Differences in reproductive allocation of male and female fishes could lead to sexual divergence in nutritional requirements, trophic ecologies, and metabolisms that may be reflected in isotopic compositions. We compared muscle C:N ratio, δ¹³C, and δ¹⁵N between mature females and males for eight fish species from 21 North American populations. We also compared isotopic compositions between muscle and ova in a subset of females to determine if observed sex differences may be associated with fractionation during oogenesis. Muscle δ¹³C and δ¹⁵N did not vary greatly between males and females for most species but significant differences were observed in walleye (Sander vitreus) and burbot (Lota lota). Among-individual variation in isotopic composition, estimated as dispersion in δ¹³C–δ¹⁵N space, did not differ significantly between the sexes. Ova had significantly higher C:N ratio and lower δ¹³C than female muscle in all species with the greatest contrast between tissues seen in burbot. Ova had significantly higher δ¹⁵N than female muscle in most species with the greatest contrast between tissues in walleye. Sex-based divergence in isotopic composition of northern fishes is most evident in lean-fleshed piscivores, and may be related to selective mobilization of nutrients from soma to ovaries.

雄鱼和雌鱼在生殖配置上的差异可能导致在营养需求，营养生态和代谢方面的性别差异，这些差异可能反映在同位素组成中。我们比较肌肉C：N比，δ ¹³ C和δ ¹⁵成熟女性和男性从21个北美人群8个种N之间。我们还比较了女性子集中肌肉和卵子之间的同位素组成，以确定观察到的性别差异是否可能与卵子发生过程中的分级分离有关。肌肉δ ¹³ C和δ ¹⁵ Ñ没有男性和女性对于大多数物种，但显著差异在角膜白斑，观察（之间变化很大桑德vitreus）和江鳕（洛塔洛塔）。其中个体在同位素组成的变化，在δ估计为分散¹³ C-δ ¹⁵ Ñ空间，没有两性之间显著不同。卵子有显著更高C：N比，降低δ ¹³比女性的肌肉下，在与在江鳕看到组织之间的最大对比度的所有物种。卵子有显著较高δ ¹⁵ ň比女性的肌肉中种类最多，在角膜白斑组织之间的反差最大。在瘦肉食肉动物中，北方鱼类同位素组成的性别差异最为明显，这可能与营养物质从体细胞到卵巢的选择性动员有关。