1. Ship strikes are one of the major threats to large whales worldwide. The potential impact from increasing vessel traffic therefore is a concern for the future of the Brazilian humpback whale (Megaptera novaeangliae) population. 2. In order to evaluate the risk of collision between large vessels and humpback whales along coastal shipping routes in the region of the Abrolhos Bank – the most important breeding ground for the species in the south-western Atlantic Ocean – commercial vessels were used as platforms of opportunity to monitor the coastal shipping routes. 3. Humpback whale density along coastal routes was estimated through multiple covariate line-transect 'distance sampling'. The number of potential collisions per year was estimated using a model based on vessel size and speed, track lengths, population density and the surfacing behaviour of whales. 4. During the peak of the 2011 breeding season, whale density on the coastal route between Belmonte and Caravelas was estimated to be 0.085 whales km -2 and between Caravelas and Barra do Riacho, 0.023 whales