The recovery plan, issued at year's end by the National Oceanic and Atmospheric Administration's Fisheries Service, cites catastrophic events like spills and mass strandings, underwater noise and the cumulative effects of stress-inducing events as the most serious threats facing a beluga population that has declined from about 1,300 in the late 1970s to roughly 340 now. Inlet belugas were listed as endangered in 2008.
"This plan is a roadmap for how NOAA Fisheries and our partners can address threats to Cook Inlet belugas and work together toward recovery," Jon Kurland, the agency's assistant regional administrator for protected resources, said in a statement.
The plan identifies 10 threats and classifies them as being of high, medium or low concern. Threats of medium concern are diseases and disease agents, including harmful algal blooms; habitat loss or degradation; reduction in prey, like salmon, eulachon and shrimp; and unauthorized take, defined by the Marine Mammal Protection Act as any unpermitted killing, injuring or harassing.
Climate change is not listed as a specific threat, but changing climate factors into other threats, the plan says.
The final recovery plan is the product of a research program that started in 2010. A draft was issued in 2015. Recovery plans are required for populations given Endangered Species Act protections under federal law.
The rapid decline of Inlet belugas, the isolated population's small size and the expansive variety of potential threats make it difficult to identify the most immediate actions to bring about recovery, the plan says.
"Until we know which threats are limiting this species' recovery, the strategy of this recovery plan is to focus recovery efforts on threats identified as of medium or high relative concern," the plan says.
Overhunting in the 1990s by Native subsistence users is generally considered the likely trigger for the initial precipitous decline, bringing the population from 655 in 1994 to 349 in 1998, according to NOAA.
But a near-complete cessation of hunting put into place in 1999 did not bring about any rebound in the population. If hunting were the only factor harming Inlet belugas, the population should have increased by 2 percent to 6 percent a year once hunting stopped, according to NOAA.
Overhunting is now considered only a low-level threat, according to the new plan. Other low-level threats are pollution and predation, according to the document.
Those low-level threats could rise in importance if new information justifies such action, according to the plan.
NOAA's plan is somewhat flexible by design, said Mandy Migura, the agency's fisheries' Inlet beluga whale recovery coordinator.
"This recovery plan is intended to be a dynamic document that will change over time based on the progress of recovery and the availability of new information," Migura said in an email.
Underwater noise has emerged as a big issue of concern for Inlet belugas, which swim in highly trafficked and industrialized waters off Anchorage and other cities and towns in the region.
The Inlet is a noisy place by nature, with its breaking waves, rapid flows of freshwater from rivers and glacial melt and strong currents that stir its sediments, the recovery plan says.
Belugas, which have fine hearing, are noisy animals as well. They make a variety of sounds, from high-pitched whistles and squeals to repeated low-frequency pulses, and are so vocal they earned the nickname: "Sea canaries."
Noises added to the environments by humans include vessel propeller and engine sounds, sounds created when piles are driven into the seabed for industrial purposes, engine sounds from some aircraft, sounds from airguns used for seismic activities and mechanical noises associated with the oil and gas industry and the military.
Downlisting to threatened status would be justified if Inlet beluga populations return to 40 percent of the environment's historic carrying capacity of 1,300, the recovery plan said. The population trend is clearly positive and the 10 identified threats have been properly addressed, the plan said.
Removal of all endangered protections would be warranted if the population bounces back to 60 percent of that 1,300-animal carrying capacity and the other criteria are met, according to the recovery plan.
One Alaska state official criticized those thresholds as unrealistic and unattainable.
Bruce Dale, director of the Alaska Department of Fish and Game's Division of Wildlife, said the criteria are too broad and "unfortunately, very tough standards."
For example, a requirement that nearly all sampled belugas show no signs of nutritional stress is not realistic when most whales available to sample are stranded animals that are dead or sick, he said. Proving the belugas' prey is abundant and available will be difficult without knowing precisely what fish they need to eat, he said.
Dale also took issue with the use of the 1,300-animal carrying capacity. That number, he said, is based on population estimates "using not-as-good techniques as we have today," he said. "We don't know if it's a good number or not."
The main problem with the recovery plan's downlisting and delisting criteria is that the cause of the belugas' problems still needs to be identified, Dale said. "Until we refine that, we can't really agree that these are good criteria," he said.
But Bob Shavelson, director of policy and advocacy for the environmental group Cook Inletkeeper, had the opposite criticism of the recovery plan, characterizing it as too lax.
"What you see is a typical recovery plan that has an enormous amount of discretion. When you combine that with a lack of funding, the result will be business as usual," Shavelson said.
The plan lacks some important rules for addressing known environmental problems in the Inlet, such as wastewater discharges and oil industry seismic noise, he said. The plan calls for further study of such issues, but no "hard and fast rule" limiting them, he said.
Shavelson dismissed Dale's complaints about recovery criteria and said the state, despite official rhetoric, does not appear to be truly committed to helping Inlet belugas reach that goal. "I've never seen them do anything proactive to do it," he said.