Brown trout in the Jaén sierras are an anomaly — native fish in a landscape that doesn't immediately suggest them, hundreds of miles south of the Cantabrian rivers and the country most people think of when they think of Spanish trout. The Madera Bajo carries them through the upper Segura basin in water that stays cold from the sierra regardless of the season in the valley below. The fish are smaller than their northern counterparts. They are also wilder, and finding them is half of what the fishing is.

• Limestone karst