Coping with copepods: do right whales (Eubalaena glacialis) forage visually in dark waters
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2017-04-05
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Citation of Original Publication
Cronin TW, Fasick JI, Schweikert LE, Johnsen S, Kezmoh LJ, Baumgartner MF. 2017 Coping with copepods: do right whales (Eubalaena glacialis) forage visually in dark waters? Phil. Trans. R. Soc. B 372: 20160067
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Abstract
North Atlantic right whales (Eubalaena glacialis) feed during the spring and
early summer in marine waters off the northeast coast of North America.
Their food primarily consists of planktonic copepods, Calanus finmarchicus,
which they consume in large numbers by ram filter feeding. The coastal
waters where these whales forage are turbid, but they successfully locate
copepod swarms during the day at depths exceeding 100 m, where light is
very dim and copepod patches may be difficult to see. Using models of
E. glacialis visual sensitivity together with measurements of light in waters
near Cape Cod where they feed and of light attenuation by living copepods
in seawater, we evaluated the potential for visual foraging by these whales.
Our results suggest that vision may be useful for finding copepod patches,
particularly if E. glacialis searches overhead for silhouetted masses or
layers of copepods. This should permit the whales to locate C. finmarchicus
visually throughout most daylight hours at depths throughout their foraging
range. Looking laterally, the whales might also be able to see copepod
patches at short range near the surface.