The Distribution, Biological Characteristics and Vulnerability of the Giant Sea Catfish, Arius thalassinus (Rüppell, 1837), to Fishing at Mafia Island, Tanzania
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Date
2015
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Abstract
The distribution and some biological characteristics of commercially
important giant sea catfish, Arius thalassinus (Rüppell, 1837) were studied at Mafia
Island. Artisanal fishing catches were sampled, caught mainly with longlines, shark
nets and ring nets. These yielded a total of 2 723 kg of A. thalassinus, comprising
756 individuals, the largest measuring 1 000 mm TL. Arius thalassinus occurred
only on the western coast of Mafia Island and the highest catch rate was 19.3
kg.fisher-1.day-1 in March when murky water was predominant. The reproductive
biology of A. thalassinus was investigated to assess its vulnerability to fishing.
Arius thalassinus reached a size at first maturity (LM50) of 520 mm TL and
exhibited a low mean (±SE) fecundity of 65.6 ± 3.37 eggs per female within the
size range of 605-970 mm TL. The hydrated oocytes were large (mean diameter
±SE = 15.2±0.12 mm). Arius thalassinus spawned once in the study year during
February and April, during heavy precipitation (124-499 mm). We therefore
conclude that its restricted distribution, large size, low fecundity, late maturation
and its reported high trophic level indicate that it would be vulnerable to fishing
pressure. It is therefore recommended that fishing for A. thalassinus be restricted
during its spawning season to ensure its sustainability
Description
Keywords
Arius thalassinus, Reproduction, Vulnerability, Artisanal fisheries, Rufiji Delta, Western Indian Ocean
Citation
Kamukuru, A.T. and Tamatamah, R.A., 2015. The Distribution, Biological Characteristics and Vulnerability of the Giant Sea Catfish, Arius thalassinus (Rüppell, 1837), to Fishing at Mafia Island, Tanzania. Western Indian Ocean Journal of Marine Sciences, p.163.