Rough-toothed dolphins in Hawai‘i
Rough-toothed dolphins leaping off the island of Hawai‘i. Photo (c) Robin W. Baird. Rough-toothed dolphins (Steno bredanensis) are the third-most frequently encountered species of toothed whale in our study, representing 11% of all odontocete sightings from 2000 through 2011. Rough-toothed dolphins are typically found in deeper parts of our study area.
Rough-toothed dolphin group. Photo (c) Greg Schorr. Although we occasionally find lone individual rough-toothed dolphins, we have documented one group of over 100 individuals (off of Ni‘ihau). The most frequently encountered group size is three individuals, although the median group size is seven. Individual rough-toothed dolphins can be identified both by the notches on the trailing edge of the dorsal fin, but also by pigmentation patterns visible in the photo above, that remain virtually unchanged for years.
Rough-toothed dolphin leaping. Photo (c) Robin W. Baird. The numerous scars on the belly of this individual are caused by cookie-cutter sharks.
A juvenile rough-toothed dolphin. Photo by Jessica Aschettino. The gently sloping rostrum, or beak, is characteristic of the species.
A rough-toothed dolphin leaping. Photo (c) Robin W. Baird. This individual has a number of small remoras on the back, and may be leaping in an attempt to dislodge them. Note the very large pectoral flippers, characteristic of this species. As well as photo-identifying individuals to examine movements and social organization, we have also collected biopsy samples of this species for contribution to genetic studies of stock structure, being undertaken by Renee Albertson at Oregon State University. Analyses of the genetic samples indicate the population off the island of Hawai‘i is genetically differentiated from the population off Kaua‘i and Ni‘ihau.
In 2011 we started deploying LIMPET satellite tags on rough-toothed dolphins off Kaua‘i and Ni‘ihau to examine movements and habitat use of this species around the Navy's PMRF range. This map shows 10 days of movements of one individual tagged in January 2012. Note these locations have not yet been filtered to remove unrealistic locations, so may change with further analyses. Through December 2015 we've deployed 15 satellite tags on rough-toothed dolphins, including eight that also record dive data, obtaining the first dive data for this species in the Pacific.
For more information on rough-toothed dolphins see:
- Baird, R.W., A.N. Dilley, D.L. Webster, R. Morrissey, B.K. Rone, S.M. Jarvis, S.D. Mahaffy, A.M. Gorgone and D.J. Moretti. 2015. Odontocete studies on the Pacific Missile Range Facility in February 2014: satellite-tagging, photo-identification, and passive acoustic monitoring. Prepared for Commander, U.S. Pacific Fleet, submitted to Naval Facilities Engineering Command, Pacific by HDR Environmental, Operations and Construction, Inc. Download PDF copy
- Baird, R.W., D. Cholewiak, D.L. Webster, G.S. Schorr, S.D. Mahaffy, C. Curtice, J. Harrison and S.M. Van Parijs. 2015. Biologically important areas for cetaceans within U.S. waters - Hawai‘i region. Aquatic Mammals 41:54-64. Download PDF copy
- Webster, D.L., R.W. Baird, B.K. Rone and D.B. Anderson. 2015. Rough-toothed dolphins on a Navy range in Hawai‘i: using LIMPET satellite-tag data to assess movements, habitat use, and overlap with Navy activities. Poster presented at the 21st Biennial Conference on the Biology of Marine Mammals, San Francisco, California, December 14-18, 2015. Download PDF copy
- Albertson, G.R. 2014. Worldwide phylogeography and local population structure of the rough-toothed dolphin (Steno bredanensis). Ph.D. Dissertation, Oregon State University.Download PDF copy
- Baird, R.W., D.L. Webster, J.M. Aschettino, D. Verbeck and S.D. Mahaffy. 2012. Odontocete movements off the island of Kaua‘i: results of satellite tagging and photo-identification efforts in January 2012. Prepared for U.S. Pacific Fleet, submitted to NAVFAC PAC by HDR Environmental, Operations and Construction, Inc. Download PDF copy
- Baird, R.W., D.L. Webster, G.S. Schorr, J.M. Aschettino, A.M. Gorgone, and S.D. Mahaffy. 2012. Movements and spatial use of odontocetes in the western main Hawaiian Islands: results from satellite-tagging and photo-identification off Kaua‘i and Ni‘ihau in July/August 2011. Annual progress report under Grant No. N00244-10-1-0048 from the Naval Postgraduate School. Download PDF copy
- Albertson, G.R., M. Oremus, R.W. Baird, K.K. Martien, M.M. Poole, R.L. Brownell Jr., F. Cipriano and C.S. Baker. 2011. Staying close to home: mitochondrial DNA analysis reveals insular population structure for the pelagic dolpin Steno bredanensis. Poster presented at the 19th Biennial Conference on the Biology of Marine Mammals, Tampa, Florida, November-December 2011. Download PDF copy
- Baird, R.W., D.L. Webster, S.D. Mahaffy, D.J. McSweeney, G.S. Schorr and A.D. Ligon. 2008. Site fidelity and association patterns in a deep-water dolphin: rough-toothed dolphins (Steno bredanensis) in the Hawaiian Archipelago. Marine Mammal Science 24:535-553. Download PDF copy The definitive version is available at Wiley InterScience
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