Spinner dolphins

How many are there?

Spotted and spinner dolphin populations are surveyed by ship in the eastern tropical Pacific ocean by the National Oceanic and Atmospheric Administration (NOAA). Distance sampling is used to estimate their abundance and to inform those who monitor by-catch and population trends. Multiple-covariate methods developed at CREEM allow the chance of detecting a dolphin in a survey to depend on sea state, swell and species. We use density surface models to estimate the distribution of dolphins within the study region and how variables, e.g. depth or sea-surface temperature, affect where dolphins are.

How can I identify a dolphin as a spinner?

Spotted and spinner dolphins often occur in mixed-species schools which may consist of a few hundred animals. Yellow finned tuna often associate with these dolphins to travel and forage together. The mural shows an adult male eastern spinner dolphin (Stenella longirostris ssp. orientalis). These animals are recognizable by their overall grey colour, long beak and triangular dorsal fin. The adult males often show a forward pointing dorsal fin. Click here to find out how to identify the spotted dolphin.


Spotted (left) and spinner (right) dolphins are the focus of large-scale dedicated research cruises using line transect methods.

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