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Urban Dolphins

November 28, 2014

California’s coastal bottlenose dolphins harbor contaminants in their blubber.



Urban dolphins. I’m Bob Hirshon and this is Science Update.

Bradford Calif b dolphin

Surfers off the California coast. (Bryce Bradford/Flickr)

In California, surfers share the water with coastal bottlenose dolphins, which rarely

venture more than 1000 meters from shore. Just 500 in number, these nomadic

cetaceans chase their prey all the way from southern Baja to San Francisco Bay.

According to marine mammal biologist Dave Weller of the Southwest Fisheries

Science Center, their proximity to urban areas exposes the dolphins to chemical


DAVE WELLER (Southwest Fisheries Science Center, NOAA):

The dolphins are very contaminated, they’ve got some of the highest levels of

DDT and PCBs of any marine mammal that we’ve observed.


Weller says so far, the dolphins appear surprisingly resilient. But the toxins build

up in their blubber over time.


So, despite the fact they seem healthy, they may be compromised, and we may not be

aware of that till some environmental change happens.


Because its small size, he says the population could be especially vulnerable to the

effects of climate change, disease, or oil spills. I’m Bob Hirshon, for AAAS, the

science society.


keith yahl flickr

Dolphins off the coast of Dana Point, California (Keith Yahl/Flickr)