FAO FISHERIES TECHNICAL PAPER   322

Cover
Determination of growth in bony fishes from otolith microstructure
CONTENTS


by
Beatriz Morales-Nin
Institut d'Estudis Avançats de les Illes Balears
Palma de Mallorca, Spain


The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.


M-42
ISBN 92-5-103115-0


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PREPARATION OF THIS PAPER

This paper is a product of the André Mayer research fellowship “Ageing Fish Through Otolith Microstructure”, awarded to the author from February 1987 to May 1988. In the course of the fellowship, in addition to other original research work, Dr Beatriz Morales-Nin prepared a first draft of this manual, which was later finalized for publication by FAO. The subject, though of interest to all scientists working on fish growth and ageing, is thought to be especially useful to those working with tropical species, where the traditional methods based on the interpretation of annual growth rings are particularly hard to apply.

The author wishes to express her appreciation to all those who made the successful outcome of the fellowship possible, particularly Dr R.L. Radtke of the University of Hawaii (Honolulu, USA), for the use of his laboratory during the fellowship, to Dr Pauly of ICLARM (Manila, Philippines), to Dr E.B. Brothers (EFS Consultants, Ithaca, USA), to Drs S. Ralston and J. Uchiyama of the NMFS (Honolulu, USA) for their help with various aspects of the research. Dr J. Csirke of FAO is warmly thanked for his support and advice and for his revision of the text.

Messrs. J.M. Fortuño and J. Biosca of the Barcelona Instituto de Ciencias del Mar (ICM) deserve special acknowledgement for helping with the scanning electron microscope and for processing the photographs, respectively. Mr J. Jansá of the Spanish Institute of Oceanography designed the cover from an idea of the author. Ms Lola Oñate and Maria Cruz Iglesias typed the text. Figures 1 and 2 were prepared by Dr A. Lombarte and Figure 3 was contributed by Dr I. Palomera (ICM, Barcelona).



Distribution:
FAO Fisheries Department
FAO Regional Fisheries Officers
Marine Directors
Marine Sciences

Last but not least the author wishes to thank her husband, José, her children Miguel, Elena and Beatriz and her sister Rosa Maria for their support throughout the fellowship period and during the preparation of this paper.

The bibliographic references are published as presented by the author.

Morales-Nin, B.
Determination of growth in bony fishes from otolith microstructure
FAO Fisheries Technical Paper. No. 322.
Rome, FAO. 1992. 51p.

ABSTRACT

Fish ageing methods based on growth increments in otoliths are described in detail. A short introduction describes otolith extraction, preparation and viewing techniques, emphasizing the study of microscopic daily growth increments. Light and scanning electron microscope viewing methods and criteria for interpretation are described. The need to test the findings is explained and age validation techniques described.


FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, © FAO 1992


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CONTENTS

1   INTRODUCTION

2   OTOLITH MICROSTRUCTURE

3   OTOLITH REMOVAL AND STORAGE

3.1   Otolith selection and removal

3.2   Otolith storage and preservation

3.3   Removal and storage of larval otoliths

4   OTOLITH PREPARATION

4.1   Morphometric measurements

4.2   Sectioning

4.3   Preparing otoliths for light microscopy

4.4   Preparing otoliths for reading with the scanning electron microscope

4.5   Otolith replication

5   AGEING

5.1   Viewing increments with the light microscope

5.2   Viewing increments with the scanning electron microscope

5.3   Ageing through analysis of increment microstructure

5.4   Ageing based on increment thickness

5.5   Ageing by reading annulae

6   VALIDATION TECHNIQUES

6.1   Direct methods

a)   Rearing and sequential sacrifice
b)   Marking otoliths

6.2   Indirect methods

a)   Assigning a birthday
b)   Growth patterns in otoliths
c)   Synchronous increment formation
d)   Progression of the median age
e)   Comparison of average lengths

7   ESTIMATING GROWTH BY LENGTH-FREQUENCY ANALYSIS

7.1   Joint application of age data and length-frequency

8   OTHER GROWTH DETERMINATION METHODS

8.1   In vitro growth

8.2   Radiometry

8.3   Lipofucsin analysis

8.4   Marking and recapture

8.5   Direct observation of growth

9   CLOSING REMARKS

10   GLOSSARY

11   BIBLIOGRAPHY