We tested the hypothesis of the proportion of higher chlorinated biphenyl (PCB) congeners increasing with increasing trophic level by comparing the respective PCB homologue distributions in an omnivore, white sucker (Catostomus commersoni), and a top predator, coho salmon (Oncorhynchus kisutch), from Lake Michigan. Adult females had the same congener and homologue proportions of total PCB concentration (ΣPCB) as adult males in both species. Hexachlorinated congeners comprised the largest proportion (32%) found in white sucker, followed by heptachlorinated (21%) and octochlorinated (18%) congeners. In contrast, pentachlorinated congeners comprised the largest proportion (33%) of ΣPCB found in coho salmon, followed by hexachlorinated (26%) and tetrachlorinated (24%) congeners. Coho salmon contained significantly higher proportions of tri-, tetra-, and pentachlorinated congeners, whereas white sucker contained significantly higher proportions of hexa- through decachlorinated congeners. Our results were opposite of the hypothesis of greater degree of PCB chlorination with increasing trophic level, and supported the contention that the PCB congener proportions in fish depends mainly on diet, and does not necessarily reflect the trophic level of the fish. Our results also supported the contention that diets do not vary between the sexes in most fish populations.

中文翻译：

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来自密歇根湖的White Sucker和Coho Salmon中的PCB同系物和同系物分布

我们通过比较杂食性白吸盘（Catostomus commerson i）和顶级捕食者银大麻哈鱼（Oncorhynchus kisutch），来自密歇根湖。在这两个物种中，成年雌性的总PCB浓度（ΣPCB）的同源物和同源物比例与成年雄性相同。六氯同类物占白色吸盘的最大比例（32％），其次是七氯（21％）和八氯（18％）同类物。相反，在银大麻哈鱼中，五氯代同源物占ΣPCB的比例最大（33％），其次是六氯（26％）和四氯（24％）同类物。银大麻哈鱼含三氯，四氯和五氯同类物的比例明显较高，而白油菜则含有六氯至十氯同类物的比例较高。我们的结果与营养水平越高，PCB氯化程度越高的假设相反，并支持以下论点：鱼类中的多氯联苯同源物比例主要取决于饮食，并不一定反映鱼类的营养水平。我们的结果也支持大多数鱼类种群的性别之间饮食没有差异的观点。