Allee effects, the suppression of vital rates at low population densities, can occur through a wide variety of mechanisms, all of which potentially apply to reintroduced populations. Reintroduced populations are initially at low densities, hence Allee effects can potentially lead to reintroduction failure despite habitat quality being sufficient to allow long-term persistence if the population survived the establishment phase. The probability of such “Allee effect failures” can be minimised by releasing large numbers of organisms, or by implementing management that reduces post-release dispersal and increases initial survival and reproduction. However, such management may be costly, and releasing large numbers of organisms may actually compromise the survival of the species. It is therefore critical to ensure that the possibility of Allee effects occurring in reintroduction projects is supported by both sound theory and direct evidence, rather than uncritical analyses of correlations that may suffer from numerous confounds. We attempt to create a decision-theoretic framework for prudent consideration of Allee effects in reintroduction strategies.

絶滅種の野生復帰のため再導入される個体群は初期サイズが小さく，アリー効果を受けやすい．そのため，いったん定着すれば長期存続できる良い生息環境でも，再導入に失敗することがある．再導入事業におけるアリー効果の可能性は，健全な理論と直接的な証拠に基づいて評価するべきである．本発表では、再導入時のアリー効果に対処するための，意思決定理論に基づくフレームワークの構築を試みる．