Evidence of feeding by the humpback whale ( Megaptera novaeangliae) in mid-latitude waters of the western South Atlantic

Abstract

The humpback whale, Megaptera novaeangliae, is a highly migratory species distributed in all oceans of the world. It has been indicated that humpbacks do not normally feed while in their tropical breeding grounds or during migration. Here we document the first evidence of recent feeding in southern Brazil, a mid-latitude area in the western South Atlantic Ocean. On 4 April 2002, the carcass of a 7.27 m humpback whale incidentally caught in Rio Grande do Sul, southern Brazil, was collected. Investigation of the stomach contents revealed that the whale had ingested large amounts of the small shrimp Acetes americanus (Decapoda: Sergestidae), as well as planktonic larvae of unidentified species of Brachyura. Applying the average swimming speed recorded for this species on the western South Atlantic coast, and the mean time passage of the food through the digestive tract of another balaenopterid, we can estimate that the feeding area is some 20.7 nautical miles off the coast. This demonstrates that the productive waters of the southern and south-eastern Brazilian coast may occasionally be used by humpback whales as an opportunistic feeding zone, and adds the shrimp A. americanus as a new prey species for the humpback whale. There is evidence that other baleen whales may also sometimes feed in this region.