How the Dutch tracked the Spanish fleet before the Downs

How did the Dutch learn where the Spanish fleet was moving before the Battle of the Downs?

English fishermen were the likely source of regular reports, possibly helped by Protestant sympathy for the Dutch cause.

The Dutch appear to have received repeated updates while the Spanish hugged the English side of the Channel. English fishermen are identified as the most likely intermediaries, possibly because some sympathized with the Protestant Dutch cause. That motive remains a plausible explanation rather than a proven fact. Coastal information networks could shape a major fleet action before formal naval reconnaissance systems existed.