The Artisanal Fishery for Octopus cyanea Gray in Tanzania

Preliminary results for the artisanal fisheries of Octopus cyanea Gray (1849) in Tanzania are provided for the period April 2000 until June 2001. A total of 2546 individual catches and 15473 specimens were analyzed from 3 sites located at Tanga, Mafia Island, and Mtwara. Size range, average weight a...

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Bibliographic Details
Published in:Ambio 2002-12, Vol.31 (7), p.528-536
Main Authors: Guard, Martin, Mgaya, Yunus D
Format: Article
Language:English
Subjects:
Animal organs
Animals
Biomass
Body Weight
Conservation of Natural Resources
Eggs
Environmental Monitoring
Female
Female animals
Fisheries
Fisheries management
Fisheries science
Fishers
Fishery economics
Fishing zones
Mafias
Male
Octopodiformes
Octopuses
Population Dynamics
Reproduction
Sex Ratio
Tanzania
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Summary:Preliminary results for the artisanal fisheries of Octopus cyanea Gray (1849) in Tanzania are provided for the period April 2000 until June 2001. A total of 2546 individual catches and 15473 specimens were analyzed from 3 sites located at Tanga, Mafia Island, and Mtwara. Size range, average weight and catch per unit effort (CPUE) were all significantly lower at Tanga and Mtwara compared to Mafia indicating that the former sites may be overfished. Abundance of smaller individuals was higher at Tanga and Mtwara, but overall biomass was lower. Octopi at each site exhibited allometric growth as indicated by analyses of the length-weight relationships. Females become sexually mature at a minimum weight of 600 g while for males the minimum weight was 320 g. Higher numbers of mature individuals were found in June of both years and correlate with peaks in the gonosomatic index. Recruitment peaked a few months after brooding periods. Sex ratios indicate females may be more prone to capture during brooding periods. Reasons for differences between sites are discussed.
ISSN:0044-7447
1654-7209
DOI:10.1579/0044-7447-31.7.528