Atso Romakkaniemi, Finnish Game and Fisheries Research Institute
The most abundant of such runs was observed in the river Tornionjoki, which flows on the border of Finland and Sweden: over 100 000 salmon spawners entered the river in 2014. This spawning run appears to be more abundant than any other currently recorded one that takes place across the rivers of the world in which the Atlantic salmon spawn.
The extraordinary speed of recovery amongst salmon populations spawning in the northern Baltic rivers serves as a great success story of fisheries management.
In the 1990s these populations were severely depleted, mainly due to a long period of overfishing. For instance, the yearly spawning runs into the river Tornionjoki comprised just some thousands of salmon and the corresponding smolt runs (i.e. juveniles leaving the river for a feeding migration) about 100 000 smolts. Now the proliferated spawning produces about 2 million smolts annually, and the population size is approaching the carrying capacity of the river. The abundance of spawners has increased in jumps, with the last major one taking place after 2010.
This positive development is a result of the multiannual salmon fisheries management plan, the 'Salmon Action Plan' (SAP), adopted by Baltic countries in 1997. The principal aim of the SAP was to increase natural reproduction in wild salmon populations to at least 50% of the estimated carrying capacity of rivers by the year 2010. The management goal led to decreased fishing intensity and to a five-fold increase in natural recruitment during the SAP period.
Since the termination of the plan in 2006, ICES has provided a consistent advice for the Baltic salmon fisheries aiming to a continued recovery of Baltic salmon populations.
The development in the northern Baltic has been contrary to the generally decreasing trend in abundance of Atlantic salmon in other areas of its range of distribution, including southern Baltic. The natural survival of salmon at sea has been widely decreasing during the past decades, which has led to successive decreases in spawning runs and reproduction.
The natural survival of salmon has also decreased in the Baltic Sea, but a significant decrease in exploitation has allowed the northern populations to recover. The long-term prospects for the viability of wild Atlantic salmon populations are in general worrying, however, due to factors like expected unfavorable ecosystem changes induced by climate warming.
Copyright: Ville Vähä