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Population dynamics and movements of skipjack tuna (Katsuwonus pelamis) in the Maldivian fishery: analysis of tagging data from an advection-diffusion-reaction model

Published online by Cambridge University Press:  15 March 2002

M. Shiham Adam
Affiliation:
Joint Institute of Marine and Atmospheric Research, Pelagic Fisheries Research Program, 1000 Pope Road, MSB 312, Honolulu, HI 96822, USA
John R. Sibert
Affiliation:
Joint Institute of Marine and Atmospheric Research, Pelagic Fisheries Research Program, 1000 Pope Road, MSB 312, Honolulu, HI 96822, USA
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Abstract

An advection diffusion reaction model was used to estimate movement and tag attrition parameters from skipjack tuna tagging data off the Maldives. Two sets of data were available from the experiments carried out during two distinct periods: 1990–1991 and 1993–1995. The results of the analysis were compared with the previous analyses and discussed in relation to management of skipjack fisheries in the Maldives and in the Indian Ocean. The movements were found to be highly variable in space and time, and few consistent patterns were observed between the two data sets. Similarly, significantly different estimates of fishing and natural mortality rates were observed from the two data sets. These differences were found, in part, to be due to the uneven distribution of tag releases in both space and time. Estimates of movement and attrition rates show that emigration from the Maldivian fishery to the rest of the Indian Ocean’s was small. The exploitation rate was found to be substantial, contributing about 30-40% of the total attrition in the fishery area. Such levels of localized exploitation may be maintained by steady immigration from outside of the Maldives, but more extensive tagging is required to be certain. The impact of tuna fisheries elsewhere in the Indian Ocean on the domestic Maldivian fishery cannot be determined until a comprehensive large-scale tagging program, including all the fisheries in the Indian Ocean, is completed.

Type
Research Article
Copyright
© Elsevier, Inra, Ifremer, Cemagref, CNRS, 2002

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