EIFAC Occasional Paper No. 14EIFAC/OP14

Cover Page
EIFAC EXPERIMENTS ON PELAGIC FISH STOCK ASSESSMENT BY ACOUSTIC METHODS IN LAKE KONNEVESI, FINLAND
CONTENTS


by

T.B. Bagenal
Freshwater Biological Association
The Ferry House
Ambleside
Cumbria LA 22 OLP
United Kingdom
E. Dahm
Bundesforschungsanstalt für Fischerei
Institut für Fangtechnik
Palmaille 9 - 2000 Hamburg 50
Federal Republic of Germany
  
  
T. Lindem
Institute of Physics
University of Oslo
P.O. Box 1048
Blindern, Oslo 3
Norway
P. Tuunainen
Finnish Game and Fisheries Research Institute
P.O. Box 193
00131 Helsinki 13
Finland

EUROPEAN INLAND FISHERIES ADVISORY COMMISSION (EIFAC)

EIFAC documents are issued in three series:

EIFAC Reports

Report of each Session in English and French

EIFAC Technical Papers

Selected scientific and technical papers, including some of those contributed as working documents to Sessions of the Commission or its Sub-Commissions. Published in English and French, or one of these languages.

EIFAC Occasional Papers

Papers of general interest to the Commission. Published in the language submitted, either in English or French; sometimes in both languages.

Copies of these documents, when still available, can be obtained from.

Secretary
European Inland Fisheries Advisory Commission
Fisheries Department
FAO
Via delle Terme di Caracalla
00100 Rome, Italy

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-40
ISBN 92-5-101234-2

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior permission of the copyright owner. Applications for such permission, with a statement of the purpose and extent of the reproduction, should be addressed to the Director, Publications Division, Food and Agriculture Organization of the United Nations, Via delle Terme di Caracalla, 00100 Rome, Italy.

PREPARATION OF THIS DOCUMENT

This is the report of the 1980 EIFAC experiments on pelagic fish stock assessment by acoustic methods in Lake Konnevesi, Finland.

The background of these experiments is described in the introduction of the report.

Distribution:For bibliographic purposes this document should be cited as follows:
Authors
EIFAC mailing list
FAO Fisheries Department
FAO Regional Fisheries Officers
Bagenal, T.B. et al., 1982 EIFAC experiments on pelagic fish stock assessment by acoustic methods in Lake Konnevesi, Finland. EIFAC Occas.Pap., (14): 16 p.

ABSTRACT
This paper reviews the origins of the exercise, the equipment (echo-sounder and trawl) used, the treatment of the catches, the estimation of fish density resulting from trawling and acoustic surveys. It provides comparisons between fish length distributions and draws conclusions on the results of the experiments.

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome 1982 © FAO


Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.

This electronic document has been scanned using optical character recognition (OCR) software. FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.


CONTENTS

1.   INTRODUCTION

1.1   Purpose

1.2   Origins of the Exercise

1.3   Time and Place

1.4   Personnel

2.   THE ECHO-SOUNDER

2.1   The Equipment

3.   THE TRAWLS

3.1   The Gear and its Operation

3.2   The Treatment of the Trawl Catches

4.   THE CATCHES

5.   THE CAPTURE-MARK-RECAPTURE EXPERIMENT

6.   THE FISH DENSITY ESTIMATED FROM THE VOLUME OF WATER FILTERED BY THE TRAWLS

6.1   The Spread of the Trawls

6.2   The Speed of Tow

6.3   The Depth of the Trawl Opening

6.4   The Volume of Water Filtered

6.5   Density of Fish

6.6   Variability in Catches

7.   FISH DENSITIES ESTIMATED FROM THE ACOUSTIC SURVEYS

7.1   Introduction

7.2   The Precision of Echo-Survey Estimates

7.3   Fish Densities

7.4   Conclusions

8.   COMPARISONS OF FISH LENGTH DISTRIBUTIONS

8.1   The Trawl Catches

8.2   The Acoustic Survey

8.3   The Trawl and Acoustic Comparisons

8.4   Conclusion

9.   GENERAL CONCLUSIONS

10.   ACKNOWLEDGEMENTS

11.   REFERENCES