Fishing pattern and interactions of fleet components in the Argyrops spinifer (Actinopterygii: Perciformes: Sparidae) fisheries of the Arabian Sea, Oman

Abstract

Background. The influx of foreign fishing vessels in the Arabian Sea, during the mid 1990’s, has sparked some conflicts between artisanal and industrial fleets and raised concerns related to the resource management implications of fish stocks in the region.  To address the lack of management data on the basic biology and stock assessment for targeted species, the Ministry of Fisheries Wealth in Oman initiated this study with a view to contributing towards the development of a management plan for the sustainable exploitation of the living resources of the sea in this region. Materials and methods. A database including biological parameters, length-frequency distributions and catches of king soldier bream, Argyrops spinifer(Forsskål, 1775), in Oman according to fleet (gear/technique) and region was compiled by monthly sampling in 2001 to 2002. In this study, length cohort  and yield per recruit analyses were examined after simulating changes in fishing effort, in length at first capture and introducing a closed season for trawlers. Results. The results showed that: (i) the status of the stock is healthy, the average fishing mortality rate is moderate (0.1) and acts in general on the adult fraction of the stock. The fishing pattern differs, however, among fleets with some fleet components fishing, in part, for immature king soldier bream. (ii) An increase in total fishing effort would not lead to any long-term substantial increase of the catch (according the uncertainty of M value); however, the spawning stock biomass would decrease significantly.  This measure affects negatively fleets that target the larger specimens. (iii) A moderate (±20%) modification of minimum length limit in catches would not affect, substantially, the sustainable yield and the spawning stock biomass. (iv) Any regulation of trawler fishing by closed season (i.e. restricted trawler activities during some seasons) would not have a significant effect on the long-term yield. Conclusion. The current pattern of exploitation and fishing effort acting on the A. spinifer stock are optimal and no changes to global fishing or length at first capture are recommended. Also, with the actual fishing effort of trawlers, no closed season is suggested. However, fleet components whose catches include some juvenile fraction should adopt more selective gear as used by the hand line fishery in the Al-Wusta region. 

Keywords

• Argyrops spinifer
• stock assessment
• fisheries man