Phnom Penh - "Turn the lights off soon, or people will see us," the young fisherman said in a muted voice that was barely audible, even in the pre-dawn quiet.The sky was moonless, and it was pitch-black at 03:30 on Cambodia's Tonle Sap Lake."We are in the conservation zone. If they catch us, we will be in trouble," explained the fisherman.To protect his identity, as fishing in restricted areas is punishable by a two-year jail sentence, he asked that Al Jazeera not reveal his name.The Tonle Sap is one of the world's most productive freshwater fisheries and the main source of protein and fatty acids for Cambodia's roughly 15 million inhabitants.The fact that fishermen are resorting to sneaking into the lake's protected areas speaks of an alarming truth: the Tonle Sap, Cambodia's "beating heart", is struggling to meet the demands of the country's growing population."Outside the conservation area there are no fish, so what should I do?" the fisherman asked rhetorically.The 28-year-old has been fishing in the Tonle Sap for more than a decade, and is well-aware of the lake's ailing health. An inland ocean In 1858, the 19th-century explorer Henri Mouhot, best known for popularising the ancient Cambodian temple complex of Angkor Wat among Europeans, said the Tonle Sap "is so full of fish that, at the time of low waters, they are crushed under boats, and rowing is often hampered by their number".Though Mouhot's account was likely an exaggeration, modern experts also confirm the abundance of fish in the Tonle Sap."There is nothing else like the Tonle Sap. It's like an inland ocean - a fish soup," said Taber Hand, a Tonle Sap specialist and founder of Wetlands Work, a social enterprise group."There are more fish by tonnage in the Tonle Sap than in both the commercial and recreational freshwater sectors of the United States and Canada combined. But the lake is a poster child for tragedy," said Hand.While many factors have contributed to the decline of the Tonle Sap's health, the source of all these problems can be attributed to human impact on the environment.Among the primary stresses on the lake's resources is Cambodia's rapidly growing population. With a reported annual growth rate of around 1.6%, Cambodia's population is expanding at a rate more than twice of that of the US and nearly eight times faster than that of Denmark.According to the World Fish Center, roughly 20kg of fish are caught in the Tonle Sap for every inhabitant of Cambodia, making it the most intensely fished inland body of water in the world.The growing population led to a corresponding increase in pressure on the lake's already over-exploited fish population.Horm Sok, a Cambodian field researcher for the environmental watchdog Conservation International, has witnessed the effects of Cambodia's population boom first hand."I've lived along the Tonle Sap since 1979 and have noticed a lot less fish being caught [per fisherman]. The population has grown so much that the fish are disappearing."According to Sok, the number of fishermen is not the only factor reducing the amount of fish in the lake. The type of gear they are using has changed, too."People didn't used to use so much illegal equipment," Sok recounted to Al Jazeera from his thatch-roofed research outpost on the Tonle Sap's floodplain."The nets [many] people use now are too fine and too long; They catch everything, so no small fish are left for the next seasons. Some people use electrified nets, which is even easier, but kills everything," Sok said.A study in mismanagement?One of the biggest blows to the biodiversity in Tonle Sap came from the nationalisation of Cambodia's fisheries and the dismantling of existing foreign-owned, industrial fishing corporations in the early 2000s.Overseeing vast areas of private fishing grounds, the predominately Chinese and Vietnamese-owned operations have long been resented by small-scale Cambodian fishermen who wanted access to the fertile fisheries the companies controlled. Seeking to garner political support, Cambodian Prime Minister Hun Sen ordered the industrial operations closed and returned ownership of the country's waterways to its people.While perhaps an act of noble intent, the populist policy made it impossible to enforce the majority of the environmental regulations to which the international companies had been subject.Though the industrial operations were responsible for harvesting vast quantities of fish from the lake, "they worked to preserve the ecosystem", explained Hand."They understood the necessity of healthy fisheries to ensure profits, and they protected their lots by force. This angered the local population, and so they were dismantled - but by playing to the people, [Sen] doomed the waterscape," said Hand.A bonanza of land-grabbing followed. The former fishing lots situated on the Tonle Sap's floodplains were bought up piecemeal and largely deforested for conversion into farmland, destroying the spawning grounds of many of the lake's fish species."The former lots have become habitat wastelands," Hand reported. "They're probably getting about 0.5% of the productivity they used to get out of those areas."Eang Sophallet, a spokesperson for the Cambodian ministry of agriculture, forestry and fisheries, disputed Hand's statements, denying that the lake faces any environmental dangers."Experts should… not only raise the negative points," Sophallet said in a telephone interview with Al Jazeera."It is better to input positive points in their analyses. We are now processing our protection mechanisms and setting up conservation areas to protect forests and fisheries. We are now strengthening and maintaining the Tonle Sap," said Sophallet.In Hand's opinion, this statement carries little weight."Cambodia has fantastic environmental laws on paper, but no one enforces them. There is no fisheries management, only maximisation [of profits]," Hand claimed.Additionally, hydropower dams, such as the controversial Lower Sesan II, are slated for construction along the length of the Mekong River and its tributaries, further endangering its future fertility.The rich sediment and nutrients that flow down the Mekong before being absorbed into the Tonle Sap provide the foundations of the lake's food chain.If just 11 of the dozens of proposed dams are built, International Rivers, an environmental NGO, predicts that more than 100 species of fish in the region could face extinction.Nevertheless, Hand believes there is still a chance to revive Cambodia's great lake if strict environmental regulations are enforced. But he is sceptical of the human willingness to sacrifice profits for the sake of an ecosystem."All the options to save the lake are present. The problem is the human priorities," said Hand."We could have our cake and eat it too, but people want to work for themselves instead of together."