Hershberger P K, Gregg J L, Hart L M, Moffitt S, Brenner R, Stick K, Coonradt E, Otis E O, Vollenweider J J, Garver K A, Lovy J, Meyers T R
U. S. Geological Survey, Western Fisheries Research Center - Marrowstone Marine Field Station, Nordland, WA, USA.
Alaska Department of Fish and Game (ADF&G) - Commercial Fisheries, Cordova, AK, USA.
J Fish Dis. 2016 Apr;39(4):395-410. doi: 10.1111/jfd.12370. Epub 2015 Mar 31.
The protistan parasite Ichthyophonus occurred in populations of Pacific herring Clupea pallasii Valenciennes throughout coastal areas of the NE Pacific, ranging from Puget Sound, WA north to the Gulf of Alaska, AK. Infection prevalence in local Pacific herring stocks varied seasonally and annually, and a general pattern of increasing prevalence with host size and/or age persisted throughout the NE Pacific. An exception to this zoographic pattern occurred among a group of juvenile, age 1+ year Pacific herring from Cordova Harbor, AK in June 2010, which demonstrated an unusually high infection prevalence of 35%. Reasons for this anomaly were hypothesized to involve anthropogenic influences that resulted in locally elevated infection pressures. Interannual declines in infection prevalence from some populations (e.g. Lower Cook Inlet, AK; from 20-32% in 2007 to 0-3% during 2009-13) or from the largest size cohorts of other populations (e.g. Sitka Sound, AK; from 62.5% in 2007 to 19.6% in 2013) were likely a reflection of selective mortality among the infected cohorts. All available information for Ichthyophonus in the NE Pacific, including broad geographic range, low host specificity and presence in archived Pacific herring tissue samples dating to the 1980s, indicate a long-standing host-pathogen relationship.
原生动物寄生虫冰岛海兽胃线虫（Ichthyophonus）存在于东北太平洋沿岸地区的太平洋鲱（Clupea pallasii Valenciennes）种群中，范围从华盛顿州的普吉特海湾向北至阿拉斯加湾。当地太平洋鲱种群的感染率随季节和年份变化，并且在整个东北太平洋地区，感染率随宿主大小和/或年龄增加的总体模式一直存在。2010年6月，阿拉斯加科尔多瓦港一群1龄以上的幼年太平洋鲱是这种地理模式的一个例外，其感染率异常高，达35%。据推测，这种异常现象的原因涉及人为影响，导致当地感染压力升高。一些种群（如阿拉斯加的下库克湾；从2007年的20 - 32%降至2009 - 2013年期间的0 - 3%）或其他种群最大体型组（如阿拉斯加的锡特卡湾；从2007年的62.5%降至2013年的19.6%）的感染率年际下降，可能反映了受感染组中的选择性死亡。东北太平洋地区有关冰岛海兽胃线虫的所有现有信息，包括广泛的地理分布范围、低宿主特异性以及可追溯到20世纪80年代的存档太平洋鲱组织样本中的存在情况，都表明宿主与病原体之间存在长期关系。
