Another segment from the BBC's The Human Planet (trailer here):
On one day of the year the Dogon people of Mali can fish in the sacred water of Lake Antogo. It's every fisherman for himself as the lake is emptied in minutes.Via Metafilter, where I found a link with some context:
Mali, and the village of Bamba in the north of Dogon country, where, since the beginning, that is to say since the Dogon arrived in this magic land in Mali long ago, a sacred fishing ritual is practiced, known as “Antogo”. A small yet very powerful lake rests just beneath Bamba. Antogo is celebrated only once a year, and only on this day is fishing allowed on the lake, it is strictly prohibited on any other day of the year...
Just about 30 minutes later a gunshot marks the end of the ritual. All fish captured will be put together and given to the oldest man of Bamba, who will ensure proper distribution among all villages.