Silver carp, an invasive species from Asia, have become notorious for their unusual jumping behavior in the rivers of the central United States. These large fish, weighing up to 100 cm, can leap up to 3 meters (10 feet) into the air in response to various stimuli, including passing boats, trains, and even geese taking off from the water.
The Science Behind Silver Carp Jumping
Researchers have studied the reasons behind this behavior and found that silver carp are predisposed for leaping due to their morphological characteristics. They possess a larger lower caudal fin and a ventral keel that may allow them to generate better thrust for jumping.
Silver carp use one of two methods of muscle contraction to escape the water: the S-start and C-start methods. The S-start response is the high-performance startle response that maximizes peak angular acceleration and velocity, generating the most thrust to break free of the water’s surface.
Broadband Sound Triggers Jumping
A study conducted in 2016 found that broadband sound (0.06 – 10 kHz) recorded from an outboard motor (100 hp at 32 km/hr) can elicit jumping behavior in wild silver carp. When played from speakers mounted on a slow-moving (3 – 6 km/hr) boat in the Spoon River near Havana, Illinois, fish jumped in 100% of the sound trials, implying that broadband sound is a trigger for jumping.
Potential Predator Avoidance and Barrier Crossing
Silver carp’s jumping behavior may serve as a potential predator avoidance tactic in response to the sound and pressure wave generated by boat motors. However, there is also a risk that if startled, they may leap near vertical or hydrological barriers in place to prevent their range expansion, potentially generating enough speed and height to clear the blockades.
Management Implications
The jumping behavior of silver carp poses challenges for their management and control. Researchers have suggested that anthropogenic sound can be used to alter the behavior of silver carp and has implications for deterrent barriers or herding fish for removal.
Dangers of Encountering Silver Carp
Encountering silver carp for the first time can be an “unexpected — perhaps frightening — experience,” according to Riecke’s report. The fish’s jumping behavior can be hazardous to boaters, especially if they are struck by a leaping fish. Silver carp are easily disturbed and will jump in response to various stimuli, including rocks thrown in the water.
Conclusion
Silver carp’s jumping behavior is a fascinating and challenging aspect of their invasion of U.S. waterways. Understanding the science behind this behavior and its potential implications for management and safety is crucial as efforts continue to control the spread of this invasive species. As researchers and resource managers work to address the silver carp problem, the public should be aware of the potential dangers and take precautions when encountering these remarkable fish.