Motorization of traditional craft and its effect on the exploitation of tuna and whitebait anchovy resources

Abstract

The impact of motorization of traditional craft on two fisheries resources, viz. tunas and whitebait anchovies, was studied. A conspicuous increase in the annual tuna catch was seen from 1984 due to the increased effort expended by the motorized craft by using more units of drift nets, hooks and lines than non-motorized craft. The tuna landing increased from 361 tonnes during the pre-motorization period to 1976 tonnes during the motorization period. On the contrary, the anchovy landing came down from 580 tonnes during the pre-motorization period to 386 tonnes on motorization. A decline was noticed in the effort expended for whitebait anchovies but the catch rate did not show a steep decline which indicated that the reduction of effort was not due to the decrease in the catch rate. The shifting over of motorized units to drift net and hooks and lines operation seems to be the major reason for the decline in the effort of boat siene and nelholi vala which are the main gears for whitebait anchovies. Indian Journal of Fisheries 41 (2): 92-9, June 1994 The motorization of traditional craft was initiated in central Kerala by 1980. It spread to northern and southern areas by 1983 (Balan et al. 1989). At Vizhinjam, the most important fish landing centre in Trivandrum, the motorization was initiated during the middle of 1982. A substantial increase in the effort from the motorized craft was recorded from A 984 which resulted in an immediate increase in the total fish catch at Vizhinjam. An account of the traditional fishery in the area has been given by Luther et al. (1982) and Nair et al. (1988) and the initiation of motorization of traditional craft in the area has been reported by Gopakumar et al. (1986). The increase in Present address: 'Scientist (SG), technical Officer, Technical Assistant the catch and catch rate of tunas and mackerel as a result of motorization has also been pointed out by Gopakumar and Sarma (1989) and Gopakumar et al. (1991). The chief gears operated by the motorized craft at Vizhinjam are hooks and lines and drift net. Motorization has extended the fishing areas of traditional craft to relatively more distant grounds and has increased the yield of certain resources like tunas which are caught chiefly by drift net and hooks and lines. This has resulted in a reduction in the operation of non-motorized units and a simultaneous decrease in the yield of certain other resources like whitebait anchovies which are caught by boat seine, shore seine and netholi vala. To analyse this aspect, the trends offish landing with particular reference to two resources, viz. 92