What are those fish that are jumping and why do they jump?
Sitting outside on a summer evening, the nearly full moon clearly reflected in becalmed waters. A stillness prevailed, punctuated by the occasional SPLASH of large fish jumping, like an exclamation point to the end of the day! The fish jumping raised a pair of often repeated questions: what kind of fish are those jumping? and why do they jump? The answer to the first question is a cinch: those are mostly likely carp. As to why they are jumping, I’ve heard lots of fishy speculation but few definitive answers. Everything from “shaking loose parasites” to simply “because they can and it’s fun.” The most satisfying answer comes from an online anglers forum. According to the Carp Anglers Group, the jumping behavior of carp is related to their bottom feeding. Carp gather food into their mouths by sucking like a vacuum along the river bottom. Along with the food particles, they also suck large quantities of bottom debris. The food items are swallowed to the stomach while the debris passes through the gill rakers. Over time, some of the bottom sediment particles accumulate on the gill rakers and interfere with respiration. Jumping from the water and splashing down is a method of back-flushing the gills to remove the accumulated debris.
Sounds plausible enough. Regardless of the reason, carp jumping on a summer evening creates just enough disturbance to call attention to the relaxing stillness.