Effects of simulated underwater vehicle lighting on fish behavior

Abstract

Little is known regarding bias attributable to fish behavior for visual transects conducted using underwater vehicles (UVs). Experiments were conducted under 2 ambient illuminations to assess the behavioral responses of 7 north Pacific Ocean groundfish species to a light stimulus that simulated the approach of a UV. Species included sablefish Anoplopoma fimbria, Pacific halibut Hippoglossus stenolepis, lingcod Ophiodon elongatus and 4 species in the genus Sebastes: blue rockfish S. mystinus, black rockfish S. melanops, copper rockfish S. caurinus and quillback rockfish S. maliger. Movement, as well as general activity, varied greatly between species. The most active species, sablefish, became agitated and moved away from the looming light source, while the least active species, Pacific halibut and lingcod, typically remained stationary. Of the 4 rockfish species, 2 demonstrated a strong response to ambient light level. Black rockfish and blue rockfish moved away from the looming light source, but avoidance was delayed under high ambient light. Bias probably differs among species, being greatest for those that are highly active and mobile, like sablefish. Further, ambient light may modulate bias, such that researchers need to be cautious about comparing results for surveys conducted at different depths and/or times of day. KEY WORDS: Fish behavior · Light response · Survey bias · Gear avoidance · ROV · Submersible Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 391: [97][98][99][100][101][102][103][104][105][106] 2009 Due to the efficiency of sound propagation in water, fish will probably first detect the sound generated by an approaching UV. Most fish have hearing in the range of 300 to 1000 Hz (Popper 2003), and both electric and hydraulic thrusters probably emit sound in this frequency range. Gadids and herring respond to approaching surface vessels with both diving and horizontal movements (Vabø et al. 2002, Handegard et al. 2003, Handegard & Thøstheim 2005. Similarly, fish may elicit avoidance behavior in response to the noise generated by trawl warps and doors (Handegard & Thøstheim 2005).Artificial lighting also constitutes a major stimulus likely to influence fish; nearly all UVs use lights for video and still photography. As an object or light approaches, the projected image on the observer's retina expands, a process referred to as visual looming (Schiff et al. 1962), which frequently triggers avoidance behaviors in animals. In the ecological literature, this has been applied in the context of predator-prey interactions, and has been used to examine factors such as perception of predator size and prey-reactive distances (Domenici 2002, Paglianti & Domenici 2006. As a UV approaches, the lights from the vehicle will appear to loom to a fish, and as with trawls (Ryer 2008), may be interpreted by the fish as a threat, resulting in avoidance behavior. Alternatively, under some conditions fish are attracted to underwater lights. We frequently use dr...

Effect of underwater lighting on observations of density and behavior of rockfish during camera surveys

“…Even red lights in a spectral range that was detectible by the sablefish caused less of a startle reaction than white (full spectrum) lights. This is consistent with laboratory studies, where the effect of light on light avoidance behavior has been shown to vary with fish activity level (Ryer et al, 2009). An active predatory fish, such as sablefish was found to have a strong reaction to light stimuli, which may be a potential reason for the absence of sablefish in a camera survey designed to assess their abundance (Lauth et al, 2004).…”

“…A study on black rockfish (Sebastes melanops) indicates they are sensitive to light in the range from 380 nm to 620 nm (Brill et al, 2008) In a laboratory study, it was found that rockfish reaction to white light from an incandescent source was generally moderate, but varied with species (Ryer et al, 2009). Based on the review of Stoner et al (2008) and research of Ryer et al (2009), we expected that the rockfish exposed to light that fell within the wavelengths of high sensitivity would have an avoidance reaction to the camera, either by moving away from the camera prior to their being observed (causing a decrease in observed density) or by moving toward the refuge of seafloor (causing an observed decrease in height above the seafloor).…”

“…However, the effects of different lighting regimes on fish avoidance behavior have only rarely been studied. A single published laboratory study by Ryer et al (2009) examined the effects of the approach of artificial lighting on seven marine fish species, and found that reactions to the light varied among them. Few field studies have examined the effect of lighting on the abundance of observed fishes.…”

TrapCam: an inexpensive camera system for studying deep‐water animals

“…Milliken Woodroffe & Round 2008). In addition, the light and sound produced by mobile, and camera-bearing platforms can alter animal behaviour significantly (Popper 2003;Ryer et al 2009), and it has been recently demonstrated that even crustacean behaviour can be greatly affected by sound transmission (Simpson et al 2011). Surface-powered 'drop cameras' can be attached to boats or surface floats (e.g.…”

“…Kross & Nelson 2011) is also not a viable option in underwater environments because of the near-constant movement of particles that would activate the video. Third, full-spectrum lighting, which can have a profound effect on animal behaviour in deep-water environments (Olla, Davis, & Rose 2000;Widder et al 2005;Ryer & Barnett 2006;Ryer et al 2009), should be avoided. Fourth, the system should be deployable on uneven substratum types without the assistance of divers, thus mandating a righting system or the ability to record in any position.…”