Mulchatna Caribou Herd Intensive Management
Frequently Asked Questions (FAQs)

What is intensive management?

Standard wildlife management entails examining populations of various wildlife species and determining the appropriate levels at which those populations should be maintained for conservation, use, and sustainability. Managers appropriately adjust population sizes by administering changes to hunting seasons (the opening and closing of hunts) and bag limits to maintain populations for sustainable harvest. In Alaska under the Intensive Management Law (AS 16.05.255) certain game species that have been identified as “providing high levels of harvest for human consumptive use” (5 AAC 92.106) may be candidates for intensive management. Intensive management is Alaska law that may be implemented when specific populations cannot be maintained by standard management practices alone. Intensive management activities can include habitat enhancement, restrict hunting seasons and bag limits, and reducing predator populations.

Why intensive management for the Mulchatna caribou herd?

The Mulchatna caribou herd provided as many as 4,770 caribou per year for the subsistence needs of more than 48 local communities, in addition to hunting opportunities for all Alaskans and nonresidents. Due to persistently low numbers, all harvest opportunity for the MCH was closed in 2021 and remains closed today. As of July 2025, the Mulchatna caribou herd was estimated at 16,276 caribou, which is about half of the lower population objective of 30,000–80,000 caribou. Intensive management is a tool the department can use immediately to try to support herd growth and recovery. 

The public requested that the Alaska Board of Game (board, BOG) and Division of Wildlife Conservation (DWC) work to rebuild the herd and restore this food source. Some of the support for the program is through resolutions from Orutsararmiut Native Council, Alaska Federation of Natives, Bristol Bay Federal Regional Advisory Council, the Nushagak Advisory Committee, and Nushagak River communities.

In January 2022 the Alaska Board of Game approved and directed the department to implement a revised intensive management program to increase the abundance of the Mulchatna caribou herd, which has been closed to hunting since fall 2021. Both the Board of Game and the Division of Wildlife Conservation were concerned that the low abundance of caribou may continue or persist for a long period because predation was forestalling or slowing herd growth. The direction by the board was to remove bears on the calving grounds to achieve the goal of improving calf survival and recruitment to enable or speed the growth of the herd.

Why kill bears and wolves?

Bears and wolves have been identified as significant caribou calf predators resulting in low numbers of calves surviving to breeding age, thereby limiting the ability of the herd to increase. Research presented to the Board of Game in January 2022 indicated that various predators, especially brown bears, were responsible for nearly 90% of newborn calf deaths during the first 2 weeks of life between 2011 and 2021. Additionally, recent analyses have indicated predation by bears and wolves is additive rather than compensatory, meaning bears and wolves are killing calves that would otherwise survive.

Wolf removal by the public is a permitted management activity outside of hunting, which uses aerial methods authorized by the Board of Game. Public removal of wolves during winter was active from 2012 to 2025. It has since closed due to being ineffective due to low and inconsistent participation that failed to regularly reduce wolf numbers to the level at which caribou overwinter survival of caribou would be expected to increase. In addition, public aerial removals did not include bears, which have typically been the major predator of newly born Mulchatna caribou calves. The board expanded the control area in 2022 to include a portion of Unit 18 (western calving area) and authorized DWC staff to remove predators from the calving grounds.

Although approved for predator control on all state lands withing the 15,584 mile² predation control area, active removal by the department is focused on the small western MCH calving area, which has historically been less than 1,000 mi² in the northwest corner, and more than 140 miles away from National Park lands and coastal bear viewing areas.

Isn’t habitat the real problem?

The high numbers of caribou in the 1990s likely decreased range quality and triggered the initial decline of the herd. After more than a decade and a half of the caribou population being under the lower end of the management objective over the herd’s very large range, the habitat should have recovered adequately to allow the herd to grow again. An important indicator of habitat status is caribou nutritional health, which has been good (see below).

Isn’t malnutrition limiting the herd’s growth?

When caribou are nutritionally limited, calf productivity is lower (first reproduction happens at an older age and the overall reproduction is at a reduced rate); and mortality is higher (smaller or weaker calves are more susceptible to predation or starvation in severe weather). Mulchatna caribou reproduction is normal, with evidence that young females (ages 2- and 3-years-old) have been in relatively good nutritional condition since about 2009, when the herd had declined to approximately 30,000 animals. Since 2024 when the department began evaluating pregnancy rates, pregnancy rates have been high, consistently exceeding 90% in adults and reaching high levels (>60%) in 22-month-old caribou.

Department research investigating the relationship between body fat and demographic rates in Mulchatna caribou has determined that lactating caribou are thinner than nonlactating caribou in autumn, but they gain fat over winter and body fat levels are high enough to support conception and pregnancy. Additionally, body mass of neonatal calves is high, indicating that mothers have good nutrition during pregnancy. This work also indicates that there is no relationship between maternal body fat and probability of calf survival, meaning that something other than nutrition is influencing whether calves live or die. The available data indicate that habitat is not limiting growth of the herd.

Isn’t disease the real problem?

Brucellosis (Brucella suis biovar 4) was documented in the Mulchatna caribou herd (MCH) over a decade ago. Brucellosis can lower caribou population size by lowering calf production and depress the recovery of a herd, especially in the short-term (over a few years). The biggest impacts from disease are typically when the disease first spreads in a herd, and the introduction of brucellosis into the herd may have been a factor in the herd’s decline from around 30,000 caribou in 2014–2016 to levels that were about half of that many caribou starting in 2018 or 2019.

In herds where brucellosis has been present for a long time, disease outbreaks are typically periodic and otherwise the disease is present at an enzootic level (low levels of clinical disease). The disease was not observed during the population peak or initial decline of the Mulchatna herd but has been present within this herd for long enough that it is not likely the factor limiting population growth presently. Research is underway assessing how brucellosis may impact herd health and calf production. Disease or death from brucellosis has not been documented in calves but some calves as well as adults develop antibodies indicating exposure. Recent research in the Mulchatna herd did not detect an effect of Brucella suis seropositivity on pregnancy or survival of the subsequent calves. Thus, brucellosis is not having a detectable impact on the probability of pregnancy, abortion, or live birth at this time. Calves are generally born large and healthy.

The lack of effect may have occurred for several reasons. First, reproductive consequences of brucellosis may occur primarily in the first pregnancy following infection, so if this was a subsequent pregnancy, then it may not have been affected. Additionally, timing of infection and the number of infected organisms (e.g., dose) and the caribou immune system function are important; females receiving smaller numbers of infective organisms earlier in gestation produced normal calves whereas females infected with larger numbers or organisms or later in gestation sometimes aborted.

Will this hurt populations of bears and wolves in Alaska?

Bear and wolf populations are healthy in western Alaska. The removal of wolves and bears in the western spring calving control area is occurring in a relatively small area surrounded by intact habitat on state and federal lands where control activities are not occurring. The 2023–2025 western Mulchatna predator removal area is more than 140 linear miles from popular bear viewing areas and there is no evidence that bears at these areas are from the interior portions of the region. Bears and wolves can move in and out of National Wildlife Refuge lands, which serve as refugia from control activities.

In this remote area bears are not widely hunted, and the reported harvest for all predators is low in and around the control area. Based on previous adjacent bear population assessments from similar habitats, the current harvest rate of brown bears in the unit by the public through hunting, combined with the 2 complete years of department-led, intensive-management efforts, reflect a total removal rate of between 7% and 8% annually, which falls short of the reported peak in public brown bear harvest in 2011. This removal rate is consistent with what is considered sustainable yield in adjacent coastal Unit 9 (4–6%), eastern and northwest Alaska (4–10%), and British Columbia (4–10%). If there is any decline in the overall bear population, it will almost certainly be minor and of short duration (3–5 years). Removals and mark–count work in spring 2025 documented a minimum of 56 individuals bears on the western calving grounds. Based on observations from other predator control programs in remote areas of Alaska, predator numbers are expected to rebound in a few years after control is suspended.

Will bears repopulate to the removal area?

In summer 2025, after two years of removal, department staff identified a minimum of 56 bears on the western Mulchatna caribou herd calving grounds. Because the bear removal area that encompasses the calving grounds is relatively small and surrounded by undeveloped lands with ample numbers of bears, bears immigrate into the removal area each year. After removal efforts are concluded, bears will continue to immigrate into and repopulate the removal area. As explained above, the overall removal rates of bears are unlikely to decrease the overall population of bears within the broader MCH region, and therefore continued immigration of bears into the removal area is nearly certain each year and once removal activities end.

Does predator control work?

Similar efforts have been successful with the Southern Alaska Peninsula (SAP) caribou herd. Following a peak of more than 10,000 caribou in 1983, the SAP began a steep decline and by 1993 the herd was below 2,500 caribou. In 2007, surveys indicated 99% of SAP calves died before reaching one month of age, which biologists attributed primarily to predation. From 2002 to 2007, estimates of calf recruitment were chronically low, and population size declined rapidly, bottoming out at approximately 657–750 caribou in 2007. In 2008, the removal of 28 wolves during calving in the spring immediately improved calf survival. Calf survival (birth to one month) increased from less than 1% in 2007 to 57% in 2008. Ten more wolves were removed over the next 2 years, after which the program was deactivated. The size of the Southern Alaska Peninsula herd, and calf-to-cow and bull-to-cow ratios increased rapidly after predator control and continued to increase substantially over the following years. Population estimates in 2016 were above 2,000 and growing.

With the continued upward trend in abundance and the population exceeding 35 bulls:100 cows in the SAP, ADF&G opened a Tier II drawing hunt for residents in RY13, which was subsequently replaced with a harvest ticket hunt in RY16. Model-predicted abundance was expected to exceed the lower management objective of 3,000 caribou by regulatory year 2019 (RY19) and is now estimated at 3,800 caribou after a minimum count was completed in July 2024. The state harvest ticket now has a bag limit of 3 caribou for residents.

How have Mulchatna caribou responded to predator control efforts?

From 1999–2022, the average calf-to-cow ratio in the western group was 24:100, prior to department-led predator control on the calving grounds. Fall composition surveys completed in October of 2023 recorded calf-to-cow ratios of 44:100 after the first year of department removal. In October of 2024 that ratio increased to 54:100 following the second year of predator removal. Calf-to-cow ratios were 52:100 in 2025. This is indicative of a significant positive response to the department’s predator removals. In all years that the department removed bears, we have seen sustained, high early calf survival in the western group. This was the highest ratio for western Mulchatna caribou since 1999 (average ratio 1999–2022 = 24:100). In comparison, 2023 surveys in the eastern group (n = 1,808) indicated calf-to-cow ratios of 32:100, with the average calf-to-cow ratio at 25:100 during 1999–2022.

Biologists determine if the associated eastern and western groups show signs of increased abundance during the post-calving aggregations, when animals group up and provide an opportunity to conduct surveys. When caribou aggregate on their summer range and weather allows, a photocensus will be conducted to determine overall abundance. From 2023 to 2024, the western Mulchatna caribou herd (WMCH) population estimate grew 13.7% (803 more caribou). The minimum count rose in parallel, increasing 20.2% (937 more caribou). When viewed over the removal years of 2023 to 2025, the western Mulchatna caribou population estimate increased 40.9% (4,728 caribou) and minimum counts rose 41.5% (1,929 caribou). The population estimate for eastern Mulchatna caribou herd (EMCH) and western Mulchatna caribou herd (WMCH) combined has increased 30.1% between 2023 and 2025.

Herd composition surveys are completed in fall aiming to sample approximately 30% of the overall population. The Division of Wildlife Conservation will continue to monitor other factors including disease and nutrition.

Progress and success are evaluated using the following criteria which are published in the Annual Report on Intensive Management for Caribou with Predation Control in Units 9B, 17, 18, and 19A,B&E Alaska Department of Fish & Game, Division of Wildlife Conservation, February 2026:  

Criteria for evaluating progress toward IM objectives: 

• Fall calf-to-cow ratios
• Fall bull-to-cow ratio
• Recruitment of calves (population growth)
• Caribou abundance

Criteria for success with this program: 

• Fall bull-to-cow ratio can be maintained at a minimum of 35 bulls:100 cows.
• Fall calf-to-cow ratio can be sustained above 30 calves:100 cows.
• The population can grow at a sustained rate of 5% annually.
• Caribou harvest objectives are met

What happens to the meat and hides of predators removed by the department?

All bears and wolves located during predator control efforts are killed as quickly and humanely as possible through approved institutional animal care and use committee review. Hides and skulls are salvaged when safe and possible to do so. Meat from black bears and some brown bears is transported to local villages and provided for subsistence uses. However, there is sometimes a lack of desire for brown bear meat. Skulls are being used for educational purposes in numerous local communities and hides are sold at the Horn & Hide Auction.

What's being done about illegal harvest? Isn't that a big problem?

Unreported harvest has been previously documented across the range of Mulchatna however multi-agency outreach and enforcement efforts have increased education and awareness about the hunt closure and the need to eliminate take for conservation. Out-of-season take had previously appeared to occur at a similar rate as other remote areas of the state but has been reduced and has not had a profound impact on the population.

Is the goal of maintaining a population of 30,000–80,000 caribou achievable?

Although the Mulchatna caribou herd is below the lower end of the population objective it is reasonable to believe that across the entire range a population of at least 30,000 is achievable.

Further Reading

March 2025 Mulchatna Caribou IM Status & Information submitted to the Alaska Board of Game: mch-im-status.pdf

Sustained Yield of Predators Under IM: Overview for the BOG [Board of Game], July 2025: rc_3_tab_1.3.pdf

In July 2025, ADF&G submitted the following white paper to the Alaska Board of Game: Sustained Yield of Predators Under IM: Overview for the BOG, July 2025 Division of Wildlife Conservation, Alaska Department of Fish & Game 

Recent research on Mulchatna nutrition: Overwinter gains in body fat challenge assumptions about winter nutrition in northern ungulates - Denryter - 2025 - Ecosphere - Wiley Online Library

Last updated May 6, 2026