Comparative efficiency and techno-economics of multifilament and monofilament gillnets on the Oguta Lake, Nigeria

Abstract

Two sets of multifilament and monofilament gillnets with similar design characteristics were fished simultaneously on Oguta Lake during two experimental trials that took place between February and October 1988, to compare their efficiency and techno-economics. Species composition and total biomass, relative abundance of commercial species, cost of the net and the financial return per net were used as techno-economic indices for comparison. Eighteen species of fish were present in both multifilament and monofilament catches during the two trials. Multifilament gillnets caught more fish (836.2 kg) than the monofilament gillnets (487.3 kg) in both trials, P<0.05 (Student's t test=2.80, d.f. = 34). A highly significant difference ( P<0.01) was observed in the relative composition of commercial species between the multifilament (297 kg) and the monofilament (86.8 kg) gillnets. Increase in negative buoyancy improved the efficiency of monofilament gillnets. Multifilament gillnets were less expensive, caught more fish and yielded more return on investment on Oguta Lake, contrary to claims by net manufacturers.