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ESR 32:1-17 (2017)  -  DOI:

Swimming kinematics and efficiency of entangled North Atlantic right whales

Julie M. van der Hoop1,2,*, Douglas P. Nowacek3, Michael J. Moore2, M. S. Triantafyllou4

1Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program in Oceanography/ Applied Ocean Science and Engineering, Cambridge, MA 02139, USA
2Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
3Nicholas School of the Environment and Pratt School of Engineering, Duke University Marine Lab, 135 Duke Marine Lab Rd, Beaufort, NC 28516, USA
4Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
*Corresponding author:

ABSTRACT: Marine mammals are streamlined for efficient movement in their relatively viscous fluid environment and are able to alter their kinematics (i.e. fluke stroke frequency, amplitude, or both) in response to changes in force balance. Entanglement in fishing gear adds significant drag and buoyant forces that can impact swimming behaviors across a range of timescales. We deployed biologging tags during the disentanglement of 2 North Atlantic right whales Eubalaena glacialis to (1) examine how their kinematics changed in response to drag and buoyancy from entanglement in fishing gear, and (2) calculate resultant changes in swimming efficiency for one individual. We observed variable responses in dive behavior, but neither whale appeared to exploit added buoyancy to reduce energy expenditure. While some of the observed changes in behavior were individually specific, some swimming kinematics were consistently modulated in response to high drag and buoyancy associated with entangling gear, affecting thrust production. In high drag and buoyancy conditions, fluke strokes were significantly shorter and more variable in shape, and gliding was less frequent. Thrust and efficiency significantly differed among dive phases. Disentanglement reduced thrust coefficients ~4-fold, leading to 1.2 to 1.8-fold lower power (W). Ideal propulsive efficiency was significantly lower when entangled, though we detected no difference in observed propulsive efficiency between the conditions. Similar to carrying heavy objects or changing shoes, we present another condition where animals perceive unique movement constraints over seconds to minutes and develop compensatory strategies, altering their movement accordingly.

KEY WORDS: Gait change · Compensation · DTAG · Buoyancy · Drag

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Cite this article as: van der Hoop JM, Nowacek DP, Moore MJ, Triantafyllou MS (2017) Swimming kinematics and efficiency of entangled North Atlantic right whales. Endang Species Res 32:1-17.

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