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GAINESVILLE, Fla. – A camera can accurately count freshwater fish, even in the thickest of underwater vegetation, a key finding for those who manage fisheries and control the invasive plant hydrilla, new University of Florida research shows.
The finding by UF/IFAS scientists can help researchers understand how many and which fish species are using dense plant habitats, said former UF/IFAS graduate student Kyle Wilson.
While cameras have been used to document fish behavior – including eating and breeding ─ this marks the first time scientists have used video to count fish in underwater plant habitats, Wilson said. In addition, no prior studies that used cameras to count fish verified their fish populations.
“It is commonly assumed that dense and invasive plants, like hydrilla, can drastically change fish habitat quality, primarily through changes in dissolved oxygen levels, water chemistry and habitat structure,” Wilson said. “Whether these changes are good or bad for fish has previously remained uncertain due to sampling problems in dense plant habitats. Using underwater cameras, we have shown that fish can and do use habitats we previously thought were too stressful for fish habitat.”
This is a big problem, especially with hydrilla, a plant that has invaded lakes throughout Florida, much of the U.S., Central America, South Africa and Australia, Wilson said. He estimated Florida spent up to $14 million per year throughout the 2000s to manage hydrilla, while the U.S. spent about $100 million per year in the 2000s for aquatic plant management.