Central America’s biggest lake still hosts bull sharks
Lake Nicaragua—Cocibolca or Mar Dulce to locals—covers 8,264 square kilometres, the largest freshwater lake in Central America. Freshwater sharks, sawfish, and tarpon share a tectonic basin that drains east to the Caribbean yet sits within sight of the Pacific.
It ranks nineteenth in the world by area and tenth in the Americas, just behind Titicaca, lies 32.7 metres above sea level and is no more than 26 metres deep. The intermittent Tipitapa River brings overflow from Lake Managua when that lake runs high. The San Juan River carries outflow to the Caribbean, historically making northwest-shore Granada an Atlantic port despite the Pacific’s nearer geography. From the mountains of Ometepe, the largest island, the Pacific is actually visible.
Volcanic Ometepe and Zapatera rise as islands; easterly winds stack sizable waves across the “sweet sea.” Scientists once named an endemic Lake Nicaragua shark before 1961 comparisons synonymized it with the widespread bull shark that ascends rivers. Researchers assumed these sharks were trapped until the late 1960s showed them leaping up the San Juan rapids much like salmon; tagged animals have reached the open sea in as little as seven days. At least 16 regional cichlids swim here too, and Amphilophus labiatus is native only to Lake Nicaragua and its neighbour Managua.
Caribbean pirates raided Granada three times. Gold Rush travellers in the late 1840s preferred the San Juan–lake–overland path as one of two Atlantic-to-Pacific shortcuts. Cornelius Vanderbilt’s Accessory Transit Company ran stagecoaches across the Isthmus of Rivas to the Pacific, and the 1916 Bryan–Chamorro Treaty gave the United States canal rights on the route until both nations cancelled it in 1970. Canal schemes that would cut through the lake raise saltwater contamination fears.
In 1981 the environment ministry, MARENA, found half the water samples it tested badly contaminated by sewage, and the 2014 drought, the worst in 32 years, led officials to suggest eating iguanas rather than water-hungry chickens. The same survey counted about 32 tons of raw sewage flowing in every day, with Pennwalt Chemical Corporation named the worst industrial polluter. Until Ometepe Airport opened, boats were the only island link; Solentiname still depends on them.
Source: Lake Nicaragua
