詳細スケールでのエゾシカ捕獲の効果をはじめて解明～効率的なエゾシカ対策に貢献～

2025-10-15 北海道大学,北海道立総合研究機構

北海道大学の上野真由美准教授らは、釧路地域での27年間のデータ解析により、エゾシカ捕獲の効果が生息密度によって異なることを明らかにした。高密度地域ほど捕獲率が高く、個体数削減効果が顕著で、低密度地域では変動が小さいことが確認された。効率的な管理のためには、高密度エリアへ捕獲努力を重点配分することが有効と結論づけた。この成果は、野生動物管理の最適化と生態系保全に貢献する。研究は『Journal of Wildlife Management』誌に掲載。

2020年までの27年間に行われたエゾシカ（図左）の捕獲強化策（狩猟規制緩和と許可捕獲に対する奨励金）により釧路地域のエゾシカ個体数は2度減少したが、その減少幅はいずれも直近のピーク個体数の約14％にとどまった（図右）。

＜関連情報＞

捕獲強化策によるニホンジカ (Cervus nippon) 個体数変動の空間的変異：27年間の解析 Spatial variation in local population dynamics of sika deer, Cervus nippon, through intensified management

Mayumi Ueno, Hayato Iijima, Yoshihiro Inatomi, Saya Yamaguchi, Hino Takafumi, Hiroyuki Uno
Journal of Wildlife Management Published: 22 July 2025
DOI:https://doi.org/10.1002/jwmg.70069

Abstract

Population reduction through hunting and nuisance control has been practiced in many parts of the world to prevent an overabundance of ungulates; however, there is limited knowledge regarding the quantitative impact of intensified hunting management and nuisance control on local dynamics within managed populations. This study examined spatial variations in the local dynamics of sika deer (Cervus nippon) along with hunting and nuisance control across 256 mesh units (23 km²/mesh unit) within the Kushiro subprefecture of Hokkaido, Japan, from 1994 to 2020 (27 years). Under enhanced management, the population declined twice but only by about 14% from the previous peak each time. Since 2017, however, the population has remained stable without further decline. Local densities ranged from 1 to 120 deer/km² within the area, with higher densities producing higher harvest rates (i.e., density-dependent harvesting). Temporal trends in local densities varied across the mesh units: in some mesh units, sika deer at a high density (≥50 deer/km²) consistently decreased by more than half, whereas in others, medium densities (25–50 deer/km²) increased following temporal fluctuations, and low densities (<25 deer/km²) remained stable throughout the same period. Thus, the extent of human-induced population reduction locally differed and was likely larger at high-density mesh units. Consequently, the impact of intensified management at the prefecture scale varies locally. Therefore, allocating management efforts to high-density mesh units is preferable for more efficient population control across the entire area.