Fishing in Bahia is an activity that has been exploiting a high diversity of teleost fish for centuries (Olavo et al. 2005; Ott 1944). Regional shark catches occur mainly on top of wooden sloops 10–13 meters long equipped with artifacts as longlines and gillnets (locally known as "esperas"). Barbosa-Filho et al. (2014) described these arts of fishing in detail. These boats capture both on the external continental shelf and in the oceanic zone (eight to 70 miles off shore) at 20 to 180 meters deep. In southern Bahia, the increase of the number of boats and the low selectivity of fisheries have greatly affected the stocks and compromised the viability of local fisheries in recent decades (Olavo et al. 2005). Nevertheless, due to the recent regional monetary appreciation of shark fins, there was an increase in the shark fishing efforts and, consequently, on the catches of these fishes.
Based on the information collected on the interviews, small cetaceans captured are regionally used as bait for longline shark fishery. In addition, eight (12.1 %) respondents reported having consumed the meat of these animals. In spite of 81.5 % (n = 53) of the fishermen be aware of dolphin use as bait, only 24.2 % (n = 16) admitted to have done this practice. However, 56.9 % (n = 37) of fishermen interviewed know at least one fisherman who had captured dolphins intentionally and only eight (12.1 %; all from Canavieiras community) admitted that have already had killed dolphins directly by using harpoon, that are usually ordered and made in regional sawmills. Among these, only three admitted to have harpooned dolphins recently, while others mentioned the practice in the past. However, this is probably an underestimation since to admit a recognized illegal activity during an interview is expected to be uncommon. Some fishermen were uncomfortable to speak about dolphin mortality as they were aware of the Federal Law (n° 7.643/87) which prohibits the capture (intentional or not) and harassment of any marine mammal in Brazilian waters. It is unknown when and how the practice of intentionally dolphin capture to use as bait have begun in the region.
The description of the dolphin harpooning is presented below. When a group of dolphins is bowriding the vessel, the largest animal is identified and a hand-held harpoon is projected at its dorsal region. Its tip is made of metal and has a wooden pole. The harpoon is tied to a thick cotton line about 400 meters long that is attached to a floatable plastic container. As the harpooned dolphin swim away of the vessel, the line is released. When the distance between the dolphin and the vessel reaches its maximum length, the container is dropped at the sea and is followed by the vessel until the animal stops swimming. When the dolphin is retrieved on board the vessel, it is stabbed and cut with a knife. Its pieces are put in hooks of longline and used as bait for sharks. It was also reported that in some occasions dolphin pieces are tied at gillnets in order to attract sharks. It was not possible to verify the pieces of the captured animals, since fishermen immediately utilized the bubbler and discard the skeleton and viscera motivated by the concern of being charged by official agencies.
Although the description of the target species resembles a small/medium-sized Delphinidae, fishermen were not able to identify it at specific level. They named it “toninha”, “golfinho” and/or “boto”, lexemes applied by Brazilian fishermen to a wide range of small cetaceans (Souza & Begossi 2007). The continental shelf where the fishery takes place is inhabited mainly by three small cetacean species: the Guiana dolphin Sotalia guianensis (Van Bénéden 1864), the bottlenose dolphin Tursiops truncatus and the rough-toothed dolphin Steno bredanensis (Lesson 1828). The distribution of oceanic dolphins such as clymene dolphins Stenella clymene and smaller blackfishes (Feresa and Peponocephala) may also overlap with the fishery ground. In this sense, the identity of the species still deserves more investigation.