Trapping data have a long and rich history of use in monitoring furbearer populations in North America but understanding the influences of variation in trapper harvest is important. Many factors besides abundance can cause variation in trapper harvest, including socioeconomics, weather, and motivation. The relationships between these extrinsic factors and trapper harvest may change temporally, which may obscure the causal understanding of variation in trapper harvest. We tested for changes in the relationships between pelt price and trapper numbers, and pelt price and harvest per trapper for raccoons (Procyon lotor) in Illinois, USA, from 1976–2018 while controlling for other socioeconomic (gasoline price, unemployment) and weather (temp, snow depth) factors. The annual raccoon harvest showed no clear trend, whereas the number of raccoon trappers declined markedly from approximately 1976–1990 in conjunction with pelt prices, after which the number of trappers remained relatively stable and were not significantly affected by pelt price. In contrast, harvest per trapper increased markedly during the 1990s and showed a significant negative relationship with pelt price pre‐1990 but a positive relationship post‐1990. We propose that declines in pelt prices resulted in a loss of less experienced or economically incentivized trappers, whereas contemporary trappers may continue trapping primarily for non‐economic reasons. Our study highlights the potential for using non‐linear relationships between trapper harvest data and socioeconomic covariates to help understand the influences of temporal variation in trapper harvest data. © 2020 The Wildlife Society.

中文翻译：

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浣熊皮的价格和捕手的收获关系暂时不一致

诱捕数据在监视北美的小熊种群中有着悠久而丰富的历史，但了解诱捕器收获变化的影响非常重要。除丰度外，许多其他因素也会导致捕捞者收获的变化，包括社会经济学，天气和动机。这些外部因素与捕虫器收获之间的关系可能会随时间发生变化，这可能会使捕虫器收获变化的因果关系难以理解。我们测试了皮草价格和捕兽器数量之间的关系以及浣熊的皮草价格和每个捕兽器的收获之间的关系（Procyon lotor），控制其他社会经济因素（汽油价格，失业率）和天气因素（温度，降雪深度），从1976年至2018年。每年的浣熊收成没有明显的趋势，而从1976年至1990年，浣熊诱捕器的数量与兽皮价格一起显着下降，此后诱捕器的数量保持相对稳定，并且不受兽皮价格的显着影响。相反，在1990年代，每个捕虫器的收获量显着增加，并且与1990年前的毛皮价格显着负相关，而与1990以后的毛皮价格呈正相关。我们建议，毛皮价格下降会导致缺乏经验或缺乏经济诱因的诱捕器损失，而当代诱捕器可能主要出于非经济原因而继续诱捕。我们的研究突出了在捕捞器收获数据和社会经济协变量之间使用非线性关系来帮助理解捕捞器收获数据中时间变化的影响的潜力。©2020野生动物协会。