7. FISH AND FISHERIES
Like its western neighbour, Norway, Sweden has a limited freshwater fish fauna. There are only about 40 indigenous freshwater species. High mountain lakes may have from only one to a half dozen species while the largest southern lakes have some 20 to 34 species. There is also an altitudinal distribution from a lesser number to a greater number of species. For example, in northern Sweden there is a relatively simple zonation of species from the Arctic highlands to the boreal coniferous forest areas and the Baltic coast region. The sequence is roughly: barren trout lakes, allopatric trout or char lakes, sympatric trout or char lakes, whitefish lakes (mostly with several other species), lakes with pike, perch and cyprinids (Nilson and Pejler, 1973).
Characteristic native forms are the resident brown trout (Salmo trutta), char (Salvelinus alpinus), various coregones or whitefishes (Coregonus spp.), grayling (Thymallus thymallus) and the anadromous Atlantic salmon (Salmo salar) and sea trout (S. trutta)1. Salmon are fished commercially and for sport, and are the result of both natural propagation and stocking. For example, the salmon stock in Lake Vättern is absolutely dependent upon artificial rearing; nevertheless, a salmon of 19.6 kg was taken there in 1991 (Andersson, 1991). The largest salmon taken in Sweden, from the Fax River, weighed 36 kg. The largest brown trout taken in Sweden (Lake Vättern) weighed 23 kg (personal communication from K. Andersson, 1992).
1 A true (and native) landlocked form of salmon is also found in Sweden. Laird and Needham (1988) call this landlocked form “Blanklox”, but Kent Andersson (personal communication of 16 August 1991) tells me that the popular Swedish name is blanklax and that it is applied to bright silvery freshrun anadromous salmon. According to Andersson, only the older people in Sweden apply this name to landlocked salmon alone. Two stocks of landlocked salmon live in Lake Vänern. Landlocked salmon were originally found in Europe in only a few lakes: Sweden (1), Finland (2), Norway (4). Both these landlocked forms and the anadromous ones are Salmo salar (Behnke, 1988)
The most widely distributed fish in Sweden is, however, the European perch (Perca fluviatilis), and pike (Esox lucius) is second. The pike-perch (Stizostedion lucioperca) has a more limited distribution in the warm eutrophic lakes, but ranks high in catches. Sweden is also an important area for the European eel (Anguilla anguilla), especially in the central and southern part of the country. In a sample of 1 670 lakes in these areas, eels were recorded in 73 percent (Svärdson, 1976a). The lampern or river lamprey (Lampetra fluviatilis) is also widely distributed along the Swedish coast, annual catches ranged from 4.7 to 27.3 t during the 1914–23 and 1937–79 periods (Sjöberg, 1980). Cyprinids such as bream (Abramis) and roach (Rutilus) and the burbot (Lota lota), are lesser elements in the fishery. The European smelt (Osmerus eperlanus) is also taken commercially but is primarily a forage fish.
The most successful introduced fishes have been from North America: the rainbow trout (Oncorhynchus mykiss) which is largely used for fishculture, the Eastern brook trout or char (Salvelinus fontinalis) also used in a minor way for aquaculture, and another char, the lake trout (S. namaycush). See also Section 9.2.
Table 7 illustrates the catch from Swedish inland waters sensu strictu as compiled by FAO from statistics furnished by the Government of Sweden for the period of 1965–86. There are no total statistics for the catch of fish in Sweden's inland waters according to the National Board of Fisheries (communications to EIFAC in 1979) the Swedish Institute (1981), and the dogmatic statement of Holmberg (1986), the EIFAC National Correspondent, and Head of Section, National Board of Fisheries, Göteborg: “For the inland fisheries [of Sweden] there are no statistics”. Consequently this abridged table furnishes only an approximation of minimum reported total commercial catch in Sweden's fresh waters, although there has been some refinement of catch statistics in recent years as is shown in Table 8. At best, these tables can only offer indications of the principal fishes taken and are of little value in indicating the relative composition of the catch. (Note the sudden appearance of reported catches of salmon and rainbow trout in 1982.)
For these reasons, it is desirable to include Table 9, showing the catch in Sweden's four largest lakes (almost one-quarter of the country's lake area) in 1976 and Table 10, which provides information on the catch of Atlantic salmon and trout in some of the country's larger rivers.
As in Finland, there is a considerable catch of freshwater or fluvial fishes (e.g., pike) in the brackish waters of the Baltic Sea - some of which are almost fresh. Two other tables are, therefore, included. Table 11 shows the 1965–87 Swedish catches of freshwater and diadromous species in Marine Statistical Fishing Area 27, which includes the Baltic. (One assumes that all of its statistics relating to freshwater fishes apply only to the Baltic.) An additional table (Table 12) shows the Swedish catch in the Gulf of Bothnia only during the 1976–78 period. It should be noted that in 1978, the value of the Swedish Bothnian catch of whitefishes or coregonids was 29 percent of the total catch and that of Atlantic salmon 26 percent of the total (Andreasson and Petersson, 1982).
Nominal catches in the inland waters of Sweden, 1965–86 (in tons)
|Other species a|
|1982||7 550||2 450b||0|
|1986||2 000||1 141e||59f|
a In the original tables, these are listed separately as follows: freshwater breams, n.e.i. (Abramis spp.), roaches (Rutilus spp.), cyprinids, n.e.i. (Cyprinidae), pike (Esox lucius), European perch (Perca fluviatilis), pike-perch (Stizostedion lucioperca), European eel (Anguilla anguilla), European whitefish (Coregonus albula), powan or pollan (C. lavaretus), Atlantic salmon (Salmo salar), trouts, n.e.i. (Salmo spp.). The catch of pike, perch and pike-perch for 1965–72 was said to have been included with that of the “freshwater fishes, n.e.i.”
b Listed as 50 t of Atlantic salmon and 2 400 t of rainbow trout
c Listed as 933 t of rainbow trout, 1 t of lake trout, and 0 t of “Salmonoids n.e.i.”
d Listed as 760 t of rainbow trout, 5 t of lake trout, and 1 t of “trout”
e Listed as 1 171 t of rainbow trout, 22 t of lake trout, and 2 t of “trout”
f Listed as 59 t of eel and 0 t of carp
... Data not available
0 Probably nil, negligible or insignificant; or less than 50 t during the 1965–73 period, or less than half a ton during later years
n.e.i. not elsewhere included
Source: 1965–69 Yearb. Fish.Stat. FAO, 36 (Publ. 1974)
1970–83 FAO Fish.Dept.Fishery Statistical Database (FISHDAB)
1984–86 Yearb.Fish.Stat.FAO, 62 (Publ. 1988)
Nominal catches in the inland waters of Sweden, 1987 (in tons)
|Freshwater breams (Abramis spp.)||3|
|Common carp (Cyprinus carpio)||0|
|Roaches (Rutilus spp.)||1|
|Pike (Esox lucius)||196|
|European perch (Perca fluviatilis)||122|
|Pike-perch (Stizostedion lucioperca)||378|
|Freshwater fishes n.e.i. (Osteichthyes)||330|
|European eel (Anguilla anguilla)||193|
|European whitefish (Coregonus albula)||705|
|Powan or Pollan (C. lavaretus)||199|
|Rainbow trout (Oncorhynchus mykiss)||1 554|
|Trouts n.e.i. (Salmo spp.)||43|
|Lake trout (Salvelinus namaycush)||27|
|Salmonoids n.e.i. (Salmonidae)||58|
0 Probably nil, negligible or insignificant, or less than half a ton
n.e.i. not elsewhere included
Source: Yearb. Fish.Stat. FAO, 64 (Publ. 1989)
Certain cyprinids are also caught in limited numbers in Baltic waters, e.g., the orfe or ide (Leuciscus idus), bleak (Alburnus alburnus), tench (Tinca tinca), common carp (Cyprinus carpio), and crucian carp (Carassius carassius). In all about 25 inland fishes are caught in the Gulf of Bothnia. An interesting phenomenon in this Gulf area is that many fish species normally considered as stationary freshwater forms migrate from the brackish Gulf waters to spawn in its tributary streams. Examples include the grayling, pike, European perch and several species of cyprinids.
A considerable quantity of the native crayfish (Astacus astacus) is also taken in Swedish inland waters. However, it has suffered heavy losses through the crayfish plague (Aphanomyces astaci), habitat loss and acidification of waters (see section 9.2). At the beginning of this century, the total crayfish catch in Sweden was about 200 t and in 1905, 90 t were exported. The crayfish plague, which appeared in 1907 speedily ravaged the Swedish populations. By 1908, crayfish export had dropped to 30 t and it has been estimated that at least 50 percent of the native Swedish crayfish population has been devastated (Brinck, 1975). As consumption of crayfish is high in Sweden, imports, especially Astacus leptodactylus from Turkey, have been substituted for the market and there have been attempts to alleviate the condition of the native stocks, including liming which has not been very effective.
The major method to restore crayfish populations in Sweden has been the importation and subsequent rearing of new resistant stocks of the signal crayfish (Pacifastacus leninsculus) from the United States. The first introduction was made in 1960 and large numbers were brought in in 1969. Further introductions of live crayfish have been prohibited for fear of diseases and parasites, and the signal crayfish stock has been perpetuated through aquaculture and stocking in Swedish waters.
Stocked in 260 Swedish lakes and rivers by 1982, breeding populations have been established and it is being exploited commercially. In several cases, its yield is even better than that of Astacus astacus. Sweden is also being used as a base for restoration of crayfish populations in other European countries (see: Abrahamsson, 1973; Karlsson, 1977; Westman, 1982; Anon./Sweden, 1984, and Fürst, 1984).
7.1 Capture Fisheries
7.1.1 Commercial fishing
Tables 7 and 11 show that the greatest tonnage of commercially taken freshwater and diadromous fishes in Sweden is derived from inland waters. However, despite the statistics in Table 7 for the 1965–84 period which showed an annual catch of about 10 000 t of freshwater fishes in Sweden, the total annual commercial catch in Sweden's fresh waters was estimated by the National Board of Fisheries (communication to EIFAC in 1979) as only 2 400 t, having a value of S.Kr. 12.5 million. Note also the drop shown in Table 7 of the catch of these fish in 1985 and 1986. The discrepancies cannot be explained by the author.
Accepting the figures around 2 400 t as the most valid, it is obvious that most of this freshwater catch comes from the great lakes of Sweden. Table 9 shows the catch in the four largest lakes in 1976. The preponderance of pike-perch (32.1 percent) in their total classified catch is clearly evident, followed among the identified fish by European whitefish (15 percent), pike (10.2 percent), powan (8.6 percent) and European perch (6.4 percent).
Special attention is called to the catches of Atlantic salmon (Tables 10 and 11)1. Salmon is an important import in Sweden and was once an important fish in about 50 Swedish streams, most of them entering the Baltic, but today less than half of these carry only a token population. Circa 1980, spawning occurred naturally in only about 15 large Swedish rivers, among them: Göta älv, Ätran, Mörrumsån, Vindelälven, Ljungan, Piteälven, Kalixälven and Torneälven - the latter shared with Finland, where it is also known as the Tornionjoki. Table 10 shows the salmon catch in some of Sweden's rivers. (Surprisingly, these figures do not appear in the FAO Fishery Yearbook's statistics, Tables 7 and 8.) The Swedish offshore catch in the main Baltic and Gulf of Bothnia has varied between 323 and 471 t annually during the 1969–78 period (Larsson, 1980). With respect to capture methods, seines are now the most important gear used in rivers and traps are also used, but only a small part of the catch is now made here. In the main basin of the Baltic, Sweden uses longlines and drift nets, while fyke nets, bag nets, drift nets, longlines and other gear are used in the Gulf of Bothnia.
1 The stock of Swedish salmon (Salmo salar) is generally divided into two groups: the “true” Atlantic salmon, which spawns in rivers of the west coast and has its feeding grounds in the North Atlantic, and the more important Baltic group, which spawn in rivers on the Swedish east coast. The Atlantic stock, badly damaged by dams and pollution, is now very small
It has been estimated that Sweden's natural smolt recruitment for the Baltic was 4 million individuals in 1900. Larsson (1980) estimated that the natural production fell to 1.4 million smolts by 1970. As with other Baltic stocks of salmon, hydroelectric dams, log transport and pollution were major reasons for this decline. Determined to have both fish and power, Sweden now has an efficient “sea-ranching” programme of rearing and releasing salmon and sea trout to compensate for the deleterious effects of hydroelectric projects on anadromous fishes and to supplement the salmonoid stocks of the Baltic. Circa 1972, the Swedish power industry operated 18 salmon-rearing stations, mostly built between 1955 and 1962. Their output in 1970 amounted to 1.7 million salmon smolts and 140 000 sea trout smolts, reared from eggs taken from upstream migrants (Johansson, 1973). By 1979, the number of salmon smolts from about 20 fish farms was 2 177 833, and it was considered that every second salmon caught in the Baltic was artifically produced (Lindroth, Larsson and Bertmar, 1982). The spawning migrants are caught in rivers using seines, gill nets, traps and electro-fishing, and retained for stripping usually in October and November. Dry pelleted feed is used, mortality is relatively low and the rearing period is one or two years as against the two to four years of the wild smolts.
Commercial catch in the four largest Swedish lakes, 1976 (in tons)
|Pike (Esox lucius)||117.7||14.2||10.8||4.3||22.5||7.5||19.0||6.6||170.0||10.2|
|European perch (Perca fluviatilis)||42.8||5.1||35.1||14.1||8.0||2.6||21.5||7.4||107.4||6.4|
|Pike-perch (Stizostedion lucioperca)||156.6||18.9||-||-||140.0||46.5||240.0||83.1||536.6||32.1|
|European eel (Angulla anguilla)||12.1||1.4||0.9||0.4||5.9||2.0||4.5||1.6||23.4||1.4|
|European whitefish (Coregonus albula)||96.0||11.6||35.8||14.4||118.0||39.1||-||-||249.8||15.0|
|Powan (C. lavaretus)||60.6||7.3||83.2||33.4||-||-||0.9||0.3||144.7||8.6|
|Trout and salmon (Salmo spp.)||14.6||1.7||15.6||6.2||-||-||-||-||30.2||1.8|
|Char (Salvelinus alpinus)||-||-||44.1||17.7||-||-||-||-||44.1||2.6|
|Grayling (Thymallus thymallus)||-||-||1.2||0.5||-||-||-||-||1.2||0.07|
|European smelt (Osmerus eperlanus)||12.8||1.5||-||-||-||-||-||-||12.8||0.76|
|Burbot (Lota lota)||79.9||9.6||2.7||1.1||7.0||2.3||3.0||1.0||92.6||5.5|
Source: National Board of Fisheries, through Sweden/EIFAC (1979)
Catches of salmon and trout in some Swedish rivers, 1972–76 (in kg)
|River||Salmon (Salmon salar)||Trout (Salmo spp.)|
|Mörrumsån||1 502||3 184||2 909||2 520||1 090||2 868||3 005||3 255||3 306||3 385|
|Dalälven||2 823||2 710||4 085||6 950||2 451||11 822||10 653||14 945||21 250||17 133|
|Ljusnan||2 924||3 708||5 410||5 856||2 958||-||-||-||-||-|
|Ljungan||1 818||1 759||1 538||1 400||904||248||155||276||200||108|
|Indalsälven||7 956||30 173||34 020||21 991||17 975||18 370||17 027||9 701||5 693||4 205|
|ångermanälven||10 528||23 447||32 184||33 163||20 749||3 550||6 807||6 421||5 593||7 615|
|Umeälven||812||3 427||2 605||1 512||1 891||1 172||1 662||3 001||2 417||3 521|
|Vindelälven||2 864||4 145||3 119||1 432||1 171||1 705||1 679||1 334||1 082||1 068|
|Skellefte älv||1 840||4 317||3 577||3 263||3 898||668||349||309||429||296|
|Luleälven||7 948||8 777||17 286||11 560||6 397||3 998||8 087||5 873||2 807||375|
|Kalixälven||7 205||11 189||5 938||3 810||3 125||2 013||1 309||876||887||933|
|Torneälven||5 122||7 772||4 818||2 678||1 520||401||659||704||568||726|
Source: National Board of Fisheries, through Sweden/EIFAC (1979)
Nominal catches of freshwater and diadromous species in Marine Statistical Fishing Area 27, Northeast Atlantic by Sweden, 1965, 1970, 1975, 1980–87 (in tons)
|Freshwater breams n.e.i.(Abramis spp.)||100||0||10||7||12||12||7||15||12||13||12|
|Roaches (Rutilus spp.)||0||0||9||1||2||2||2||1||4||2||2|
|Cyprinids n.e.i. (Cyprinidae)||0||0||1||0||1||0||0||0||0||0||0|
|Pike (E. lucius)||300||300||374||304||249||284||295||401||446||411||375|
|European perch (P. fluviatilis)||200||200||187||175||117||119||116||169||225||157||129|
|Pike-perch (S. lucioperca)||0||0||58||101||172||131||99||140||124||128||120|
|Freshwater fishes n.e.i.||100||200||43||40||30||22||16||22||16||24||2|
|European eel (A. anguilla)||1 800||1 200||1 399||1 112||887||1 161||1 199||1 073||1 118||830||703|
|European whitefish (C. albula)||200||300||1 239||1 195||716||958||381||576||891||1 162||1 148|
|Powan (Pollan) (C. lavaretus)||400||400||554||508||315||375||309||338||316||367||433|
|Atlantic salmon (S. salar)||600||600||644||599||482||549||447||794||1 090||1 110||1 215|
|Trouts (Salmo spp.)||100||100||106||67||7||39||16||62||62||45||49|
|Salmonids, n.e.i. (Salmonidae)||0||100||1||0||0||0||6||8||7||9||14|
|Rainbow trout (Oncorhynchus mykiss)||-||-||-||-||-||-||-||916||1 778||2 673||2 834|
|Total||3 800||3 400||4 625||4 109||2 990||3 652||2 893||4 515||6 089||6 931||7 036|
0 Probably nil, negligible or insignificant; or less than 50 t during the 1965–73 period, or less than 0.5 t during later years
- Not represented.
n.e.i. Not elsewhere included
Source: 1965 Yearb.Fish.Stat.FAO. 36 (Publ. 1974)
1970–83 FAO Fisheries Department Statistical Database (FISHDAB)
1984–87 Yearb.Fish.Stat.FAO, 64 (Publ. 1989)
Stocked in Baltic and west coast rivers, there has been an average return (based on tagging) to the commercial fishery in the Baltic area of about 10–12 percent, or 400 kg for 1 000 released fish. According to Lindroth (1972) this was highly profitable from an all-Baltic view, say at least US$ 1.60 in the fishery for each US$ 1.00 cost, but “… the return to Sweden, who pays the price, is just around the point of unprofitableness”. Since then, other Baltic countries are aiding in defraying the coasts of smolt production (see, for example, the review on Finland).
In Sweden, eels are both imported and exported. The Swedish eel fishery is mainly an inshore one carried out all along Swedish coasts except the northern part of the east coast. However, stocking of lakes in Sweden with eels was done as early as the eighteenth century, and the number of naturally migrating elvers coming to Sweden during the last few years has decreased, stressing the need to restock the inland waters. Restocking with yellow eel (10–100 g) caught in the sea or cultured has been followed, and since 1976 elvers have been imported from France and Great Britain. Fear of introduction of infectious pancreatic necrosis (IPN) virus stopped this traffic but it was resumed following quarantine. The commercial catch of silver eel in the Baltic in 1984 was 1 047 t which was similar to the last 10-year average (Holmberg, 1986). Fyke nets, eel pots and pound nets are all used.
Commercial gear for other inland fishes varies in Sweden. At Lake Vättern, where some 30 commercial fishermen are employed (1988), gill and trap nets are mainly employed and the fleet uses hydroacoustic equipment, radar, and telecommunications. The commercial gear used for pike-perch includes gill and trap nets in lakes Mälaren and Hjälmaren and trawls in the latter. Gill nets take about 75 percent of their catch. Fyke nets are used for pike during the spawning season; gill nets the rest of the year. On Lake Vänern there were about 200 commercial fishermen on the lake, half of whom made fishing their full occupation (1988). Large by-catches of lesser fish such as bream (Abramis brama), white bream (Blicca bioerkna) and roach (Rutilus sp.) hinder the use of trawls. European perch are a bycatch of the commercial fishery for pikeperch and eel. In 1976, the number of professional fishermen in the fresh waters of Sweden amounted to 570 part-time fishermen.
7.1.2 Sport fishing
As nets are permitted for some types of sport fishing in Sweden, the term “angling” is not synonymous with “sport fishing” in this country, where concepts such as “household fishing” or “free-time fishing” - as opposed to “commercial fishing” further confuse the issue. For example, during 1986 about 3 900 persons fished in Lake Vänern using 41 000 nets. This was considered “household fishing”.
Pike, European perch and pike-perch are the main sport fish. Others include: brown trout and sea trout, char, grayling, Atlantic salmon and the introduced salmonids, the American rainbow trout and lake trout. The world's record brown trout (17 kg) caught by sport fishing methods was taken in Sweden in 1991 (Andersson, 1991a).
Swedish anglers claim that trout are their preferred sport fish and coarse fishing, i.e., for cyprinids, occurs only sparingly, although there is some advertisement of areas where they can be fished (e.g., for bream in the Stockholm area). Unlike the situation in Norway or Iceland, rod fishing for salmon is very limited in Sweden. Two of the best salmon streams, which are also flyfishing waters, are the Mörrum on the south coast and Ätran on the west coast. The River Mörrum is a famous sea trout and salmon stream. An average fly-caught sea trout weighs about 3.6 kg and a fly-caught salmon of 22.9 kg was taken in 1991. Licenses for such fishing are not cheap; for example, in 1990 a license for the first day of the season costs S.Kr. 900 or about US$ 160, and the lowest price during the season was S.Kr. 105 or about US$ 20. The largest salmon (26 kg) taken by sport fishing methods in Sweden came from the river Dal in 1990. (Personal communications from K. Andersson, January 1992, and Salo, 1991.)
Catch of Swedish fisheries in the Gulf of Bothnia, 1976–78
|European perch (Perca fluviatilis)||30||25||28|
|Pike-perch (Stizostedion lucioperca)||-||-||2|
|Burbot (Lota lota)||11||8||8|
|Other freshwater fishes||3||28||28|
|European eel (Anguilla anguilla)||10||8||10|
|European whitefish (Coregonus albula)||1 249||1 092||1 050|
|Powan (pollan) (C. lavaretus)||360||347||296|
|Atlantic salmon (Salmo salar)||235||293||222|
|Sea trout (S. trutta)||50||62||44|
|Flounder (Platichthys flesus)||1||2||3|
|Cod (Gadus morhua)||41||73||312|
|Baltic herring (Clupea harengus)||6 329||5 893||5 725|
|European whitefish roe||107||83||91|
|Fish for reduction||103||240||193|
|Total||8 558||8 180||8 039|
Source: Andreasson and Petersson (1982) after Swedish Yearbook of Fishery Statistics 1977–79
A survey of the 15–74 age group in Sweden reported by Johansson and Norling (1980) showed that 2 million Swedes, i.e., 24 percent of the total population, were sport fishermen. This is the highest such proportion in Europe. Twenty percent of this group owned fishing rights. Seventy percent used only rod and line. Twenty-eight percent used nets as well or nets exclusively (4 percent). The Swedish sport fishing catch was estimated at 7 500–11 500 t annually by Sweden/EIFAC (1979). Note that even the lesser figure was three times the commercial catch as estimated by the same source. Confirmation of the importance of the sport fishing catch is afforded by Rundberg (1977) who estimates the total angler catch in Lakes Mälaren and Hjälmaren to be at least twice that of their commercial fishery. Similarly, Paulson and Stetson (1983) in a study of the River Dalälven found that sport fishermen valued the salmon as sixteen times higher than the commercial fisherman's price.
Even in Sweden's largest lake, Lake Vänern, the ultimate goal now seems to be to develop a recreational fishery “with an all-round service of high quality in different price ranges for both Swedish and foreign tourists” (Petersson, 1990). Andreasson, Ask and Bengtsson (1990) summed it up by saying, “Professional freshwater fisheries are, in the main, of little importance [in Sweden] but there is extensive recreational fishing and this is increasing all the time. Official reports suggest that out of a total population of 8 million people , 2 570 fish at least once a year, while 12 percent fish more than twenty times a year”.
According to Cedrins (1987), aquaculture in Sweden has had two different types of development: (i) small-scale production run by a single family, and (ii) large-scale cultures in industrial plants. Small-scale culture includes production of rainbow trout and salmon in net cages, and European crayfish and signal crayfish in ponds. Large-scale productions consist mainly of eel, flatfish, and giant river prawns produced in heated effluents. Most fish farms concentrate on producing fish of more than 2 kg, for which the best market prices are obtained. There is a very small amount of aquaculture of cyprinids but emphasis is on the other species mentioned.
Since the cultivation of fish for consumption did not develop rapidly, and is still not common, many of the statistics (especially the past ones) are confusing.
Sweden/EIFAC (1979) stated that the annual Swedish aquaculture production was then about 200 t of rainbow trout.
There were more than 500 fish farms in the country in 1979, but most of them were very small, mainly private farms which raised fish for stocking inland waters. About 25 of these produced 40 percent of the fish: rainbow trout, brown trout, char (Salvelinus alpinus), and American Eastern brook trout (char). Brown (1977, 1983) provided different figures, stating - without giving dates - that both rainbow trout and Atlantic salmon are cultivated for food here, there are about 100 private farms raising fish and about 300 t of rainbow trout and 100 t of Atlantic salmon are raised. However, the same figure in each of his papers shows a production of 390 t of rainbow trout in 1972. Fish Farming International (1984) says that Sweden produced 400 t of trout in 1983. However, Anon./Sweden (1984) said that in 1984 the number of fish farms in Sweden for rainbow trout in fresh, brackish and salt water was about 300 and that the production in 1982 was about 2 000 t, mostly in net cages. Cedrins (1984) states that in 1982, Swedish fish farms produced about 2 400 t of fish.
Holmberg (1986) said that in 1984, the total yield of Swedish aquaculture for consumption was 1 631 t of fish which converted to a round fish production of 1 925 t. The dominant species produced was rainbow trout, 1 844 t. He gave the total value of Swedish aquacultural production in 1984 as S. Kr. 52 million. He also reported that the number of aquacultural enterprises in Sweden in 1984 was 637, of which 156 produced fish for consumption and 168 cultivated fry for stocking.
The most recent figures on aquacultural production of inland species in Sweden are shown in Table 13.
At one time Sweden imported trout eggs and live fish from Denmark, Finland and Norway but this is now illegal. There are a number of Swedish companies which supply fish foods.
Production from aquaculture of inland species in Sweden, 1986–89 (in tons)
|Common carp (Cyprinus carpio)||...||...||0||0|
|European eel (Anguilla anguilla)||59||193||233||190|
|Rainbow trout (Oncorhynchus mykiss)||3 785||4 388||6 783||6 634|
|Atantic salmon (Salmo salar)||160||224||363||771|
|Brown trout (Salmo trutta)||2||2a||0||0|
|Chars (Salvelinus spp.)||22||27||77||98|
|Crayfishes (Astacus spp., Cambarus spp.)||1||1||3||4|
... not available
0 more than zero but less than half a ton
Source: FAO, Fish.Info., Data & Stat.Serv., (1991)
The present development in cage culture has caused some conflicts in Sweden due to nutrient loading. The P-loading falls in the range of 10–15 kg P/t of fish produced in a season and, in some cases, cages placed in oligotrophic lakes have created mesotrophic or even eutrophic conditions. Methods to reduce both phosphorus and nitrogen loading are underway in order to meet the conditions stated in Sweden's Environmental Protection Act. Fish farms larger than 10 t for finfish must pass the regulations of this Act and make full applications to the authorities. As there are 15 to 20 authorities in Sweden, the procedure is complicated (Ackefors, 1989).
As in Norway, sites with aquacultural potential have been reviewed so that administrators in charge of land planning and development can help avoid conflicts with industrial sectors and pollution.
8. OWNERSHIP, ADMINISTRATION, MANAGEMENT, INVESTIGATION AND AGREEMENTS1
1 Based on Gaudet (1974), Wendt (1982), and Andreasson, Ask and Bengtsson (1990). This entire description may not be up-to-date
Ownership of both water and fishing rights are private. Owners generally have fishing rights, however, only on their own small sections of the water body. These are called “divided water rights”. In joint ownership, however, fishing rights over the entire water body are enjoyed by all of the owners in common. These are called “undivided fishing rights”. In the first case, an owner may use or manage his part of the water however he likes, without respect of the views of the owners of other parts. Consequently, if the separate owners do not agree on goals, proper management of the water and its fishery is impossible. In the second case, undivided water rights, the individual owners have no right to act independently (for example, to stock fish) and all owners must agree as to the use and management of the water body.
With such situations, conflicts of interest are frequent, and it has been necessary, therefore, to have the organization of “fishery management units”. Such units are probably exclusive to Sweden. Although there is no national policy as to the size and structure of these units, efforts are made to joint biologically homogeneous areas. In some countries with many small lakes, there may be many small units each comprising only one or a few lakes. In others, the aim has been to include all water courses or lakes within extensive areas. There were about 800 units in 1988 and it has been estimated that the final number will be close to 1 650 (Andreasson, Ask and Bengtsson, 1990).
The Government and municipalities also grant public use of some areas. Among the perhaps 40 000 km2 of lake area, more than 2 000 areas are reserved for licensed fishing where the public is allowed to fish at a fee paid to the landowner. In the five largest lakes, some areas are open to public use; these are the only public fresh waters. Swedish citizens may fish in these with hooks, rods and gill nets generally. Special permission is required from the countries to fish with pound nets and traps in public waters on the coast and in the five major lakes.
8.2 Administration and Management
The administration of inland fisheries in Sweden falls within the competence of the Ministry of Agriculture, although having a large degree of independence.
8.2.1 The State fishery administration consists of three central boards:
National Swedish Board of Fisheries. This board, which is concerned with commercial and sport fishing and aquaculture, consists of a Director-in-Chief and six members appointed by the King. When scientific matters are dealt with, there are four members appointed by the King. The Board is organized into: (a) an Administrative Bureau dealing with laws, statutes, administration, finance, staffing, etc.; (b) a Freshwater Fishery Bureau dealing with those aspects of fishery and water laws, statues and local fishery administration to the extent that these questions are not handled by the Administrative Bureau, as well as with the sport fishery, education of fishery workers, conservation, etc.; (c) an Institute of Freshwater Research (see section 8.3); (d) a Marine Fishery Bureau, and (e) a Marine Laboratory.
The State Agriculture Marketing Board deals with price regulations and support, and import/export problems.
Board of Agriculture, the chief authority of the Country Agricultural Board.
8.2.2 Local administration
Sweden is divided into seven districts: two are marine, four are freshwater, and the most northern district includes both freshwater and marine (brackishwater) fisheries. The freshwater district boundaries follow those of the watersheds. A fishery inspector in each district works with country agricultural boards and their fishery consultants to develop and conserve fisheries, counteract water pollution, and give expert advice. A fishery engineer, dealing with fishways, hatcheries, ponds and other construction is also attached to local administration. Fishery assistants head the hatcheries.
County Agricultural Boards may be assigned to the local administration although they and their fishery consultants fall under direction of the Board of Agriculture. Each board has a fishery committee with representatives of different fishermen. In accordance with the water law, these boards and their consultants are responsible for fishery conservation work within their area. They collect fishery statistics, organize training courses for fishermen, and regulate potential environmental issues.
8.3 Scientific and Research Services
The scientific and research activities under the Board of Fisheries are carried out by the “Sotvattenslaboratoriet” (Institute of Freshwater Research) at Drottningholm. The Institute carries out investigations on freshwater fishes and their food organisms, water pollution, stream and lake regulation, trials of fishing gear, etc.
Limnological and environmental studies allied to fisheries are carried out at the institutes of limnology at the University of Uppsala and University of Lund.
There is also a Salmon Research Institute at Alvarleby concerned with the biology of salmon, conservation of stocks, the influence of water projects on salmon, breeding, stocking and disease control - especially in connexion with the rearing of salmon and trout financed by hydroelectric power companies.
The National Veterinary Institute is generally responsible for fish disease control.
In addition to these institutions, research is carried out at various other institutes such as the Swedish University of Agricultural Sciences and the Swedish Hydropower Board.
8.4 Other Agencies
The Swedish Angler's Association, the only nation-wide angler's association in Sweden, had about 100 000 members, and about 60 000 of these belonged to sport fishing clubs in 1980.
In each of Sweden's 24 counties, there is a regional body coordinating the club's work and activating non-club members.
8.5 International Agreements
Sweden and Finland established a joint Swedish-Finnish Boundary-River Commission for the drainage basin of the Torneälven (Tornionioki in Finnish) in 1971, including monitoring and joint salmon cultivation. There is also an agreement between Sweden and Finland on water quality in the Gulf of Bothnia.
Sweden also has a bilateral agreement with Norway concerning uses of the Trysilelva-Klarälven-Göta älv system.
9. STATE OF THE FISHERY
The average annual yield per hectare in inland waters (lakes) in Norway has been estimated to be only about 2–4 kg/ha. The average annual yield from Sweden's inland waters is about the same or somewhat higher (Sweden/EIFAC, 1979).
The average, maximum and minimum annual yields over a period of years in four of Sweden's largest lakes are shown in Table 14. It would appear from these calculations as well as from the full range of the original data that the catch per hectare has declined severely in at least two of these lakes.
The statistics shown in Tables 7 and 8 are of little value in indicating changes in the Swedish inland fishery. It is known, however, with respect to Atlantic salmon that the size and mean age of returned fish has decreased (Carlin, 1969). It also appears from some catch records that there has been a decline in the eel population along the Baltic coast since about 1940 (Svärdson, 1976a).
9.2 Factors Affecting the Fishery
Not only does Sweden have a generally large water area with respect to its land mass, but an extremely large number of well distributed lakes and streams. It thus provides for a wide distribution of aquatic resources, as well as many (and large) areas for fishing.
The original quality of these waters was high, on the oligotrophic side, of course, and favourable factors in this respect lie in the rapidity of stream flow, large areas of water subject to oxygenation and the situation of much of the industry near the mouths of rivers. Furthermore, Sweden's runoff, 22 035 m3 per caput annually, provides a large volume of water for the dilution of effluents. However, as in Finland, this runoff figure is somewhat misleading, since the heavily populated and industrial areas have much less water per caput for effluent dilution. For example, the runoff per caput in Norrland is about ten times that of the more populated Svealand and Götaland.
The harmful effects of pollution, especially from the wood industry, have been mentioned before, and for some years the nutrient level, derived from a variety of sources, in Swedish lakes has continued to rise. This was particularly noticeable in the large lakes in settled areas. For example, about 40 percent of the P and N in Lake Mälaren came from urban areas and about 30 percent of its input of N from chemical industries (Ahl, 1970). Although Vänern, Vättern and the deeper parts of Mälaren were originally oligotrophic, they have become progressively more eutrophic following the rapid growth of cities with industrial development. Thanks to increased purification of waste water and sewage during the last decades the eutrophication has diminished to a large extent and in some lakes there is even a growing oligotrophication instead, e.g., in Vättern. The situation, in fact, does appear to be improving (see section 9.3). Nevertheless, Sweden estimated that it would take Lake Vänern 30 years to respond to the present-day reduction of industrial pollution (ECE, 1978).
Unfortunately, many streams and lakes in Sweden are being acidified because of the increase in acidic air-borne emissions: sulphur and nitrogen oxides from industry in Western Europe. Originating at considerable distances, and therefore beyond the immediate control of Sweden and other affected countries, this phenomenon has been intensified by SO2 emissions from increased power production. Circa 1975, the total number of Swedish lakes acidified to below pH 6 was probably around 10 000, and those acidified below a pH of 5.5 total about 5 000 (Dickson, 1975). Holmberg (1982) said that about 9 000 Swedish lakes were affected by acidification, amounting to about 10 percent of the country's lakes and about 10 percent of the total lake area. At times when snow is melting, Sweden has about 20 000 lakes, which can achieve critically low pH values, i.e., less than 5.5 (Sweden/EIFAC, 1979). Such changes, accompanied by decreases in phytoplankton and increases in heavy metals, not only lower aquatic productivity, but cause fish kills and alter fish population structures. The most sensitive fish species are roach and minnow (Phoxinus phoxinus). Salmonids are less sensitive and the most tolerant are pike, perch and especially eel.
Allied perhaps with acifidification is an increase in mercury content in fish, especially pike, in the forest lakes of southern and central Sweden. These concentrations have increased sharply during this century and about 40 000 lakes larger than 0.01 km2 are now affected by these elevated mercury levels (Johansson, 1985).
The great variations in natural stream flow in Sweden have necessitated the elaboration of many new hydrological systems, including new lake systems, in order to develop hydroelectric power. The deleterious effects of both hydroelectric and logging on anadromous fishes in Sweden have already been mentioned, as have the attempts to compensate for such effects. Fortunately, Swedish power law has demanded that positive steps must be taken to prevent and mitigate damages to fisheries by power development. Hatchery production and the methods of fish stocking used to sustain such stocks have been quite successful (see section 7.1). Other factors, however, such as offshore fishing by other nations obviously lessens the supply of sea-run salmonids returning to the Swedish fishery.
Catches and yield in four large Swedish lakes
|Lake||Record period||Area km2||Total catch tons||Yield kg/ha/year|
Source: Vänern - Petersson (1990)
Vättern 1986–Essvik (1990)
Vättern (1970–77), Mälaren and Hjälmaren, National Board of Fisheries, through Sweden/EIFAC (1979)
Aside from blocking migration, hydroelectric development has cut down stream habitat and changed lake levels, thereby affecting both spawning and food production. The present swing toward nuclear power generation creates another problem for fish, thermal heating of water courses.
There has also been some damage to fisheries through other types of water use. For example, through ditching and canalization, the surface water of the Kävlivy River has disappeared over a 150-year period.
Although the wide distribution of aquatic resources provides a safeguard to otherwise somewhat limited native stocks, several changes have been engendered by the introduction of exotic species. In Norrland, for example, the original ecosystems of many lakes were quite simple, containing only one, two or three fish species or even being barren. A common sequence as regards the history of these lakes has been: (i) introduction of either brown trout or char into the barren lakes; (ii) addition of another species (trout or char) to produce a two-species system, and (iii) finally addition of a third or even more species such as whitefish, burbot or pike (Nilson and Pejler, 1973).
In addition to fish species, attempts have been made to improve yield by stocking new invertebrate food organisms in impounded waters, e.g., Mysis relicta, Pallasea quadrispinosa and Gammaracanthus lacustris.
Transfer of fish between waters and introduction into new lakes has been popular among Scandinavian fishing right owners since time immemorial (Svärdson, 1976), but it is now illegal to move live fish from one water to another without a license. These transfers, including changes due to competition (as well as various limnological changes already described) have altered and continue to alter the Swedish fish populations and thus both the quality and quantity of the yield.
For example, the North American lake trout (Salvelinus namaycush) has been introduced into some 70 Swedish waters since 1959 to enhance fishing in lakes subject to hydroelectric development, reduce dwarfed populations of coregonids and fill a vacant niche in large lakes with a cold-water hypolimnion (Gonczi and Nilsson, 1984). Another species, the pike-perch, has increased decidedly in certain waters apparently as a result of cultural eutrophication; conversely European perch have decreased in these waters for the same cause as well as by the increase in pike-perch. In new reservoirs, roach often take over, but the stress of acidification affects them sooner than several other species, pH values of around 5.5 seem critical to their reproduction. Lastly, the selective fishing action of the growing body of sport fishermen - with their preference for predator species, such as pike - may also affect population structure.
Factors other than manmade influences also limit the yield from Swedish inland fisheries. The waters are generally cold, are deficient in minerals and there is a short growing season for aquatic organisms. For example, in northern Sweden, where the “growing” or “vegetative” period is about 90 days, the growing season for salmon smolts (water temperatures above 10°C) is only 90–120 days. As in Finland and Norway the yield from fishing is further limited because of the long period of ice cover, although the growing use of snow-mobiles is increasing winter fishing.
With the exception of some of the larger lakes as well as some important parts of the coastal waters, fishing rights belong exclusively to the riparian owner. It is difficult, therefore, to manage all of them either for the highest yield or for all classes of users. There have been conflicts in use between commercial fishermen and sport fishermen - a major one being the practice of some of the non-professional fishermen of using nets and in some cases selling their catch. In the past, the fishery laws have been generally formulated to support commercial fisheries. Changes in this concept were outlined by Johansson and Norling (1980).
The use of public funds for the development of fisheries, especially in remote or depressed areas, has also been practised in Sweden.
As in all countries, increased water use will place further demands upon an already decreasing fish habitat. The Swedish IHD Committee (1973) estimated that the demands for industrial and urban use in Sweden would increase to 8 700 million m3 annually by the year 2000. Such an amount from all sources would still be equivalent to less than 5 percent of the entire surface runoff. Although their supply in some areas would obviously be diminished, fisheries would still have large quantities of water. Furthermore, according to ECE (1978) the “present” demand in Sweden from industry is only half of what was forecast ten years ago, and there has been a decline in water needed for both basic industry and thermal cooling.
The prospect for diminished acidification of waters is not, however, a happy one. Trends indicate that “… if the present development continues, in less than 50 years about 50 percent of our [Swedish] lakes and rivers may have pH values of 5.5 or even 5.0” (Anon., 1971)1. There is a tendency, therefore, for already soft waters of western Sweden to become more acidic like those of central Sweden. Some of the most exposed and valuable waters are being limed to offset acidity. Sweden has increased its expenditures for this purpose sixfold between 1978/79 and 1983/84 and by 1983 had limed about 1 500 of 18 000 totally acidified lakes (Gahnströhm, 1984) but this procedure is expensive and only a stop-gap. Sweden has also set introduced emission controls, removed sulphur from flue gases, and set limits for sulphur content in the fossil fuels it uses, and is working on international agreements to limit sulphur discharge1.
1 Reference seen but not relocated
1 Not only have lakes and streams been affected. About one-tenth of the trees in southern Sweden have also been damaged. The pulp and paper companies of Sweden have reduced their own sulphur emission from 103 000 t in 1975 to around 30 000 t in 1983 (Economist, 1984)
Despite the eutrophication of lakes in southern Sweden during the first part of this century, improved sewage treatment especially since 1969–70 has greatly improved the situation. In 1976, all communities with populations larger than 200 were to have sewage treated to 90 percent phosphorus reduction (Ahl, 1975).
Albeit damage to the aquatic environment through man's use, Sweden has nevertheless made a decided effort to overcome these ill effects and it is expected that this will continue. The water laws in Sweden (unlike those in many countries) have been generally helpful in indicating that remedial steps should be taken or compensation provided in case of damage through use. There has also been a growing resistance to dam construction, and industries have been encouraged to locate in areas least sensitive to pollution. The high population of active sports fishermen aids such efforts as do new environmental laws regulating pollution.
Unlike many of the other maritime nations, Sweden's sea fisheries have never gained large importance, and the country's fishery scientists have been more active in research on inland waters. They have also been more active than the scientists of many European nations in establishing modern forms of fish management. Appraisal of waters, the use of chemicals to eradicate undesirable populations of fish, calcination of lakes and streams and the introduction of exotic organisms are among the country's continued efforts to maintain and increase fish populations. Stocking, of several species of fish, is one of the major measures of fish management, and hatchery development of salmonoid stocks has reached a high level. The output is high and will increase in brackish and salt water. Sweden has, however, been cognizant of the protection of natural genetic resources, and - at least in some instances - made attempts to prevent stocked fish from mixing with wild populations and thus diluting their beneficial characteristics. There is also a growing interest in crayfish and eel aquaculture.
Such a foundation, coupled with Sweden's wealth of waters and relatively low population density even in an industrialized country presages continuance of a good inland fishery.
A study submitted to the National Board of Fisheries in 1976 estimated the total optimal yield of fish of commercial interest in Swedish lakes and reservoirs at some 16 000 t. It also stated that if the fishery were aimed at an exploitation of available protein resources, it would seem possible to harvest a total of some 33 000 t.
It seems apparent, however, that recreational fisheries already dominate the picture, and may be changing the composition of the commercial catch through concentration on particular species. Restrictions on the use of gear such as nets by sports fishermen have already been placed in some areas, and it seems entirely possible that only angling will be allowed on most or all waters at some time in the future. Similarly, there will be less discrimination between foreign and Swedish sportsmen, and an increase in the use of license fees to manage fisheries.
Sport fishing is one of the most extensive outdoor activities in Sweden and with the expected good resource management will continue at a high level.
Abrahamsson, S., 1973. The crayfish Astacus astacus in Sweden and the introduction of the American crayfish Pacifastacus leniusculus. In Freshwater crayfish. Papers from the First International Symposium on Freshwater Crayfish, Austria, 1972, edited by S. Abrahamsson. Lund, Sweden, Studentlitteratur, pp. 27–40
Ackefors, H., 1986. Prospects and limitations for aquaculture in Scandanavia. Institute of Freshwater Research, Drottingholm, Report No. 63, pp. 5–16
Ackefors, H., B. Larsson and L. Nyman (eds), 1983. Fish breeding and aquaculture. Swedish Council for Planning and Coordination of Research in cooperation with the National Marine Resources Commission, Report No. 83:6, 69 p.
Ahl, T., 1970. I. Principal features in the chemistry of Lake Mälaren. In Uppsala Symposium. Eutrophication in large lakes and impoundments/L'eutrophisation dans les grands lacs et les retenues d'eau, compiled by C.P. Milway. Paris, Organisation for Economic Co-operation and Development, pp. 169–95
Ahl, T., 1975. Effects of man-induced and natural loading of phosphorus and nitrogen on the large Swedish lakes. Verh.Int.Ver.Theor.Angew.Limnol., 19 (Part 2): 1125–32
Andersson, K., 1991. Laxar ur underjorden. Arbetet, Båt & Fiske, 16 August 1991, p. 12
Andersson, K., 1991a. Rekordbjässen. Arbetet, 22 November 1991, p. 25
Andreasson, S. and B. Petersson, 1982. The fish fauna of the Gulf of Bothnia. In Coastal research in the Gulf of Bothnia, edited by K. Müller. The Hague, Dr. W. Junk Publishers, pp. 301–15
Andreasson, S., L. Ask and B. Bengtsson, 1990. The organization of fishery management units in Sweden. In Management of freshwater fisheries. Proceedings of a symposium organized by the European Inland Fisheries Advisory Commission, Göteborg, Sweden, 31 May–3 June 1988, edited by W.L.T. Van Densen, B. Steinmetz and R.H. Hughes. Pudoc.Wageningen, pp. 462–5
Bengtsson, B.E., 1982. The pollution situation in the Gulf of Bothnia. In Coastal research in the Gulf of Bothnia, edited by K. Müller. The Hague, Dr. W. Junk Publishers, pp. 431–7
Bergsten, K.E., 1961. Sweden. In A geography of Norden. Denmark, Finland, Iceland, Norway, Sweden, edited by A. Sømme. New York, John Wiley and Sons, pp. 293–349
Berntsson, K.E., 1971. An account of some aspects of the fishery for eels in Sweden. EIFAC Tech.Pap./Doc.Tech.CECPI, (14): 105–12
Brinck, P., 1975. Crayfish in Sweden. In Freshwater crayfish. Papers from the Second International Symposium on Freshwater Crayfish. Held at Baton Rouge, Louisiana, U.S.A., 1974, edited by J.W. Avault, Jr., Baton Rouge, State University of Louisiana, pp. 77–81
Carlin, B., 1969. Salmon conservation in Sweden. In Atlantic Salmon Association Centennial Award Fund. Series of lectures by Dr. Borje Carlin. Quebec, Atlantic Salmon Association, pp. 5–6
Cedrins, R., 1984. Marknadsutreckling och ekonomiska framtisdsmojligheter för svenskt vattenbruk. Vatten, 40:23–31
Dickson, W., 1975. The acidification of Swedish lakes. Rep.Inst.Freshwat.Res.Drottningholm, (54):8–20
Dickson, W., 1978. Some effects of the acidification of Swedish lakes. Verh.Int.Ver.Theor.Angew.Limnol., 20:851–6
Economist, 1984. Sweden's paper-chase. Economist, 292(7356):64–5
Essvik, B., 1990. Fish stocks of Lake Vättern: exploitation and fishery management. In Management of freshwater fisheries. Proceedings of a symposium organized by the European Inland Fisheries Advisory Commission, Göteborg, Sweden, 31 May–3 June 1988, edited by W.L.T. van Densen, B. Steinmetz and R.H. Hughes. Pudoc.Wageningen, pp. 467–71
FAO, 1979. Sweden, Fishery Country Profile. Rome, FAO, FID/CP/SWE Rev.1:4 p.
Fürst, M., 1984. Introduction of the North American crayfish (Pacifastacus leniusculus (Danal) into Sweden. EIFAC Tech.Pap./Doc.Tech.CECPI, (42) Suppl.Vol.2:400–4
Fürst, M., J. Hammer and C. Hill, 1985. The introduction of Mysis relicta in Sweden: effects on fish in impounded lakes. In Habitat modification and freshwater fisheries, edited by J.S. Alabaster, Proceedings of a symposium of the European Inland Fisheries Advisory Commission, London, Butterworth, pp. 202–6
Gahnström, G., 1984. Short-term effects of liming on sediment oxygen uptake in an acid lake. Verh.Int.Ver.Theor.Angew.Limnol., 22 (Part 2):760–4
Gonczi, A.P. and N.-A. Nilsson, 1984. Results of the introduction of lake trout (lake charr, Salvelinus namaycush) into Swedish lakes. EIFAC Tech.Pap./Doc.Tech.CECPI, (42) Suppl.Vol.1:392–9
Hanson, A., 1978. Swedish policy for water quality protection. In Water development and management. Proceedings of the United Nations Water Conference, Mar del Plata, Argentina, March 1977, edited by A.K. Biswas. Oxford, Pergamon Press, Vol. 1, Part 4:1965–78
Holmberg, B., 1978. Sweden. In Reports from EIFAC member countries. Biennium 1976–78. (Meeting Paper), Rome, FAO, EIFAC/78/Inf.7:66 (mimeo)
Holmberg, B., 1982. Sweden. In Country reports of EIFAC member countries for inter-sessional period 1980–82, edited by K. Tiews. (Meeting Paper). Rome, FAO, EIFAC/XII/82/16:78–81 (mimeo)
Holmberg, B., 1986. Sweden. EIFAC Occ.Pap./Doc.Occ.CECPI, (16):115–7
Hult, J., 1964. Main inland fisheries problems, Sweden. EIFAC 60–3, Rev., 1 p.
Johansson, C. and I. Norling, 1980. Background paper to Sweden's country review. Sportfishing in Sweden. Paper presented at the Technical Consultation on Allocation of Fishery Resources, Vichy, France, 24–29 April 1980, 16 p. (mimeo)
Johansson, K., 1985. Mercury in sediment in Swedish forest lakes. Verh.Int.Ver.Theor.Angew.Limnol., 22(Part 4):2359–63
Johansson, N., 1973. Furunculosis in Swedish fish farms, 1951–1971. In Symposium on major communicable fish diseases in Europe. Panel reviews and relevant papers edited by W.A. Dill. EIFAC Tech.Pap./Doc.Tech.CECPI, (17) Suppl. 2:189–95
Larsson, P.O., 1987. Public sea-ranching with Atlantic salmon, Salmo salar, at the Swedish west coast. In European Aquaculture Society, Aquaculture Europe '87, International Conference and International Exhibition, Amsterdam, June 2–5, 1987, p. 65
Lindroth, A., 1972. Artificial salmon stocks in the Baltic. (Advisory Committee on Marine Resources Research meeting paper) ACMRR/IABO:1/72/2:5 p.
Lindroth, A., P.-O. Larsson and G. Bertmar, 1982. Where does the Baltic salmon go? In Coastal research in the Guf of Bothnia, edited by K. Müller. The Hague, Dr W. Junk Publishers, pp. 387–414
Müller, K. (ed.), 1982. Coastal research in the Gulf of Bothnia. The Hague, Dr W. Junk Publishers, 462 p.
Nilson, N.-A. and B. Pejler, 1973. On the relation between fish fauna and zooplankton composition in North Swedish lakes. Rep.Inst.Freshwat.Res.Drottningholm, 53:51–77
Noring, I., 1968. Socio-economic studies of sport fishing in Sweden. EIFAC Occas.Pap., (1):11–23
Paulson, L. and A.-B. Stenson, 1983. Ekonomiska och syselsättningsmassiga effekter av Älvkanneby laxfiske. In Lax: en utredning beträffande förntsättmingarna för det svenska laxfisket. Bilag. 5, edited by L. Hannerz, 25 p.
Petersson, Å., 1990. ‘Salmon Fund Vänern’ a project for restoration of salmon stocks in Lake Vänern. In Management of freshwater fisheries. Proceedings of a symposium organized by the European Inland Fisheries Advisory Commission, Göteborg, Sweden, 31 May–3 June 1988, edited by W.L.T. van Densen, B. Steinmetz and R.H. Hughes. Pudoc. Wageningen, pp. 472–6
Rundberg, H., 1977. Trends in harvests of pikeperch (Stizostedion lucioperca), Eurasian perch (Perca fluviatilis), and northern pike (Esox lucius) and associated environmental changes in lakes Mälaren and Hjälmaren, 1971–74. J.Fish.Res.Board Can., 34:1720–4
Sjoberg, K., 1980. Ecology of the European river lamprey (Lampetra fluviatilis) in northern Sweden. Can.J.Fish.Aquat.Sci., 37(11):1974–80
Svärdson, G., 1976. Interspecific population dominance in fish communities of Scandinavian lakes. Rep.Inst.Freshwat.Res.Drottningholm, 55:144–71
Svärdson, G., 1976a. The decline of the Baltic eel population. Rep.Inst.Freshwat.Res.Drottningholm, 55:136–43
Sveriges Officiella Statistik, 1978. Statistiska Centralbyrån, Statistisk årsbok för Sverige 1978, Årgång 65. Stockholm, Sveriges Officiella Statistik, 597 p.
Sveriges Officiella Statistik, 1982. Statistiska Centralbyrån, Statistisk årsbok för Sverige 1982/83, Årgång 69. Stockholm, Sveriges Officiella Statistik, 579 p.
Sveriges Officiella Statistik, 1983. Statistiska Centralbyrån, Statistisk årsbok för Sverige 1984, Årgång 70. Stockholm, Sveriges Officiella Statistik, 569 p.
Sveriges Officiella Statistik, 1984. Statistiska Centralbyrån, Statistisk årsbok för Sverige 1985, Årgång 71. Stockholm, Sveriges Officiella Statistik, 568 p.
Sveriges Officiella Statistik, 1989. Statistiska Centralbyrån, Statistisk årsbok för Sverige 1990, Årgång 76. Stockholm, Sveriges Officiella Statistik, 565 p.
Sveriges Officiella Statistik., 1990. Statistiska Centralbyrån, Statistisk årsbok för Sverige 1991, Årgång 77. Stockholm, Sveriges Officiella Statistik, 563 p.
Sweden, 1972. Report from Sweden. In FAO/EIFAC country reports on fish diseases and their control and national and international traffic of live fish and fish eggs. (FAO/EIFAC meeting paper). Rome, FAO, FO:EIFAC 72/SC II Symp. 9:57–61 (mimeo)
Sweden/EIFAC, 1979. Information on inland water fisheries production in Sweden (Response to the EIFAC Secretariat). Unpubl.
Swedish Institute, 1981. Fisheries in Sweden. Fact Sheets on Sweden, 2 p. (mimeo)
Wallstein, M., 1978. Situation of twenty-fice Swedish lakes now and 40 years ago. Verh.Int.Ver.Theor.Angew.Limnol., 20(Vol.2):814–7
Wendt, C., 1982. Sweden country review. In Allocation of fishery resources. Proceedings of the Technical Consultation on Allocation of Fishery Resources held in Vichy, France, 20–23 April 1980, edited by J.H. Grover. FAO/American Fisheries Society, pp.600–1
Wiederholm, T., 1978. Long-term changes in the profundal benthos of Lake Mälaren. Verh.Int.Ver.Theor.Angew.Limnol., 20(Vol.2):818–24
Willén, E., 1984. The large lakes of Sweden: Vänern, Vättern, Mälaren and Hjälmaren. In Ecosystems of the world 23. Lakes and reservoirs, edited by F.B. Taub, Amsterdam, Elsevier Science Publishers B.V., pp. 107–34
Willén, T., 1970. II. The biological section. In Uppsala Symposium. Eutrophication in large lakes and impoundments/L'eutrophisation dans les grands lacs et les retenues d'eau, compiled by C.P. Milway. Paris, Organisation for Economic Co-operation and Development, pp. 197–224
Willén, T., 1972. Biological aspects on the large lakes in South Sweden. Verh.Int.Ver.Theor.Angew. Limnol., 18:370–8
Willén, T., 1975. Biological long-term investigations of Swedish lakes. Verh.Int.Ver.Theor.Angew. Limnol., 19(Part2):1117–24
Anon., 1984. Sweden. National report. (Prepared for the inter-sessional period of 1982–84 for the 13th Session of EIFAC, Aarhus, Denmark, 23–30 May 1984):3 p. (mimeo)