Nehring R Barry, Alves John, Nehring Joshua B, Felt Benjamin
Colorado Division of Parks and Wildlife, 2300 South Townsend Avenue, Montrose, Colorado, 81401, USA.
Colorado Division of Parks and Wildlife, 151 East 16th Street, Durango, Colorado, 81301, USA.
J Aquat Anim Health. 2018 Dec;30(4):264-279. doi: 10.1002/aah.10039. Epub 2018 Aug 21.
Placer Creek, a tributary of Sangre de Cristo Creek in Colorado's San Luis Valley, supported an allopatric core conservation population of native Rio Grande Cutthroat Trout Oncorhynchus clarkii virginalis during much of the 20th century. After the failure of gabion barriers in the late 1990s, Brook Trout Salvelinus fontinalis infected with Myxobolus cerebralis invaded from Sangre de Cristo Creek. By 2005, whirling disease (WD) and competition from Brook Trout reduced Rio Grande Cutthroat Trout numbers to less than 10% of the total trout population. New barriers were constructed in 2006 and the stream was treated with rotenone in 2007 and 2009 to eliminate all fish prior to the reintroduction of Rio Grande Cutthroat Trout. Results of WD research studies in Montana, California, and Colorado indicated it might be possible to break the life cycle of the parasite in some situations. Our management interventions included (1) reducing the fish population in the stream to zero for approximately 14 months, (2) introducing lineage V and VI Tubifex tubifex worms, which are not susceptible to M. cerebralis, and (3) eliminating a small off-channel pond that provided optimal habitat that sustained a localized high-density population of lineage III T. tubifex, the oligochaete host susceptible to M. cerebralis. Electrofishing during the fall of 2009 and spring of 2010 indicated the drainage was devoid of fish. Fry, juvenile, and adult Rio Grande Cutthroat Trout were stocked in September and October of 2010 and 2011. Approximately 975,000 lineage V and VI T. tubifex were introduced into Placer Creek between 2010 and 2012 as possible oligochaete competitors for the lineage III worms. The off-channel pond was filled in, and the surface was reseeded in April 2012. No evidence of M. cerebralis infection was detected among more than 280 Rio Grande Cutthroat Trout tested between July 2012 and July 2016, indicating the parasite had been eradicated from the Placer Creek basin upstream of the barriers.
普拉瑟溪是科罗拉多州圣路易斯谷基督圣血溪的一条支流，在20世纪的大部分时间里，它支撑着一个异域分布的本地格兰德河割喉鳟（Oncorhynchus clarkii virginalis）核心保护种群。20世纪90年代末石笼屏障失效后，感染了脑粘体虫的溪红点鲑（Salvelinus fontinalis）从基督圣血溪入侵。到2005年，旋转病（WD）和溪红点鲑的竞争使格兰德河割喉鳟数量减少到总鳟鱼种群数量的不到10%。2006年建造了新的屏障，并在2007年和2009年用鱼藤酮处理了溪流，以便在重新引入格兰德河割喉鳟之前清除所有鱼类。在蒙大拿州、加利福尼亚州和科罗拉多州进行的旋转病研究结果表明，在某些情况下有可能打破寄生虫的生命周期。我们的管理干预措施包括：（1）将溪流中的鱼类数量减少到零约14个月；（2）引入对脑粘体虫不敏感的V系和VI系颤蚓；（3）消除一个小型支流池塘，该池塘提供了最佳栖息地，维持了对脑粘体虫敏感的III系颤蚓的局部高密度种群。2009年秋季和2010年春季的电捕鱼表明该排水区域没有鱼类。2010年和2011年的9月和10月投放了格兰德河割喉鳟的鱼苗、幼鱼和成鱼。2010年至2012年期间，大约97.5万条V系和VI系颤蚓被引入普拉瑟溪，作为III系颤蚓可能的寡毛类竞争者。支流池塘被填平，并于2012年4月重新播种了地表植被。在2012年7月至2016年7月期间对280多条格兰德河割喉鳟进行检测，未发现脑粘体虫感染的迹象，这表明在屏障上游的普拉瑟溪流域，该寄生虫已被根除。
