The shape (derived from landmark-based geometric morphometrics), condition (Fulton index) and diet (determined through gut content analysis) were described for the pike icefish Champsocephalus esox (Channichthyidae) from Última Esperanza sound, south-west Patagonia, Chile. Based on the length-weight relationship, females were heavier at length than males. Nevertheless, the Fulton index was similar between males and females. The morphospace of C. esox showed high intraspecific variability in the dorsoventral position of the tip of the snout, anus and the ventral insertion of the pectoral fin, as well as the anteroposterior position of the premaxilla, opercle and anus. This indicates the existence of phenotypic plasticity, leading to specimens with larger jaws and heads but shorter trunks, or specimens with shorter jaws and heads but larger trunks. This phenotypic plasticity was independent of size and sex. The feeding incidence was similar between sexes (34.1% and 47.2% for males and females, respectively). Diets consisted of only fish, small notothenioids of the genus Patagonotothen (P. tessellata, P. cornucola and P. sima), showing similarities between males and females. Finally, C. esox is the second notothenioid species, and the first outside of Antarctica, to display phenotypic plasticity in its body shape.

中文翻译：

---

梭子鱼 Champsocephalus esox（Teleostei: Channichthyidae）的形状、状况和饮食：表型可塑性的证据？

描述了梭子鱼的形状（源自基于地标的几何形态测量学）、状况（富尔顿指数）和饮食（通过肠道含量分析确定）大头鱼（Cannichthyidae）来自智利巴塔哥尼亚西南部的Última Esperanza sound。根据身长-体重关系，女性的身长比男性重。尽管如此，男性和女性的富尔顿指数相似。的形态空间C. esox显示出在鼻子尖端的背腹位置，肛门和胸鳍的腹侧插入以及前上颌骨，鳃盖和肛门的前后位置的高种内变异性。这表明存在表型可塑性，导致标本具有较大的颌骨和头部但躯干较短，或标本具有较短的颌骨和头部但较大的躯干。这种表型可塑性与大小和性别无关。两性之间的摄食率相似（男性和女性分别为 34.1% 和 47.2%）。饮食只包括鱼，该属的小鱼巴塔哥诺托森(P. tessellata,P.cornucola和P. sima)，显示男性和女性之间的相似性。最后，C. esox是第二个在其体形中表现出表型可塑性的物种，也是第一个在南极洲以外的物种。