Expert calls killer whales
Margaret Krahn says killer whales "are what they eat." She and her colleagues study the way chemicals move up the ocean food chain.
DB: This is Earth & Sky. Killer whales are the most widely distributed marine mammal in the world.
JB: That’s why they can be used as a “sentinel species” – an indicator both for ocean health and for the health of humanity – according to Margaret Krahn. Krahn is with the Northwest Fisheries Science Center in Seattle. She and her colleagues screen bits of blubber from live killer whales for contaminants such as DDT, PCBs, and the flame retardant PBDE.
Margaret Krahn: If killer whales really are what they eat, then we should be able to find chemical signals that the prey leave behind in the tissues of the killer whales.
DB: In other words, chemicals move up through the food chain. They’re transferred from prey to predator, for example, from wild salmon to killer whale. Krahn looks at how pollutants are transferred from salmon or other whale prey to the whales.
JB: One goal is to see how these same chemicals might biomagnify, as she said, when humans eat salmon or other seafood. She talked about balance, reminding us that eating seafood has positive health benefits for humans.
Margaret Krahn: There’s tremendous advantages of eating seafood. So you have to balance the good things about eating seafood against whatever might be detrimental, or slightly so.
DB: For today, that’s our show. Thanks today to NOAA, the National Oceanic and Atmospheric Administration. We’re Block and Byrd for Earth & Sky.
