ISSN 1239-6095
© Boreal Environment Research 1998

Contents of Volume 3 Number 4

Tuunainen, P. 1998. Preface. Boreal Env. Res. 3: 305.
Abstract
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Salonen, E. 1998. The vendace stock and fisheries in Lake Inari. Boreal Env. Res. 3: 307–319.
Abstract
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Parmanne, R. 1998. Herring fishery in the Bothnian Sea (southern Gulf of Bothnia) and the North Sea: similarities and differences. Boreal Env. Res. 3: 321–328.
Abstract
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Sarvala, J., Helminen, H. & Auvinen, H. 1998. Portrait of a flourishing freshwater fishery: Pyhäjärvi, a lake in SW-Finland. Boreal Env. Res. 3: 329–345.
Abstract
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Salmi, P., Salmi, J. & Moilanen, M. 1998. Strategies and flexibility in Finnish commercial fisheries. Boreal Env. Res. 3: 347–359.
Abstract
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Setälä, J., Honkanen, A., Vihervuori, A., Nylander, E., Söderkultalahti, P. & Tuunainen, A.–L. 1998. Review of the fish market in Finland. Boreal Env. Res. 3: 361–370.
Abstract
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Muotka, T., Mäki-Petäys, A., Kreivi, P. & Högmander, H. 1998. Spatial associations between lotic fish, macroinvertebrate prey and the stream habitat: a multi-scale approach. Boreal Env. Res. 3: 371–380.
Abstract
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Rahkonen, R. & Pasternack, M. 1998. Effect of experimental Diphyllobothrium dendriticum infection on the blood leucocyte pattern of brown trout at two temperature levels. Boreal Env. Res. 3: 381–386.
Abstract
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Soivio. A., Myllynen, K., Pakkala, J. & Jokela, S. 1998. Smolting of the brown trout (Salmo trutta L.) in Lestijoki water. Boreal Env. Res. 3: 387–393.
Abstract
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Jutila, E., Ahvonen, A., Laamanen, M. & Koskiniemi, J. 1998. Adverse impact of forestry on fish and fisheries in stream environments of the Isojoki basin, western Finland. Boreal Env. Res. 3: 395–404.
Abstract
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Vuorinen, P. J., Keinänen, M., Peuranen, S. & Tigerstedt, C. 1998. Effects of iron, aluminium, dissolved humic material and acidity on grayling (Thymallus thymallus) in laboratory exposures, and a comparison of sensitivity with brown trout (Salmo trutta). Boreal Env. Res. 3: 405–419.
Abstract
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Ikonen, E. & Torvi, I. 1998. Why were the effects of M74 mortality not visible in the spawning run of Baltic salmon in 1997 in the Gulf of Bothnia? Boreal Env. Res. 3: 421–422.
Abstract not available
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Tuunainen, P. 1998. Preface. Boreal Env. Res. 3: 305.

Finnish fisheries research has a long history. The first studies on fish and fisheries were conducted the late 1700s and by the end of the 1800s concepts of the factors influencing fish stocks were already rather similar to present ones. By the early 1900s large numbers of fisheries studies were being carried out in both inland waters and the marine area. The need to promote research activities was growing. On 17 November 1923, 75 years ago, an act was passed making it possible to start regular fisheries investigations in Finland. The Bureau of Fisheries Investigation was established in January 1924 and operated under the Board of Agriculture until 1971. The present Finnish Game and Fisheries Research Institute, established in 1971, has continued the work of the Bureau of Fisheries Investigation. This volume of the Boreal Environment Research (BER) was compiled to mark the 75th anniversary of Finnish fisheries research. The aim is to give an idea of the kind of fisheries research our institute is currently engaged in. It does not cover the whole field of research but merely gives some examples of ongoing research activities. Our research projects tend increasinly to be joint projects with other institutes and with universities in Finland and abroad. On behalf of the Finnish Game and Fisheries Research Institute, I have the pleasure to thank all the authors as well as the editorial staff of the BER for their efforts in compilation of this volume.

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Salonen, E. 1998. The vendace stock and fisheries in Lake Inari. Boreal Env. Res. 3: 307–319.

Vendace (Coregonus albula) has a short history (30–40 year) in Lake Inari, being introduced into the watercourse in the 1950s and 1960s. The growth of the stock was slow at the beginning, but increased rapidly in the 1980s due to three strong, successive year classes in 1983, 1984 and 1986. All these years, and also in 1989, summers were quite warm and the water temperature favourable after the ice-break. The peak stock size was recorded 1987, and after that, there was a slump. In the middle of the 1990s, the stock size had stabilized to a very low level compared with the situation in the end of 1980s, and the vendace stock concentrated mostly in the southern parts of the lake. The vendace fishery flourished for less than five years. The peak year concerning fisheries and catches was 1989 with a vendace catch of nearly 3 kg ha–1 and a total catch of about 5 kg ha–1, rather high figures in subarctic northern regions. After 1989, the vendace catch decreased rapidly. It seemed that the fishing effort of some years (1989 and 1990) was so heavy that the spawning stock size gradually decreased to a level, where the revival was difficult. Unfavourable weather conditions with cold summers at the beginning of 1990s, and, at the same time, quite hard pressure of predation by abundantly stocked salmonids on vendace contributed together to the fact that only very scanty year-classes were born. This, in turn led to a collapse of the vendace stock in the 1990s.

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Parmanne, R. 1998. Herring fishery in the Bothnian Sea (southern Gulf of Bothnia) and the North Sea: similarities and differences. Boreal Env. Res. 3: 321–328.

In recent years, herring catches have increased in the Bothnian Sea (southern Gulf of Bothnia, northern Baltic). The assessment of a fish stock by virtual population analysis (VPA) is sensitive to the input values used, and thus the results include uncertainties. In this paper I examine, also independently of the results of the virtual population analysis, if there are signs of overfishing in the Bothnian Sea herring stock. The situation there is compared with that in the North Sea, where changes in the fishery leading to the collapse of the herring stock are well documented. Results from the Bothnian Sea show that changes in the herring catch composition, growth, maturity and larval abundance due to fishing have been minor. According to VPA and the other parameters measured, so far there are no obvious biological signs of the herring overfishing in the Bothnian Sea.

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Sarvala, J., Helminen, H. & Auvinen, H. 1998. Portrait of a flourishing freshwater fishery: Pyhäjärvi, a lake in SW-Finland. Boreal Env. Res. 3: 329–345.

Fish yields from Pyhäjärvi, a lake in southwestern Finland, (ca. 34 kg ha–1 a–1) are much higher than expected from published relationships between yield and nutrient concentrations or primary production in lakes. The basis of this fishery has been studied since 1983 in a series of ecosystem and fisheries projects. Here we review the historical development and present state of this fishery, analyse its biological and economic basis, and speculate on its future in the changing world. The main targets of the commercial fishery have been the coregonids vendace and whitefish, both introduced into the lake during this century. However, in the 1990s, the vendace stock has declined, and the less valuable perch, roach, smelt and ruffe have become dominant in the catch. This change in the fish community seems to be primarily due to climatic factors. The main reason for the high fish yields in Pyhäjärvi is the very efficient fishery: the annual harvest approaches the total production of vendace. The simple morphometry of the lake and its short food chains contribute to the productivity of the fishery. The intensive fishing itself enhances the productivity of the vendace population. Under the prevailing food-limiting conditions, exploitation focusing on juveniles leads to faster growth and higher reproduction rates, allowing high harvest rates without a population collapse. However, the recent decline of the vendace population in Pyhäjärvi shows the vulnerability of a heavily exploited fish stock under adverse environmental conditions.

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Salmi, P., Salmi, J. & Moilanen, M. 1998. Strategies and flexibility in Finnish commercial fisheries. Boreal Env. Res. 3: 347–359.

Strategies chosen by Finnish commercial fishermen in order to adapt to the changes and uncertainties in their occupation, and in society were analyzed by using a reclassification of the material obtained from the earlier interview-based survey. The data were collected by means of structured questionnaires and qualitative thematic interviews. The characteristics of the strategies and the transition between the groups were examined. The low profitability of fishing in monetary terms of, for instance, static fishing strategy and the withdrawers was interpreted through the high importance of the work itself and the values it offers for the fishermen. Most of the Finnish commercial fishermen depend on the availability of other incomes in addition to fishing revenues, which act as a `buffer' against fluctuations in the fishing revenues. The strategic response of the fishermen had expanded the activities of their enterprises in two main ways: investing in more efficient and larger vessels or forward integration closer to the needs of the consumers. Structural heterogeneity and differences in orientation and strategies form a challenge for the planning and management of commercial fisheries. In addition to the common way of categorizing the fishermen according to gear or fishing area, consideration of fishermen also as differently-oriented groups could help the decision makers to better assess the consequences of their actions.

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Setälä, J., Honkanen, A., Vihervuori, A., Nylander, E., Söderkultalahti, P. & Tuunainen, A.–L. 1998. Review of the fish market in Finland. Boreal Env. Res. 3: 361–370.

In this paper Finnish fish market is described on the basis of the compiled official fisheries statistics and studies carried out by the Finnish Game and Fisheries Research Institute. The total fish consumption in Finland was about 320 000 tonnes in 1996, FIM 1 400 million in value. One half of the fish was used for human consumption and the other half as feed for fur animals. Baltic herring (Clupea harengus) and rainbow trout (Oncorynchus mykiss) are the most important species to Finnish consumers. In 1996, the Finns consumed 30.4 kg fish in ungutted weight per capita, of which these two species covered nearly one half. There are over 200 fish wholesale and processing companies in Finland, most of them are very small. In 1995, 30 000 tonnes of fish, mainly Baltic herring and rainbow trout, were used for processing. In 1992, there were some 250 specialized fish retail stores. However, nowadays the most important shopping places for fresh and processed fish are self-service shops and supermarkets.

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Muotka, T., Mäki-Petäys, A., Petri Kreivi, P. & Högmander, H. 1998. Spatial associations between lotic fish, macroinvertebrate prey and the stream habitat: a multi-scale approach. Boreal Env. Res. 3: 371–380.

We adopted a multiscale approach to examine the spatial relations between stream fish, macroinvertebrate prey, and habitat characteristics in a boreal stream. The study site was divided into 279 cells, and abundances of brown trout and Arctic bullhead were quantified at each cell. Depth, water velocity, substrate size and aquatic vegetation were measured, and benthic samples collected, at each quadrat. Shaded contour plots showing the spatial distribution of selected variables within the sample space were produced and fish distributions were superimposed on these plots. High-density patches of trout and bullhead were in separate sections of the riffle, and bullhead were closely associated with their benthic prey, especially semisessile macroinvertebrates. Semivariograms were produced for two variables, water depth and density of semi-sessile invertebrates. There was spatial dependence, especially in the density data, at lags shorter than 2 metres. Kriging was then used to create maps displaying the spatial patterns of the variables within the sample space. We believe this kind of multi-scale sampling strategy combined with standard geostatistical tools and statistical modeling will prove valuable in the study of aquatic consumer-resource interactions.

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Rahkonen, R. & Pasternack, M. 1998. Effect of experimental Diphyllobothrium dendriticum infection on the blood leucocyte pattern of brown trout at two temperature levels. Boreal Env. Res. 3: 381–386.

Leucocyte composition in the peripheral blood of brown trout Salmo trutta m. lacustris (L.) aged 1+ was studied in relation to Diphyllobothrium dendriticum (Cestoda) infection at two temperature levels, heated about 15 °C and non-heated which decreased from 11 °C to 7 °C. Blood samples were taken from control and infected fish 12 weeks post infection. The D. dendriticum infection (1–6 per fish) had a significant increasing impact on lymphocyte and neutrophil counts at both temperature levels while thrombocytes were more numerous in control fish, particularly in non-heated water. The total leucocyte counts were not influenced by the D. dendriticum infection. The present water temperatures created differences only in thrombocyte and total leucocyte counts, which were increased in non-heated aquaria.

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Soivio. A., Myllynen, K., Pakkala, J. & Jokela, S. 1998. Smolting of the brown trout (Salmo trutta L.) in Lestijoki water. Boreal Env. Res. 3: 387–393.

The brown trout (Salmo trutta L.) of the Lestijoki strain, reared to the pre-smolt stage in fish farm conditions, were tested for their smolting ability in water from Lestijoki, a river in western Finland, during final winter before smolting. Reference fish were reared in local ground water. During the pre-smolt winter the fish were analysed for their gill ATPase activity, condition factor (CF) and osmoregulatory ability after exposure in 30% balanced sea water solution. The osmoregulatory ability of the gills was severely altered by the water quality of Lestijoki water. The decrease of condition factor (CF) and changes in gill Na+, K+-ATPase activity revealed an attempt of smolting in fish reared in the river water. The results of this investigation questions the ability to give Lestijoki a reproductive brown trout stock by re-establishing the species.

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Jutila, E., Ahvonen, A., Laamanen, M. & Koskiniemi, J. 1998. Adverse impact of forestry on fish and fisheries in stream environments of the Isojoki basin, western Finland. Boreal Env. Res. 3: 395–404.

The effects of forestry on fish and fisheries were studied in the Isojoki basin, western Finland. The most abundant fish species in the study area, brown trout (Salmo trutta L.), was found in 27 of 50 brooks studied. Enzyme electrophoresis revealed at least five genetically differentiated stocks of brown trout in the brooks. Regression analysis indicated that the population density of brown trout was positively dependent on the abundance of pools, stony bottom material (2 to < 10 cm in diameter), undercut banks in the streams, and water pH, while the abundance of ditches in the catchment area and shading by the tree canopy affected the density negatively. Incubation experiments showed that sedimentation with mineral and humus material impaired the survival of trout eggs in the rapids. The results suggest that dredging of brooks and increased soil erosion due to drainage may threaten the reproduction and genetic diversity of trout stocks in the brooks and main river.

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Vuorinen, P. J., Keinänen, M., Peuranen, S. & Tigerstedt, C. 1998. Effects of iron, aluminium, dissolved humic material and acidity on grayling (Thymallus thymallus) in laboratory exposures, and a comparison of sensitivity with brown trout (Salmo trutta). Boreal Env. Res. 3: 405–419.

Iron alone, as well as aluminium, can be acutely lethal in humus-free acidic water. In a simultaneous laboratory exposure to both Fe and Al the toxic effects on grayling were even more pronounced. Water acidity increased and dissolved humic material reduced the toxicity of Fe and Al. As toxic effects, the ionoregulation of yolk-sac fry was disturbed, swimming activity decreased and mortality increased. Based on mortality and swimming activity, brown trout yolk-sac fry tolerated, depending on the Al concentration, nearly half a pH unit more of acidity than those of grayling. The gills of the affected one-summer-old grayling were damaged, leading to decreased oxygen uptake and disturbed ionoregulation. In cold water (3 °C), one-summer-old grayling did not recover completely from the sublethal exposure. Some tributary waters of Isojoki, a river in West-Central Finland, were toxic to grayling yolk-sac fry. These waters had rather high Al and Fe concentrations but were humic and only slightly acidic. It is concluded that increased concentrations of Fe and Al increases the harmfulness of waters in forestry land use or peat production areas even in humic and slightly acidic waters.

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