Aquaculture, Aquarium, Conservation & Legislation
International Journal of the Bioflux Society
Non-native freshwater fishes in Poland:
Michał Nowak, Paweł Szczerbik, Krzysztof Tatoj, and Włodzimierz Popek
Department of Ichthyobiology and Fisheries, Univeristy of Agriculture in Kraków, ul. T. Spiczakowa 6, 30-199 Kraków, Poland, EU. Corresponding author: M. Nowak,
Abstract. The number of non-native fish species in Poland has already passed 30, and has being still growing consecutively from the end of 19th century. It is rather difficult to assess impact of all these introductions on native fauna, however it seems reasonable to say that most of them have rather negatively affected indigenous biocenoses. Due to increase of number of new alien fishes found in Polish inland waters observed in the last years, some regulations regarding limitations of introductions should be applied.
Key Words: biodiversity, conservation, ichthyofauna, non-native fishes, Poland.
Streszczenie. Liczba gatunków obcych w polskiej ichtiofaunie rośnie sukcesywnie od końca XIX w. i aktualnie przekroczyła już granicę 30. Wpływ wszystkich tych introdukcji jest trudny do oszacowania, jednak wydaje się, że większość z nich miała zasadniczo negatywne skutki dla rodzimej fauny. Z uwagi na, widoczny zwłaszcza w ostatnich latach, wzrost ilości nowych gatunków znajdywanych w wodach śródlądowych Polski, wydaje się, że niezbędne są zasadnicze działania na rzecz ograniczenia przyszłych introdukcji.
Key Words: bioróżnorodność, gatunki obce, ichtiofauna, ochrona przyrody, Polska.
Rezumat. Numărul speciilor străine de peşti din Polonia a trecut de 30, crescând constant de la sfârşitul secolului al XIX-lea. Impactul acestor introduceri asupra faunei native este destul de dificil de estimat, fiind rezonabil să conchidem că cele mai multe afectează mai degrabă negativ biocenozele autohtone. Datorită faptului că au fost semnalate din ce în mai multe specii străine noi de peşti în apele interioare ale Poloniei în ultimul an, este necesară aplicarea unor reglementări privind limitarea introducerilor.
Cuvinte cheie: biodiversitate, conservare, ihtiofaună, specii străine de peşti, Polonia.
Introduction. Non-native species pose a serious problem in modern conservation of biodiversity. Their potential commercial value, magnitude of introductions and translocations, uncertain origin and taxonomic position of some species, wide spectrum of influence of exotic taxa on native biocenoses and many other reasons (listed by Copp et al 2005) cause the debate about alien species probably endless. For the present moment at least two scientific journals, Biological Invasions and Aquatic Invasions, are regarding mainly this topic. The number of papers published on this subject is exceptionally high, and it is still arising. It has already exceeded the number of 20 000 (Casal 2006; Rosenthal 2008).
List of non-native fish species in Poland has increased with time, and new species are presently being added. Before 19th century there were probably only two species, in the beginning of 21st century the list consist of about 35 fishes. Staff (1950) listed 57 freshwater species (including lampreys and excluding fishes from outside of the current territory of Poland) among which 6 were non-native (ca. 11%). The same number of alien species was given by Gąsowska (1962), however her key to fishes and lampreys consist of 62 freshwater taxa. In the fundamental The freshwater fishes of Poland (Brylińska 1986) 15 non-native fishes were considered. In the revised edition of this book (Brylińska 2000) the list was much longer and consisted of 29 (including some taxa not recognised as alien by authors of that book) of the total number of 84 taxa included (almost 35%). For the present moment the most comprehensive studies on alien fish species in Poland were performed by Witkowski (1989, 1996a,b, 2002). Nevertheless, they are somehow out-of-date now, and there is an urgent need for some additions and corrections. Finely, this author considered as more as 31 fish species to be non-native to Polish ichthyofauna (Witkowski 1996a,b, 2002).
The issue of fish introductions seems an urgent matter. Dynamics of changes in number of non-native species (Fig. 1) shows a radical increase of new invasions (or sometimes just of new findings), especially during the last decade. In this paper we reviewed current status of, as far as we know, all alien fish species that have ever been introduced into Polish fresh waters. However, the review is rather not definite, and probably it cannot never be, due to continuous efforts of professional fishermen, sport anglers, and irresponsible aquarists, who one by one, are trying to import and acclimatize new fishes.
Figure 1. Dynamics of changes in number of non-native fishes in Polish ichthyofauna in following decades.
See Table 1 for more details.
Background. The terms “non-indigenous”, “non-native”, “alien” or “exotic” are used herein exchangeable. Their definition follows that of Copp et al (2005), i.e. they are ones that does not occur in the given geographical area without, direct or indirect, intentional or unintentional, human activity. All species that have colonised since the Neolithic (6000 BP) are considered non-native. In contrary, “native” or “indigenous” species were present in the area before Neolithic (Copp et al 2005). All other terms, derived from these, are rather intuitional, and they follow Copp et al (2005) too. A taxon, equally native or not, is considered to be “invasive” if it spreads and reproduces on high rate, and its occurrence causes significant alterations in natural native ecosystems (cf. Copp et al 2005).
The territory of Poland is split into three sea basins, i.e. Baltic (99.7% of the territory), Black (0.2%), and North Sea (0.1%). Within the largest one, the Baltic Sea basin, four drainages are distinguished, i.e. of Vistula (55.7%), Odra (Oder) (33.9%), Niemen River (0.8%), and the drainage of coastal rivers (9.3%). Only short parts of four rivers are draining to Black Sea, i.e. Czarna Orawa River and Czedaczka Stream, via the Danube River drainage, and Strwiąż River and Mszanka Stream, via the Dniestr (Dniester) River drainage. Only a few small rivers (e.g. Izera and Dzika Orlica) are draining to North Sea, via the Laba River drainage (Fig. 2). This distinction must to be stressed, because the definition of non-native species refers to a “geographical area”, not a country.
The ichthyofauna of Poland consists of more than 80 freshwater fishes. The number cannot be given definitely due to some ambiguities in cases of certain species complexes (e.g. Carassius “gibelio”, Gobio gobio complex or Cobitis taenia complex; cf. for example Nowak et al 2008a). At least 25 species are non-native (Witkowski 1996a,b; Copp et al 2005; Grabowska et al 2008; Nowak et al 2008c and in press), and it is more than 30% of the total number.
Figure 2. Drainages of Poland. 1, the Vistula River drainage; 2, the Odra (Oder) River drainage; 3, rivers draining direct to Baltic Sea; 4, the Niemen River drainage; 5, the Danube River drainage; 6, the Dniestr (Dniester) River drainage; 7, the Laba River drainage.
Main patterns of introductions. The first introduction in the history of Polish fresh waters was associated with domestication of the common carp Cyprinus carpio. The most probably the first introductions took place about 12th or 13th century (Balon & Hoffmann 1995; Wojda 2004; Balon 2004). Since that time the common carp achieved exclusive place in the fisheries of Poland. Its production in pond cultures reached about 24 500 tons/year in mid-1990s, and now is consecutively depressing, flirting about the value of 16-17 000 tons/year (Wojda 2004; Lirski & Myszkowski 2008a,b). It makes Poland 1st or 2nd (after Czech Republic, depending on year) producer of the common carp in Europe.
Surprisingly, the newest molecular investigations showed that another alien species was imported together with C. carpio, the European bitterling Rhodeus amarus, species widely considered to be a native one throughout Europe (Van Damme et al 2007; Kottelat & Freyhof 2007). It was probably introduced in 12th or 13th century and widespread together with increase of carp cultures during the next eight centuries (Van Damme et al 2007). For many years R. amarus was considered to be a native fish, and is currently even protected by national legislation in Poland (Ministry of Agriculture and Rural Development 2003).
In the end of 19th century angling and fishery associations intensified their efforts to make the native ichthyofauna “more attractive”. In that period mainly North American species were tried to introduce.
One of them was the rainbow trout Oncorhynchus mykiss. This species is native to the Pacific drainages of western North America and Kamchatkan Peninsula (Englund & Polhemus 2001; Crawford & Muir 2008). The first introduction into fresh water of Poland took place between 1882 and 1889 (Goryczko 2000a). In 1904 eyed eggs of O. mykiss were imported from Sweden to the hatchery Złoty Potok and this year was considered the beginning of pond culture of O. mykiss in Poland (Goryczko 2000a). Now this species has a great commercial importance. Its production in 2007 reached almost 17 000 tons (Bontemps 2008). Rainbow trout is present (usually as single specimens, however sometimes mass escapes from cultures take place) in about 20% of Polish rivers (Witkowski 1996a,b). Its presence in natural environment is mainly an effect of escapes from ponds. Although the rainbow trout seems to be very adaptable to new environments, there are no self-sustaining populations in Poland. It is probably due to the lack of suitable spawning grounds (MacCrimmon 1971) or maladaptive adaptation (caused by domestication), which can prevent fish from establishing naturally reproducing stocks (Saegrov et al 1996; Landergren 1999). On the other hand, self-sustaining populations were reported from other European countries: Sweden, Norway, Denmark, and Czech Republic (Svardson & Nilson 1985; Frier et al 1995; Saegrov et al 1996). Although the rainbow trout competes for food and territorial space with native brown trout Salmo trutta, its negative impact is rather low because of usually limited number of specimens in open waters. Due to different terms of spawning they do not hybridize with S. trutta.
Meanwhile, another fish was acclimatized, the brown bullhead Ameiurus nebulosus. Probably the first introduction took place in 1885 in Barnówek, near Szczecin (Horoszewicz 1971; Nowak et al, in press). Contrary to the rainbow trout, brown bullhead fully acclimatized in Poland (as in the whole Europe, in fact), and in short time became a successful invader (Kornijów 2001; Bryliński & Chybowski 2000; Nowak et al, in press).
The most probably in 1890 another North American salmonid was introduced, the brook trout Salvelinus fontinalis. After the World War II this species was released in degraded parts of rivers in southern part of the Vistula River drainage (Staff 1950). It was probably introduced to some rivers of the Odra River drainage (Gąsowska 1962). Also initially fishless Tatra Mountains Lakes were stocked with S. fontinalis (Witkowski 1996a; Goryczko 2000b) and probably it contributed to extinction of relic crustacean circumpolar fairy shrimp Branchinecta paludosa (Gliwicz 1963; Smagowicz & Dyduch 1980). S. fontinalis is known to be more acid-tolerant then the brown trout S. trutta, and the purpose of its introduction was also to compensate the loss of S. trutta in acidified waters (Larsen et al 2007). Currently, only a few trout farms in southern Poland breed the brook trout, and refugees from these places are consecutively being record in open waters (Szczerbik, pers. observ.).
A few years later, in the beginning of 20th century, two centrarchid species were introduced. Probably in 1912 the largemouth bass Micropterus salmoides, and in 1926 the pumpkinseed Lepomis gibbosus were tried to acclimatize in some water bodies (Staff 1950; Rolik & Rembiszewski 1987; Witkowski 1996a,b; Copp et al 2005; Przybylski 2006). In the 1950s and 1960s M. salmoides was bred in some farms in central and southern Poland (Terlecki 2000). The basses generally failed to acclimatize, and only the second one, L. gibbosus, forms established populations in isolated sites of heated waters from power plants in the Odra River drainage (Rolik & Rembiszewski 1987; Terlecki 2000; Przybylski 2006).
In 1920s (Pax 1921; Kulmatycki 1926) and 1967 (Ejsmont & Słoniewski 1969) an endangered endemic species of the Danube River drainage, the European mudminnow Umbra krameri, was recorded. However, only in the last record taxonomic identity of the specimens was definitely confirmed, and there is a possibility that it was U. pygmea instead of U. krameri in these two others (Witkowski et al 1995; Kostrzewa 1998; Bryliński 2000; Kostrzewa et al 2004). It was probably introduced accidentally, with transports of stocking fish, e.g. C. carpio (Witkowski et al 1995; Witkowski 1996a; Kostrzewa 1998; Bryliński 2000).
The Prussian carp Carassius “gibelio” was recorded and identified in Poland for the first time in the early 1930s (Gąsowska 1934, 1936; Staff 1950). During the 20th century it has expanded within the territory of whole Poland, and now is one of the most abundant fish species, as well as one of the most popular in aquaculture (Szczerbowski & Szczerbowski 1996). Initially recognised as distinct species C. gibelio (Gąsowska 1934), subsequently treated as a subspecies of the goldfish C. auratus gibelio (e.g. Gąsowska 1936, 1962; Staff 1950; Rolik & Rembiszewski 1987; Szczerbowski & Szczerbowski 1996), and recently again reconsidered as distinct species C. gibelio (Kottelat 2006; Kottelat & Freyhof 2007), however, due to complex system of reproduction, dozens of years of confusions with C. auratus or even C. carassius, and low quality of most part of older literature data, its taxonomic status is still rather unclear (cf. Kottelat 2006; Kottelat & Freyhof 2007; Kalous & Bohlen 2002; Kalous et al 2007a,b), so we applied the specific name in parentheses, C. “gibelio”. Despite those, the Prussian carp is invasive throughout Europe and established in most of the European countries (Kottelat & Freyhof 2007).
Mentioned above species of Carassius, the goldfish C. auratus, is also present in the open water bodies of Poland. However, it seems rather impossible to estimate when it appeared in Poland for the first time. In Europe it is present the most probably from the 17th century. The goldfish is often abundant in ornamental garden ponds, as well as in aquarium cultures, and refugees from those places sometimes appear in open fresh waters (Szczerbowski & Szczerbowski 1996; Kottelat & Freyhof 2007; Szczerbik & Nowak, pers. observ.).
The next four species were introduced in mid-1960s. The first one, grass carp Ctenopharyngodon idella, in 1964. The next two, the bighead carp Hypophthalmichthys molitrix, and the silver carp Hypophthalmichthys nobilis, in 1965 (Krzywosz 2000a,b). In the next year a coregonid native to Siberia, the peled Coregonus peled, was imported from USSR (Szczerbowski 2000). C. idella and Hypophthalmichthys spp. were imported mainly for the reason of aquaculture. Additionally they were thought to be a solution for increasing eutrophication, as potentially herbivorous fishes (Rolik & Rembiszewski 1987; Krzywosz 2000a,b). However, they all failed to compete the eutrophication, and there was found that they cannot reproduce in the climate of Poland (Krzywosz 2000a,b). It is contrary to the C. peled, which successfully acclimatized in the lakes of northern Poland, where it hybridized with native C. maraena (often treated as C. lavaretus s. lato; for the taxonomic considerations on this issue see Kottelat & Freyhof 2007). Contrary to the many other coregonids, the peled is relatively resistant to the low oxygen concentration and high temperatures of water. For these reasons some hopes were putted to its commercial use in the aquaculture however its production in pond cultures is rather of minimal importance (Szczerbowski 2000). Nevertheless, according to Mamcarz (1992), by 1983 C. peled has been introduced to 254 lakes in Poland, with about 42% of successful acclimatization.
In the same period, in mid-1960s, an action of so-called “translocation” of the huchen Hucho hucho took place. The only native populations of this species lived in the Czarna Orawa River system (Black Sea basin), and depressed due to degradation of the ecosystem, and building a dam reservoir on the border with Slovakia (former Czechoslovakia). The last adult specimens were caught in the river in 1963, and since then successive action of introduction of H. hucho to certain rivers within the drainages of Vistula and Oder River (Baltic Sea basin) is being conducted. It is quite successful, and this species established in these new ecosystems very well (Witkowski 1996c, 2001; Witkowski et al 2007).
In 1973 the second Pacific salmon, Oncorhynchus gorbuscha, was release to Vindava River (former USSR), and in the autumn 1974 one specimen was caught in the, Bukowo Lake (a coastal lake connected directly with Baltic Sea) within the territory of Poland. As far as the authors are aware, no more specimens of this species have ever been recorded in the country. Also in the 1970s another salmonid fish, Salvelinus alpinus, was tried to introduce into water bodies of southern Poland, fortunately, without any results (Rolik & Rembiszewski 1987).
In the same time, as speculated by Rolik & Rembiszewski (1987), and Witkowski (1996a,b, 2000), the Baikal black grayling Thymallus baicalensis might appeared in the Nysa Kłodzka River system. According to these authors, T. baicalensis was stocked in some dam reservoirs in Slovakia, and especially in one farm on the Štenava River (Czech Republic, the Nysa Kłodzka River system, the Odra River drainage), from where it escaped due to a flood. Some anglers reported occurrence of strange-coloured graylings in the mid-1970s (Witkowski 2000). However, not a single record has ever been confirmed. Moreover, according to data from the Czech Republic (Hanel & Lusk 2005; Lusk, pers. comm.) and Slovakia (Oliva et al 1968; Holčik 1998; Koščo, pers. comm.) published documentation of the introductions of T. baicalensis to the water bodies of former Czechoslovakia is so incomplete and fragmented, that possible occurrence of that species in Polish waters is of rather low probability. Moreover, during the newly conducted investigations (Jurczyk & Brzuzan 2003, 2004) any mtDNA sequences of T. baicalensis were found in the grayling samples from southern Poland.
Meanwhile, in 1970s, some species of sturgeons were introduced for the reasons of aquaculture. These were the Siberian sturgeon Acipenser baerii, the Russian sturgeon A. gueldenstaedtii, the Starry sturgeon A. stellatus, and cross-hybrid of A. ruthenus and H. huso, called bester (Kolman 2000). It is fairly probable that some other species may be involved, as well as hybrids of these ones. For the present moment sturgeons aquaculture is a growing up branch of inland fisheries in Poland (Kolman 2000, 2006). Since the time of start of sturgeon aquaculture in Poland some specimens have been recorded in Baltic Sea, and Vistula and Odra River drainage (e.g. Keszka & Stepanowska 1997).
In 1984-1985 the next coregonid species, the muksun Coregonus muksun, was tried to acclimatize in Mazurian Lakes, the most probably without any positive results (Szczerbowski 2000).
For the reason of commercial usage of heated water from power plants, two exotic species were introduced in 1989 and 1990, the black buffalo Ictiobus niger and the sharptooth catfish Clarias gariepinus (Adamek 1993; Witkowski 1996a,b; Kotusz 2000a). Experiments with the first one were quit in relatively short time, and now only one farm in Poland breeds I. niger (Kottelat & Freyhof 2007). Just the opposite the second species, C. gariepinus, which very well filled into the niche in market, and its importance has consecutively grown during the last years (Adamek 1993; Chybowski 2000).
Also in 1990 another warm-water exotic species was imported. In the experimental unit of the Polish Academy of Sciences in Gołysz were conducted experiments with the Nile tilapia Oreochromis niloticus as a potentially commercial fish in heated water of power plants. In the following years it was introduced to some heated water bodies, among others to Rybnik Reservoir on Ruda River (the Odra River drainage). In 2000 the Nile tilapia was recorded from that river below the dam (Kotusz 2000b; Kotusz et al 2000). In such water bodies, with an appropriate water temperature, O. niloticus forms well established populations (Nowak, Tatoj & Szczerbik, pers. observ.).
A few years after these introductions the next exotic fish was imported, this time from North America. The American paddlefish Polyodon spathula was thought to be cultured in carp farms. Currently it is of rather low interest however it is stocked in some farms in Poland (Kolman 2000).
In the end of 20th and begining of 21st century invasions of small-sized fishes is being observed. First was the round goby Apollonia melanostoma (taxonomic status of the round and monkey gobies is under still running debate; we applied the newest nomenclature, considering molecular data of Brown & Stepien (2008), and placing these two species in the genus Apollonia, whereas the racer goby remains in the genus Neogobius), which was recorded for the first time in Baltic Sea near Hel (Skóra & Stolarski 1993). During the following years it has colonized whole southern coastal of Baltic Sea, and is inserting the lower parts of Vistula River (Kostrzewa & Grabowski 2002; Kostrzewa et al 2004; Grabowska et al 2008).
Figure 3. The Chinese sleeper Perccottus glenii (carp ponds in Kraków-Mydlniki, Poland, by P. Szczerbik, 2008).
The next invader was recorded one year after. In the carp ponds in Gołysz a cyprinid fish, the stone moroko Pseudorasbora parva was found (Witkowski 1991). Irrespective, its distribution and density of populations suggested that this species was introduced somehow earlier, probably in the late 1980s (Witkowski 1991; Kotusz & Witkowski 1998). For the present moment the stone moroko inhabits numerous small water bodies, mainly commercial carp ponds and heated lakes in south-western and central Poland (Kotusz & Witkowski 1998; Kapusta et al 2008; Nowak et al 2008a).
In 1993 (Antychowicz 1994) and 1994 (Terlecki 1995) another alien species was caught in the middle stretch of Vistula River, the Chinese sleeper Perccottus glenii (Fig. 3). Number of its localities increased with every year, and reached the number of 15 (officially confirmed; Nowak et al 2008b; Nowak & Popek 2008), however a real number is without any doubts much higher, probably even over 100 (most of them reported by anglers; Witkowski 2002, 2003; Nowak, Szczerbik & Tatoj, pers. observ.).
During the next four years another two Ponto-Caspian gobies has joined the previous one (the round goby), i.e. the racer goby Neogobius gymnotrachelus in 1995 (Danilkiewicz 1996) and the monkey goby Apollonia fluviatilis (see the remarks on A. melanostoma, above) in 1997 (Danilkiewicz 1998). Both were recorded for the first time in Western Bug River (the Vistula River drainage). Not surprisingly, both were found in Vistula River itself a few years later (Kostrzewa & Grabowski 2001, 2002, 2003; Kostrzewa et al 2004; Grabowska et al 2008). In 2008 the fourth Ponto-Caspian goby appeared in Vistula River, the tubenose goby Proterorhinus semilunaris (Grabowska et al 2008; the name Proterorhinus marmoratus, traditionally considered to be the name of the tubenose goby that is currently invading central Europe, is restricted to marine populations within the Caspian Sea basin; cf. Kottelat & Freyhof 2007).
In the end of 1990s (Witkowski et al 1995; Kostrzewa 1998) two isolated sites of exotic eastern mudminnow Umbra pygmea were found in the Odra River drainage. The specimens were probably released from aquaria however it was not definitely concluded (Witkowski et al 1995; Kostrzewa 1998; Witkowski & Kotusz 2000; Kostrzewa et al 2004).
From 2000 some occasional records of single specimens of the pirapitinga Piaractus brachypomus have been noted (Boeger et al 2002; Witkowski 2002; Witkowski & Kotusz 2003; Więcaszek et al 2007). This fish is reported by anglers from different water bodies from time to time. All these specimens are definitely released by aquarists.
In addition, in 2007 a second ictalurid species was found, the black bullhead Ameiurus melas (Nowak et al 2008c and in press). However it has not been definitely established yet whether it has spread from adjacent countries during last years, or was intentionally introduced in 1885, together with A. nebulosus (cf. Nowak et al, in press). It seems possible that the black bullhead remained confused with the brown bullhead for over 100 years. Their very high morphological resemblance might cause such misidentifications (see Fig. 4).
Beside of all these records described above, Witkowski (2002) reported also some findings of Astronotus ocellatus, Serrasalmus sp., Poecilia sp., and Xiphophorus sp. from heated water bodies. However these were not accompanied with any detailed description (cf. Tab. 1).
Figure 4. The black bullhead Ameiurus melas (Latorica River, Slovakia, by M. Nowak, 2008). This species was found in Poland for the first time in the summer 2007.