Ceratonova shasta is an endemic myxozoan parasite that impacts salmonid populations in the Klamath River (USA). High densities of C. shasta actinospores negatively affect the survival of migrating juvenile salmonids. Each year, approximately five million fall‐run Chinook Salmon Oncorhynchus tshawytscha smolts are released from a hatchery that is located below Iron Gate Dam, and they travel through an infectious zone where the densities of C. shasta spores are elevated and when disease risk is often highest. We examined several documented hypotheses regarding potential factors that contribute to the effects of C. shasta on salmonids in the Klamath River. Our results suggest that hatchery‐origin smolts may exacerbate the effects of the disease, as evidenced by an associative relationship between the prevalence of infection in out‐migrating hatchery fish with the densities of waterborne C. shasta spores in subsequent seasons (the following fall and spring). We found no evidence that the number of natural spawners, another potential contributor of spores, predicted peak spore density the following spring. Our findings warrant consideration in discussions of hatchery releases and management of flow regimes, and they identify avenues for future research to advance our understanding of how to reduce the adverse effects of C. shasta on salmonids in the Klamath River.

中文翻译：

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孵化场-奇努克鲑鱼中的感染率与切拉诺瓦沙斯塔孢子的丰富性有关：对管理和疾病风险的影响

Ceratonova s​​hasta是一种流行的粘虫寄生虫，会影响美国克拉马斯河的鲑鱼种群。高密度的C. shasta肌动孢子会对迁移的幼鲑科鱼类的生存产生负面影响。每年，大约有五百万只秋季运行的奇努克鲑Oncorhynchus tshawytscha幼体从位于铁门大坝下方的孵化场中释放出来，并经过一个传染性区，那里的C. shasta孢子密度很高，并且经常有疾病风险最高。我们研究了一些有关潜在因素的假说，这些因素可能对C. shasta的影响有影响。在克拉马斯河的鲑鱼上。我们的研究结果表明，孵化场起源的软体动物可能会加剧疾病的影响，这一点已得到证明，在随后的季节（随后的秋季和秋季），迁出的孵化场鱼的感染率与水传播的C.shasta孢子密度之间存在关联关系。弹簧）。我们没有发现证据表明自然产卵的数量（孢子的另一个潜在贡献者）可以预测次年春季的最高孢子密度。我们的发现值得在孵化场释放和流动状况管理的讨论中加以考虑，并且它们为将来的研究确定了途径，以加深我们对如何减少C. shasta对克拉马斯河鲑鱼的不利影响的理解。