The Clyde has a long history of fishing. Dating back to the 1800’s, the Clyde herring fishery was one of the most important in Scotland. Boats from all over Scotland would travel to Arran to participate. 
Up until the last century, Lochranza was one of the main fishing centres on the West Coast of Scotland, with over 400 men making a living from fishing herring. The fishery was a hard life, sailing on a Monday and often not returning until Saturday morning by when the mend would have been soaked through for days. Big fishing fleets would leave the island and come back laden with herring to be traded or sold, if not done so elsewhere. 

Have a look at the papers published about the herring fishery in the Clyde.