Pugnose minnow (Opsopoeodus emiliae) is a small, reclusive species that is widespread in North America, but is one of the rarest fishes in Canada, found in less than 12 known localities in southwestern Ontario. In contrast to most pugnose minnow populations across the global range, Canadian populations are primarily found in turbid systems, potentially indicating persistence in suboptimal conditions. We used data from a multi‐gear species and habitat survey in the Canard River, Ontario, a system dominated by agricultural inputs and the best‐known capture site of the species in Canada, to parameterise multi‐gear occupancy models for understanding the relationship between pugnose minnow occupancy and microhabitat features, including the role of turbidity. Almost 300 pugnose minnow were captured, representing the largest single collection of the species in Canadian history. The best occupancy model indicated that the probability of pugnose minnow occupancy was highest in the deepest sites with the lowest water clarity (i.e. high turbidity); however, competing models suggested that occupancy was highest at sites with wild celery (Vallisneria americana) and higher water clarity, signifying that habitats with low turbidity may be utilised if sufficient physical cover exists. Together, our results suggest that Canadian pugnose minnow populations occupy and potentially favour turbid conditions, possibly to avoid visual predators in clearer habitats. It remains uncertain whether this abiotic association represents a long‐term, viable, local adaptation or whether persistence of pugnose minnow in the Canard River is at risk unless significant water quality improvements can be made.

中文翻译：

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濒危鲦鱼（Opsopoeodus emiliae）在物种分布区北缘的栖息地关系

Pugnose minnow (Opsopoeodus emiliae) 是一种在北美广泛分布的小型隐居物种，但它是加拿大最稀有的鱼类之一，在安大略省西南部不到 12 个已知地点发现。与全球范围内的大多数 pugnose minnow 种群相比，加拿大种群主要存在于混浊系统中，这可能表明在次优条件下的持久性。我们使用来自安大略省卡纳德河的多齿轮物种和栖息地调查的数据，该系统以农业投入为主，是加拿大最著名的物种捕获地点，参数化多齿轮占用模型，以了解pugnose minnow 占有率和微生境特征，包括浊度的作用。捕获了近 300 条鲇鱼，代表了加拿大历史上最大的单一物种收藏。最佳占用模型表明，在水清澈度最低（即高浊度）的最深地点，鲦鱼被占用的概率最高；然而，竞争模型表明，在有野生芹菜（美洲苦苣苔）和更高水清澈度的地点，占用率最高，这意味着如果存在足够的物理覆盖，可以利用低浊度的栖息地。总之，我们的结果表明，加拿大鲦鱼种群占据并可能喜欢混浊的环境，可能是为了避免在更清晰的栖息地中出现视觉捕食者。这种非生物关联是否代表一种长期的、可行的、