The harbour was protected by a small rocky island, Tristan's island, a military harbour in the Middle-Ages and... a crooks’ lair, during war of religion, with the terrible La Fontenelle! Yes, Douarnenez depending of that island, so they called the city Douar Enez, "Island’s land" in Breton...
The harbour’s activity began in the 1st century with salted fishes (we found tanks dating back to the 3th century) and with the garum’s producing. The garum? A kind of vinegar blend with fermented fishes juice.
Pline said that to make garum, we had to let anchovy's heads and intestines rotting then we added salt and herbs. A very expensive sauce, for special occasions!
Then, the small city became a very important fishing port. In 1851, the first fish canning factory was created, thanks to the brand new sterilization process founded by Appert: the invention of the can!
Yes, Douarnenez is THE city of sardines! The harbour made sardines cans since centuries. But in the 19th century, we had 1 000 sardines boats and about 30 factories, like Connétable, a famous French brand created in 1853! They called people from Douarnenez who worked in those factories (especially women) penn sardin, "sardines’ heads" in Breton!
But decline came in the beginning of the 20th century: sardines split from the Breton waters, they wanted to see if the sea was bluer elsewhere, probably... Nowadays, they use foreign sardines but they still preserved them into tins: so the small harbour is the capital city in Europe for fishes canning factory!
In Rosmeur harbour, trawlers replaced the small schooners. Rosmeur is the fishing port with its quays surrounding by coloured houses. Port-Rhu is the trading harbour, with quays raised in the 19th century.