Aacl bioflux aquaculture, Aquarium, Conservation & Legislation




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Consequences of introductions and additional problems. One of the better known consequences of introductions is the phenomenon of non-native parasites and pathogens that are translocated together with host species. This problem was discussed for many times, and in various aspects (e.g. Czeczuga et al 2002; Witkowski 2002; Košuthová et al 2004; Gozlan et al 2005, 2006; Uzunova & Zlatanova 2007). There are many examples of parasites and pathogens brought to Poland with non-native fishes. Two of them, that are better known, are Khawia sinensis and Bothriocephalus acheilognathi, tapeworms introduced most probably with H. molitrix, H. nobilis and C. idella from Far East (Pańczyk & Żelazny 1974). Since the first records in 1973 (Pańczyk & Żelazny 1974) they have successfully spread within the territory of Poland, where they live off native cyprinid fishes (Łozińska-Gabska 1981).

In the last years a special attention was given to Cyprinid Herpesvirus, CyHV-3 (Koi Herpesvirus, KHV), which has been brought with ornamental carps (nishigikoi C. carpio) from Far East due to completely unregulated translocations among countries. For the present moment it poses a serious risk to the carp aquaculture (e.g. Ruszczyk 2004; Antychowicz 2007). As many as 20 other herpesviruses have been recognized in Poland so far (Siwicki et al 2006).

A similar problem is of accidental introductions of small fish imported together with stocking material, or by ballast waters of ships. These are particularly P. glenii, P. parva, and the Ponto-Caspian gobies (Apollonia, Neogobius and Proterorhinus). They might be very dangerous to native biocenoses. Especially well-documented is the first species, the Chinese sleeper. It is established that in small water bodies it can strongly depress populations of native fishes, often additionally declining for other reasons, like the whetherfish Misgurnus fossilis or the lake minnow Rhinchocypris percnurus (called in the literature Phoxinus, Morocco, or Eupalasella percnurus or pereunurus; according to recent molecular investigations of Sakai et al (2006) it is placed in the genus Rhinchocypris), as well as macroinvertebrates and amphibians (Reshetnikov 2003, 2008; Koščo et al 2003; Nowak et al 2008b). Numerous studies were conducted to assess the role and threats that are induced by these small invaders (beside of the works cited above, e.g. Simonović et al 2001; Kostrzewa & Grabowski 2003; Kostrzewa et al 2004; Gozlan et al 2005; and many others). These fishes, i.e. P. glenii, P. parva, and the Ponto-Caspian gobies, are considered fully invasive, what means that they can disrupt and negatively alter native biocenoses.

The Atlantic salmon Salmo salar disappeared from the territory of Poland in the mid-1980s and its last spawning area was Drawa River (Wiśniewolski et al 2004). The restoration program for the Atlantic salmon in Polish rivers started in 1985 and it is based on material obtained from Daugava River (Latvia), because Latvian population of S. salar was the most similar to extinct Polish salmon (Bartel 2002). Eyed eggs were imported from Latvia in 1985 and in 1989 the first part of stocking material was released into some Polish rivers. Beside of the effects of that action, the question is: is it still restitution/reintroduction or rather introduction/translocation of very similar but not exactly the same fish?

Additional problem connected with the Atlantic salmon stocking are refugees from open marine salmon farms, which can negatively affect native (or restituted) populations of this species (Fiske 2006). It is rather not possible to these refugees to spawn with native salmons in the conditions of Poland, however such cases were reported a few times, so such possibility cannot be definitively excluded (Fleming et al 2000; Garant et al 2003). Nevertheless, their impact may be significant even without successful reproduction (Young et al 2008; Perry et al 2008).

The endemic population of the lake trout Salmo trutta (most often referred to as “morpha lacustris”), occurs naturally only in Lake Wdzydze and some neighboring lakes. However, it was introduced into different dam reservoirs (Wajdowicz 1972, 1976; Bartel & Prokuski 1992; Bartel et al. 1996), rivers (Jakubowski & Penczak 1976; Bartel & Zieliński 1978) and even the Baltic Sea (Backiel & Bartel 1967). The question is: is it still native species or an alien one, if stocked into these new ecosystems? The similar question occurs in a case of the brown trout translocations between different river drainages. It seems that release of fish taken from one drainage into another may cause the disturbance of genetic integrity of autochthonous populations and even their extinction.

As it was already mentioned, alien species can often successfully hybridize with native fishes, and produce fertile or infertile offspring. In the context of Poland the very examples of that process are S. fontinalis which hybridize with the native brown trout S. trutta producing infertile so-called “tiger trouts”, and non-native Coregonus spp. that extremely easy hybridize with native coregonids (C. albula, C. maraena), and these hybrids ale fully fertile. Hybridization of Carassius spp. was conducted in artificial conditions (Smartt 2007). For the present moment there is no evidence that it takes place in Poland. Nevertheless, it probably occurs, and tends to be one of the reasons of decline of native C. carassius. In fact such cases of hybridization have already been reported from adjacent Czech Republic (Papoušek et al 2008). However, the problem is much more complex, regarding various levels of ploidy of C. auratus complex (auratus, gibelio, and langsdorfii; the last one was found in Czech Republic in 2000; Kalous et al 2007a), their complex system of reproduction, and ambiguities in identification of these species themselves and their hybrids (Szczerbowski & Szczerbowski 1996; Kalous et al 2007a; Kottelat & Freyhof 2007; Papoušek et al 2008).

During last years another interesting phenomenon is being observed. In those water bodies where A. nebulosus were introduced earlier than A. melas, the second one is successfully replacing the previous invader (Koščo & Pekárik 2008). It is not clear whether it is due to higher potential “invasivness” of the black bullhead, or to changing environmental conditions (i.e. the global warming effect; Koščo & Pekárik 2008).

From time to time there are still some voices for introduction of the next species to the Polish fresh waters. Following the case of H. hucho translocated from the Czarna Orawa River system to some rivers in southern part of the Vistula and Odra River drainage (Witkowski et al 2007), and mentioned above translocations of S. salar and S. trutta, an introduction (called “translocation” too) of A. ruthenus was postulated (Kolman 1996). However, ongoing action of restitution of the native sturgeon, Acipenser oxyrinchus/sturio, may dismiss further such inventions. In fact, restitution of the Baltic sturgeon is in some way questionable itself, because there are no living native populations of sturgeons in the Baltic Sea, at least as far as we know. For the present moment the last self-sustaining natural populations of A. sturio live only in the Gironde River drainage (France) and Rioni River drainage (Georgia) (Kolman 1996). These drainages are nearly completely disconnected from the Baltic Sea basin. A. oxyrinchus lives in Atlantic drainages of North America from Labrador to Florida (Popovic et al 2008). Fry of A. oxyrinchus for the restitution was imported from St. John River (Canada) (Kolman 2008). The case is additionally complicated due to ambiguities in identification of these extinct sturgeons. It is still unclear which species inhabited the Baltic Sea basin. For the many years it was considered, that the only one native species was A. sturio (e.g. Kolman 1996, 2000), but the analysis of ancient DNA showed that rather A. oxyrinchus was the prevalent species. There are strong evidence that A. oxyrinchus colonized the Baltic Sea during the Medieval Little Ice Age (or earlier) and replaced A. sturio there (Birstein et al 1998; Ludwig et al 2002; Popovic et al 2008). On the other hand, analyzes of ancient mtDNA showed that the most of samples from archeological excavations and museums in Poland revealed A. oxyrinchus haplotype but A.sturio haplotype was also present (Stankovic et al 2007; Popovic et al 2008). Recent molecular investigations showed that the case is much more complex. Tiedemann et al (2007) suggest that A. oxyrinchus did not replace native sturgeon in the Baltic Sea but it introgressed with A. sturio population, thus the extinct Baltic sturgeon had a hybrid nature.

For all these reasons, sturgeons released to Baltic Sea seem to be not the same that had lived there for ages and evolved in disconnection both from European populations of A. sturio and American populations of A. oxyrinchus, and they are completely different fish. The question is same as in the case of restitution of S. salar (and probably any other further restitution action): is it restitution of a native species, or introduction of an alien one? If Baltic sturgeon is definitely extinct, there is no possibility to restore it. In this context sturgeons imported from Canada are non-native fish. Irrespective, it does not dismissed the question, what is better to do, accept the extinction of Baltic sturgeon (what particularly is a fact), or introduce non-native sturgeons from Canada.


Conclusions. Summarizing, one should answer the question: are all of these introductions bad (cf. Gozlan 2008)? Main stream of considerations presented in this paper were focused on negative aspects of presence of non-native fishes in Poland. Nevertheless, it must be said, that some benefits also are achieved. Probably the most important are these of aquaculture, especially of the common carp and the rainbow trout production, which are the most valuable branches of Polish inland fisheries (cf. Wojda 2004; Lirski & Myszkowski 2008a; Bontemps 2008). In details these consequences, both benefits and negative effects, were discussed by numerous authors, in Poland especially by Witkowski (1989, 1996a, 2002) and Kostrzewa et al. (2004), and dozens of direct investigations on certain species.

It should be also stressed that aquaculture without alien species is not possible for the present moment, and probably it cannot be possible anyway (Gozlan 2008). Fish species have been translocated for ages, they are being translocated now, and most probably they will be translocated in future. It is not only due to reason of aquaculture. Cases of H. hucho transferred from one drainage to another (even from one sea basin to another) within the territory of one country, or S. salar brought to Poland from adjacent Latvia (however within one sea basin) were of conservational significance. Some questions stated above in the previous section show our concerns of this matter. We consider that introductions should be omitted and avoided as much as it is possible, and should be processed only in special cases, after thorough analyses of risk, impact and profits. Also it is very important to educate people about possible consequences of seemingly innocent releasing exotic fish to open waters (cf. Elvira & Almodovar 2001).

When take a look on Figure 1 and Table 1, and when assess a number of introduced species, even only those that have established in open fresh waters, it may seems astonishing how many new non-native species were found in last 20 years. If then one compare this number with the, anyhow incomplete, review of their impacts, it should be clear why the authors are so preoccupied by the issue of introductions.

After all, we would like to cite a significant thought of Holčik (1991) that “one fact remains certain: only few species are generally accepted as having been beneficial introductions”.


Table 1

Checklist of non-native fishes that occur in the fresh waters of Poland




Species

Year of introduction

Reason of introduction

Main reference

Acipenseridae

Acipenser ruthenus

1890s, 1970s

Aquaculture

Kolman 2000

Acipenser baerii

1970s

Aquaculture

Kolman 2000

Acipenser gueldenstaedtii

1970s

Aquaculture

Kolman 2000

Acipenser stellatus

1970s

Aquaculture

Kolman 2006

A. ruthenus x Huso huso

1970s

Aquaculture

Kolman 2000

Polyodontidae

Polyodon spathula

mid-1990s

Aquaculture

Kolman 2000

Cyprinidae

Cyprinus carpio

ca. 1200

Aquaculture

Balon & Hoffmann 1995

Rhodeus amarus*

ca. 1200

Accidental

Van Damme et al 2007

Carassius auratus

ca. 1930 (?)

Ornamental

Szczerbowski & Szczerbowski 1996

Carassius gibelio*

ca. 1930 (?)

Unknown / accidental

Szczerbowski & Szczerbowski 1996

Ctenopharyngodon idella

1964

Aquaculture

Krzywosz 2000a

Hypophthalmichthys molitrix

1965

Aquaculture

Krzywosz 2000b

Hypophthalmichthys nobilis

1965

Aquaculture

Krzywosz 2000b

Pseudorasbora parva*

late 1980s

Accidental

Witkowski 1991

Catostomidae

Ictiobus niger

1989

Aquaculture

Kotusz 2000a

Salmonidae

Oncorhynchus mykiss

1881-1889

Aquaculture

Goryczko 2000a

Oncorhynchus gorbuscha

1973-1974

Aquaculture

Rolik & Rembiszewski 1987

Salvelinus fontinalis*

1890

Aquaculture

Goryczko 2000b

Salvelinus alpinus

1970s

Angling

Rolik & Rembiszewski 1987

Hucho hucho1,*

1955

Conservation, angling

Witkowski et al 2007

Thymallidae

Thymallus baicalensis

1973-1974

Accidental

Witkowski 2000

Table 1 (cont.)




Species

Year of introduction

Reason of introduction

Main reference

Coregonidae

Coregonus peled2

1966

Aquaculture

Szczerbowski 2000

Coregonus muksun

1984-1985

Aquaculture

Szczerbowski 2000

Odontobutidae

Perccottus glenii*

1990s

Accidental

Nowak et al 2008b

Ictaluridae

Ameiurus nebulosus*

1885

Aquaculture

Bryliński & Chybowski 2000

Ameiurus melas*

1885 (?)

Aquaculture (?)

Nowak et al, in press

Clariidae

Clarias gariepinus

1990

Aquaculture

Chybowski 2000

Loricariidae

Pterygoplichthys gibbiceps

2006

Aquarium release

Keszka et al 2008

Cichlidae

Oreochromis niloticus(*)

1990

Aquaculture

Kotusz 2000b

Astronotus ocellatus

2000s

Aquarium release

Witkowski 2002

Centrarchidae

Micropterus salmoides

1912 (?)

Aquaculture, angling

Staff 1950; Terlecki 2000

Lepomis gibbosus*

1927 (?)

Aquaculture, ornamental

Przybylski 2006

Serrasalmidae

Piaractus prachypomus

2000

Aquarium release

Witkowski & Kotusz 2003

Serrasalmus sp.

ca. 2000

Aquarium release

Witkowski 2002

Gobiidae

Apollonia melanostoma3

1990

Natural spreading

Skóra & Stolarski 1993

Neogobius gymnotrachelus*

1995

Natural spreading

Danilkiewicz 1996

Apollonia fluviatilis*

1997

Natural spreading

Danilkiewicz 1998

Proterorhinus semilunaris*

2008

Natural spreading

Grabowska et al 2008

Umbridae

Umbra krameri

1921, 1967

Accidental

Kostrzewa et al 2004

Umbra pygmea

1990s

Releasing from aquaria

Witkowski & Kotusz 2000


1 Native in the Polish part of Czarna Orawa River and Czedaczka Stream, introduced in some rivers within southern part of the Vistula and Oder River drainage

2 C. peled hybridised with native C. maraena

3 This species was record for the first time in 2007, so data are lacking; however, it probably forms established population, or will do it in the next years

* Species forms established populations



(*) Species forms established populations only in heated water bodies (e.g. power plants)

References
Adamek J., 1993 [Breeding and culture of the alevins of the African catfish (Clarias gariepinus Burchell 1822). Part 1. Introduction and breeding]. Kom Ryb 6:19-21. [In Polish]

Antychowicz J., 1994 [Perccottus glehni in our waters.] Kom Ryb 2:21-22. [In Polish]

Antychowicz J., 2007 [Fighting fish diseases in Poland with special attention on koi herpesvirus infection]. Kom Ryb 5:25-28. [In Polish]

Backiel T., Bartel R., 1967 [Effect of trout stocking in the light of tagging results]. Rocz Nauk Roln 90:365-388. [In Polish]

Balon E. K., 2004 About the oldest domesticates among fishes. J Fish Biol 65 (Suppl. A):1-27.

Balon E. K., Hoffmann R. C., 1995 The common carp, Cyprinus carpio: its wild origin, domestication in aquaculture, and selection as coloref nishigikoi. Guelph Ichthyol Rev 3:1-55.

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