Scientist in America are electrocuting lakes and the reason is alarming |
Water in parts of the United States is being shocked on purpose. Not for spectacle, and not to remove rubbish, but to count what is living below the surface. State wildlife teams and university researchers have been lowering electrodes into lakes and wetlands, sending controlled bursts of electricity through the water. The method briefly stuns fish so they float up, allowing them to be netted, recorded and released. It is called electrofishing, and it has become a routine tool in areas where invasive species are spreading. In Florida, where fragile wetlands are under pressure, the technique is now tied to a larger concern about ecosystem decline and the unexpected role of one eel-shaped predator moving quietly through restored waters.
Why US scientists use electricity in lakes to track invasive species
The problem circles back to the Florida Everglades, a vast wetland protected in part by Everglades National Park. For decades, restoration projects have tried to repair altered water flows that damaged fish populations and wading bird colonies. Billions have been spent to return something close to the original rhythm of wet and dry seasons.Then another pressure appeared. The Asian swamp eel, known scientifically as Monopterus albus, began spreading through south Florida waterways around 2012. It did not arrive as part of any plan. Like many invasive species, it likely entered through the aquarium trade or accidental release. Once established, it proved difficult to remove.Researchers monitoring Taylor Slough, one of the park’s main drainages, began noticing changes. Long-term community data showed that after swamp eels became established, average fish and decapod species richness fell by about 25 percent. Diversity and evenness also dropped. The community shifted towards grass shrimp and a smaller number of hardy fish species.The figures are stark. Total biomass of small fish and decapods declined by roughly 68%. The most important prey species for nesting wading birds fell by around 80%. That matters because birds such as herons, egrets and ibises depend on seasonal pulses of small aquatic animals to raise chicks.It is not dramatic in appearance. Fewer fish. Fewer crayfish. A simpler food web. But the change runs through the system.
Electrofishing helps track elusive swamp eels
Swamp eels are slippery in every sense. They can breathe air, survive in low oxygen water and move across damp ground between ponds. Nets alone often miss them. Standard trapping methods struggle. This is where electrofishing comes in.By placing high-voltage electrodes into water bodies such as Lake Underhill in Orlando, scientists create a temporary electric field. Fish within range are stunned for a short period and float to the surface. Teams then collect, measure and identify them before releasing most back into the lake.Even stunned swamp eels can twist free. Still, the method gives researchers a clearer snapshot of what is present and in what numbers. It also allows examination of stomach contents. Understanding what the eel is eating helps predict which native species are under most pressure. Electrofishing does not aim to wipe out the invader. On large mainland systems, eradication is rarely realistic. Instead, wildlife managers focus on limiting the spread and building a detailed record of change.
Long-term monitoring reveals deeper ecosystem shifts
The Everglades restoration effort depends heavily on data. Monitoring projects began in the 1990s to measure progress as water flow patterns were adjusted. Scientists track fish abundance, decapod production and bird nesting success.When an invasive predator enters that system, the effects can be subtle at first. Individual populations decline. Certain species become scarce. Over time, the whole assemblage begins to look different.Introduced predators often fill niches that were previously empty. In some cases, native prey have few defences. Behaviour changes. Some species retreat to less suitable habitats. Others vanish locally.Ecologists sometimes describe ecosystem collapse as a state where biodiversity is lost and normal function does not recover without major intervention. Whether the Everglades will reach that point is uncertain. But the direction in Taylor Slough has concerned researchers enough to warrant closer tracking. Electrofishing surveys feed directly into that assessment. Each sampling round adds another layer to a long timeline. Numbers go up or down. Certain species reappear. Others fade further.
Managing spread is now the priority
There have been isolated success stories in removing invasive mammals from small islands. On large connected wetlands, the reality is different. Once a species like the Asian swamp eel spreads through canals and marshes, containment becomes the practical aim. Scientists use the data gathered from shocked lakes to map expansion. If eels move into other major drainages of the Everglades, similar declines in prey biomass could follow. That would tighten food supplies for breeding birds that restoration plans were designed to support.So the electricity in America’s lakes is less about spectacle and more about measurement. A brief pulse in the water, a few stunned fish rising, clipboards filling with figures. In a landscape shaped by water levels and slow ecological change, it is one of the clearer ways to see what is shifting underneath.
