Young orca has highest pollution level in study

SEATTLE – A 3-year-old killer whale appears to be among the most contaminated orcas living in Puget Sound, contradicting what government researchers expected to find when they started testing the whales for flame retardant and pesticides in a new study.

The researchers said they were expecting to find the highest concentrations of pollutants in the older males and the lowest levels in the older females who are known to clear contaminants out of their systems when they give birth to and nurse their calves.

They have already started to double-check this finding by testing another young male killer whale in J pod, said Brad Hanson, a study author and wildlife biologist with the Northwest Fisheries Science Center of NOAA Fisheries in Seattle.

The results of the follow-up test confirmed the initial findings, so further research on this topic is planned. The scientists expressed concern about the younger whales being more vulnerable to the effects of pollution.

“We’ll be looking at similarly aged animals in K and L pods,” Hanson said.

The team of U.S. and Canadian researchers found a decreasing level of some pollutants in the orcas that call the Puget Sound and southern Canada home. But PCBs – polychlorinated biphenyls, which have been banned since the 1970s – are still showing up in their bodies and presumably having a negative impact on their health, the study by NOAA Fisheries and Canadian researchers found.

“The endangered southern resident killer whales that ply the transboundary water of British Columbia and Washington state are iconic symbols of this special part of the world, and we owe it to them to protect their habitat and their food supply from our chemical legacy,” said Peter Ross, co-author of the report and a research scientist with Canada’s department of fisheries.

Another finding that intrigued the scientists was how the mixture of contaminants in a whale seemed to be dependent on where it spends the winter. Whales tested from the L pod, which has been seen off the coast of California during the past few winters, have more pesticide residue than those from the J pod, which remains in or near the Puget Sound all year.

Whales from the third pod of southern resident killer whales – called the K pod – were not included in the study because they were not in the Puget Sound when the testing was done, Hanson said.

He said it’s not surprising that killer whales would have relatively high levels of contaminants in their skin and blubber.

“They’re a top predator. Virtually everything that moves up through the food chain is going to end up in killer whales,” he said.

A study like this helps track trends in the ecosystem and may give clues to why the killer whale population has declined, the researchers said in the report published Wednesday in the Marine Pollution Bulletin.

The three pods of killer whales known collectively as the “southern residents” have been listed as “threatened” under the U.S. Endangered Species Act and “endangered” under a similar law in Canada.

“There’s some concern about the level of the flame retardants. Because they haven’t been banned yet, we expect the levels will just keep increasing until they’ve been banned, said Gina Ylitalo, program manager in the environmental assessment program at the NOAA Fisheries center in Seattle.

The other aims of the study were to trace the paternity of younger whales and track any changes in whale diet.

The data was collected by shooting a dart at a whale that grabs a piece of skin and blubber the size of an eraser from a mechanical pencil and then pops into the water where it floats until the whale swims away and the scientists can go back and pick it up.

Only a small number of the whales have had samples taken, but more will be tested in the near future, Hanson said.