Theories abound in the media, but evidence suggests that the seals could be eating fish spiked with a toxic alga called Pseudo-nitzschia. To be sure, researchers funded by the National Centers for Coastal Ocean Science (NCCOS) are testing the water for algal cells and their powerful toxin, domoic acid.
In addition, scientists at one of NCCOS's Charleston laboratories are analyzing seal tissues for signs of toxicity. While this event is no threat to the seal population, people dine on the same food sources as the animals do. Confirmation of domoic acid poisoning would lead to extensive monitoring to ensure seafood safety.
News updated in October 2012:"Marine, NOAA officials warn local officials on threat of dead seals" | SeacoastOnline.com (link no longer available)