Caddisflies
The Gave de Pau runs from Gavarnie down through Lourdes, past Pau, and joins the Gave d'Oloron at Peyrehorade to form the main Gave system — the salmon river of Béarn. Salmon fishing is closed across the Adour and Gaves basin under the 2026 prefectoral order. It is snowmelt-fed freestone with limestone character in the middle reaches, and the trout fishing is the reason to come. The upper valley above Lourdes is wild-trout country: limestone springs keep the water cold and the hatches coming through July and August. The AAPPMA network maintains multiple no-kill fly-only parcours, all barbless, and the stewardship is serious. Check the regulations before fishing.
A short, awaited early-season emergence arrives around 15:00, per departmental federation reporting — the insect itself has never been identified, so this is surface-activity evidence rather than a named hatch. OFB monitoring upstream of the Oloron confluence separately confirms a rich caddis and mayfly fauna (including Ephoron and Potamanthus among the mayflies), though it can't say which of them produces that afternoon rise.
- Limestone