However, dolphins in these areas can also coexist with humans. For example, in the town of Laguna in south Brazil, a pod of bottlenose dolphins resides in the estuary, and some of its members cooperate with humans. These cooperating dolphins are individually recognized by the local fishermen, who name them. The fishermen typically stand up to their knees in the shallow waters or sit in canoes, waiting for the dolphins. Now and then, one or more dolphins appear, driving the fish towards the line of fishermen. One dolphin then displays a unique body movement outside the water, which serves as a signal to the fishermen to cast their nets (the entire sequence is shown here, and a detailed description of the signal's characteristics is available here). In this unique form of cooperation, the dolphins gain because the fish are disoriented and because the fish cannot escape to shallow water where the larger dolphins cannot swim. Likewise, studies show that fishermen casting their nets following the unique signal catch more fish than when fishing alone, without the help of the dolphins. The dolphins were not trained for this behavior; the collaboration began before 1847. Similar cooperative fisheries also exist in Mauritania, Africa.