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.

A dual stable isotope approach (δ13C and δ15N) was used to investigate inter- and intra-specific variations in feeding ecology and habitat use of 7 delphinids from coastal/estuarine, continental shelf and offshore marine environments from southern Brazil: Tursiops sp., Orcinus orca, Stenella frontalis, Steno bredanensis, Delphinus delphis, Pseudorca crassidens and Lagenodelphis hosei. Teeth from 50 specimens acquired from stranded animals were analysed in this study. Tursiops sp. and O. orca are the most coastal species, and had the highest δ13C values followed by the continental shelf species S. frontalis, S. bredanensis and D. delphis. Lagenodelphis hosei showed the lowest δ13C value, demonstrating its typical offshore habitat. One group of P. crassidens had the lowest δ15N values, indicating their low trophic level feeding habit while two specimens of the same species showed the highest mean nitrogen isotope value. This first study on stable isotope values of delphinids from southern Brazil provides substantial new information about the trophic ecology, habitat use and feeding environments of these animals.

The string eel Gordiichthys leibyi is reported for the first time from the western South Atlantic, based on a specimen taken from the stomach of a yellowtail snapper collected off the coast of Mucuri, Bahia, Brazil.