THE LAKE

Tasik Kenyir was formed by the construction of  two major dams in 1982, the Jenagor Dam in the south-east and the Saddle Dam in the north (Fig. 1). The lake lies at latitude 4^o 41' north and longitude 102^o 40^' east. The main function of the dams is to generate hydro-electric power. The Sultan Mahmud Hydro-Electric Power Plant at Jenagor Dam currently generates 400 mega watts  of electricity at any one instant.
The lake was inundated in 1986. Before the inundation the area was occupied by rural settlements, oil palm plantations and fruit orchards. The villagers have since moved and formed new settlements around the lake. The total water surface area of the lake is about 36,900 hectares, with a surrounding catchment area of 260,000 hectares. At its maximum the water level in the lake can store 23.6 million cubic metres of water of which 7.4 million cubic metres is used to generate power.
The shoreline of this lake is rather steep since it was formed in a hilly terrain. The average depth  of the lake is about 100 metres. In the open areas the water is rather still but becomes more turbulent towards the feed rivers. The upstream portions of the feed rivers are rather fast flowing with numerous rapids. The river systems in the area were lost with the inundation of the lake. The rivers that flow into the lake are Sungai Lasir, Sungai Pertang, Sungai Lepar, Sungai Genung, Sungai Lawit, Sungai Petuang and Sungai Ketiar (Fig. 1). The rivers that flow into the lake from the National Park in the south-west include Sungai Cacing and Sungai Terenggan.
The fish fauna that once dominated these rivers have presumably adapted to the lacustrine habitat.  During the north-east monsoon, with heavy rainfall the riverine species of fish found in the lake migrate upstream towards the tributaries of the feed rivers to spawn.

PHYSICO-CHEMICAL PROPERTIES OF THE LAKE WATER

Weather conditions play an important role in influencing the physical and chemical nature of the lake water. During the wet north-east monsoonal months of October to January the water level  in the lake often rises to its maximum (145 metres at Jenagor Dam). During this period the lake water in the open areas is very much clearer (with light penetration to about 4 metres) while in the shallower peripheral areas of the lake the water becomes more turbid due to the influx of sediment load eroded by the turbulent feed rivers.
Surface temperatures of the lake do not fluctuate very much (around 28 – 30 ^oC) while in the upstream portions of the feed rivers water temperatures as low as 23.0 ^oC have been recorded.
Dissolved oxygen in the surface waters of the lake ranges from 6 to 7 mg/l and this decreases with depth to 0 mg/l at depths greater than 15 metres. Thermoclines have been recorded at depths of 8 to 10 metres, below which there is a sharp decline in dissolved oxygen levels.
The low nutrient levels, that is, nitrates and phosphates in the lake water, as shown by conductivity readings (21 to 56 Fmhos/cm) suggest that the lake has a low biological productivity. Nevertheless, the exploitable fish population in the lake has been estimated to be around 13kg/ha/yr.
Zooplankton study (Fig. 3) from January 1992 to January 1993 had identified four species of Cladocerans (Cerodaphnia comuta, Diaphanosoma excisum, Bosminopsis deitersi and Moina macrura); four species of Cyclopoid copepods (cyclopoid nauplii, cyclopoid copepodids, Thermocyclops crassus and Mesocyclops leukarti) and one specie of insect larvae (Chaoborus sp.).


Physico-chemical analysis of lake water                 Plankton sampling

FISHERIES ACTIVITIES IN THE LAKE

Tasik Kenyir has been long acknowledged as an important source of freshwater fish. Currently there are more than fifty licensed fishermen operating in the lake, engaging gears such as drift gill nets (pukat insang)(Fig. 4) and long-lines with multiple hooks (rawai). Bottom fish traps (bubu) which were once popularly used for catching catfish (ikan Baung) have now been outlawed in an attempt to conserve their stock in the lake. In 1999 a total of 24.5 metric tons of fish were harvested from the lake. The fish were landed at designated sites such as the Jenagor and Saddle dams. The major species of fish landed are Snakehead (Toman), Catfish (Baung) and River Barb (Lampam Sungai). A description of most of the fish species is given later in this publication.
Fishery exploitation in the lake is managed by the Department of Fisheries Malaysia in order to prevent or minimise illegal fishing activities. Controls in fishery exploitation are brought about through licensing of fishing boats and gears so that fish stocks in the lake may be maintained at sustainable levels.
The assessment of stocks of fish in the lake are also carried out periodically by staff of the Freshwater Fisheries Research Centre in Batu Berendam, Malacca, engaging sampling gears such as the drift gill nets. Findings from these studies are expected to provide the basis for fishery management in the lake.


A river barb caught in a drift gill net in the lake

Efforts are also underway at the Batu Berendam Research Centre to carry out experimental breeding of the commercial species of food fish found in the lake, in the hope that research results may assist in replenishing the fish stocks in the lake, in the years to come.
Other related activities include experimental culture of selected species of fish in suspended cages in the lake, in an effort to determine the suitability of these species in cage culture. They include the Red Tilapia, the Catfishes (Baung and Patin) and the Carps (Jelawat and Kelah). In 1999 the culture experiments produced a harvest of 20 metric tonnes of fish with an estimated value of RM114,000.00. Fish rearing cages have also been supplied to poor residents in the area, together with fish fry and fish feed so that they may be encouraged to culture fish in the lake and earn an extra income from the harvests, besides having adequate supplies for home consumption. The Department of Fisheries has thus for released about 20,000 fry of the Tilapia into the lake, as part of a programme to increase fish production in the lake.

THE LAKE ’S TOURISM POTENTIAL

It is the desire of the Malaysian government to develop Tasik Kenyir as a prominent tourist destination. Under The Sixth Malaysia Plan (1991 to 1995) out of a total allocation of RM 38 million to developed all  lakes in Malaysia , a sum of  RM14.255 million was provided for the development of Tasik Kenyir. A management committee for the development of tourism in the lake plays a catalytical role in the various projects that are being implemented to ensure that the necessary facilities and conveniences are available to visitors to the lake, including boats and chalets.