Over the past century, populations of Lake Trout Salvelinus namaycush have declined throughout the Great Lakes basin due to overfishing, habitat destruction, introduction of invasive species, and associated recruitment issues from high thiaminase, as well as emerging infectious diseases. To combat these declines, state and federal fishery management agencies undertook substantial stock enhancement efforts, including more stringent regulation of sport and commercial catch limits and increasing hatchery propagation of Lake Trout stocked into Great Lakes basin waterways. One state fish hatchery involved in these rehabilitation efforts experienced mass mortality events in 2012 and 2017. In 2012, following a period of abnormally heavy rain, hatchery staff observed abnormal behavior followed by increased mortalities in two strains of Lake Trout fingerlings, reaching upwards of 20% mortality and totaling a loss of approximately 100,000 fish. In 2017, following another heavy-rain season, 6-8% of 2-year-old Lake Trout experienced morbidity and mortality similar to that observed in 2012. During the 2012 event, Brook Trout Salvelinus fontinalis and splake (Lake Trout × Brook Trout hybrid) reared in flow-through systems receiving water from diseased Lake Trout remained clinically unaffected. Molecular analyses revealed all lots of affected Lake Trout were infected with the salmonid herpesvirus-3 (epizootic epitheliotropic disease virus [EEDV]), a disease that caused complete depopulation of this hatchery in the late 1980s and until 2012 was never again detected in this hatchery or in Michigan. Further sampling detected EEDV in apparently healthy 5-year-old Lake Trout and in wild Mottled Sculpin Cottus bairdii collected in the hatchery source water. The ability of the virus to replicate in tissues of infected fish was verified by exposing naïve Lake Trout to the filtered tissue homogenates of infected fish resulting in similar disease signs. Despite the virus going undetected for many years, these two EEDV episodes clearly demonstrate the continued presence of this deadly herpesvirus in the Great Lakes basin.

中文翻译：

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密歇根州孵化场繁殖的湖鳟鱼中鲑鱼疱疹病毒 3 感染（流行性上皮病）的复发

在过去的一个世纪里，由于过度捕捞、栖息地破坏、入侵物种的引入以及高硫胺素酶引起的相关招募问题以及新出现的传染病，整个五大湖流域的纳梅库什湖鳟鱼的数量都在下降。为了应对这些下降，州和联邦渔业管理机构进行了大量的种群增加工作，包括更严格的体育和商业捕捞限制规定，以及增加放养到五大湖流域水道的湖鳟的孵化场繁殖。2012 年和 2017 年，参与这些恢复工作的一个州鱼类孵化场发生了大规模死亡事件。 2012 年，在经历了一段异常大雨之后，孵化场工作人员观察到异常行为，随后两种湖鳟鱼种的死亡率增加，死亡率高达 20%，总共损失了大约 100,000 条鱼。2017 年，在另一个大雨季节之后，6-8% 的 2 岁湖鳟的发病率和死亡率与 2012 年观察到的相似。杂交）在接受来自患病湖鳟鱼的水的流通系统中饲养，在临床上没有受到影响。分子分析显示，所有受影响的湖鳟鱼都感染了鲑鱼疱疹病毒-3（流行上皮病病毒 [EEDV]），在 1980 年代后期到 2012 年，这种导致该孵化场种群完全减少的疾病从未在该孵化场或密歇根州再次被发现。进一步采样在明显健康的 5 岁湖鳟鱼和孵化场源水中收集的野生斑驳杜鹃花中检测到 EEDV。病毒在受感染鱼类组织中复制的能力是通过将幼稚的湖鳟暴露于受感染鱼类的过滤组织匀浆中而得到验证的，这会导致类似的疾病迹象。尽管该病毒多年未被发现，但这两次 EEDV 事件清楚地表明这种致命的疱疹病毒在五大湖盆地继续存在。病毒在受感染鱼类组织中复制的能力是通过将幼稚的湖鳟暴露于受感染鱼类的过滤组织匀浆中而得到验证的，这会导致类似的疾病迹象。尽管该病毒多年未被发现，但这两次 EEDV 事件清楚地表明这种致命的疱疹病毒在五大湖盆地继续存在。病毒在受感染鱼类组织中复制的能力是通过将幼稚的湖鳟暴露于受感染鱼类的过滤组织匀浆中而得到验证的，这会导致类似的疾病迹象。尽管该病毒多年未被发现，但这两次 EEDV 事件清楚地表明这种致命的疱疹病毒在五大湖盆地继续存在。