Orca calf's carcass raises more pollution questions

The carcass of a prematurely born orca calf turned up on a beach in the San Juan Islands, raising further questions about the effects of industrial contaminants on local orcas' reproductive systems, researchers announced Monday.

The find at Open Bay on Henry Island, just north of San Juan Island, is significant because few dead orcas are recovered, usually just about seven per year worldwide, said Joe Gaydos, regional director of The Seadoc Society, a research institution affiliated with the University of California-Davis.

But the orca calf's carcass was so badly decomposed and picked over by scavenging animals that it's questionable how much can be learned by studying the remains, said Gaydos and Brad Hanson, a wildlife biologist with the National Marine Fisheries Service.

"It's pretty far gone, so there's not a lot we can do with it," Hanson said.

However, he said it's likely that DNA testing will show whether the orca was from the three family groups, or pods, that frequent the San Juans and nearby waters. Other types of orcas do show up in local waters from time to time, though. One of those, found in 2002 at Dungeness Spit, carried extremely high levels of PCBs, industrial chemicals that were banned in the 1970s.

PCBs are known to interfere with orcas' reproductive and immune systems and their growth rates. The local orcas carry some of the highest levels of PCBs of any marine mammals worldwide.

The calf's death "raises some eyebrows about what's really going on. We know that with the level of contaminants that they have they're probably susceptible to some disease, and we want to see what we can do to help with that," Gaydos said.

For example, Hanson said, it's well-known that brucellosis causes premature calving in cattle, and brucellosis was found in the so-called "transient" whale found at Dungeness Spit in 2002. Other diseases could be at work. Scientists are still learning which diseases affect orcas.

The calf could have been stillborn, researchers said. What appeared to be the placenta was near the carcass.

Researchers will see how much material they can recover from the carcass during a necropsy later this month. For now, the recovered remains are frozen.

The dead orca was first spotted and photographed July 26 by a beachcomber who is a part-time resident of Henry Island. But he did not report it to the San Juan County Marine Mammal Stranding Network until Aug. 1.