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How big can sea trout grow?

Specimens weighing over 10 kgs have been caught in Scottish and Welsh rivers, but the place to find really big ones (perhaps 15+ kg) is Tierra del Fuego, at the southern tip of South America. Another area where sea trout growth is very fast and a large size can be reached is the Baltic Sea. In the UK, big sea trout can be relatively young, fast-growing, individuals (perhaps 4 – 6 years old) that have spent two or more years at sea before returning, or slower-growing, repeat spawners which have reached large size by living longer. Multiple spawning (mostly annual) is much more common among sea trout than among salmon. Prior to the 1990s, when local stocks collapsed, old sea trout weighing several kilos were common in the rivers and lochs of north-west Scotland.  Sadly, few of these fish are found there now.  In this region, both longevity and annual marine growth had fallen significantly by the end of the 1900s, with huge implications for both fisheries and egg deposition levels. However, large, young, fast-growing sea trout remain a feature of rivers entering the southern North Sea and English Channel, from rivers such as the Tweed, Coquet and Wear. Wales also remains a stronghold for fast-growing, large sea trout, some of which survive to spawn several times.