Kreuder C, Miller M A, Jessup D A, Lowenstine L J, Harris M D, Ames J A, Carpenter T E, Conrad P A, Mazet J A
Wildlife Health Center, School of Veterinary Medicine, University of California, Davis, California 95616, USA.
J Wildl Dis. 2003 Jul;39(3):495-509. doi: 10.7589/0090-3558-39.3.495.
Detailed postmortem examination of southern sea otters (Enhydra lutris nereis) found along the California (USA) coast has provided an exceptional opportunity to understand factors influencing survival in this threatened marine mammal species. In order to evaluate recent trends in causes of mortality, the demographic and geographic distribution of causes of death in freshly deceased beachcast sea otters necropsied from 1998-2001 were evaluated. Protozoal encephalitis, acanthocephalan-related disease, shark attack, and cardiac disease were identified as common causes of death in sea otters examined. While infection with acanthocephalan parasites was more likely to cause death in juvenile otters, Toxoplasma gondii encephalitis, shark attack, and cardiac disease were more common in prime-aged adult otters. Cardiac disease is a newly recognized cause of mortality in sea otters and T. gondii encephalitis was significantly associated with this condition. Otters with fatal shark bites were over three times more likely to have pre-existing T. gondii encephalitis suggesting that shark attack, which is a long-recognized source of mortality in otters, may be coupled with a recently recognized disease in otters. Spatial clusters of cause-specific mortality were detected for T. gondii encephalitis (in Estero Bay), acanthocephalan peritonitis (in southern Monterey Bay), and shark attack (from Santa Cruz to Point Año Nuevo). Diseases caused by parasites, bacteria, or fungi and diseases without a specified etiology were the primary cause of death in 63.8% of otters examined. Parasitic disease alone caused death in 38.1% of otters examined. This pattern of mortality, observed predominantly in juvenile and prime-aged adult southern sea otters, has negative implications for the overall health and recovery of this population.
对在美国加利福尼亚海岸发现的南海獭（Enhydra lutris nereis）进行的详细尸检，为了解影响这种濒危海洋哺乳动物生存的因素提供了一个绝佳机会。为了评估近期死亡原因的趋势，我们对1998年至2001年期间刚死亡并进行尸检的海滩搁浅海獭的死亡原因的人口统计学和地理分布进行了评估。原生动物脑炎、棘头虫相关疾病、鲨鱼攻击和心脏病被确定为所检查海獭的常见死亡原因。虽然感染棘头虫寄生虫在幼年海獭中更易导致死亡，但弓形虫脑炎、鲨鱼攻击和心脏病在壮年成年海獭中更为常见。心脏病是海獭中新发现的死亡原因，弓形虫脑炎与这种情况显著相关。遭受致命鲨鱼咬伤的海獭患先前存在的弓形虫脑炎的可能性是其他海獭的三倍多，这表明鲨鱼攻击（这是长期以来公认的海獭死亡来源）可能与海獭中一种新发现的疾病有关。在埃斯特罗湾检测到弓形虫脑炎的特定病因死亡率空间聚集，在蒙特雷湾南部检测到棘头虫腹膜炎的特定病因死亡率空间聚集，在从圣克鲁斯到阿尼奥纽角检测到鲨鱼攻击的特定病因死亡率空间聚集。由寄生虫、细菌或真菌引起的疾病以及病因未明确的疾病是63.8%接受检查的海獭的主要死亡原因。仅寄生虫病就导致38.1%接受检查的海獭死亡。这种主要在幼年和壮年成年南海獭中观察到的死亡模式，对该种群的整体健康和恢复具有负面影响。
