Author: John R. Hunter

Publisher: Food & Agriculture Org.

Published: 1986

Total Pages: 88

ISBN-13: 9789251024713

Weaknesses in understanding of tuna distributions and movements have constrained the development of rational management policies. Uncertainties exist in: the selection of management plans and catch and effort data that are representative of a stock; quantification of exchange of adults among management jurisdictions and fishing gears; and identification of the relationships between the environment and tuna movements. This report summarizes a series of discussions between a panel and groups of experts on how to increase understanding of these and other tuna problems. We discuss the uncertainties in current management policy caused by lack of understanding of tuna movement dynamics. We describe and evaluate the research approaches presently used to describe the movements of tunas--mark and recapture and acoustic tracking-- and those which might be used or are just being applied, including new tagging systems, measurement of physiological state and microconstituents of mineralized tissue. Actions needed to improve the knowledge of tuna movements are: 1) establish international arrangements to share tuna movement data, to analyse movements on an oceanwide and worldwide basis and to link international oceanographic programs; 2) increase number and kinds of observations of movements of tuna in the vertical plane; 3) develop and use technology for tracing the actual paths followed by tunas over extended periods and for measuring movements independent of the fishery; and 4) conduct intensive studies on tuna movement dynamics which combine old with the new technologies discussed in the report.