Balstad Laurinne J, Godwin Sean C, Krkošek Martin, Lewis Mark A, Baskett Marissa L
Department of Environmental Science and Policy, University of California, Davis, 2132 Wickson Hall, One Shields Avenue, Davis, 95616 CA USA.
Center for Population Biology, University of California, Davis, 2320 Storer Hall, One Shields Avenue, Davis, 95616 CA USA.
Theor Ecol. 2025;18(1):23. doi: 10.1007/s12080-025-00617-8. Epub 2025 Jun 6.
Mitigating negative downstream impacts of parasitic disease in aquaculture settings entails tradeoffs: reducing parasite loads has economic and conservation benefits, but treatment is often expensive and frequent treatment can lead to resistance evolution. Options for mitigating these potential trade-offs depend on the management context. For example, in the sea louse-salmon system, managers use discrete treatment applications to control louse burdens, applying treatment when parasite burdens exceed a target threshold. To analyze the effect of a threshold-based control of disease treatment on economic, conservation, and evolutionary outcomes, we incorporate discrete treatment into a dynamical model of sea louse-salmon systems with disease spillover to wild populations. The model follows both salmon hosts and sea lice through domestic, wild, and migratory populations, with treatment occurring when sea lice exceed a target threshold. Our model shows that simultaneous economic and conservation win-wins are possible: there are treatment threshold choices that lead to relatively high wild juvenile salmon population sizes and relatively low economic losses, especially when treatment is very effective or treatment is cheap. However, positive evolutionary outcomes are harder to capture and occur most often when treatment efficacy is low and the treatment threshold is either near zero or very high. Expanding the management toolbox beyond choices of treatment threshold and treatment efficacy could help managers better capture positive economic, evolutionary and conservation outcomes in the system.
降低寄生虫负荷具有经济和保护效益，但治疗通常成本高昂，且频繁治疗会导致抗性进化。减轻这些潜在权衡的方法取决于管理背景。例如，在海虱 - 鲑鱼系统中，管理者使用离散的治疗应用来控制海虱数量，当寄生虫数量超过目标阈值时进行治疗。为了分析基于阈值的疾病治疗控制对经济、保护和进化结果的影响，我们将离散治疗纳入了一个具有疾病溢出到野生种群的海虱 - 鲑鱼系统动态模型中。该模型跟踪鲑鱼宿主和海虱在养殖、野生和洄游种群中的情况，当海虱超过目标阈值时进行治疗。我们的模型表明，经济和保护方面同时实现双赢是可能的：存在一些治疗阈值选择，可导致相对较高的野生幼鲑种群数量和相对较低的经济损失，特别是当治疗非常有效或成本低廉时。然而，积极的进化结果更难实现，并且最常出现在治疗效果低且治疗阈值接近零或非常高的情况下。将管理工具箱扩展到治疗阈值和治疗效果之外的选择，可能有助于管理者在系统中更好地实现积极的经济、进化和保护结果。
