Stock Structure of Bottlenose Dolphins

Same dolphin photographed on two different occasions
Photo Credit: SEFSC Beaufort Lab

dolphin with satelite tag

A bottlenose dolphin fitted with a radio and satellite tag
(Tursiops truncatus)
Photo Credit: SEFSC Beaufort Lab

Isotope Fractionation graphic
Photo Credit: Science Education Resource Center, Carleton College

(click for larger image)

The Marine Mammal Protection Act (MMPA) specifies that "population stocks should not be permitted to diminish beyond the point at which they cease to be a significant functioning element in the ecosystem of which they are a part" and defines a population stock, or stock, as "a group of marine mammals of the same species or smaller taxa in a common spatial arrangement, that interbreed when mature."

Complying with the MMPA means that we have to correctly identify stock structure, which can be more complicated that it sounds. As a result, much of our research focuses on defining the complex stock structure of bottlenose dolphins (Tursiops truncatus) along the Atlantic coast of United States.

We have been doing so using multiple approaches that focus on different ecological or evolutionary scales:

Movements of individual dolphins using telemetry/tagging during periods of months to a year
Resightings of individual dolphins using photo-identification over many years
Ecological signals from individual dolphins using stable isotope ratios over periods of months to a lifetime
Genetic structure of groups of dolphins providing evolutionary history, in collaboration with our colleagues at the SEFSC marine mammal genetics lab in Lafayette, LA

Stock structure definitions are integral for managing the populations of bottlenose dolphins, which interact with fisheries throughout their range and may still be recovering from an epizootic that occurred in 1987-1988.

Stock Structure of Bottlenose Dolphins

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Fisheries Service