FAO FISHERIES AND AQUACULTURE PROCEEDINGS
16

Estimation of tuna fishing capacity from
stock assessment-related information

Workshop to Further Develop, Test and Apply
a Method for the Estimation of tuna fishing capacity
from stock assessment-related information
14–16 May 2007
La Jolla, California, United States of America

Edited by
William Bayliff
Senior Scientist
Inter-American Tropical Tuna Commission (IATTC)
c/o Scripps Institution of Oceanography
La Jolla, California, United States of America

and

Jacek Majkowski
Fishery Resources Officer
Fisheries Management and Conservation Service
Fisheries and Aquaculture Management Division
FAO Fisheries and Aquaculture Department
Rome, Italy

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Bayliff, W.H.; Majkowski, J. (eds.)
Estimation of tuna fishing capacity from stock assessment-related information:
Workshop to Further Develop, Test and Apply a Method for the Estimation of Tuna Fishing Capacity from Stock Assessment-Related Information. La Jolla, California, United States of America, 14–16 May 2007.
FAO Fisheries and Aquaculture Proceedings. No. 16. Rome, FAO. 2009. 53p.

ABSTRACT

These Proceedings include (i) the Report of and (ii) the paper presented at the Workshop to Further Develop, Test and Apply a Method for the Estimation of Tuna Fishing Capacity from Stock Assessment-Related Information. The Workshop was hosted by the Inter-American Tropical Tuna Commission (IATTC) in La Jolla, California, USA, from 14 to 16 May 2007. It was organized by FAO’s Japan-funded Project on the “Management of Tuna Fishing Capacity: Conservation and Socio-Economics” in collaboration with and with in-kind support of several international and national fisheries institutions involved tuna fisheries research and management. The paper presented at the Workshop describes peak-to-peak (PP) and general additive modeling (GAM) approaches to estimate fishing capacity and related quantities from stock assessment information. The PP and GAM methods were applied to seven stocks of bigeye, yellowfin and skipjack tuna of the Pacific, Indian and Atlantic Oceans. The estimated trends in overcapacity with both methods were consistent across most of the stocks, showing increasing trends at the beginning of the time series and reaching maximum values during the late 1990s, followed by decreasing trends after that. For most of the stocks analyzed, overcapacity was positive during a part of the time series. Sensitivity tests revealed greater estimates of capacity output when the stock assessment data were most disaggregated. Further tests revealed that the estimates of overcapacity were lower when low variability in effort deviations was permitted in the stock assessment. The Report of the Workshop outlines the discussions carried out at the Workshop, some proposals for further research, recommendations and conclusions of the Workshops.