A five-year state study says that boosting the harvest of cow elk around Mount St. Helens accomplished its goal of reducing the size of the herd.
The Washington Department of Fish and Wildlife released in March a population assessment done between 2009 and 2013 in game units Winston 520, Loowit 522, Margaret 524, Coweeman 550 and Toutle 556.
The state substantially increased the number of antlerless permits around the volcano starting in 2007, trying to bring the herd size into better balance with available habitat and lessen intermittent large winter die-offs.
“Attempts to reduce elk population via liberalized hunter harvest beginning in 2007 were apparently successful, based on our estimates of elk abundance,’’ according to the 126-page document.
Elk hoof disease was not part of the research, although 16 elk with some hoof irregularity were handled.
The study estimates the elk population in the five game units was 4,290 in 2009, peaked at 5,132 in spring of 2011 and dropped to 2,717 in spring of 2013.
Scott McCorquodale, a Ph.D research scientist with the agency, is the lead author. He has studied deer and elk extensively, including movements of deer in the Klickitat area while working for the Yakama Indian Nation.
“Undoubtedly, the major factor in the reduction was the considerable cow elk harvest that occurred during the study,’’ McCorquodale said in an interview last week. “This affected population dynamics by the combination of direct losses of elk killed, and indirectly by the removal of wombs from the herd, reducing reproductive capacity.’’
Other authors were Pat Miller, Stephanie Bergh and Eric Holman, all Department of Fish and Wildlife biologists in Southwest Washington.
The Mount St. Helens herd is the largest in Washington. The animals are spread across 14 game units from just south of Puget Sound to the Columbia River and Interstate 5 to U.S. Highway 97.
The five units studied are the herd’s core range.
Historically, the units supported the highest elk density, much of the hunting and present complex management challenge including hunter access, elk effects on industrial forestry and periodic winter-kill on the mudflow of the upper North Fork of the Toutle River.
The purpose of the study was to better quantify elk numbers and document recent trends in condition, productivity and survival.
With help from a helicopter, the researchers captured and radio-marked 150 elk.
Among the findings of the study:
• Total elk and cow elk numbers declined, with the larger decreases in the Winston and Coweeman units, the westernmost of the study area. Declines were greatest in the western portions of Coweeman and Winston.
• Elk populations declined in Margaret unit 524.
• Data implied stable-to-increasing elk numbers in Loowit unit 522.
• Data for Toutle 556 did not clearly indicate a decline although raw counts and model estimates were the lowest in 2013 observed during the five years.
• Calf survival was higher in years with significant late summer and early fall moisture, presumably because of enhanced forage production and quality during the time when calves are increasingly dependent on foraging and less on nursing.
• Numerous elk killed by winter conditions were noted four of the five years on the state’s Mount St. Helens Wildlife Area on the upper North Toutle mudflow. Only two dead elk were found in the mild winter of 2009-2010, but 71 winter-killed elk were detected in 2012-13. The 71 were the third highest observed since surveys began in 1999.
• Annual survival rates for cow elk were relatively high at 85 percent except the final year and in Coweeman unit during all five years. In the final year of study, the survival rate of cows was 51 percent to 66 percent.
The last year of the study (2012-13) had a relatively high snowfall, drought conditions prior to winter, and a relatively high antlerless harvest in fall of 2012.
• Annual bull elk survival was 56 percent. That was higher than the 49 percent in a previous study at Mount St. Helens completed in 1994.
• Body fat levels in late fall from hunter-killed elk were about 8 percent for lactating elk and 10 percent for non-lacating elk. Elk on high-quality diets are capable of fat levels in the 15 percent to 18 percent range.
However, among populations of elk on the west side of the Cascade Mountains for which data has been collected, elk at Mount St. Helens appear relatively typical.
Similar work in 1985 at Mount St. Helens early in the elk recolonization after the massive 1980 eruption found about the same levels of body fat.
• The pregnancy rate in February was estimated at just less than 70 percent. That is on par — or slightly better — than historic western Washington and Oregon elk data, but slightly lower than the most recent data for western Washington and western Oregon Cascades elk herds.
The study says reducing the elk population around Mount St. Helens by increasing the harvest of antlerless animals made sense, given the evidence of strong food limitation on body condition, modest pregnancy rates, over-foraging and periodic winter die-offs.
There may be a lag time before the reduction in elk numbers results in improved food availability and healthier animals.
Although the wet climate of Southwest Washington produces lots of greenery, what’s nutritious and palatable elk forage is actually quite small.
The Washington Fish and Wildlife Commission will adopt elk permit levels for 2014 on Friday in Olympia. The department is proposing a reduction of about 400 permits for units around Mount St. Helens.