|EIFAC Occasional Paper No. 21||EIFAC/OP 21|
AGE DETERMINATION OF ANGUILLA ANGUILLA (L) AND RELATED SPECIES
|Leif Asbjørn Vøllestad||Østfold Country Moss||Norway|
|Raymonde Lecomte-Finiger||Université de Perpignan||France|
|Bert Steinmetz||Ministry of Agriculture and Fisheries The Hague||the Netherlands|
MARKING AND TAGGING METHODS APPLIED TO EEL, ANGUILLA ANGUILLA (L.)
|Jan Nielsen||Country of Vejle||Denmark|
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PREPARATION OF THIS DOCUMENT
These two reviews were presented at the meeting of the EIFAC Working Party on Eel in Bristol (UK) 1988. Thereafter they were finalized for publication.
The Ministry of Agriculture and Fisheries -the Netherlands- kindly offered to print the report.
|Distribution:||For bibliographic purposes this document should be cited as follows:|
EIFAC mailing list
FAO Fisheries Department
FAO Regional Fishery Officers
Vøllestad, L.A., R. Lecomte - Finiger, B. Steinmetz, Age determination of Anguilla anguilla (L.) and related species. EIFAC Occas. Pap., (21): pag. 1 – 28.
Nielsen, J., Marking and tagging methods applied to eel, Anguilla anguilla (L.). EIFAC Occas. Pap., (21): pag. 1 – 24.
AGE DETERMINATION OF ANGUILLA ANGUILLA (L.) AND RELATED SPECIES
LEIF ASBJØRN VØLLESTAD
Østfold County, Environmental Administration, Moss, Norway, and Department of Biology, University of Oslo, Oslo, Norway.
Universite de Perpignan, Laboratoire de biologie Marine, Perpignan Cedex, France
Ministry of Agriculture and Fisheries, Directorate of Fisheries, The Hague, The Netherlands.
This report presents a description and discussion of the different methods used in eel ageing studies during the last decade. Four main types of techniques are used: 1) grinding or slicing; 2) burning and cracking; 3) clearing of whole otoliths in alcohol; and 4) methods using advanced technology. Grinding and slicing is the most common with almost all institutes introducing their own modification of the general method. In very few cases has the validity of the method been documented. The available evidence indicate that burning and cracking give a good approximation of true age. This method has proved to be accurate in a number of tests. Other method have proved useful in specific cases, but further studies are necessary.
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3. DESCRIPTION OF METHODS
3.1 Grinding and sliceing
3.2 Burning and cracking
3.3 Whole otoliths
4. COMPARISON OF METHODS
Conclusions and recommandations