Tilapia farming methods in Mozambique
by Dr Gianluigi Negroni, ALVEO S.c.a.r.l, Italy
The main species farmed is in Mozambique is Tilapia (Oreochromis niloticus), in addition Tilapia mossambicus is more suited to the environment in this country due to better resistance to disease and the difficult conditions present in said area. Tilapia is the common name for a vast number of freshwater fishes of the family Cichlid.
This is one of the largest families of fishes, containing more than 1,800 members, some of them in use in aquaculture. Members of the family range from very small ornamental species used in the aquarium industry to large food-size species rose in the fish-farming industry.
Tilapia hatcheries can be highly technical for industrial purposes or less technologically intensive, in the form of simpler structures. In Mozambique, we have the two types as there are several communal famers that produce their own fingerlings.
Industrial hatcheries are normally divided in the following sections: quarantine area, broodstock tanks, spawning tanks, corral systems, reproduction ponds, eggs and larval rearing systems, fry tanks, fingerling tanks, filter and water inlet/outlets, warehouses and services areas.
Earthen ponds are more commonly used in Mozambique for tilapia farming and represent the oldest fish farming facility that has been used for many generations. A good pond will showcase the following characteristics:
- A well-designed water supply but also easy drainage. This means a slight slope (0.5%) of the pond floor from the water inlet to the drainage point
- Good water quality (pH around 6)
- The drainage outlet (standpipe or monk) must be studied with care
- Water inlets and outlets must be at opposite ends in order to ease water exchange within the pond
- Good impermeability of the pond as a whole and strength/integrity of the pond's walls and edges
- Clay soil quality
- Access and possibility to work around the pond which must be accessible to vehicles (tractors, trucks, trailers etc.)
Sizes of ponds must be adapted to the species but also be easy to manage. If the width exceeds 50 metres, it becomes difficult to pull nets for harvest (eg if 3-to-4 men on each side are necessary to pull a 60 metre net), thus rendering the ponds impractical.
The other more intensive system used in Mozambique is the use of floating cages. Some commercial farms in Mozambique are using this technology. Some economists consider that the Tilapia fish cage system is the most economic and efficient method used in Mozambique. It needs an appropriate water body that can absorb fish faeces throughout the year.
There are many possibilities for obtaining floating cages for growing fish, from locally made ones (usually cheaper but more fragile) to high technology cages. The selection can only be made according to the overall practical considerations concerning the site, the production targets, and the project's economics.
While the optimal size for a tilapia cage is unknown, one should consider that the bigger the cage, the cheaper it costs in both material and equipment. Choice will be determined by considering the ease of management and the final production cost. It appears that a cage of a dimension of 100m2 is a good compromise; in Mozambique it cages range from 8-50m3, with very good results.
Concerning the depth of the nets, the technical possibilities and maintenance expertise will determine the choice. If the net is deep, special diving equipment will be required for daily checking of the nets and eventual repairs. If the depth does not exceed 3-3.5 metres, repairs and maintenance can be made through free diving.
Good care must be paid towards the mooring and anchoring systems. This will be selected based upon the speed of the current, winds and any effect that could move the cage and require a special study. Note that mooring systems for square cages are cheaper than those for round cages.
Nets are the subject of very careful selection. Their quality must be beyond reproach since the security of the fish stocks depends largely on the net strength. Mesh size must be adapted to the fish size and must not allow the fish to trap itself by the gills. On the other hand, small sized meshes can be subject to fouling which restricts the water flow through the cage. Larger farms will also invest in net-washing equipment, which imposes the need to have cages with adequate net-removal facilities.
Inputs feed and fingerlings
Selected Tilapia fingerlings are available in Mozambique from the larger farms or auto-produced in the artisanal farms. Pelleted feed for starter and grow out are imported in Mozambique from South Africa and Zambia (on the Cabora Bassa Dam). It is important to know that tilapia has the possibility to be a filter feeder, harvesting the water microorganism (green water technologies) that could be developed by fertilising the pond. Development is slower (more than double time than with feed).
Mozambican Fisheries Management
The legal basis of Mozambican fisheries is given and enforced by the Fishery Law 22/2013 of November 1st (substitute the Law 3/90 of September 26th) Fisheries Law 3/90 of 26 September 1990 and subsequent regulations, being the fisheries management regime based on TAC/quotas and limited entry regulation (licensing/effort allocation) accomplished by closed seasons and mesh size regulation.
These management measures are revised periodically, with a view of keeping their effectiveness, based on results of stock assessments for the most valuable resources and economic performance of the fleet, among other tools.
In 1996, a Fisheries Administration Commission (Conselho Administracoe das Pescas, CAP) was established, aiming to improve the involvement of the private sector and fishing communities in management decision making. It congregates representatives of the Fisheries Public Administration and of the fishing industry (industrial, semi-industrial and artisanal fisheries associations). This forum is an advisory body to the Minister and discusses and analyses issues such as quota and vessels allocations, magnitude and period of closed seasons, state of exploitation of capital resources and recommendations of management measures addressed by the research component.
Therefore, final decision on fisheries administrative matters is taken by the Fisheries Authorities upon consultation of this forum. The regional and international matters are also discussed in the forum before a national decision is taken.
The Co-management Committee (Comité de Co-gestão - GCC) is the participatory management forum at local, district and provincial level. The GCC is composed of the local authority of the Fisheries Administration or its representative, representatives of the Community Fisheries Councils, fishing vessel owners, fishery research, fishery extension, local maritime authority, fish processors and fishery traders. Could be convened by the CCP represented in the GCC.
The Community Fisheries Council (Conselho Comunitário de Pesca -CCP) is a non-profit Community organisation whose task is to contribute to the participatory management of fisheries, to ensure compliance with existing management measures, to manage conflicts resulting from fishing activity with a view to sustainability activities in their geographical area and improving the living conditions of the local population.