Development experts say poverty amidst the populations surrounding Malawi’s second largest water body, Lake Chilwa, has placed the lake under intense threat.
Dr. Rodney Lunduka, an environmental research expert with the London based International Institute for Environment and Development (IIED) says that competition for natural resources has exerted pressure on the lake and its catchment area, declared a Ramsar site.
He observes that poor populations surrounding Chilwa has over the past decades increasingly depended on the lake’s wetlands natural resources for survival, where they realized about US$ 19 million or US$21,305/km2 of the wetland annually
“With 77,000 people living in the wetland its value translate into benefits of US$242 per wetland inhabitant,” he says explaining that “the main reason for the recognition of increased value in the watered areas is that while watered land had long been recognized as an important strategy to improve family food security and income, it has gained even more value in people eyes in the wake of the drought and floods in the past two decades”.
Lunduka observes that “Due to increase in drought incidences and erratic rainfall as a result of climate change, irrigation has been promoted and more land is being cleared go grow more rice and irrigated maize.
“This has increased soil erosion causing siltation and reduced water flowing into the lake there by reducing fish productivity,” he notes.
The development expert estimates that the loss in value due to reduction in fish productivity in Lake Chilwa is about US$ 1,003,580 per year.
“An additional US$ 249,460/year is lost on site in irrigation lands due to loss in soil fertility and siltation,” he says noting that to supplement their income after crop failure or reduction in fish catches the communities in the catchment have increased hunting birds and doing craftwork with lake reeds.
“An increase in bird hunting is causing an estimate loss of US$59,238 per year from reduction in birds’ population,” he says. “An additional US$8,473,433/year worth of food crops is estimated on top of eliminating the losses to fisheries and birds resources”.
Lake Chilwa, Africa’s twelfth largest lake, has a basin that provides livelihood opportunities to more than 117, 031 families with its resources such as water, fish, birds and grass for thatching and constructing houses and boats, mats, fish traps, birds’ traps and baskets.
The lakes catchment area alone directly supports more than 77,000 households who utilize it for fishing, irrigation, birds hunting and rain fed agriculture.
One of Malawi’s leading hydrologists, Dr.Henri Njoloma said that changing rainfall pattern in Malawi due to the changing climate resulting in uneven and unpredictable rainfall distribution has contributed to the reduced productivity of natural resources such as land and water.
The 2,400km2 lake, which varies considerably in size depending on precipitation in the catchment, is situated southeast of Lake Malawi and Lake Malombe, a swelling of Shire River. 1,500km2 is open water while 578km2 is in swamps and marshes and 580km2 is grassland which becomes inundated seasonally.
Its catchment of 8,349km2 is shared between Malawi (5,669km2) and Mozambique (2,680km2).
The four to five meter shallow lake contains 14 species of fish of which 3 hardy species are more abundant Mlamba Clarias gariepinus), Matemba (Barbus paludinosus) and Makumba (Oreochromis shiranus chilwae). The fish in the lake move seasonally between the lake and its tributary rivers.
At peak level about 6,000 men are engaged in small scales fishing activities which are valued up to US$17 million per year, notes Lunduka.
He says that the value of the lake also accrues to middlemen and marketers. “Its mean annual value is more than 10 times as high as the value of harvest from rice fields, the second most important activity in the wetland area” he says.
Lake Chilwa has about 160 species of resident and 41 species of Palearctic migrant waterbirds respectively. About 22 species of Palearctic birds are regular visitors to Lake Chilwa between September and April every year.
It supports about 23 species including the African Spoonbill Platalea alba, Fulvous Whistling Duck Dendrocygna bicolor, Black-headed Heron Ardea melanocephala and secretive marsh birds like Lesser Moorhen Gallinula angulata and Lesser Gallinule Gallinula alleni which qualifies the catchment for the Ramsar criterion of 1% level of
individuals per population.
The total waterfowl population of Lake Chilwa is estimated at a conservative figure of about 354,000. Predators such as the resident Pinkbacked Pelican Pelecanus rufescens, the Grey-headed Gull Larus cirrocephalus and the migrant White-winged Black Tern Chlidonias leucoptera are common in the open water, especially in Kachulu Bay, a major fishing centre.
Birds of prey found on the lakes wetland include the African Marsh Harrier Circus aeruginosa and the much less common Fish Eagle Haliaetus ranivorus. The Yellow-billed Kite Milvus aegypticus and the Lesser Kestrel Falco naumannii also represent the palearctic migrant birds of prey in the Lake Chilwa wetland.