Directional and Non-directional Movements of Bat Rays, Myliobatis californica, in Tomales Bay, California
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The goal of this project was to determine if bat rays, Myliobatis californica, display oriented movements and are thus a viable model species for the further study of geomagnetic topotaxis in elasmobranches. We tracked one male and three female rays during September 1998 and August and September 2001 in Tomales Bay, California. The rays exhibited two modes of travel: (1) rapid and highly directional movements in a straight line along the length of the bay and (2) slow and non-directional movements within small areas. Directional movements were defined as point-to-point vectors in the paths of the bat rays that were oriented in similar directions, and the distribution of these was clustered rather than dispersed and uniform. Mean rates of movement during directional swimming approached 0.5 m s−1. In contrast, vectors in the path of bat rays were at times oriented in varying directions, and a distribution of these was widely dispersed as we would expect if the rays were moving randomly. These were defined as non-directional movements. Oriented straight-line swimming is consistent with the species either being able to orient to the bathymetry of the bay or possessing a compass and (or) piloting sense.
Keywordstelemetry orientation navigation
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- Gruber, S.H., Nelson, D.R., Morrissey, J.F. 1988Patterns of activity and space utilization of lemon sharks, Negaprion brevirostris, in a shallow Bahamian lagoonBull. Mar. Sci.436176Google Scholar
- Kalmijn, A.J. 1984Theory of electromagnetic orientation: a further analysisBolis, L.Keynes, R.D.Maddrell, S.H.P. eds. Comparative Physiology of Sensory SystemsUniversity PressCambridge525560Google Scholar
- Karl, S., Obreski, S. 1976The feeding biology of the bat ray, Myliobatis californica, in Tomales Bay, California Simensted, C.A.Lipovski, S.J. eds. Fish Food Habit StudiesFirst Pacific N.W. Technical WorkshopAstoria181186Google Scholar
- Landesman J.G. 1984. Horizontal and vertical movements and seasonal population shifts in the blue shark, Prionace glauca, near Santa Catalina Island, California. Ph. D. Thesis, California State University, Long BeachGoogle Scholar
- Nelson, D. 1987The use of ultrasonic tracking in telemetry studiesHerrnkind, W.F.Thistle, A.B. eds. Signposts in the sea: proceedings of a Multidisciplinary Workshop on Marine Animal Orientation and MigrationTallahasseeFlorida118129Google Scholar