three objectives:
A CA facilitates a broad European perspective of the subject, secures relevant information that can be shared among partners and reduces the risk of duplicated work. Most importantly, it can initiate and encourage new multinational initiatives in technological and theoretical development within the field. The fact that much past European effort in tagging has neither been directly applied nor the results properly published, supports the idea that an international initiative can provide an improved platform for future scientific approaches in the field.