Tonle Sap Lake: Cambodia Economy and Environment

Introduction to Tonle Sap Lake

Tonle Sap lake is the largest freshwater lake in SE Asia. Literally, Tonle translates to English as “fresh” and Sap translates as “lake”. However, the significance of the lake is that it’s fishery sustains the livelihoods of over 1,000,000 inhabitants who live in the surrounding provinces.

Tonle Sap was also the food source that sustained the ancient Khmer city of Angkor. It is no coincidence that location of Angkor was in close proximity to the lake.

Tonle Sap River Flow Phenomenon

The Tonle Sap lake is connected to the Mekong river by the 75 mile long Tonle Sap River. When the Mekong enters its seasonal flood stage the result is that the Tonle Sap river reverses course. This phenomenon is caused because the Mekong overpowers the water flowing downstream from the great lake.

As a result, the water is now flowing into Tonle Sap Lake instead of exiting it. Therefore, the size of Tonle Sap lake fluctuates greatly during the year. Hence, this expanding and contracting of the lake is metaphorically compared to a heartbeat.

Subsistence Fishing Tonle Sap Lake

The local villagers primarily use nets to capture the fish. Mostly, the fisherman do everything manually although a few of them are able to afford more automated equipment. Unfortunately, many families who rely on fishing do not have access to the more modern equipment.

Automated Fishing Equipment Tonle Sap lake and Tributaries.

Example of the automated fishing mechanisms used on the Tonle Sap lake and tributaries.

In contrast, the vast majority of the village fisherman must manually work their nets. The fishing nets are tethered to the shoreline or to their boats. When traveling up the tributary rivers avoiding the positioning of these nets is like traveling through a maze.

fishing on tonle sap lake

The fishing nets are spread out across the water leaving only a narrow passage way along this Tonle Sap lake tributary.

fishing on Tonle Sap Lake and River

These are shore based fisherman in a more narrow stretch of the Tonle Sap river.

fishing on tonle sap

Although it would be considered a delicacy for most of the locals, other food sources such as small turtles and snails are also consumed.

food diversity on tonle sap lake

We were served a variety of local food when we attended the Prey Chas school opening ceremony. This was a community development project that I had funded in a small community located along a Tonle Sap lake tributary.

Is The Tonle Sap Lake Fishery Sustainable?

Unfortunately, the sustainability of the Tonle Sap lake fishery resources is not certain. As of 2007, the Tonle Sap’s largest commercial fishing operations reported that their annual catch has been consistent year over year. However, the subsistence fisherman report that their annual take has dropped by 50-70% over the previous decade.

Additionally, the size of the fish being caught on Tonle Sap lake has dropped substantially with a much higher proportion of smaller fish. This implies that the fishery is becoming depleted and the resources are not being replaced.

Traveling the Tonle Sap Tributaries

There is a ferry service that operates in between Siem Reap to Battambang. The route passes across the northern tip of Tonle Sap lake and enters the tributaries in order to get to Battambang.

Unfortunately, every year there are fatalities caused from the passing wake created by the larger ferry boats. This is because the wake can capsize the smaller fishing boats and the occupants drown in the river.

However, even for the ferry travel is not easy as they can become stranded on mud banks or the propeller can get entangled in river plants.

travel on the tonle sap lake and tributaries.

The propeller is caught up in the undergrowth of this Tonle Sap tributary.

While we were traveling from Battambang to my Prey Chas, Cambodia community development project we used some less traveled sections of the tributary rivers.  This was done more efficiently in a smaller and faster moving boat.

Flooding on Tonle Sap Lake

The reversal of the Tonle Sap river results in a massive increase in size of Tonle Sap lake. Therefore, villages surrounding the great lake must be able to stay above the high water line. The construction of the houses and public buildings in the local village Prey Chas reflect this necessity. 

The local school is situated 15 feet above ground to stay above the flood line. Buildings that are not elevated must be able to float on the water surface of they will become inundated during the flood season. 

School Construction on Tonle Sap lake and tributaries.

Photo of the local school building project that I funded in Prey Chas Cambodia. This is a photo of the completed school project that was taken after the school opening ceremony that I attended in November 2014

Photo of me with the Governor of Battambang Province in Cambodia. I was presented here with the Cambodia development medal of honor and a certificate.

Elevated Houses in Prey Chas Cambodia located on Tonle Sap Tributary.

The construction of local homes in Prey Chas Cambodia must take into account the rapidly fluctuating water levels of the great Tonle Sap lake.

Conclusion

Sustainability of the Tonle Sap lake fishery is essential for the survival of the inhabitants of the surrounding provinces. Unfortunately, the Cambodian government has limited resources to regulate over fishing.

It can be inferred that the commercial fishing industry is under reporting their annual catch which explains why the subsistence fisherman are reporting sharply dropping catch levels. Subsistence fishing now requires significantly more effort to procure enough fish to survive on.

I last traveled through the area around Tonle Sap lake in November 2014 to attend the school opening. We made use of small open boats and I was astounded by the number of fish that were apparent to the naked eye. This was because small fish were literally jumping into the boat as we traveled over the water. Fortunately, the virility of the Tonle Sap fishery seems to be holding up for now!

This is the most common method of transportation on the Tonle Sap lake and surrounding tributaries. Small fish were literally jumping into the boat as we drove along the Tonle Sap waterway!

Additional resources:

https://www.internationalrivers.org/resources/protecting-the-fisheries-of-tonle-sap-lake-1742
https://en.wikipedia.org/wiki/Tonl%C3%A9_Sap