Green’s Dictionary of Slang

the practice of angling for geese with a hook and line, the bait being a worm or snail.

1839		H. Brandon Dict. of the Flash or Cant Lang. 165/2: Snaggling – driving geese into a corner in a stubble-field; the man [...] throws among them a line with a hook and a worm at the end; the goose swallows it, is pulled away and bagged.
1859		Matsell Vocabulum 82: snagling [sic] Stealing poultry by putting a worm on a fish-hook, thereby catching the fowl, then twisting their necks and putting them in a bag.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.