Emmanuel, B.E.

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The techno – economic and efficiency of coloured gillnets operations in a tropical lagoon in south western Nigeria was carried out in 2013. A total of 1083 fishes, belonging to 13 families were caught in both green (588) and white (495) gillnets in in Lagos Lagoon. A total of 56kg of fish was landed by both gillnets at 31.5kg for green and 24.5kg for white gillnet. Ethmalosa fimbriata had the highest weight (18.81kg) and percentage frequency of 33.59% while Eleotris vittata had the lowest weight (0.11kg) and percentage frequency of 20%. The average catch per trip was 59 and 50 for green and white gillnet, respectively, while the average weight of fish caught per trip for green gillnet was 3.2kg and 2.4kg for white gillnet. Statistically, the chi-square test showed that there was significant difference between the catch composition of the coloured nets (green and white) throughout the study as well as between the day and night catches. The green gillnet landed a total of 200 fish during the day and 388 fish at night while the white gillnet landed a total of 171 fish during the day and 324 fish at night. The green gillnet fin-fish least condition factor (0.4) was found in Cynoglossus senegalensis and the highest condition factor (6.2) was found in Caranx hippos. The white gillnet fin –fish least condition factor (0.4) was found in Liza dumerilli and the highest (3.4) was found in Sarotherodon melanotheron. The green net caught of 31.5kg was sold for N7, 875, N785 per trip at N250/kg of fish while white gillnet caught of 24.5kg that was sold for N 6, N 145, N 615 per trip at N250/kg of fish. The durability of the nets depended on the maintenance and timely mending. The use of green coloured gillnet influenced the efficiency of the net catch ability. Although the green coloured gillnet is more expensive to construct but the catch output justifies the cost. Keywords: Fish, coloured net, gillnets, efficiency, tropical lagoon.