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 determineif 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 lock gates than when it was off; however, when analyzed by a GLMM this effect was shown to be no greater than the effects of river discharge or temperature. Additionally, lock entrance rates were lower, albeit non-significantly, when the sound was off. A number of factors may have contributed to the limited efficacy of this deterrent system including the sound itself.
Bibliographical noteFunding Information:
We thank the Minnesota Department of Natural Resources (MN DNR) for their financial support as well as the U.S. Fish and Wildlife Service (USFWS), specifically Jenna Merry and her staff for providing help during fish capture and tagging events. A special thanks to lockmaster Jane Matheson and the U.S. Army Corps of Engineers (USACE) LD8 crew. We are also grateful to the MN DNR and Wisconsin Department of Natural Resources for issuing the fish collection permits needed to perform this research. Thank you to the Minnesota Aquatic Invasive Species Research Center for providing office space and paying for this publication. Lucas Lagoon and Rosie Daniels helped with fieldwork and Nate Banet kindly helped create Figure 1. We thank our reviewers and editor for their many helpful comments.
Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as well as the Minnesota Outdoor Heritage Fund via the MN DNR. A Twin Cities boy scout troop generously donated funds to pay for the speakers. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
© Riesgraf et al.
- Bigheaded carp
- Invasive species
- Lock and dam