Pantropical spotted dolphins in Hawai‘i

Pantropical spotted dolphins (Stenella attenuata) high speed swimming off the island of Hawai‘i. Photo by Robin Baird. Pantropical spotted dolphins are the second-most frequently encountered species in our study - between 2000 and 2012 we had 398 encounters with this species. Like false killer whales, pantropical spotted dolphins are found both in shallow waters (<100 m) and in deep offshore waters (over 4,000 m).

Pantropical spotted dolphin mother and calf. Photo by Greg Schorr. Group sizes we've encountered for this species have ranged from lone individuals to an estimated 350 individuals - the mean group size is 65.

Juvenile pantropical spotted dolphin leaping, presumably to try to dislodge a remora. Photo by Daniel Webster

Juvenile pantropical spotted dolphin leaping, this one with two remoras. Photo by Jay Barlow

Although we find pantropical spotted dolphins close to shore (particularly in the 4-island region), off the island of Hawai‘i they are most frequently seen in waters deeper than 1,000 m and groups can be found in very deep water far offshore. This graph shows the sighting rates per 100 hours of search effort by depth.

Pantropical spotted dolphin. Photo by Barb Taylor. This species often bowrides - this photo was taken of an individual bowriding on our research vessel.

With pantropical spotted dolphins we try to collect genetic samples from most groups for studies of population structure - this work was part of a Ph.D. thesis by Sarah Courbis at Portland State University. Her work has shown evidence that there are multiple populations of spotted dolphins within the main Hawaiian Islands, as has been demonstrated for spinner dolphins and common bottlenose dolphins. A copy of her thesis and a publication from this research can be downloaded below.

A pantropical spotted dolphin with a wound from a vessel propeller. Photo by Annie Gorgone

Small fishing vessels in Hawai‘i regularly "fish" spotted dolphins, repeatedly trolling through groups to try to catch associated tuna. Photo by Annie Douglas

A pantropical spotted dolphin with line injuries on the dorsal fin, most likely caused by interactions with fishing gear. Photo by Kira Goetschius.

Pantropical spotted dolphin porpoising. Photo by Daniel Webster

For more information on pantropical spotted dolphins see the following:

  • Courbis, S., R.W. Baird, F. Cipriano and D. Duffield. 2014. Multiple populations of pantropical spotted dolphins in Hawaiian waters. Journal of Heredity 105:627-641. Download PDF copy
  • Baird, R.W., D.L. Webster, J.M. Aschettino, G.S. Schorr and D.J. McSweeney. 2013. Odontocete cetaceans around the main Hawaiian Islands: habitat use and relative abundance from small-boat sighting surveys. Aquatic Mammals 39:253-269. Download PDF copy
  • Burgess, W.C., E.M. Oleson and R.W. Baird. 2011. A hydrodynamic acoustic recording tag for small cetaceans and first results from a pantropical spotted dolphins. Poster presented at the 19th Biennial Conference on the Biology of Marine Mammals, Tampa, Florida, November-December 2011. Download PDF copy
  • Courbis, S.S. 2011. Population structure of island-associated pantropical spotted dolphins (Stenella attenuata) in Hawaiian waters. Ph.D. Dissertation, Portland State University. Download PDF copy
  • Courbis, S., R.W. Baird, F. Cipriano and D. Duffield. 2009. Population structure of pantropical spotted dolphins near the main Hawaiian Islands: evidence of multiple genetic stocks. Poster presented at the 18th Biennial Conference on the Biology of Marine Mammals, Quebec, October 2009. Download PDF copy
  • Baird, R.W., A.D. Ligon, S.K. Hooker, and A.M. Gorgone. 2001.Sub-surface and night-time behaviour of pantropical spotted dolphins in Hawaii. Canadian Journal of Zoology 79: 988-996. Download PDF copy

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