Non-physical barriers, including the use of underwater strobe lights alone or paired with sound or bubbles, are being considered as a means to prevent the upstream migration of invasive silver carp Hypophthalmichthys molitrix and bighead carp H. nobilis. To optimize potential optical deterrents, it is necessary to understand the visual sensitivity of the fishes. Dark-adapted H. molitrix and H. nobilis were found to possess broad visual sensitivity between 470 to 620 nm with peak spectral sensitivity at 540 nm for H. molitrix and 560 nm in H. nobilis. To assess the effect of a strobe light on vision, dark-adapted H. molitrix, H. nobilis and common carp Cyprinus carpio, were exposed to three different 5 s trains (100, 200, or 500 ms on–off flashes) of white light and the recovery of visual sensitivity was determined by measuring the b-wave amplitude of the electroretinogram (ERG). For all species, the longest recoveries were observed in response to the 500 ms flash trains (H. molitrix mean ± SE = 702.0 ± 89.8 s; H. nobilis 648.0 ± 116.0 s; C. carpio 480 ± 180.0 s). The results suggest that strobe lights can temporarily depress visual sensitivity, which may render optical barriers less effective.
Bibliographical noteFunding Information:
information Funding for L.R. was provided by the University of Minnesota Duluth Undergraduate Research Opportunity Program.The authors wish to thank M. Mensinger and A. Mackiewicz for support with the ERG procedures, R. Calfee for providing fish and B. Yliniemi for assistance with designing the strobe-light stimulus.
Funding for L.R. was provided by the University of Minnesota Duluth Undergraduate Research Opportunity Program.
© 2018 The Fisheries Society of the British Isles
- H. molitrix
- H. nobilis
- fish vision
- nonphysical barrier
- strobe lights