Lake Mainit
09°26'N, l25°32'E; near the extreme northern tip of Mindanao Island in the Municipalities of Mainit, Alegria, Jabonga and Kicharao, on the boundary between Surigao del Norte and Agusan del Norte Provinces.
13,836 ha.
Biogeographical Province:
Wetland type:
Description of site:
A large freshwater lake on a narrow plain between hill ranges near the northern tip of Mindanao. The lake is fed by fourteen small rivers and streams; it has one outlet, the Lalinawan River, which flows south into Pagusi Lake and the Tubay River, and eventually into Butuan Bay. The shoreline is steeply shelving, and the maximum depth of the lake is about 200 metres. The pH values range from 6.5 to 7.8.
Climatic conditions:
Humid tropical climate with no proper dry season but a very pronounced period of maximum rainfall from October to January (Type II). The average annual rainfall is 3,180 mm, and the mean monthly temperatures range from 27°C to 30.5°C.
Principal vegetation:
Marshy areas of the lake are dominated by Hydrilla verticillata, Pistia stratiotes, Chara sp and Cladophora sp. Most of the surrounding area is under cultivation.
Land tenure:
No information.
Conservation measures taken:
The regional office of the Bureau of Forest Development has an on-going reafforestation programme in the area.
Conservation measures proposed:
Land use:
Fishing, mainly for goby, tilapia, mudfish, freshwater catfish and carp (Glossogobius giurus, Tilapia sp, Ophicepha!us striatus, Clarias sp and Cyprinus carpio). Other species in the catches include eel, milkfish, climbing perch and plasalit (Anguilla sp, Chanos chanos, Anabas testudineus and Trichogaster sp). Land around the lake is intensively cultivated. Various timber companies operate in the water catchment area, and several small and medium sized industries are dependent on the forest resources of the area.
Possible changes in land use:
Disturbances and threats: Indiscriminate gathering of raw materials for small scale industries.
Economic and social values: Economic and social values: The lake supports an important fishery; fish production was estimated at 369 metric tonnes in 1977. The economy of the municipalities around Lake Mainit is heavily dependent upon the agricultural production concentrated around the perimeter of the lake.
Fauna: The rich fish fauna includes non-migratory, migratory and introduced species. No information is available on the waterfowl.
Special floral values: No information.
Research and facilities: Various studies have been carried out on the lake's fisheries and other hydro-biological resources.
References: Bureau of Fisheries and Aquatic Resources (1984-85); Gracia et al. (1981); NACIAD (1985).
Criteria for inclusion: 1b, 1e.
Haribon Foundation.