Concerted Action "Improvements of Tagging Methods for Stock Assessment and Research in Fisheries" (CATAG), FAIR. CT.96.1394,  FINAL REPORT May 1999 (DRAFT)



Tagging is an old tool in biology, and is economically valuable for European aquaculture, fish husbandry, stock assessment and fisheries management, as well as to the commercial enterprises that provide tag technology. Traditional methodology is dependent on catching and handling the fish before release and recovering a proportion of the tags through the commercial fisheries. Such procedures involve substantial uncertainty about the survival and welfare of the fish and recovery of reliable data. There are also doubts as to whether data obtained from a relatively small number of individuals are representative of the population at large. Quantitative use of tagging data therefore requires a set of assumptions, which may be difficult or even impossible to control. Nevertheless, quantitative applications of tagging results represents an alternative to traditional assessment methodology and, most importantly, can provide assessments that are independent of many of the serious problems associated with other methods. Tagging is also an obvious tool in aquaculture and ranching programmes, where strict control of the cultured population is essential to avoid adverse affects on natural populations.

Because of the uncertainties associated with traditional tagging methods, investment in new development has until now been limited. Despite a lack of investment, however, modern technology has produced a number of new possibilities by developing: (a) sophisticated electronic tags which can collect large amounts of data on individual fish over long periods; (b) small and intelligent tags for mass tagging; and (c) automatic tagging techniques, which may remove substantial uncertainty connected to fish survival and welfare. As discussed in the previous chapters, the full potential of these new developments has not yet been recognised. Despite this under-utilisation, however, these techniques have the potential to collect information far more economically than is feasible by conventional means. To elevate tagging to a reliable and recognised tool for collecting quantitative fish population assessment data, as well as detailed biological and behavioural information, an integrated and aimed investment programme is needed over a period of at least 5-10 years. The network established during this Concerted Action the potential to support and secure efficient utilisation of development costs.


CATAG participants have identified many areas of tagging applications, methods and technologies that need stimulation and financial support. The following recommendations have the highest priority. More detailed recommendations may be found at the end of each of the chapters produced by the four working groups.

9.3.1. Technological improvements

9.3.2. Biological improvements

9.3.3. Data collection, handling and modelling

9.3.4. Legislation and welfare

 9.3.5. Communication and training

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