Current issues in stocking

Mortality of stocked salmon has risen

The number of salmon originating from hatcheries has decreased substantially in the Baltic Sea over the past 10-15 years. The most probable reason for this is increased post-smolt mortality during early sea migration, because the number of releases has not decreased. The decreased contribution of hatchery salmon to catches is clearly shown in recent genetic stock mixture analyses.

Salmon catches have declined

The decline in stocking results has been accompanied by a decrease in catches. The Finnish salmon catch was over two million kilos in the early 1990s, but has been only 0.5 million kilo in the period 2001-2006. Salmon fishing has decreased markedly, for example because of tightened regulations, but this does not explain such a big change in catch sizes. The national catch quotas have not been filled in the Gulf of Finland, nor in the Gulf of Bothnia or the Baltic Main Basin. In the Gulf of Finland, only half the quota has been filled.

At the same time, wild salmon stocks have recovered, and natural fry production is nowadays an important regulating factor for salmon fishing in the Baltic Sea. However, the increased production of wild salmon has not been able to compensate for the lack of stocked salmon.

Profitability of salmon releases has decreased

Along with falling catches, the economic profitability of salmon releases has decreased. In the early 1990s in the Gulf of Finland, 1-2 euros/catch kg were spent on rearing and stocking costs. During the period 1991-2001, the sum was 5.6-12.2 euros/catch kg, depending on the rearing method and age of the released smolt, and since 2001, there have been no signs of improvement.

If the costs of stocking are compared with the professional fishermen’s producer price of salmon (3.4 euros/kg), all salmon releases in 1999-2001 were unprofitable. When the net profit of non-commercial fishing is also taken into account (estimates taken from Simojoki river), stockings are partially profitable, with 2-year-old smolts giving the best results. However, it should be noted that the estimated profit of true recreational fishing in Simojoki, 21euros/per catch kg, may overestimate the profit in the Gulf of Finland, where subsistence fishing and household use of fish account for a larger part of the non-commercial fishing. For the release of the most inexpensive 2-year-old smolts(?) to be profitable, the net benefit of non-commercial fishing in the Gulf of Finland should be at least 9 euros/catch kg

Weak results in sea trout stockings too

Since the early 1990s, the profitability of sea trout releases has clearly decreased. The trend is the same in all sea areas, but the most dramatic drop has taken place in the Gulf of Finland. Contrary to salmon, natural smolt production has also further decreased in most of the coastal trout rivers.

On the basis of catch and release statistics, in the early 1990s, 2-4 euros were spent on trout releases per catch kilogram. In 2002, 4-20 euros, depending on the sea area, were needed to produce the same result. In 2002, the situation was best in the Archipelago Sea and the Baltic Main Basin area (4 euros/catch kg), and worst in the Gulf of Finland (20 euros/catch kg).

Too strong non-commercial sea fishing of trout is probably the principal reason for the weak natural smolt production and unsuccessful releases of the species. Since 1995, the situation has deteriorated still further because of decreasing post-smolt survival rates of released smolt. During the 1990s and early 2000s sea trout have been caught more efficiently and at a younger age than before. More than half the sea trout are caught during their first sea-year. Catching of young, undersized fish has increased both in the Gulf of Bothnia and the Gulf of Finland.

Cooperation helps to solve the problems

Concurrent weakening of release results all over the Baltic Sea indicates that the causes of the phenomenon may be common: changes either in hatchery rearing, the environment or fishing practices. Research focusing on the problem in different countries should be organized in a coordinated way. Networking and common research programmes guarantee the best possible expertise. The participation of several countries increases funding possibilities, because international research funding will also be available (EU, The Nordic Council of Ministers).

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