What is the most common age of sea trout at first spawning?

In British and Irish rivers, most sea trout seem to become sexually maturity at overall age 3+, although there is wide variation (1+ to about 6+).  Some return from the sea to spawn in their first sea year, most appear in their second, some in their third and more rarely in their fourth.  Sea age at maturity appears to be influenced by marine growth rate, but also may be affected by earlier growth pattern as parr. Mean sea age at maturity has been found to be 3 – 4 years in north Norwegian populations versus 1 – 2 years in France and Spain.