Caddisflies
Gammarids
The Authie runs quietly along the old border between Picardy and the Pas-de-Calais, from Coigneux down through Auxi-le-Château and Dompierre to the Baie d'Authie where it meets the Channel in a wide tidal mouth. It's the Canche's less-famous sister — same geology, same hatches, less pressure, and a surprising number of genuinely large fish in the lower meadows where the valley broadens. Wild brown trout through the upper reaches, grayling in the steadier pools, and a sea trout run that brings decent fish up from the bay in autumn. The mayfly comes off around the third week of May; the evening sedge hatches through June can be almost absurd. Much of the best water is private estate, but the AAPPMA beats around Auxi are good and unfussy. A river that rewards knowing it.
In chalk-spring and karst trout systems, generally stable temperatures broaden olive and other mayfly activity from early spring into autumn, with strong evening caddis, steady subsurface scuds and buzzers where clear groundwater and weedbeds develop, and terrestrials from meadow and woodland banks rounding out the food calendar, depending on how fast each river drops and clears after rain.
- Chalk