Salmon (Salmo salar)

 

The Baltic Sea carries populations of Atlantic salmon that have been practically isolated from the Atlantic for thousands of years. Salmon spawn in rivers and the progeny stays in the rivers for a period of 1-5 years depending on how far north the river is situated. Most salmon migrate in a post smolt stage to the main feeding areas in the Main Basin and return to their home rivers after 2-4 years. In the sea salmon feed mainly on sprat and herring.

 

The Baltic salmon is exploited in the off shore fishery by the use of drift nets and long lines. In the coastal areas the most common gears used are trap nets and a non commercial fishery with ordinary nets. In rivers seine nets and sport fishing are the most abundant methods.

 

In at least 60 Baltic rivers wild salmon populations were spawning in the middle of the 19th century. Today a majority of the Baltic rivers are unsuitable for salmon due to dammings, mainly for hydroelectric power production. This prevents the spawning migration, by diverting the rivers to a chain of water magasins and thus destroying the fast running river stretches suitable for wild salmon populations. In some of the rivers not dammed, water pollution can prevent a full utilisation of the potential production capacity. The recruitment to the total Baltic salmon stock now consists of about 90% compensatory reared salmon, released in the smolt stage. The present wild populations are very week due to a harvest pattern based on the status of reared populations but simultaneously overexploiting the wild salmon. Besides this long term decline caused by damming, water pollution and the fishery, an environmentally related syndrome named M74 has since the beginning of the 1990s caused a major reduction in the smolt production in most parts of the Baltic. In hatcheries the syndrome could be balanced with a treatment with Thiamine, hardly possible for practical and economic reasons in rivers with wild salmon. During years 1997-99, IBSFC took a number of resolutions to prevent further decline and to promote a recovery of the populations to at least 50% of the best estimate of the potential. The most efficient action taken was definitely the reduction of the salmon quota in the Baltic. In the very late 1980s, the off shore and coastal fishery captured not less than 1 million salmon annually. The present quota (for year 2000) is set to 450 000, a slight increase from the lowest point of 410 000 fish (1997-99).

 

Wild populations

 

The number of salmon parr in rivers with wild salmon is now more than doubled compared to the years in the mid 1990s. The number of wild smolts estimated to leave rivers in year 2000 is almost double the best recorded since the early 1980s. Also number of spawners entering rivers with wild salmon have increased. Thus, the catches in rivers of wild salmon in the late 1990s has more than tripled compared to the late 1980s, this in spite of the heavy losses of alevins in the middle 1990s due to the M74 syndrome. These smolt year classes have during later years been the base for the salmon run to rivers.

 

Reared populations

 

The production of reared salmon smolt has been above 5 million for several years. Of these, some 3,5 million are released due to legal obligations as a compensatory measure for a lost production due to hydro electric production. After release, reared smolt have the same life pattern in the sea as wild smolt and in most rivers the smolt rearing is based on collected eggs from migrating spawners, returning to the river of release. In Finland the annual production of about 2 million salmon smolt is based on broodstocks held in hatcheries. In this context it must be noted that salmon populations reared for compensatory purposes still carry unique and valuable genetic characteristics.

 

Salmon fishery

 

The fishing pattern of salmon has changed substantially during this century. The total annual catch levels were about 1500 tonnes in the 20ies and 30ies; salmon were caught in rivers, river mouths and off shore. Before WW2 only about 1/3 of the fishery took place off shore. After WW2, the off shore fishery expanded, due to development in fisheries techniques (both boats and gear) to take in the late 1980s around 85% of the total catch. Besides the change in fishing pattern, total catch increased to around 5000 tonnes in the 1980s. Bigger catches are based on the increased smolt releases. This expansion could take place as the reared part of the stock was less sensitive to exploitation than the wild component of the stock. After the adoption of a TAC for salmon in the Baltic Main Basin and the Gulf of Bothnia the catch levels have decreased substantially and are for 2001 limited to a total catch of 450 000 fish which corresponds to some 2 000 tonnes.

 

Management of salmon in the Baltic area

 

The status of Baltic salmon has been discussed since the beginning of this century and some national efforts to regulate the fishery have been taken. The establishment of IBSFC (1974) provided for international and more effective management. This body now manages Baltic salmon as two units, salmon in the Gulf of Bothnia and the Main Basin as one and salmon in the Gulf of Finland as the other. The management decisions are normally based on advice given by ICES. Since the early 1990s the effective part of the regulations is a TAC in numbers. The TAC level adopted is now based on the need of the wild salmon populations. Besides the measures adopted by IBSFC, to protect the wild populations, additional national regulations aiming to direct the fishery to harvest reared populations are implemented.

 

To monitor the development and create even more specific rules for the management of the Baltic salmon, a detailed "Salmon Action Plan 1997-2010" was adopted by IBSFC in February 1997. For full text of this Plan, see "Documentation / Resolutions".