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Review |
Foraging and prey-search behaviour of small juvenile rainbow trout (Oncorhynchus mykiss) under polarized light
1 Institut Maurice Lamontagne, Fisheries and Oceans Canada, CP 1000, 850 route de la Mer, Mont-Joli, Quebec, Canada, G5H 3Z4,
2 Simon Fraser University, Department of Biological Sciences, 8888 University Drive, Burnaby, British Columbia, Canada V5A 1S6 and
3 Institute of Marine Research, Austevoll Aquaculture Research Station, N-5392 Storebø, Norway
*Author for correspondence at address 2 (e-mail: inigo{at}sfu.ca)
Accepted April 19, 2001
Several fish species appear to be polarization sensitive, i.e. to be able to discriminate a light sources maximum plane of polarization from any other plane. However, the functional significance of this ability remains unclear. We tested the hypothesis that polarized light improves the prey location ability of free-swimming rainbow trout (Oncorhynchus mykiss) in laboratory aquaria. We found that prey location distances increased while the vertical component of prey location angle decreased under polarized compared with unpolarized (diffuse) illumination. The average frequency distribution of the horizontal component of prey location angle was more bimodal under polarized than unpolarized illumination. These results indicate that polarization sensitivity enhances prey location by juvenile rainbow trout.
Key words: polarization, salmonid, rainbow trout, Oncorhynchus mykiss, zooplankton, ultraviolet light, target contrast, foraging, prey-search behaviour.