COUNTRY REPORT OF FINLAND FOR THE INTERSESSIONAL PERIOD OF THE EUROPEAN INLAND FISHERIES ADVISORY COMMISSION

(EIFAC)

1986 – 1987

by

Outi Heikinheimo-Schmid, Markku Pursiainen
Kai Westman and Pekka Tuunainen¹

¹ Finnish Game and Fisheries Research Institute, Fisheries Division, P.O. Box 202, SF-00151 Helsinki 15, Finland

Introduction

Finland's inland waters cover 33 520 km², which is about 10 % of the country's total area. There are over 60 000 lakes, 17 of which have a surface area of more than 200 km². The lakes are shallow, the average depth being 7 m. Together, they have a total shore length of 130 000 km. Nearly one hectare of lake area and about 30 m of shoreline are available per capita of the population (4.9 million). The total length of the rivers exceeds 20 000 km.

Government responsibility for both inland and marine fisheries and their management in Finland is vested in the Ministry of Agriculture and Forestry. The fisheries administration comprises eleven districts, each headed by a fisheries biologist. Each district is divided into uniform fishery areas in order to facilitate planning of the fisheries and their management. Regional plans for fisheries are under preparation in the fishery areas.

In 1986 some 587 000 people were engaged in fishing in inland waters. About 2 200 of them were professional or semiprofessional fishermen and the rest fished for recreation and their own use.

The total catch from inland waters was estimated at about 29 000 tons in 1986. This was about 20 % of the total catch for the country (Appendix 1).

The commercial catch from inland waters in 1986 was 5 500 tons (Appendix 1). The main species in the catch are perch (Perca fluviatilis), pike (Esox lucius), vendace (Coregonus albula) and roach (Rutilus rutilus).

Damming of rivers and water level regulation of lakes and reservoirs, mainly for hydro-electric power generation, have created severe problems in fisheries management. Due to extensive water protection measures, pollution of waters has strongly diminished. About 80 % of the lake area in Finland is classified as good or excellent, and in 18 % of the lake area the water quality is satisfactory. In about 2 % of the lake area the water quality is passable or heavily polluted by industry or sewage.

Acidification creates problems mainly in small and medium-sized lakes. The occurrence of radioactive compounds in fish, due to the Tshernobyl accident, has been studied.

Extensive fish stocking programs form the main part of the management of the economically important fish stocks. The total number of fish released in 1986 was 52 million (excluding newly hatched juveniles). More than 75 % of these were whitefish (Coregonus lavaretus s.l.) (Appendix 2).

Production of rainbow trout (Salmo gairdneri) for human consumption in 1986 was 10 900 tons (Appendix 2).

The water legislation was reformed in 1987, and many of the changes concern the fisheries. More attention is now paid to the recreational value of the waters. The number of limnological and fishery experts in the water courts has been increased.

The EIFAC National Committee, chaired by the EIFAC correspondent for Finland, is responsible for liaison between EIFAC and Finland and works on subjects of current interest to EIFAC.

I FISHERIES BIOLOGY AND MANAGEMENT

1. Economic aspects of commercial and recreational fisheries

In 1986, the value of the total catch from inland waters (29 000 tons) was 205 million FIM (40.4 million USD). This was 46 % of the value of the total catch in Finland in the same year.

The value of the total catch from inland waters taken by professional fishermen (5 500 tons) in 1986 was 43 million FIM (8.5 million USD), 67 % of which was due to the vendace catch. Commercial fishing in inland waters is mainly a part-time occupation. In 1986, only 16 % of the 2 245 professional fishermen had more than half of their income from fishing. The annual profitability of commercial fisheries is studied by means of daily records kept by some 70 fishing households or enterprises in inland waters.

Vendace is the most important fish species in the catch of the commercial fishery in inland waters, with annual catches of about 4 000 tons during the 1980s. As regards other species, the Lokka and Porttipahta Reservoirs in Northern Finland have become to significant professional fishing areas for e.g. whitefish and pike.

Transportation from the fishing areas to the markets is one of the chief factors limiting the use of fish from inland waters. In 1985, the state began to support transportation of fish in certain experimental areas in northern Finland.

A study on the imports, exports and consumption of fish in Finland was published in 1986 (69). The annual human consumption in 1978–1983 was about 30 kg per capita, calculated as fresh fish, and about 70 % of this was covered by the domestic supply.

Subsistence and recreational fishing is of great economic and social significance in Finland. Perch and pike are the most important species in the catch. More than half of the catch is taken with gill nets. In 1986, the value of the catch (23 600 tons) was estimated at 161 million FIM (32 million USD).

A personal fishing licence (22 FIM = 5 USD from 1.1.1987) and the permission of the water owner are generally required for every kind of fishing, but district licences enable angling with natural bait and ice fishing with rods without the permission of the water owner.

The numbers in brackets ( ) refer to the numbers in the bibliography.

The values in USD are calculated according to the mean rate of exchange of the year in question.

The annual catch of the native crayfish (Astacus astacus) was about 1.5 million individuals according to the nationwide questionnaire on subsistence and recreational fishing in 1984. The value of the crayfish catch was 10.5 million FIM (1.7 million USD).

There are no statistics on the lamprey (Lampetra fluviatilis) catch in 1984–1987. In 1983 it was 2.3–2.4 million individuals, which is about 100 tons. The value of the catch was estimated at 4.3 million FIM (800 000 USD).

2. Survey and appraisal of inland waters

Studies were continued on the population dynamics and causes of year-class fluctuations in the vendace, which is the most important species for the commercial fisheries in lakes. A symposium was organized by the University of Kuopio in 1986 on the management of vendace stocks (31), and a national working group was formed to plan and guide the research on vendace in Finland.

The final report of the research program on the causes of the exceptionally high fish yield in Lake Pyhäjärvi, Säkylä, has been published (62). Lake Pyhäjärvi is the most productive vendace lake in Finland (annual catch 20–40 kg/ha). The high fish yield was found to be due not only to favourable circumstances for reproduction of vendace, but also to the interactions between the fish populations and their food animals, and between the fish stocks and fishing. The detailed mechanisms are still obscure, but effective fishing seems to be decisive in realizing the productive capacity of the lake.

The echocounting method of estimating pelagic fish numbers, developed within EIFAC, has been used in 12 lakes in Finland during 1986 and 1987 (19, 20).

A program for research on Lake Saimaa in the years 1988–1990 was drawn up. Attention will be mainly directed to fish stock assessments, interactions between fish stocks, the success of fish stocking, the effects of pulp mill effluents and prevention of the effects of oil accidents. The program will be carried out jointly by units subordinate to three different ministries, the Ministry of Education, the Ministry of Agriculture and Forestry and the Ministry of Environment (54).

An international evaluation of scientific research in hydrobiology in Finland was organized in 1986 by the Academy of Finland. The Evaluation Committee emphasized the necessity of cooperation between the research workers and institutes involved in fisheries research, and the importance of the research on vendace, especially on the stock-recruitment relationship (11).

3. Management of inland waters

3.1. Restoration of waters

Restoration measures have been carried out in more than 30 rivers in order to improve the reproduction areas of salmonids, increase crayfish production and to provide opportunities for recreational fishing. At the same time follow-up research has been continued. Reports were published of the research project conducted by the Finnish Game and Fisheries Research Institute on the results of restoration of log floating routes in different rivers with valuable fish and crayfish stocks (16).

3.2. Stocking

In 1986 the number of salmonids (Salmo and Salvelinus sp.) released at the age of one summer or more was 7.5 million, but more than half of these were released in the sea. The corresponding number for whitefish species was 39.6 million, for other fish 5.2 million and for crayfish 39 000 (Appendix 2). The value of the input was 80 million FIM (16 million USD).

In addition, transfer stocking was performed with some fish species and with crayfish and lamprey.

3.3. Marking and tagging

To evaluate the stocking results in inland waters, and for research purposes, 46 700 salmonids (mainly brown trout, Salmo trutta m. lacustris), 1 900 whitefish and 200 other fish were tagged with Carlin tags in 1986. In addition, 165 000 salmonids and 223 000 whitefish were marked with microtags (“nose tags”) in 1986 and 1987.

The Finnish Game and Fisheries Research Institute handles all the tag returns. Data-processing, correspondence and payment orders are directed automatically.

3.4. Introductions

No introductions of fish or crayfish for stocking purposes were allowed by the veterinary authorities, since they wished to prevent the possible spread of communicable fish diseases, mainly viruses, at present unknown in Finland.

4. Research programs shared with other countries

Cooperation has been continued between Finland and the neighbouring countries. In the Tenojoki (Tana) River on the Finnish-Norwegian border, the yearly studies on the Atlantic salmon (Salmo salar) stock include preparation of catch statistics, catch sampling, and assessments of parr densities. Since 1984, joint studies on salmon are also carried out in the Näätämönjoki (Neiden) River.

The Finnish-Soviet Border Water Commission has continued its work, chiefly in Lake Inari and Lake Pyhäjärvi (Karelia). The reports of the research on water quality, bottom fauna, periphyton and fish stocks in Lake Pyhäjärvi (Karelia) were published in 1987 (4, 5, 21). Finnish-Soviet cooperation was continued in investigations on salmonid smolt production in Finnish and Soviet Karelian rivers. Soviet specialists from the Institute of Biology of Inland waters, Borok (Academy of Sciences of the USSR), in cooperation with Finnish biologists, carried out biotelemetrical studies in Lake Saimaa to examine movements of brown trout and land-locked salmon (Salmo salar m. sebago) after stocking. Joint Soviet-Finnish research on the Neva River salmon and its hatchery stocks was continued. Material was collected for genetic and phenetic comparison of different brown trout stocks.

Research on the fish stocks and fisheries in the Tornionjoki River was continued in cooperation with the Finnish-Swedish Border River Commission and the Swedish fisheries authorities.

Liaison has been continued with inland fisheries researchers in Poland, attention being concentrated on fish culture, and research on whitefish, vendace and sea trout.

Preliminary agreement was reached with Czechoslovakia regarding cooperation in studies concerning the propagation and management of the asp (Aspius aspius).

Finland will participate in the Regional Project for the Management of Fisheries in Lake Tanganyika, coordinated by FAO. A report of a Project Identification Mission was completed in 1987. The plan includes a mobilization period of 12 months, a 3-year period of research work and a follow-on project of 5 years.

5. Other subjects

The International Symposium on Biology and Management of Coregonids was organized in Finland, Joensuu, in 1987. There were about 120 participants from 13 countries. The proceedings of the symposium will be published in “Finnish Fisheries Research” in 1988. The symposium included 80 presentations or posters (24).

II FISH CULTURE AND DISEASES

1. Fish culture

1.1. Fish farms and the production

The rainbow trout is practically the only fish species farmed for food in Finland, although a few attempts have been made to develop the farming of Baltic salmon in net cages in brackish water. There also exists growing interest in cultivation of whitefish and arctic char and in crayfish farming, but at the moment these are practised only on an experimental scale. In 1986, 361 farms produced 10 900 tons of fish for human consumption, of which 65 per cent was reared in brackish water in net cages.

Fish for stocking purposes are produced either intensively in land-based fish farms (mostly salmonids) or extensively in large ponds with a natural food supply (mostly whitefish, grayling (Thymallus thymallus), pike, pike-perch (Stizostedion lucioperca) and some cyprinid species). Many farms producing rainbow trout also rear other salmonids for stocking. In 1986, the number of salmonids produced for stocking purposes, excluding newly hatched larvae, was 7.5 million (42 % for inland waters). The natural rearing ponds had a total area of c. 9 800 hectares, producing about 44.8 million, mostly one-summer-old, juveniles (Appendix 2). During the 1980s the annual production of pike-perch fingerlings for stocking has risen from some hundred thousand to more than 2.5 million.

1.2. Economic evaluation of aquaculture

The value of aquaculture products in 1986 calculated as the producer price, was 246 million FIM (48 million USD) for rainbow trout and 80 million FIM (16 million USD) for stocked fish. In a study made by the Regional Development Fund of Finland Ltd. in 1985 it was calculated that the value of the fish caught for human consumption was 225 million FIM (36 million USD), while that of the farmed fish was 215 million FIM (35 million USD). The value of the fish imported in the same year was 380 million FIM (61 million USD) and that of exported farmed fish only 64 million FIM (10 million USD).

1.3. Fish nutrition research

The farmed fish mainly receive dried fish feeds. Low-value fish (mainly smelt) and Baltic herring are of some importance. The use of herring in inland water farms is decreasing because or the possibility of transferring communicable fish diseases from the sea with the feed.

Fish feed development is continuously researched in cooperation with the manufacturers and fish farmers. The main goals are to achieve better feed utilization, to reduce wastage of nutrients from the feeds, and to develop feeds that will improve the quality of fish for consumption and stocking, and for brood stocks. New types of feeds are also needed for intensive cultivation of non-salmonid fish species and freshwater crayfish farming.

1.4. Development of aquaculture technology

The main factors examined at the fish farms in recent years have been the shape and construction of the rearing basin, the use of automatic feeders and microprocessor-controlled optimized feeding programmes, and systems for controlling illumination and temperature. The development of the aquaculture technology also includes examination of the physiology of fish for stocking, especially Baltic salmon, produced by various techniques and under different conditions.

The methods used in crayfish farming are also being rapidly developed due to the growing interest in crayfish production.

Brood stocks are mainly kept in fish farms, and to avoid selection occurring during cultivation from generation to generation, new brood stocks are primarily obtained from the natural spawn of known native or released stocks. A rainbow trout breeding program has been started by creating the basic brood stock families, which will be used in a new state fish farm planned especially for this purpose.

The use of warm water in fish culture for stimulating the growth of the fish is constantly increasing. For example, 15 % of the salmon smolts released in 1987 were one year old. The year 1987 saw the start of the second fish farm using warm-water effluents from a nuclear power plant. This fish farm rears salmon and rainbow trout and also experiments with other species.

The problems caused by long distances between fish farms and the stocking sites can be partly avoided by developing the transportation techniques and by using release ponds in the most important stocking localities.

2. Fish and crayfish diseases

The number of farms belonging to the official Fish Health Control System run by the National Veterinary Institute has increased to 141 during 1986–1987.

In summer 1986 furunculosis caused by Aeromonas salmonicida subsp. salmonicida was diagnosed in Finland. The infection emanated from Atlantic salmon brood fish captured in the Baltic, in the Gulf of Bothnia. Later, the infection was reported from nine fish farms, mainly in northern Finland. Atypical strains of A. salmonicida causing disease in brown trout and sea trout have also been isolated on five farms; two on the coast and three in the middle of the country.

Some cases of ASA disease (A. salmonicida var. achromogenes) have been recorded during 1986–1987.

During 1987 screening for Yersinia ruckeri was conducted. Earlier, the bacterium had been isolated from farmed whitefish and Atlantic salmon, but it was now found in wild fish only (53).

A new pathogen, Pseudomonas anquilliseptica, was isolated in summer 1986 from cage farms in south-western Finland. Both trout and salmon were affected.

The first observations of Gyrodactylus salaris in Finland are from 1985. Since then the parasite has been identified on 11 farms; seven cases on Atlantic salmon and four on rainbow trout. Mortality due to gyrodactyliasis has not occurred.

Another parasite (Hexamita salmonis) has been a problem with rainbow trout fingerlings. Losses have been recorded in both 1986 and 1987. During autumn 1987, a new virus belonging to the Rhabdoviruses was isolated from sea trout in northern Finland. The identification of the virus is in progress.

Some new cases of crayfish plague appeared in 1986–1987. Research on plague resistant signal crayfish as plague spreaders has continued. Under culture conditions, juvenile signal crayfish have shown rather high plague mortality. Haemolymph studies on Aphanomyces -infected crayfish and signal crayfish have continued (23).

The number of finds of the parasite Psorospermium haeckeli has risen to 11 in southern Finland. The haemolymph values of infected crayfish are under study. P. haeckeli can cause mortality in certain conditions in both natural crayfish populations and aquaculture stocks (41).

III FISH AND POLLUTED WATER

1. Fish farm effluents

The most serious factor limiting the growth of the fish farming industry in Finland is the problems caused by the fish farm effluents. In fresh waters, eutrophication is the main nuisance; organic loading and direct oxygen uptake are of less importance. Net cage farming can cause changes in the primary production because of nitrogen loading and also change sediment conditions (64).

In land-based fish farms part of the phosphorus loading can be avoided by the removal of suspended solids from the outflowing water. Self-purifying circular basins and swirl concentrators are generally used, but in some cases drum sieves and even flotation of the flushing water are also needed to avoid environmental problems. The observed reduction of solids by the swirl concentrator has varied between 50 and 80 % and the reduction of phosphorus between 20 and 40 %.

2. Biological monitoring

Standard toxicological and physiological methods for evaluating the effects of effluents on fish at different stages of development are available for administrative use. Biological monitoring is playing an increasing role in environmental protection in Finland.

These methods will be increasingly used in monitoring the effects of effluents and, for example, in compensation stocking programs. In 1987 a five years' research program “Fish diseases as water quality indicators” was started.

Water quality criteria have been prepared for fishing waters and will be evaluated over a period of some years.

International cooperation with the Helsinki Commission, ICES and OECD continues in this field.

3. Bioaccumulation of toxic and radioactive substances in fish

A national program for monitoring the concentrations of chlorinated hydrocarbons and heavy metals in fish has been in progress since 1978. The results obtained have revealed that the mercury, DDT and PCB concentrations in fish in the loaded water areas are continuously decreasing. The monitoring program has been extended to cover organic compounds such as toxaphene, chlordanes and polychlorinated dibenzodioxins and furanes.

Monitoring has been conducted on the occurrence in fish of radioisotopes released during the nuclear power plant accident in Tshernobyl in 1986. Samples have been collected from large lakes supporting commercial fisheries and from small lakes having only recreational fisheries. The deposition was heaviest in central Finland and there the fish in small and medium-sized lakes contain rather large amounts of radioisotopes, mainly Cs-137. Perch have the highest levels of radioactivity and in large perch (length >20 cm) the activity has slightly increased from the year 1986 to 1987, but in small perch it has decreased somewhat. At the same time the content of Cs-137 in pike has nearly doubled. The consequences for the fisheries of radioactive pollution of fish has not yet been evaluated. The monitoring program will continue.

4. Acidification of inland waters

The five-year research project on acidification due to air pollution, initiated in 1985, was continued. The fisheries part of this project is conducted by the Finnish Game and Fisheries Research Institute in co-operation with the University of Helsinki. Data on fish populations and water quality were collected from 80 small lakes in different parts of Finland.

Both test fishing and interviews of local people have indicated that many lakes in southern Finland have lost their roach populations because of increased acidity. Acidification has also affected the reproduction of perch, which is an acidity tolerant species, but only a few completely fishless lakes have been found. These are all located in the southern coastal area of Finland (32, 50, 51, 65). Recently, studies have been initiated on the effects of acidity on the reproductive mechanisms of fish, e.g. fertilization of eggs, hatching and development of the fry. The effects of acidification, including the effects of aluminium in precipitation, are being examined in both laboratory and field experiments.

Crayfish test fishing have been done in about 20 small lakes and brooks which are acidified or threatened by acidification. The crayfish populations are seriously affected in several of these waters. In some crayfish reproduction has completely ceased (22).

5. Physical habitat modification

An extensive research project on the ecology of regulated lakes, conducted by the Technical Research Centre in cooperation with the Finnish Game and Fisheries Research Institute, has been completed and the final report will be published in 1988. The most important subjects were the effects of water level regulation on the littoral zone; the vegetation, the bottom fauna and the fish fry.

A model describing the ecosystem of regulated lakes is being developed by the National Board of Waters and Environment in cooperation with the Finnish Game and Fisheries Research Institute and the Technical Research Centre of Finland. The goal of the project is to evaluate the effects of lake regulation on fish stocks more accurately than before, so that the results can be used, for example, in water court lawsuits.

In 1987 final reports were published on a five-year research program concerning the effects of water level regulation, pulp mill effluents and other habitat modification on the water quality, littoral vegetation, bottom fauna, fish stocks and fisheries in Lake Kemijärvi, northern Finland. The measures recommended for fisheries management in the lake were effective fishing with non-selective fishing gears, and stocking with plankton-feeding whitefish, large brown trout young and pike-perch (14, 40).

The report on the rehabilitation of salmon (Salmo salar) and sea trout (Salmo trutta m. trutta) in the Vantaanjoki River was published in 1987. The original sea trout stock was destroyed by damming and pollution of the river, but due to effective water protection measures, the water quality is now good enough for reproduction of salmonids. Releases of sea trout and salmon fry and fingerlings have been successful. A fish ladder was constructed in the mouth of the river to allow upstream migration of the mature salmonids and sport fishing in the river (17).

The Committee for Water Protection in the Forestry and Peat Industry has completed its work, and will issue a report in 1988.

Acknowledgements

The information for this country report was obtained from the members of the EIFAC National Committee for Finland and many other specialists in different fields. The list of the literature was compiled by Saara Lintu. We wish to thank all of them for their contributions and Anna Damström for checking the English language.

SELECTED LITERATURE

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2. AHLFORS, P., KUMMU, P. & WESTMAN, K. 1987. Karppi Suomessa -katsaus kalastus, viljely- ja istutustoimintaan 1951–1981 (Carp (Cyprinus carpio) in Finland - a review of fishing, culture and stocking in 1951–1981). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja, 70. p. 1–22.

3. AHONEN, M. 1987. Kalkituksen, lannoituksen ja istutustiheyden vaikutukset Inarin luonnonravintolammikoiden siianpoikastuottoon vuosina 1976–1983 (The effects of liming, fertilizing and stocking density on whitefish fingerling production in natural food ponds in Inari during 1976–83). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja (in press).

4. AUVINEN, H. 1987. Fisheries in the Finnish zone of Lake Pyhäjärvi (Karelia). Finnish Fish. Res. 8 (in press).

5. AUVINEN, H. 1987. Growth, mortality and management of whitefish (Coregonus lavaretus L.), vendace (C. albula L.), roach (Rutilus rutilus L.) and perch (Perca fluviatilis L.) in Lake Pyhäjärvi (Karelia). Finnish Fish. Res. 8 (in press).

6. BAGGE, P. & HAKKARI, L. 1987. The littoral and pelagic occurrence of Coregonus albula L. in northern Päijänne in 1977–1981. Biol. Res. Rep. Univ. Jyväskylä 10, p. 157–166.

7. ERONEN, T., HANSKI, A., HYYTINEN, L. & KAIJOMAA, V-M. 1986. Vuoksen vesistöalueen lohi-ja taimenkantojen hoidon puiteohjelma (A general management plan for salmon (Salmo salar m. sebago) and brown trout (Salmo trutta m. lacustris) stocks in the Vuoksi watercourse). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja 49. 117 p.

8. ESKELINEN, U. 1986. Nevalaxprogram - produktionsmodell, volymutveckling, odlings- och utsättningsresultat (Rearing and research program for river Neva salmon in Finland). Fiskodlingskonferens i Skellefteå 18.–20.3.1986 (Proceedings of salmon farming symposium), p. 86–99.

9. ESKELINEN, U. 1986. Kalanviljely Suomessa vuonna 1983 (Abstract: Fish farming in Finland in 1983). Suomen Kalatalous 52, p. 29–31.

10. ESKELINEN, P., LAMPI, A.-M. & MÄKINEN, T. 1987. Egg production and quality of Atlantic salmon fed on different dry, semi-moist and fresh feeds. In: Utfodring/ produktkvalitet vid odling av fisk. Föredrag vid odling av fisk. NJF-seminar Nr. 116. Njf-utredning/ rapport nr. 38.

11. Evaluation of scientific research in hydrobiology in Finland. Helsinki. Publications of the Academy of Finland 5/1986. 56 p.

12. GIBSON, D.I. & VALTONEN, E.T. 1987. A new species of Crepidostomum (Allocreadiidae: Digenea) from northeastern Finland, with comments on its possible origin. Systematic Parasitology (in press).

13. HAKKARI, L. & BAGGE, P. 1987. Reproductive success of Coregonus albula L. in polluted and unpolluted areas of L. Päijänne during the years 1977–1986. Biol. Res. Rep. Univ. Jyväskylä 10, p. 149–156.

14. HEIKINHEIMO-SCHMID, O. & HUUSKO, A. 1987. Kemijärven kalatalouden nykytila ja ehdotukset kalakantojen hoitotoimenpiteiksi (The present state of fisheries in Lake Kemijärvi and fish stock management schemes). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja 69. 212 p.

15. HEINONEN, M. 1987. Suur-Saimaan siikojen taksonomia ja geneettinen muuntelu (Taxonomy and genetic variation of Lake Suur-Saimaa whitefish). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja 59. 88 p.

16. HONKASALO, L. & JOKIKOKKO, E. 1987. Uittoperkaukset ja perattujen jokien kunnostus kalatalouden kannalta (Dredging of rapids for log floating and their restoration for fisheries). Helsinki. RKTL, kalantutkimusosasto Monistettuja julkaisuja 71, p. 1–45.

17. IKONEN, E., AHLFORS, P., MIKKOLA, J. ja SAURA, A. 1987. Meritaimenen ja lohen elvyttäminen Vantaanjoen vesistössä (Rehabilitation of the sea trout (Salmo trutta m. trutta) and the salmon (Salmo salar) in the Vantaanjoki watercourse). Helsinki. RKTL, kalantut-kimusosasto. Monistettuja julkaisuja 62. 106 p.

18. JUNTUNEN, K. 1987. Kromosomimääritys apuna siikojen taksonomisten ongelmien ratkaisemisessa (Use of chromosome determinations in solving problems in whitefish taxonomy). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja 64. 77 p.

19. JURVELIUS, J. & HEIKKINEN, T. 1987. The pelagic fish density, biomass and growth of vendace, Coregonus albula L., monitored by hydroacoustic methods and trawling in a Finnish Lake. Aqua Fennica 17 (1), (in press).

20. JURVELIUS, J., HEIKKINEN, T., VALKEAJÄRVI, P. & LINDEM, T. 1987. Fish density and fish species composition in relation to the phosphorus concentration in some pelagic areas of Lake Päijänne. Biol. Res. Rep. Univ. Jyväskylä 10, p. 189–199. (in press).

21. JURVELIUS, J., LINDEM, T. & LOUHIMO, J. 1987. The number of fish in the pelagic areas of Lake Pyhäjärvi (Karelia). Finnish Fish. Res. 8, (in press).

22. JÄRVENPÄÄ, T. 1986. Veden vähähappisuuden ja happamuuden vaikutukset ravun hemolymfaan (Effects of water with a low oxygen content and low pH value on the crayfish haemolymph). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja 54. 60 p.

23. JÄRVENPÄÄ, T., NYLUND, V., RAILO, E. & WESTMAN, K. 1986. The effects of the crayfish plague fungus Aphanomyces astaci on the haemolymph of Astacus astacus and Pacifastacus leniusculus. In: BRINCK, P. (ed.), Freshwater crayfish VI, p. 223–233.

24. JÄRVINEN, A. 1987. Vendace and whitefish - the coregonids of Finland. Helsinki. A survey for the International Symposium on Biology and Management of Coregonids, Joensuu, Finland, 1987. 16 p

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26. Kalataloudelliset tilastot vuodelta 1983. Statistik över fiske och fiskodling i Finland år 1983. Statistics on fishing and fish farming in Finland in 1983. 1986. Suomen Kalatalous 52, p. 42–135.

27. KALLIO-NYBERG, I. & PRUUKI, V. 1987. Tornionjoen lohikannan kutunousu ja monimuotoisuus (The spawning run and polymorphism in salmon (Salmo salar) stocks in the River Tornionjoki). RKTL, kalantutkimusosasto. Monistettuja julkaisuja, 70. p. 44–74.

28. KETTUNEN, J. ja HILDEN, M. 1986. Populaatioanalyysi ja sen herkkyys parametrien muutoksille (Population analysis and its sensitivity to parameter changes). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja 56. 50 p.

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37. MUTENIA, A. & VIHERVUORI, A. 1987. Ammattikalastuksen kannattavuuden kehitys Inarijärvellä vuosina 1976–1985 (Profitability of professional fisheries in Lake Inari in 1976–1985). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja (in press).

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40. NENONEN, M. (ed.). 1987. Kemijärven tila ja kalatalous (English summary: The state and fisheries of Lake Kemijärvi. Final report and proposal for future action). Helsinki. Vesi- ja ympäristöhallinnon julkaisuja 13. 134 p.

41. NYLUND, V. 1986. Ravun loisen, Psorosperium haeckeli Hilgendorf rakenne, haittavaikutukset ja taksonominen asema (The structure of the crayfish parasite Psorosperium haeckeli Hilgendorf and its harmful effects and taxonomic position). Helsinki. RKTL, kalantutkimusosasto.Monistettuja julkaisuja 55, p. 1–60.

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44. PENNANEN, J.T. 1987. Kokemäenjoen vesistön toutaimen hoito- ja suojeluohjelma (A program for the management and protection of the asp in the Kokemäenjoki watercourse). Helsinki. RKTL, kalantutkimusosasto. Monistettuja julkaisuja 60. 56 p.

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Appendix 1.

FISH CATCHES IN 1986, 1000 kg.

Appendix 2.

KALANVILJELY SUOMESSA VUONNA 1986
— FISKODLING I FINLAND åR 1986
— FISH CULTURE IN FINLAND IN 1986

¹⁾ Tuotannosta kirjolohta 99 %. Jäännös lohta ja taimenta — Av produktionen 99 % regnbágslax.
Resten lax och öringg. — 99 % of production rainbow trout. The rest salmon and brown trout.

²⁾ Tuotantoluvut perkaamatonta painoa. — Produktionssiffrorna som orensad fisk. — Production in kg ungutted fish.

³⁾ Lohi-, taimen- ja nieriälajien osalta syömäänoppineita, vapaasti uivia poikasia. - Beträffande lax, öring och röding, yngel som börjat äta och sim mar fritt. - Salmonids free-swimming fries.

⁴⁾ Hauen osalta esikesäisiä, muutaman viikon ikäisiä poikasia. - Beträffande gäddan nykläckta, nágra veckor gamla yngel. - Pikes a few weeks old younglings.

Istutustuotannon arvo 1986 Mmk 80
Utsättningsproduktionens värde 1986 M FIM 80
Value of stocking-production 1986 M FIN 80