In many areas of the world dolphins are viewed as competitors
to humans. However, Ayeyarwady dolphins in the Ayeyarwady River in Myanmar are revered by
local people and they provide direct economic benefits via their role in a cooperative fishery with cast-net
fishermen. The fishermen summon the dolphins by tapping the sides of the boat with a conical wooden pin.
If the dolphin “agrees” to help the fishermen, one animal slaps the water surface with its tail flukes. One
or two lead dolphins then swim in smaller and smaller semicircles, corralling the fish towards the shore,
while the other animals remain outside the guard against escapes. With a wave of the half submerged flukes,
the dolphins then deliver a concentrated mass of fish to the fishermen and “signal” then to
cast their net. Using the technique the fisher can catch as
much fish in a single net cast as they normally do during a whole
day of fishing without the dolphins. The dolphins
benefit from the activity by preying on fish whose movement
are confused by the sinking net and those that are momentarily stuck on mud bottom after the net is pulled
up. Then Ayeyarwady dolphins and cast-net fishermen using this fishing practice in the Ayeyarwady River
since a long time ago.
