Compiled by KIFI RESEARCH UNIT
Edited by : Evans Simasiku
LAKE LIAMBEZI FISHERY
The Lake Liambezi fishery developed from scratch in 2008. Fishing started on the lake with subsistence catches in 2009 dominated by Clarias gariepinus, with few of the tilapiines. In 2010, the rapid increase in large cichlid species inspired many fishermen to enter the fishery. This practice developed in a small-scale fishery at Shamahuka landing site (Figure 1). Shamahuka is the major landing site along Lake Liambezi from where catches are mainly transported to the fish market in Katima Mulilo urban. As the tilapiine cichlids multiplied and grew rapidly, they began to appear in the fishermen’s gillnet catches, leading to an influx of fishermen from outside the area, such as Zambia and the Democratic Republic of Congo (DRC). O. andersonii and T.rendalli comprised approximately 90% of the fishermen’s gillnet catch on the lake (Tweddle et al. 2011).
The fishermen fishing Lake Liambezi are mostly of the Subia tribe origin and come to the lake specifically to fish. In 2010, a register of all participants in the fishery was compiled and restricted to residents of Muyako fishing village in which Liambezi is situated (Tweddle et al. 2011). The registration system was not exclusive, as the owner of the registered and licensed gear would be local and employed foreigners with good fishing skills from Zambia. During the same period, 125 fishermen, 91 canoes, and an average of two fishermen per canoe were registered in November 2010 (Tweddle et al. 2011). The most important fishing villages’ around the lake are Kalengwe, Muyako, and Mahundu in the east, Zilitene/Kwena to the north and Masokotwani and Lusu to the west. Temporary fish camps are located on small islands in the western and southern part of the lake.
The types of gear used on the newly inundated lake are the monofilament and multifilament gillnets, with limited use of the prohibited dragnets and mosquito nets (Simasiku, 2011. pers. obs.). Gillnets are readily available on the open market in Katima Mulilo (Simasiku, 2009. pers.obs.) and from dealers in Zambia at low cost. The low cost of nets and the relative ease with which fish are caught in the lake, makes commercial fishing an attractive option for potential entrepreneurs. Nets are obtained un-mounted and mounted by the fishermen prior to fishing activities. In gillnet construction both the top and bottom ropes made of hessian material. The bottom rope is twisted into the meshes and bricks attached at irregular intervals to serve as weights. The highly buoyant pieces of white fume box are tied to the top rope at an interval of 1 m to serve as floats. Gillnets are hung 2.5 m deep and mounted at 50 percent of the stretched length. Nets are usually set out in series over two weeks and inspected for fish each morning. Dugout canoes (mukolo) remain the mode of transport in access to fishing various grounds and deployment of fishing gear on the Lake (Simasiku, 2009.pers.obs.). Of all the wood species used in construction of canoes, only kiaat and possibly sausage trees are the best (van der Waal, 1990).
Since 2009, fish trade was resumed as an influx of Namibians, Angolans, Zambians, and Congolese settled at Shamahuka landing site for weeks or months while topped up their target consignments of fish for sale (Simasiku, pers. obs.). Fish were caught mainly by the Namibian fishermen and sold to both local and foreign fish traders. While at the lake, most of the foreign fish traders split and dried their fish or preserve them in salt before shipping them to Livingstone and Lusaka in Zambia, or further, in to the Democratic Republic of Congo (DRC) (Tweddle et al, 2011). Alternatively, fish would be transported by taxi to local markets at Bukalo and Katima Mulilo urban.
Previous reports on the Lake Liambezi Fishery and its production prior to it drying up in the 80’s were presented by van der Waal, (1980). A total mass production of 637 tons per year was computed in 1974, dropping down to 115 tons in 1976. This decline in catches was concurrent with a rise in lake levels. Apart from the continued search for appropriate fisheries management models, some authors have outlined some challenges of managing fluctuating ecosystems, which are mainly caused by climatic influence. Winpenny, (1991) stated that fisheries are highly prone to natural variability in their environment, which can be both complex and unpredictable, and may interact with human inter-versions to produce serious consequences on the fishery. Accurate assessments of the resource situation are observed by the rapid response of many freshwater fish stocks to fluctuating environmental conditions. The aim of this study was to
account for landing statistic data at Shamahuka landing site in order to:
- Asses the harvesting patterns of the local fishermen on the lake.
- Determine the annual exploitation level of the commercial species since fishing resumed in 2009.
- Correlate climatic factors such as water level, temperature, and lunar phase with the fish catches on the lake.
- Evaluate the contributory value of Lake Liambezi into the Katima Mulilo Fish Market.
Figure 1. Increase in fishing activities (a & b) at Shamahuka landing site between February – November 2010, Zambian truck loaded with fish stuck in mud at Muyako village (c) and theNamibian bakkie loaded with fresh fish for export to Zambia (d) (adapted from Tweedle, 2011 and Shapi 2012).
MATERIAL AND METHODS
Shamahuka landings and Market data
Monthly catch landing surveys were conducted twice a week at Shamahuka landing site between May 2011 and April 2012. Individual fishermen landing their catch were approached and questioned regarding their net types, stretched mesh sizes, net length and frequencies of fishing activities. It was difficult to record the catches directly from the fishermen as they were in a hurry to get their catches to the fish market, making recording impossible. However the daily catch of their fish per net was collectively placed in a large plastic cooler and weighed using a hanging scale under a pole tripod with a large platform below (Figure 2). The weighting station was strategically placed on the shore point where most fishermen landed their catch. Personal observations and secondary sources were employed during data collection. In addition to the catch data being recorded at Shamahuka landing site, staff from the Ministry of Fisheries and Marine Resources in conjunction with the Namibian Nature Foundation (NNF) recorded the origin and weight of fresh fish entering the Katima Mulilo Fish Market. All fish from various fishing areas were brought into the market using three different sized cooler boxes; large, medium and small and weighed using the hanging scale as described above.
Most fishermen on Lake Liambezi have showed a high preference for monofilament gillnets than multifilament due to high catch efficiency associated with the monofilament net type. The most frequently mesh size in use per net type was the 3.5 and 4” (inches). This practice is sustainable, however the use of 3” to catch fish in the lake by certain individuals may destruct and prevent juvenile recruitment. In addition, the study signify the importance of stock assessment, yield calculation, and catch trends over time as a basis to gain information on the response of the fish stocks relatively with change in climatic factor such as water level, temperature, and lunar phase. Above all, temperature and lunar phase were the two determinant factors on the catch rates from the lake. This implies that, in addition to fishing effort the fishery of Lake Liambezi is highly influenced by temperature and lunar phase. Sarch and Allison (2000) noted that the apparently greater importance of climate as confirmed by this study relative to fishing, in driving the dynamics of fish stocks in many Africa’s inland waters suggests that effort should be redirected at protecting wetland functions and broader ecosystem integrity. This calls for other alternative sources of income generation to be identified and promoted. The total mass production of 2544 tonnes removed from the entire lake per year, may underestimate the actual value of the lake but indicates that Lake Liambezi is a highly productive water body. The high supply of fish from Lake Liambezi to the Katima Mulilo Fish Market implies that the lake has an important bearing on the nutritional requirement of the Caprivi’s population. However the variability of such ecosystem and the responsiveness of catches by gear type and species both in space and time can provide a basis for management.
Full report (including Climate data, data analyses, results etc) is available on request...