Motivations and drivers of trapper catch per unit effort in Alaska

Abstract

Indices of abundance based on harvest alone have long been used to track furbearer populations. However, abundance indices based on harvest alone do not account for variation in trapping effort. To my knowledge, adjusting harvest-based furbearer abundance indices to account for effort has not been previously examined in Alaska. Understanding how effort varies among trappers, and how social issues and external factors such as human conflict and fur prices affect effort, can give a clearer understanding of why trapping effort changes. A trapper's motivations may determine how strongly various external factors and social issues influence trapping effort. I sent a questionnaire to trappers of interior Alaska and used nine years of statewide data from the Alaska Trapper Questionnaire (distributed annually by the Alaska Department of Fish and Game) to address these issues. Across five regions from 2004-2013, I found that total fur harvest increased with per-capita trapper effort (R² = 0.125, p = 0.02). Variation in average winter temperature across game management regions explained 42% of variation in trapping effort, but annual variation in temperature, snow depth, fur prices, and fuel prices did not affect effort. Corresponding to these statewide findings, surveys of trappers in interior Alaska indicated that economic gain was not a strong motivation to trap, a finding that differs from previous studies. The most important social issues and external factors affecting trapping effort were access to land and the perceived abundance of furbearer populations respectively. To determine the motivations of interior Alaskan trappers, I used a k-means cluster analysis that identified four groups of trappers: management (17% of trappers), recreational (39%), subsistence (18%), and solitary (26%). Each group is represented by its strongest motivation for trapping. To improve the use of harvest as an index of furbearer abundance, I recommend accounting for trapping effort by calculating catch-per-unit-effort (CPUE), a metric commonly used in fisheries. I further recommend that resource managers should focus their efforts on reducing human conflicts while maximizing the non-monetary benefits of trapping. Resource managers should take advantage of questionnaires to help understand the fluctuations in furbearer populations and understand the motivations of trappers.