Anchorage Daily News

Declaring Cook Inlet beluga whales an endangered species — as the National Oceanic and Atmospheric Administration did Friday — was only the first step toward protecting them. Now federal biologists are trying to figure out exactly what’s endangering them.

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The newly released “Conservation Plan for the Cook Inlet Beluga Whale” — a 128-page report compiled by the National Marine Fisheries Service — takes a preliminary stab at the question, listing 18 possible threats to the local whale population.

Five of those threats would pose a “high” risk of jeopardizing the belugas were they to occur, the study says. Among them are two natural dangers: disease and strandings of whales on mud flats.

Three are man-made dangers: whale poaching, food reduction (by damaging salmon habitat or over-fishing) and unnatural noise in the water (such as off-shore drilling, pile-driving in the construction of a Knik Arm bridge or expansion of the Port of Anchorage).

The report also lists as “unknown” the impact on belugas that might result from three man-made dangers: Oil and gas spills, systematic water pollution (including the partially treated sewage Anchorage discharges into Cook Inlet) and environmental change (such as ocean warming).

“Certainly oil and gas development and all in-water activities that might introduce pollutants are a concern,” says Fisheries Service biologist Brad Smith, one of the conservation plan authors.

Listing the Cook Inlet belugas as endangered — federal biologists estimate there are only 375 of the animals left — means any federal agency that authorizes activities in the Inlet must first determine whether such actions will hurt the whales.

Smith foresees several current activities requiring approval, starting almost immediately, and that’s where the conservation plan might apply.

Next year, for example, the federal Environmental Protection Agency will consider renewing the city’s special waiver to discharge partially treated sewage into the Inlet. Now the EPA will have to consult with the Fisheries Service first to see if that agency approves.

On the positive side, Smith said, tissue samples taken from local belugas so far show only low levels of contamination from heavy metals and certain other toxic contaminants, like PCBs and DDT.

Cook Inlet beluga whales had much lower levels of PCBs and DDT than whales sampled off St. Lawerence Island, and about half the concentrations of whales off Arctic Alaska, the conservation plan says.

But now the agency will be taking a closer look at beluga tissue for other contaminants, like fire retardants and pharmaceuticals, Smith said. If discovered, they could prompt a closer look at the city’s sewage out-fall.

Construction noise at the Port of Anchorage could also pose a problem. Belugas are highly dependent on their sense of sound, which allows them to locate prey and predators in murky water. Noisy pile-driving operations at the port, where the city is in the process of filling in about 135 acres of Knik Arm, are known to cause problems for the whales.

The agency has already begun working with the port and the municipality to set special conditions on their permits to require full-time whale observers whenever they’re driving pilings.

“We established safety zones” for the whales, Smith said. “And whenever observers see beluga whales that are about to enter those zones, they are on their walkie-talkies and they order a shut-down.”

One threat that’s now listed as “low” is the traditional harvest of Cook Inlet belugas by Native Alaskans. That’s because hunting is no longer allowed and won’t be until the five-year average of the beluga population starts growing again, Smith said.

The agency began curtailing the subsistence harvest almost 10 years ago, assuming that action alone would allow the population to bounce back. But it didn’t. So now it’s examining the other 17 threats.

Even natural disasters, like the occasional stranding of belugas on the mud flats in Turnagain Arm, are worrisome because their total numbers are now so low, the conservation plan says.

More than 700 belugas have become stranded in upper Cook Inlet since the Fisheries Service began keeping track in 1988. A majority usually survive. In the past five years, however, 53 belugas have died from strandings.

Sometimes it’s the fault of killer whales, the beluga’s only marine predator, which occasionally chase large pods of belugas into upper Cook Inlet at low tide. A pair of killer whales — a cow and her calf — were seen feeding on belugas in Turnagain Arm just last month, Smith said.

“When we had 700 or 800 whales, that level of predation probably wasn’t a big deal. But now that we’re at less than 400 animals, that level of removal may be enough to prevent their recovery.”

Find George Bryson online at adn.com/contact/gbryson or call 257-4318.