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
- Electronic tag technology generally has a limited market: public funding and pre-market investment are essential
to rapid and sustained progress.
- Mass tagging methodology for stock assessment should be carefully revisited with respect to utilisation of
the great technological advances made in recent years.
- Data storage tags need more memory and longer life; PIT tags need more range. Sensors need to be smaller and
able to measure a wider range of variables (including physical data such as compass heading, tilt angle and acceleration
and biological parameters such as growth and feeding rates and blood hormone levels).
- More reliable methods of estimating geographical position for fish fitted with data storage tags are urgently
required. Indirect methods (e.g. sequentially released pop-up tags) and direct methods (e.g. geomagnetic sensors)
need to be investigated, further developed and tested.
- Automated mass tagging and in situ submerged tagging (especially for deep-water fish) are both highly
desirable technologies requiring further development to improve efficiency and quality of assessments.
- Improvements in anti-fouling and anti-inflammatory performance of tag materials are needed.
- Development of tags that can be applied to fish predators (as well as birds and mammals) to collect information
about feeding rates and prey preferences should have a high priority.
9.3.2. Biological improvements
- Evaluation of the effects of capture stress, handling and pre-release treatment of tagged fish should be given
a high priority.
- Tagging methods, including use of anaesthesia, should be evaluated and optimised. New techniques should ideally
be preceded by effective feasibility studies.
- Evaluation of the effects of tags upon fish behaviour and swimming performance should be conducted systematically.
- Investigation of fish behaviour in relation to the environment and fishing gears is a priority research area.
9.3.3. Data collection, handling and modelling
- Tagging is much more widely employed in northern Europe than in southern Europe or the associated Atlantic
islands. It is recommended that tagging initiatives should be encouraged in these southern ecosystems.
- It is recommended that user guidelines be established for theoretical approaches and assumptions in modelling.
- Development of techniques of data fusion (combining data from tags, scientific surveys, fisheries and environment
[GIS systems]) should have a high priority.
- Clarification and quantification of underlying assumptions (e.g. about tagging mortality, tag shedding, mixing
of tagged and untagged populations) is required.
- Studies of predator-prey interactions should have a high priority. Biological observations and theoretical
developments are required, as well as new technology.
9.3.4. Legislation and welfare
- Tagging for husbandry should be removed from legislative control and not require expensive and unnecessary
training of operators.
- A detailed evaluation of hypothermia as an alternative to anaesthesia is required.
9.3.5. Communication and training
- Workshops are needed to encourage exchange of ideas amongst oceanographers, biologists, engineers and veterinary
- Practical training courses for fish tagging, handling and anaesthesia are required.
- Workshops are needed to investigate guidelines for time series analysis for interpretation of information recorded
by data storage tags.
- Retention and extension of the tagging network created under the CATAG initiative is highly desirable for maintaining
momentum and establishing technological standards in this field.
- The CATAG website should be maintained and developed, as an educative as well as a research tool. This will
require funding, and it is recommended that the EU considers means by which this support might be provided.
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