Wild smolt production continues to be the primary measure used in the management of Baltic salmon. Current production of wild salmon smolt is estimated to be at approximately 85% of its total potential across all Baltic Sea rivers. To evaluate salmon stocks, a Bayesian modeling framework is applied, which provides projections under different fishing scenarios. The use of this modeling is essential for informing management strategies and supporting the long-term sustainability of salmon populations.
In regard of sea trout, assessment methodologies and alternative management strategies are still in development. While some wild sea trout stocks have reliable smolt production estimates, the total wild smolt production for the entire Baltic Sea remains unknown. The Workshop on Sea Trout (WKTRUTTA) has been actively working on improving the assessment process and identifying appropriate management measures.
Salmon catches have been on a continuous decline since the 1990s. By 2023, commercial salmon fishing was largely restricted to the Gulf of Bothnia, the Åland Sea, and the Gulf of Finland. The gradual reduction in catches is partly attributed to regulatory measures aimed at protecting stocks, as well as environmental factors affecting salmon survival rates. In order to support declining wild stocks, hatchery-reared smolts continue to be released into the Baltic Sea. In 2023, approximately 3.6 million hatchery-reared smolts were released, supplementing the estimated production of 3 million wild smolts naturally.
One of the major concerns for salmon populations is post-smolt survival. Since the mid-2000s, the survival rate of wild post-smolts has typically fluctuated between 10% and 20%. However, a sharp decline was observed in 2021, when the survival rate dropped to a low of 7,7%. Over the long term, hatchery-reared smolts have consistently shown lower survival rates compared to wild smolts, raising concerns about the overall effectiveness of stocking programs in replacing lost natural production.
Changes in environmental conditions, such as sea temperature and prey availability, are influencing salmon migration patterns and survival, compounded by pressures from mixed-stock fisheries. These shifts, alongside ongoing habitat degradation, migration obstacles, and pollution, underscore the need for adaptive, stock-specific management strategies. Some river populations remain particularly vulnerable, highlighting the importance of targeted conservation efforts. Rebuilding measures, including fisheries restrictions, habitat restoration, and the removal of migration barriers, are crucial to improving the natural reproductive success of salmon and sea trout.
Misreporting of catches remains a challenge, especially concerning the classification of salmon and sea trout. There is evidence to suggest that some sea trout landings may actually include misreported salmon, which creates uncertainty in assessing the actual status of sea trout stocks. This issue complicates stock assessments and hinders the effectiveness of management strategies.
Sea trout stocking efforts have remained consistent, with approximately 3.5 million hatchery-reared smolts released annually in recent years. Despite these efforts, the overall wild smolt production remains poorly quantified, making it difficult to assess the long-term sustainability of sea trout populations in the Baltic Sea.
With a view to the future, management efforts will need to focus on improving survival estimates, adjusting stock assessments, and implementing strategies to mitigate the environmental threats facing salmon and sea trout populations. Improving and strengthening data collection on wild sea trout production, and addressing misreporting issues should be taken into consideration to ensure the effectiveness of future management actions.
