Investigation and Assessment of Technical and Economic Efficiencies of Gillnet Types with Different as against the Usual Same, Hanging Ratios at the Top and Down Ropes, Compared with a Standard Gillnet, in the Volta Lake, Ghana

Abstract

The study was conducted at ten fishing sites, in Stratum VII of the Volta Lake, comparing the technical and economic performances of gillnet types with different as against the usual same, hanging ratios at the top and down ropes, with a standard gillnet of hanging ratio 0.5 at the top and down ropes. The shape of a mesh size is controlled by the hanging ratio and is one of the most important factors affecting yield and selectivity of gillnets. The objective was to determine whether gillnet types with different hanging ratios at the top and down ropes could be superior in enhancement of the performance of monofilament gillnets over the usual gillnet types with same hanging ratios at the top and down ropes, by determining principally the; fishing efficiency, cost efficiency and the index of economic efficiency of the net types, under the same fishing conditions. In April – June 2016, the depth of the fishing sites, the quantity and value of fish caught, and the costs of the fishing operations were determined; and in February 2017, the length frequency distribution of Oreochromis niloticus and Sarotherodon galileus, caught by the net types was recorded for differences. The results showed that the gillnet types with different hanging ratios at the top and down ropes, recorded superior efficiencies over the gillnet types with same hanging ratios. It was concluded that different hanging ratios, at the top and down ropes, combined with slack netting constituted a superior intervention for enhancing technical and economic efficiencies of monofilament gillnets. The insignificant difference in the LFD of the Tilapiine species caught could be attributed to the absence of hard spines favoring capture by gilling by all the net types, over entangling, a property of only slack nets which could result in difference in the sizes of fish caught.