The franciscana dolphin (Pontoporia blainvillei) is a coastal dolphin endemic to the western South Atlantic Ocean. The dolphin is listed as vulnerable in the IUCN Red List, with incidental catches in gillnet fisheries the greatest conservation concern for this species. Insights into the feeding habits of this dolphin are essential to understand its distribution, movements and use of habitat, which are fundamental for effective management of the species. The feeding habits of franciscana dolphins were investigated from analyses of stomach contents of animals incidentally caught by two fishing operations from southern and northern regions of the southern Brazilian coast. In this study we investigate the existence of intrapopulation (sexual maturity and sex-related) variation in the diet of the franciscana dolphin, evaluating the spatial (northern and southern geographic areas) and seasonal influences. The analyses were based on Linear and Generalized Linear Models (LM and GLM). The majority of identified prey species were bottom-dwelling teleosts and the squid Doryteuthis sanpaulensis. The most important prey differed spatially and seasonally between northern and southern regions of the study area, and our results revealed significant differences between sexes and sexual maturity stages, mainly related to prey species sizes. This variation might indicate differences in prey selection, availability or habitat use patterns among these groups. In any case, these dietary differences are likely to minimize intraspecific competition for food resources, and/or indicate spatio-temporal variation in prey availability.

中文翻译：

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巴西南部附近的 francisscana dolphin (Pontoporia blainvillei) 饮食的种群内变化

弗朗西斯卡纳海豚 (黑斑病) 是南大西洋西部特有的沿海海豚。海豚在 IUCN 红色名录中被列为易危物种，刺网渔业中的偶然捕获是该物种最大的保护问题。深入了解这种海豚的摄食习惯对于了解其分布、活动和栖息地的利用至关重要，这对于有效管理该物种至关重要。通过对巴西南部海岸南部和北部地区的两次捕鱼作业偶然捕获的动物胃内容物的分析，研究了弗朗西斯卡纳海豚的摄食习惯。在这项研究中，我们调查了弗朗西斯卡纳海豚饮食中存在的种群内（性成熟和性别相关）变异，评估空间（北部和南部地理区域）和季节影响。分析基于线性和广义线性模型（LM 和 GLM）。大多数已确定的猎物物种是生活在海底的硬骨鱼和鱿鱼圣保尔金丝雀. 研究区北部和南部地区最重要的猎物在空间和季节上存在差异，我们的研究结果显示性别和性成熟阶段之间存在显着差异，主要与猎物种类大小有关。这种变化可能表明这些群体在猎物选择、可用性或栖息地使用模式方面存在差异。无论如何，这些饮食差异可能会最大限度地减少种内对食物资源的竞争，和/或表明猎物可用性的时空变化。