Pilchard rings...couldn't believe it the first time I saw it, but it works (i think they're illegal now)
Basically a series of light wire rings around 1" in diameter, hooked together like a chain. A length of red yarn is woven through top to bottom and a weight is attached to keep the "chain" vertical. You hook this to a line and hang it over the side of a pier. Pilchards strike at the red yarn and gill net themselves in the loops. Different size rings catch different size bait.