DESIGN AND CONSTRUCTION OF SQUARE SHAPED CAGES FOR FISH CULTURE

Oluwatobi Abel Ogunseye
Aquaculture and Fisheries Management, Federal University of Agriculture Abeokuta, Ogun State
October, 2014
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Abstract

The increasing demand for fish in Nigeria cannot be met by capture fisheries thus the increase in fish farming all over the country. However, the bulk of Aquaculture production is land-based with very few cage culture farms, particularly commercial cage culture. Therefore to meet the protein demand and food security of the fast growing population of Nigeria, it is necessary to design and construct fish cages that can be developed and built with local materials within the country. To accomplish this; the definition of design parameters and the proposed floating cage for fish farming was carried out. The suitability of species was analysed based on biological, marketing and environmental criteria. The design parameters for the cage were based upon literature and guidelines of different types of fish cages within and outside Nigeria. In designing the fish cage, important factors were considered and these include: Nature of the construction materials i.e. strength and rigidity of the material, netting material that allows for free flow of water thus enabling high oxygen exchange, durability of materials in water without deteriorating quickly and cost of materials i.e. cheap and readily available materials.
Square shaped floating fish cages with a netting bag for culturing various species of freshwater fish was constructed, using polyethylene (PVC) pipes as the frame for holding the nets and floatation materials, and two different synthetic netting materials of ¾†and ¼†mesh sizes was interlaced, with one as inner liner for the cage while the other served as the wall of the cage to protect fish from predators. Four floating fish cages were attached together with each measuring 4 m × 4 m and 4 m in depth and each having an estimated capacity to harvest 5 – 8 tons of fish depending on fish species. In this study, the engineering aspect is addressed however, it would be necessary to consider the biological and socio-economic aspect also which further studies will consider.
This study shows the design and construction of floating fish cages which could be used by fish farmers in lagoons, reservoirs and lakes at a lower cost.Cage culture could have multiplier effects: providing jobs, increased economic inputs, increased fish production and reduced pressure on traditional fisheries, therefore, supporting their sustainability.