Fishermen from the Brazilian town of Laguna have developed a unique symbiotic relationship with dolphins: they rely on the intelligent creatures to help them catch fish! Studies have revealed that there’s a particular group of about 20 bottlenose dolphins that work alongside the fishermen, while the rest of the local dolphins prefer to look for food on their own.
The dolphins work together to herd groups of mullet towards the fishermen. They then use head- or fin-signals to alert the fishermen as to when and where the nets should be thrown. The system works well for both parties: neither could survive without the other. The fishermen get to catch all the fish they need, while most of the stray fish that manage to escape the nets swim right into the dolphins’ mouths. The water is so murky near Laguna that the fishermen could never catch fish as efficiently without the dolphins’ help. That’s why they only fish when the marine mammals show up.