Negombo Lagoon: Second to none in its flora and fauna
(Continued from last week)
Negombo Lagoon is characterised by high biodiversity in its flora and fauna. The mangrove community in the lagoon is the most diverse of all mangrove communities in the west coast of Sri Lanka. The zonation of plants and animals in the mangroves is not as spectacular as that in South East Asia, because of the low tidal fluctuation, but in the number of species of plants and animals in the lagoon, mangroves, seagrasses and mudflats, it is second to none.
Negombo Lagoon is rich in biodiversity, both on land and water
Twenty-nine plant species have been collected from the mangrove community of Negombo Lagoon of which 18 are true mangroves and 11 are mangrove associates. There are four species of seagrasses distributed in the shallow areas of the lagoon. One hundred and forty species of fish, 12 species of prawns, 19 species of crabs, 22 species of molluscs, 36 species of polychaetes and numerous species from other taxa have been reported from Negombo Lagoon.
Adding further to the biodiversity of the lagoon is the biodiversity of the Muthurajawela swamp. It has about 192 plant species, distributed over seven major vegetation communities. The vertebrate fauna of Muthurajawela includes 40 species of fish, 14 species of amphibians, 31 species of reptiles, 102 species of birds and 22 species of mammals. Seventeen of these vertebrate species are endemic to Sri Lanka.
Muthurajawela also helps to mitigate floods, raise the water level in local wells and filter water before discharging into the lagoon. The Department of Wildlife Conservation has rightly recognised the conservative value and declared Muthurajawela as a wildlife-bird sanctuary and established the Muthurajawela Visitor Centre.
Fishery resource–Fish, prawns and crabs are the main resource of the lagoon. Many of these species migrate to the lagoon as it provides a safe and a suitable habitat and a source of food, and return to the sea when they are adults. The prawns and fish that go back to the sea, replenish two important fishing grounds located 5–10 km north and south of the Negombo Lagoon mouth. Sail boats fish in the northern fishing grounds in the sea off the shores of Negombo-Wellavidiya, and motor boats fish in the southern fishing grounds in the sea off the shores of Pamunugama- Hendala. The estimated catch from all gears operated inside the lagoon in 1997 was 613 t of shrimp and 1044 t of others (mostly fish). The production from trawlers operating outside the lagoon was 270 t of shrimp and 239 t of others, showing the importance of the lagoon in prawn and shrimp fishery (FAO Fisheries Circular No 958). In 2001, the annual catch from the lagoon was 362 t of prawns and 662 t of fish (Jayawardene 2001). In general, most authors consider the annual fish production from the lagoon to be between 65-150 kg/ha, and any lagoon that produces more than 100 kg/ha/yr is considered to be a highly productive lagoon (Pillai 1965, Jayakody 1994).
In the lagoon fishing takes place all year round using 22 fishing methods, of which 13 are entirely traditional. The annual fish catch from the lagoon, as exemplified by the total catch in 2001 was mainly from the trammel nets or disco nets (466 t), stake seine nets or kattudel (215 t) and brush piles or athu kotu (204 t). Fingerlings of Groupers–kossas (Epinephelus sp. and Cephalopholis sp.) are collected from the brush piles and sold to collecting centres, from where they are exported for fattening and for sale in South-East Asian restaurants. Some centres have exported 12–15 million fish fingerlings during the grouper season, after rains (NARA 1988). In addition to food fish, 63–251 ornamental fish are also caught from a Brush pile per month (Anis et al. 2015). Thus, about 8000 people depend on the fishery in the lagoon for their living. The Department of Fisheries and NARA studies and manages the fishery resources of the lagoon.
Eco-tourism – As Negombo Lagoon-Muthurajawela ecosystem is located close to Katunayake and Colombo, it has significant eco-tourism value, which needs to be further developed. It could be made as popular as Yala for the tourists, who are visiting Sri Lanka for a short period. The Muthurajawela Visitors Centre is a great asset, and what is required is more publicity in Colombo, Negombo and Katunayake hotels and in tourist websites in the internet, and work on organised transport, safety, comfort and well-trained guides. Morning and evening tours could begin or end from Muthurajawela, watching birds, crocodiles, monitor lizards, toque monkeys, painted bats, and occasionally otter, slender loris and rusty-spotted cat. Some binoculars may be provided for identifying migratory birds and hand-outs or booklets for identifying plants and animals would be useful.
Once in the Negombo Lagoon, mangroves, sea grasses, fishing methods (e.g. brush pile, crab pots, cast nets, gill nets, trammel net (disco net), katta, scoop nets, gawana dela, kadippu dela, karakgediya) could be demonstrated. The boat trip could take the tourists to the Dutch Fort and the small church there, and they could be entertained with a brief history of Negombo, with its importance in the pre-colonial period, the arrival of Portuguese in 1505, their decline of power by 1630s, invitation of the Dutch to replace the Portuguese by the king of Kandy, the initial capture of Negombo from the Portuguese in 1640 by Philip Lucas, the Dutch Director-General of East Indies, setback in 1644 when the Kandyan army was defeated and the recapture of Negombo by the Portuguese, and again recapture of Negombo by the Dutch in 1646. The armistice between Portugal and Holland angered King Rajasinghe II of Kandy, and he provoked a conflict between both nations by passing through the territories of one to attack the other. On one occasion he captured the fort of Negombo and sent the Dutch commander Adrian Vander Stell to his countrymen holding the Galle Fort. The Dutch managed to regain control of Negombo from the King by diplomatic means.
There are also stories among old folks (that need to be verified) off how a Portuguese ship trapped in the Negombo Lagoon escaped to the sea via land using logs and sails, while the Dutch waited at the mouth of the lagoon to attack her. The Ministry of Tourism and Sri Lanka Tourism Development Authority together with the Department of Wildlife Conservation could further develop this area, as tourism is gaining grounds in the country.
Sustainable use of mini products – The lagoon and the peat bog provide other products in small quantities, including timber, tannins, lime, corks, floats, bait, fish food, animal feed, peat and manure. Eating oysters raw with lemon is not popular among Sri Lankans, though tourists in hotels would like them, and the potential for tropical oyster farming is there in Negombo. Besides, soft shell crab farming and molluscan farming and other aquaculture potentials exist around Negombo. After the closure of prawn farming, it has become all the more important to carry out proper Environmental Impact Assessments, (EIA) which should include mitigating measures and continuous monitoring and operating licences, before venturing into any such project that may impact Negombo Lagoon and Muthurajawela. Bee keeping (apiculture) is associated with the honey mangrove (Manda gas) and small-scale mangrove planting and management (silviculture) may be attempted at suitable sites, as done in large scale in the mangroves of Malaysia. The Forest Department looks after the mangroves and vegetation in the Negombo Lagoon-Muthurajawela ecosystem.