Kenai Moose Predation Study Update

John Crouse, Director of the Moose Research Center with Alaska Dept. of Fish and Game, assessing the rump fat thickness of an adult female moose via ultrasound imaging. Photo courtesy of Alaska Fish and Game.

Safari Club International Foundation recently contributed $20,000 to the Alaska Department of Fish and Game (ADFG) for moose population research on the Kenai Peninsula of Alaska. This research will aid wildlife biologists in analyzing what factors may be contributing to a decline in the local moose population. This information will provide wildlife managers with a guide for assessing harvest quotas and regulations, which will benefit the long-term sustainability of the Kenai moose population.

Current population estimates on the Kenai suggest there are approximately 10 bulls for every 100 cows. Generally, well-balanced moose populations will have a male to female ratio of 20 to 30 bulls per 100 cows on the Kenai. In 2011, the ADFG implemented two-year moose hunting restrictions in response to this disparity in the male to female moose ratio. These restrictions allow hunters to only harvest bulls with antlers at least 50 inches wide or with at least 4 brow tines on one side. Additionally, access for non-resident hunters has been restricted. Although hunters may find a greater challenge in their quest for legal bulls, these harvest restrictions will provide a degree of recovery time while researchers attempt to identify what may be influencing the population decline. Research will focus on the influence of the reduced number of bulls on breeding potential, and if predator control measures and/or habitat modification are also necessary for a well-balanced moose population.

Current Progress: The study is at the halfway point, and researchers have collared 100 cows with GPS tracking devices and 98 of them with Vaginal-Implant Transmitters (VIT). VITs are activated during the birthing process and allow for immediate monitoring of calves at birth. While the cows were anesthetized, researchers also collected rump fat measurements to determine body condition, and as an indicator of habitat conditions for moose. Twinning rates are another indicator of habitat conditions, which currently account for 40-45% of the pregnancies this season. Twinning rates for moose on the Kenai have been as high as 72% in the past, which is believed to be due to better browsing conditions. The pregnancy rate for this season is 84%, which is on the low end for a normal moose population.

A calf mortality study was included in the project to determine how predation is impacting moose survival. GPS collars were fitted to 54 calves for tracking and to date, only 14 remain alive with the majority of deaths attributed to brown bear depredation. Monitoring of the adult moose and calves will continue into the fall of 2012 to provide researchers with a more complete assessment of how predators, habitat and reduced bull numbers are impacting the population, and the subsequent management implications.

Wildlife agencies use the best available science to strategically determine harvest quotas and regulations. Adjusting harvest quotas and restrictions relative to the status of a population is the foundation of sustainable use management. SCI Foundation particularly supports projects that foster the sustainable-use framework. By placing priority on maintaining viable populations now, we will ensure a healthy moose population will be available for generations to come.

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