Evaluation of a broadband sound projected from the gates of a navigation lock in the Mississippi River shows it to be a weak deterrent for common carp and unable to block passage

There is an urgent need to block the passage of carp and other invasive fishes through
navigational locks in large rivers. Although the broadband sound of an outboard motor
has been shown to strongly repel three species of carp in laboratory flumes and to a
lesser extent inside of a lock chamber, it has not yet been tested to see if it can stop
carp from entering a lock. To test this possibility, we attached speakers to lock gates
and played the sound of an outboard motor while measuring its efficacy by tracking
free-ranging transplanted tagged common carp in its vicinity. Eight groups of 20 carp
were tested while the sound system was turned on and off for 2 week periods. When
the sound system was on, these carp spent approximately one-third less time in
front of the gates than when it was off which when modeled by GLMM was shown
to no greater than the effects of river discharge or temperature. Further, there was
no indication that this sound blocked carp from entering and presumably passing
through the lock. However, the number of times that tagged carp entered the lock
was low even when the sound was off. A number of factors may have contributed
to the limited efficacy of this deterrent system including the sound itself.