Movement and foraging behavior of short-finned pilot whales in the Mid-Atlantic Bight: importance of bathymetric features and implications for management

Citation

Thorne, L. H., H. J. Foley, R. W. Baird, D. L. Webster, Z. T. Swaim, and A. J. Read. 2017. Movement and foraging behavior of short-finned pilot whales in the Mid-Atlantic Bight: importance of bathymetric features and implications for management. Marine Ecology Progress Series DOI: 10.3354/meps12371

Abstract

Shelf break systems are ecologically important regions of the ocean, and are often characterized by enhanced productivity and high densities of species from lower to upper trophic levels. Along with associated submarine canyons, shelf break regions provide important foraging habitat for deep-diving odontocetes such as pilot whales. Short-finned pilot whales Globicephala macrorhynchus are found throughout tropical and subtropical waters, but there is little information on the habitat use of this species in the northwest Atlantic. We examined the movements and foraging behavior of short-finned pilot whales using data from satellite tags (n = 33) deployed off Cape Hatteras, North Carolina, USA in 2014 and 2015. Pilot whale tracks ranged from Cape Lookout, North Carolina north to Georges Bank, with movements and habitat use primarily focused north of Cape Hatteras. We observed 2 distinct modes of behavior, with most pilot whales showing a strong affinity for the continental shelf break and others following offshore meanders of the Gulf Stream for all or part of the observed track. We used first passage time (FPT) to assess area-restricted search behavior, and found that FPT was significantly higher close to the shelf break and in submarine canyons. Our results demonstrate the importance of steep bathymetric features to the foraging habitat and distribution of short-finned pilot whales in this region. In addition, our findings suggest that pilot whales in the Mid-Atlantic Bight may have developed specialized foraging behaviors for targeting steep bathymetric gradients, and that their latitudinal distribution may be limited to regions where this foraging strategy is effective.

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