Habitat and Biology
Depth zone: Shelf (50 m - 200 m). Vertical distribution: Demersal/Benthic.
Together with other southeastern salmon stocks in the Baltic, the Atlantic salmon Salmo salar in the Gulf of Finland forms a stock complex that is genetically distinct from salmon in the western Baltic Sea and the Gulf of Bothnia, differences that mirror the postglacial colonization history. There are only a few small rivers left in the Gulf of Finland which could be defined as purely wild. In addition, natural reproduction exists in a few other rivers where stocking of reared salmon also occurs. The characteristic salmon life history includes spawning in autumn and a juvenile freshwater stage that lasts one to two years. Smolts then leave the rivers for a feeding migration at sea. Salmon from the Gulf of Finland take a great part of their feeding in the Main Basin area and are partly harvested there. Catches in the Gulf of Finland also consist to some extent of salmon originating from the Gulf of Bothnia. The Gulf of Finland salmon feed mainly on herring and sprat during the sea migration. Environmental influence on the stock
Wild production of salmon in the Gulf of Finland occurs in small rivers. Water level and flow conditions during the time for upstream migration and spawning are of importance for successful reproduction in these rivers. Environmental conditions have a marked effect on the status of salmon stocks. Problems in the freshwater environment play a significant role in explaining the poor status of stocks in many rivers in the southern Baltic Sea and the Gulf of Finland. In many cases, river damming and habitat deterioration have had a devastating effect on freshwater environmental conditions.
The reasons for the decrease in post-smolt survival are still unclear, but the post-smolt survival has been found to be negatively correlated with seal and smolt abundance, and positively correlated with the abundance of herring.
Jurisdictional distribution: Shared between nations
Considered a single stock: No
The salmon landings in the Gulf of Finland in 2011 were 47 t in the coastal fishery, less than 1 t in the offshore fishery, and 5 t in the river fishery (Tables 220.127.116.11 and 18.104.22.168). The total catch increased slightly from 44 t in 2010 to 52 t in 2011, but the total catch is still relatively low compared to previous years. The TAC has been gradually reduced since 1996 and is presently 15 thousand fish (Table 22.214.171.124). In 2009, 90% of the TAC was utilized, but in 2010 and 2011 only around 50% of the TAC was utilized. The fishery is also regulated by a number of national and international measures.
The catch distribution between offshore, coastal, and river catches in the Gulf of Finland has changed drastically in recent years. Exploitation has changed from targeting mixed stocks offshore to focusing on local stocks in coastal areas and in rivers. The coastal fishery with trapnets has moved from the outer archipelago to areas closer to the coast and river mouths. Trapnets with modifications to prevent seals entering the trap are in use in some parts of the coastal fishery and under development in others.
Effects of the fisheries on the ecosystem
|Catch distribution ||Total catch (2011) is 0.058 kt, where 90% are landings and 10% discards |
The current salmon fishery probably has no or only minor influence on the marine ecosystem. However, the exploitation rate on salmon may affect the riverine ecosystem through changes in species composition. There is limited knowledge on the magnitude of these effects.
ICES advises on the basis of precautionary considerations that catches of wild salmon should be kept to a minimum. To maintain a low bycatch of wild salmon in the coastal salmon fisheries, effort should be reduced in these fisheries. Additional measures to minimize catch of wild salmon in coastal fisheries close to the wild salmon rivers should be considered. Such measures could include relocation of coastal fisheries away from sites likely to be on the migration paths of Gulf of Finland wild salmon, relocating fisheries away from rivers and river mouths supporting wild stocks, and protection of wild salmon (from poaching) when they return to rivers. Also, reduction in exploitation in the fishery in the Main Basin needs to be considered as salmon from the Gulf of Finland to a large extent have the Main Basin as their feeding area.
Overall Assessment Results
Assessment ModelQuality consideration
Information about the exploitation rate of wild salmon in the mixed-stock fisheries is limited, and there is a lack of knowledge about the level of mixing of stocks during the migrations between the Gulf of Finland, Main Basin, and Gulf of Bothnia.
Establishment of an index river in the Gulf of Finland should be considered, where electrofishing and counting of smolts and spawners is regularly carried out.Scientific basis
No analytical assessment model has been developed for the Gulf of Finland salmon. The advice is based on a qualitative assessment, taking into account trends in parr densities, smolt production, and exploitation rates.
|Working group report ||WGBAST |
Management unit: YesManagement plans
No explicit management objectives have been agreed for Baltic salmon since the International Baltic Sea Fishery Commission (IBSFC) ceased to exist after 2006. In 2011, the EU Commission presented a proposal for the establishment of a multiannual plan for the Baltic salmon stock (COM/2011/0470 final), but the plan has not yet been accepted.
Biological State and Trend
Wild stocks: The only remaining native and self-sustaining salmon populations of the area exist in three Estonian rivers. These wild salmon populations are genetically different from each other, indicating that there are still native salmon stocks left, but there is also some evidence of straying among rivers. In two of the rivers (Kunda and Vasalemma), the estimated smolt production has been clearly below 50% of the potential in the last three years. In the third Estonian river (Keila) smolt production has increased significantly and the estimated smolt production has exceeded 50% of the potential production in the last two years. Electrofishing surveys indicate that parr densities vary considerably over time. In 2011, young-of-the-year parr abundance declined compared to 2010 in the Keila and Vasalemma rivers, but increased somewhat in River Kunda (Figure 126.96.36.199). River Keila is currently not considered to be in a critical state, whereas the situation is more precarious in the rivers Kunda and Vasalemma, where parr densities have remained at low levels and no apparent increasing trend has been observed.
Mixed stocks: The seven Estonian mixed salmon stocks in the Gulf of Finland (Purtse, Selja, Loobu, Valgejõgi, Vääna, Jägala, and Pirita) have been supported by smolt releases to a varying extent. Releases to the Vääna river were stopped in 2005. Since 2007 the river Kunda strain has been used in releases to the Selja, Loobu, Valgejõgi, Jägala, and Pirita rivers. The Narva strain is used only for releases to the Purtse and Narva rivers. From 2010 to 2011, abundance of young-of-the-year wild-born parr decreased in all of these rivers (Figure 188.8.131.52).
In River Luga in Russia, the annual natural smolt production has been estimated to vary between 2000 and 8000 smolts. Surveys also indicate some natural reproduction in the Russian river Gladyschevka. Both these populations are supported by long-term releases and there are no national plans to attain self-sustainable populations in these rivers. Because of pollution and damming of rivers wild salmon production disappeared in the 1950s in rivers on the Finnish side of the Gulf of Finland. Natural reproduction of returning salmon released as smolts has been observed in a suitable habitat in the lowest part of the River Kymijoki.
Reared stocks: Most of the salmon in the Gulf of Finland originate from smolt releases (Figure 184.108.40.206). Despite major releases, the catches have decreased considerably in the last few years, indicating a low post-smolt survival of reared salmon. Tagging results also provide evidence of decreased survival of reared smolts.
Source of information
The above excerpts are from the first two pages of the ICES advice, the supporting information to this advice can be read in full at the following reference:
ICES. Salmon in Subdivision 32 (Gulf of Finland). Report of the ICES Advisory Committee, 2012. ICES Advice, WGBAST 2012. http://www.ices.dk/committe/acom/comwork/report/2012/2012/sal-32.pdf