Tanzania installs tuna attracting devices

The Director General for Tanzania Fisheries Research Institute (TAFIRI), Dr Benjamin Ngatunga

Tanzania has partnered with Mauritius in pursuing the technology that will lure migratory tuna fish to one area in deep sea waters. At the moment five Fish Aggregating Devices have been installed near Latham Island in the Indian Ocean.

The move will enable fishermen to catch them easily. The Director General for Tanzania Fisheries Research Institute (TAFIRI), Dr Benjamin Ngatunga, told the ‘Sunday News’ in an exclusive interview recently that the partnership will culminate in the installation of Fish Aggregating Devices (FADs).

Fish Aggregating Devices (FADs) are floating objects that are specifically designed and located in specific areas in the sea so they attract tunas and hence enable fishermen to find their catch easily.”No one understands exactly why tunas are attracted to FADs, but the ropes, floats and the other materials used presumably mimic the build-up of driftwood and seaweed found naturally in the sea,” he said.

Dr Ngatunga explained that the devices have been placed on the southern side of Zanzibar and to the East of Dar es Salaam approximately 10 nautical miles from the city.He said that tunas and other pelagic species are often attracted to floating objects such as coconuts, logs, seaweed, and plastic bottles. The devices are installed on the surface of the water.

These are often found at current boundaries which are areas of the ocean that are usually productive and therefore good locations for tuna to search for food.An FAD comprises a large anchor (up to one metre long), a heavy-duty mooring chain (usually about 30m in length) and a mooring rope, with about 50 purse-seine floats strung at the surface.

Dr Ngatunga explained that it was important to recognize that FADs do not increase the biomass of fish in that they do not increase size of a fish population but instead aggregate them in one place, making them easier to catch.”Schools of tuna fish never ‘live’ under a FAD, but rather associate with a good feeding ground for a few days or weeks before moving on,” according to Dr Ngatunga.

“Latham Island is indeed proving to be a hotspot among anglers coming from Dar es Salaam and Zanzibar with catches amounting to 700 kilos of fish a day,” he said.Dr Ngatunga added that last year there was a huge presence of anglers in the area thanks to extensive persuasion to long-line fishermen.

According to the West Indian Ocean (WIO) website, fishing captains have reported locating individual schools of tuna that exceeded 1,500 metric tonnes in total weight and may hold more than a million individual fish.”This partnership with Mauritius is one of our biggest achievements at the institute. We now have five FADs after recently adding two more near Latham Island in the Indian Ocean,” he said.

The website states that there are several successful FAD programmes in the WIO, including in Seychelles, Comoros, and Mauritius where a programme has been underway since 1985. There are currently 21 FADs around Mauritius in depths ranging from 400 to 3,000 metres and at distances ranging from 1.5 to 12 nautical miles from the coast.

Inshore, shallow-water FADs are also being tried in Tanzania mainly in Tanga and Latham Island. Others are in use in Kenya, although with variable success. The technology of FAD-design continues to improve and in some areas around the world like in Hawaii and Western Pacific and FADs can last for two to three years.

FADs also help provide a number of options for assisting fishers who are affected by the presence of a Marine Protected Area, though a careful evaluation is required before deciding to spend resources on a FADs programme with costs ranging between 3,000 and 5,000 US Dollars.

Meanwhile TAFIRI has just secured funding from the World Bank to conduct research on the possibility of engaging in a cage culture at large scale through using a Public Private Partnership approach.Cage culture is a production option for farmers with existing watershed ponds.  Because these ponds are difficult to drain, fish produced in them can only be harvested if they have been confined in cages for rearing.

Dr Ngatunga said that an investor wanted to invest in this form of aquaculture and had already purchased cages but the government intervened demanding that the research institute conduct an experiment before they can be allowed.”We have got the funds and the area we will be conducting the experiments will be in Mwanza and this starts this year. We will use Nile Tilapia during the experiment,” he said.

Malawi is currently excelling in Tilapia fish sales where more than six tonnes are harvested every six months in Lake Nyasa using cage culture.He said that the institute had also adhered to the directive of the East Africa Community ministers to start research trials to domesticate Nile Perch in Lake Victoria basin.

Dr Ngatunga explained that TAFIRI would be collaborating with neighbouring Uganda in this project with the major aim of seeking a breakthrough in producing artificial feeds in the form of pellets as opposed to eating live fish which they are used to.

By MASEMBE TAMBWE, Tanzania Daily News