ABSTRACT: For successful evaluation of the overall effects of salmon louse infestation on brown trout population dynamics, it is crucial to have a realistic understanding of how lice infestation distributions are generated and how they should be interpreted. Here, we simulated the potential effects of spatio-temporal variance in lice larvae densities, temporal variance in sea trout marine migration timing and spatial variance in marine habitat use on lice infestation distributions. We show that, when sampling populations with individual variation in marine behaviour, e.g. from post-smolts to veteran migrants, we must expect multi-modal mixture lice infestation distributions. Applying standard statistical distributions, such as the Poisson, negative binomial or zero-inflated distributions, can be too simplistic and give biased results. Temporary increases in salmon lice load in a given area may have inconsistent effects among individuals of a population and may be critical for vulnerable groups such as post-smolts, dependent on timing. For many analyses, it will be necessary to resolve the contributions from groups of fish with different lice infestation expectations due to spatio-temporal differences in habitat use within the overall mixture distribution. Another consequence is that different data sources, obtained by different methods or sampled at different locations and periods, must be expected to give different lice infestation distributions, even when sampling the same population. We also discuss additional factors that may complicate the interpretation of salmon lice infestation distributions on sea trout, such as lice-induced mortality, and behavioural changes, such as premature return to less saline water for delousing.

中文翻译：

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野生褐鳟种群中鲑鱼虱子的侵染产生多态混合物分布

摘要：为了成功评估鲑鱼虱子侵染对鳟鱼种群动态的总体影响，至关重要的是要对虱子侵染的分布如何产生以及如何解释有一个现实的了解。在这里，我们模拟了虱子幼虫密度的时空变化，鳟鱼海洋迁移时间的时空变化以及海洋生境利用中空间变化对虱子侵扰分布的潜在影响。我们表明，当对海洋行为具有个体差异的人群（例如从后软体动物到退伍军人移民）进行采样时，我们必须期望多模式混合虱的侵扰分布。应用标准统计分布（例如泊松分布，负二项式分布或零膨胀分布）可能过于简单，并且会产生偏差。在给定区域内鲑鱼虱子负载的暂时增加可能在种群个体之间产生不一致的影响，并且可能取决于时机，这对于脆弱的群体（如后软体动物）至关重要。对于许多分析，由于混合混合物总体分布中栖息地使用的时空差异，有必要解决虱子侵染预期不同的鱼类群体的贡献。另一个后果是，即使对同一种群进行采样，也必须期望通过不同方法获得或在不同位置和时期采样的不同数据源具有不同的虱子侵扰分布。我们还讨论了其他因素，这些因素可能会使对海鳟的鲑鱼虱子侵扰分布的解释复杂化，例如虱子引起的死亡率和行为改变，