A genetic analysis based on mitochondrial DNA control region sequences was conducted to investigate both species identity and populations genetic structure of South American Bryde's whales. The genetic analysis was based on historical, biopsy and stranding samples from Chile (n= 10) and Brazil (n= 8). For comparative purposes published sequences of the Bryde's whales from different localities of the Indian and Pacific Oceans (including Peru, n= 24) were incorporated into the analysis. Results of the phylogenetic analysis identified the Bryde's whales of South America as Balaenoptera brydei. No statistically significant genetic differentiation was found between Chilean and Peruvian Bryde's whales. However, striking differences were found between western South Atlantic (Brazil) and eastern South Pacific (Peru and Chile) animals. In addition, striking genetic differences were found between all South American localities and those from the western North Pacific, Fiji and Java. These results suggest movement of B. brydei in the eastern South Pacific in the latitudinal range corresponding to Chile and Peru. These results also suggest no or very limited mov ement of whales between the South Pacific and the South Atlantic Oceans. This is consistent with the notion that B. brydei is not distributed further south of approximately 40ºS on both sides of South America.

Surface feeding behavior of 37 identified humpback whales in the Magellan Strait are reported with the aim of describing feeding behavior and investigating whether differences in prey type determine the feeding strategy in this area. A total of three lunging and one bubbling behaviors are reported, of which two ('single straight-line bubble curtain' and 'sub-surface skimming') are novel behaviors for this species and each feeding behavior tended to be consistent in regards to the prey species available at a given time. However, our data set did not contain a sufficient sample size to fully interpret this association with the available prey species.