April 2019

After hatching, the alevins stay in their gravel nests for several more weeks, feeding on their yolk sacs. They ‘swim up’ from the gravels in April in order to start feeding; at this stage they are known as ‘fry’. This is a particularly hazardous stage in their lives as they disperse and establish territories in order to seek shelter from predation and high flows, while also taking advantage of food drifting past in the currents. Many fry are lost in the first few days and weeks after emerging.

Many older juveniles, known as ‘parr’, that have typically spent 1 or 2 years growing in freshwater, start the transformation process that enables them to adapt to sea-water. The fish become silvery, abandon territories and start to shoal up and migrate downstream as ‘smolts’. The main smolt run typically takes place in April in more southerly rivers, but later in cooler rivers further north.