Why have no actual Asian carp been found in the areas where eDNA testing has identified them?
Asian carp are still below a threshold of detection using traditional fishing gear. Electro-fishing is successful in detecting bighead and silver carp when they are in high abundance. The Chicago Sanitary and Ship Canal is, in some places, nearly 30 feet deep, which is another disadvantage to using traditional sampling methods. In the early spring and late fall, the water is cooler and produces less algae (a main food source of bighead and silver carp diets), and the fish tend to reside a bit deeper than they would during warmer months. With decreased metabolism (not as much food), they are also less active and therefore harder to detect.
