The wolves of Southwest Alaska share something in common with the wolves of Denali, according to a new National Park Service-sponsored study, they love fish – salmon to be specific.
Following on the pioneering work of U.S. Geological Survey biologist Layne Adams in Denali National Park and Preserve in 2010, researchers who spent five years monitoring the diets of six wolf-packs in Lake Clark National Park and Preserve have documented high use of salmon by wolves there.
A few Lake Clark area wolves even appear to have adapted to a prey-switching strategy that takes advantage of the decades that Alaska state salmon managers have devoted to boosting salmon runs to streams draining into Bristol Bay.
“Over three years, one group of wolves consistently consumed salmon in summer and switched to terrestrial prey in winter,” the National Park Service said in a media release promoting the study. “This use of salmon is likely widespread, though infrequently documented among wolves that live where salmon is abundant.
“During summer, diets of five wolves consisted of at least 50 percent salmon, while the diets of 17 wolves consisted of primarily terrestrial prey,” reported the scientists from the Park Service, the University of Alaska and the Environmental and Natural Resources Institute in the study published in the Canadian Journal of Zoology in August.” Over three years, one group of wolves consistently consumed salmon in summer and switched to terrestrial prey in winter.”
The summer use of salmon by wolves has broad ecological implications. Fall starvation from lean summers is a significant source of mortality for wolves, which in the wild live difficult and always dangerous lives.
“In the Superior National Forest (of Minnesota) from 1968 to 1976,” L. David Mech, one of the country’s best known researchers writes in “Wolves: Behavior, Ecology and Conservation,” “annual wolf mortality rates ran from 7 to 65 percent and 58 percent of that mortality was natural, primarily due to fall pup starvation and intraspecific strife.
“In Denali National Park, Alaska, annual mortality averaged 27 percent and varied from 13 percent to 41 percent from 1986 through 1994, most (81 percent) of the mortality was natural.”
A plentiful supply of salmon to help wolves get through the critical late summer/early fall period when prey such as caribou and moose are at their fittest is good for wolves. It is not necessarily good for their prey.
Lake Clark forms the headwaters for the Kvichak River drainage. Since the early 2000s, the Alaska Department of Fish and Game has managed the river for an escapement of 2 million to 10 million sockeye salmon per year.
Escapement is the number of salmon escaping commercial fishermen to reach the spawning grounds. More than 3.1 million went up the Kvichak this year.
The salmon bring back from the sea a bounty of nutrients to fertilize the Lake Iliamna/Lake Clark region of Alaska west of Anchorage. The fish make the area a good place to be a grizzly bear, a species that preys heavily on salmon, and not a bad place to be a fish-eating wolf.
But what is good for predators is not always good for their prey.
“The use of salmon as exhibited by wolves in Lake Clark is likely widespread where salmon are abundant and this finding should be taken into consideration in the conservation and management of wolves and their prey,” the scientists wrote in the Journal of Ecology.
“One result of a salmon diet is that wolf numbers were substantially higher where salmon were plentiful than would be expected for the ungulate abundance alone,” Adams wrote in that 2010 Denali study.
The Lake Clark study, according to a National Park Service press release, noted that along with the finding “a high use of salmon and salmon carcasses….The study also found a possible increase in wolf pack stability in packs making regular use of salmon as a food resource.”
Pack stability can be a good thing or a bad thing for prey. Research is all over the place on what wolf hunting and trapping do to wolf packs, let alone whether eliminating packs through wolf control lowers or increases wolf predation.
“Wolves play an important role in the wildlife dynamics of Lake Clark National Park and Preserve and are highly sought by both park visitors and local trappers and hunters,” the Park Service said. “As apex predators, wolves impact natural systems which have adapted to and evolved in the presence of wolves.”
Wolves also cause endless debates in Alaska. The state is now feuding with the federal government over wolf management. Citing high wolf numbers in some parts of Alaska, the state wants to liberalize hunting and trapping. The feds want to ban killing methods federal bureaucrats find unattractive.
In Lake Clark Preserve as elsewhere in Alaska, researchers found that although most of their wolf packs were stable, there were a lot of wolves prone to take a walkabout.
“Dispersers” as they are called are so common in the 49th state that Mech, while studying the blended genetics of wolves in Central Alaska was moved to observe that “the wolves of Denali are the wolves of Alaska.”
“Wolves from Lake Clark have been documented traveling as far as 157 miles in search of a new territory,” the Park Service said. “Most young adult wolves leave the pack they were born into, seeking a mate of their own. Because wolf packs defend their territory against other wolves, those who leave must find a territory not already in use by other packs.”
But not all dispersers leave permanently.
One of the 22 wolves the researchers collared, a female yearling, circumnavigated Iliamna Lake, the third largest lake entirely within the United States. It was a 234-mile trek that took more than 17 days, but brought her back to the area from which she left.
Maybe she just liked the taste of those fabled Bristol Bay sockeye.
“Wolves may continue to consume salmon long after spawning has ended if carcasses remain available, even during the winter, and especially in years when snowfall is poor or in areas where lakes and rivers remain clear of ice,” the researchers reported. “In the Lake Clark region, there are no late-winter runs of salmon, yet the Telaquana wolves were observed feeding on salmon carcasses frozen at lake shores throughout the
fall and at the time of their capture in December.
“Because salmon have a relatively high lipid content compared with terrestrial prey sources, social groups of wolves that are provisioning young may be more likely to seek out a diet rich in salmon.
“Our study indicates that diet switching in wolves may be more widespread than previously thought. Given the ubiquity of salmon across much of Alaska, wolves throughout the state may be using nonungulate resources, such as salmon, as predictable alternatives, or even as a primary food source in some regions. A
more in-depth examination of the influence of salmon on terrestrial
predator–prey systems is warranted.”
Maybe it’s time to start thinking of wolves in the salmon-rich corners of Alaska as the equivalent of the healthy and well-fed domestic cats that kill an estimated 1.3 to 4 billion birds in the United States ever year.
“Cats may rank as the biggest immediate danger that living around people brings to wildlife,” Science News reported in 2013. And plenty of people love their cats even if the only thing they kill for is the sport.