During 1985–1990, two groups of killer whales in Prince William Sound, Alaska, experienced unusually high rates of mortality, while seven others did not. Those affected were AB pod, part of the southern Alaska population of resident (fish-eating) killer whales, and the AT1 transient (marine mammal–eating) group, a very small, reproductively isolated population that last reproduced in 1984. In 1985–1986, several AB pod members were shot by fishermen defending their catch from depredation, which explains some of the deaths. Understanding the other deaths is complicated by the Exxon Valdez oil spill (March 1989) and uncertainties about the causes and times of the deaths. For AB pod, possible factors involved in the post-spill mortalities are delayed effects of bullet wounds, continued shooting, oil exposure, and consequences of being orphaned. For the AT1 group, possible factors are oil exposure, small population size, old age, and high-contaminant burdens. An analysis of possible effects of inhalation of volatile organic compounds, contact with the oil slick, and ingestion of oil with water or prey did not reveal route(s) of exposure that could explain the mortalities. The cause(s) of the killer whale deaths recorded following the oil spill remain uncertain.

在 1985 年至 1990 年期间，阿拉斯加威廉王子湾的两组虎鲸出现了异常高的死亡率，而另外七组则没有。受影响的是 AB pod，阿拉斯加南部常驻（吃鱼）虎鲸种群的一部分，以及 AT1瞬变（吃海洋哺乳动物）种群，这是一个非常小的、生殖隔离的种群，最后一次繁殖是在 1984 年。 1985 年 - 1986 年，几名 AB 吊舱成员被渔民射杀，以保护他们的渔获物免受掠夺，这解释了其中一些死亡事件。埃克森瓦尔迪兹号使了解其他死亡事件变得复杂石油泄漏（1989 年 3 月）以及死亡原因和时间的不确定性。对于 AB 吊舱，与泄漏后死亡相关的可能因素是枪伤的延迟效应、持续射击、石油暴露以及成为孤儿的后果。对于 AT1 组，可能的因素是接触石油、人口规模小、年老和高污染物负担。对吸入挥发性有机化合物、与浮油接触以及将油与水或猎物一起摄入可能产生的影响进行的分析并未揭示可以解释死亡原因的暴露途径。石油泄漏后记录的虎鲸死亡的原因仍然不确定。