alver, Alburnus charusini Herzenstein in Zogrtaff and Kavraiskii, 1889, Alburnus striatus Petrov, 1926

Nonindigenous Occurrences: It is currently present in Cyprus through accidental introduction (Vinyoles et al. 2007). Its range extends throughout most of the Iberian Peninsula, including Italy, Portugal, Spain (Kottelat 1997). Between 2002 and 2003, Bleak in the Catalonian basins was limited within the Llobregat, Ebre, Fluviá, and Muga basins; however, by 2008, it had increased its range to include the Ter and Foix basins (Maceda-Veiga et al. 2010). Bleak is also in Morocco (Clavero et al. 2015) and throughout the Ob River basin, Russia (Interesova 2016).

Potential pathway(s) of introduction: Transoceanic shipping (ballast water).

From its native range, Alburnus alburnus was locally introduced to the Iberian Peninsula, Spain, Portugal, and Italy (Kottelat 1997). This fish species was intentionally introduced to the Northern Iberian watershed by anglers in an attempt to increase the stock of forage for nonnative fish predators and was used as a popular live baitfish (Vinyoles et al. 2007). Alburnus alburnus is found in the Seine, Loire, and Rhine Rivers, which naturally discharge into the Atlantic Ocean (Leuven et al. 2009).

Through travel across the Atlantic Ocean from Europe, Alburnus alburnus may suffer mortality in ballast water due to its inability to survive waters with high salinity, limiting its introduction to the Great Lakes (Wheeler 1978). However, it has been shown that 35% of “No Ballast on Board” (NOBOB) vessels, which are exempt from mandatory ballast exchange, possess at least 1 tank with ≤ 5‰ salinity, thus enhancing the potential for Alburnus alburnus to survive transport overseas to be introduced into the Great Lakes (Niimi and Reid 2003).

Currently, the geographical distribution of Alburnus alburnus does not cover water bodies connected to the Great Lakes basin. Alburnus alburnus is not a popular aquarium fish and is not available for purchase online. Alburnus alburnus is not available as live baitfish for online purchase in North America. Bleak was classified as a ‘high invasiveness risk’ species in Great Britain rivers under the Aquatic Species Invasiveness Screening Kit developed by Copp et al. (2016) (Dodd et al. 2019). There are import restrictions regarding the transport of Alburnus alburnus to the United Kingdom (Clarke 2006). It is predicted that the geographical range of this species will expand due to climate change (Lehtonen 1996).

Alburnus alburnus has a high probability of establishment if introduced to the Great Lakes (Confidence level: High).

If Alburnus alburnus were introduced to the Great Lakes, it has the potential to spread rapidly (Kolar and Lodge 2002). The climate of the Great Lakes is similar to the native range of Alburnus alburnus and this species is likely capable of enduring overwintering conditions in the Great Lakes basin (Reid and Orlova 2002; Grigorovich et al. 2003; EPA 2008). It is likely that the Great Lakes contain an abundant food source for this species, but they also contain natural predators (e.g., Largemouth Bass Micropterus salmoides and Northern Pike Esox lucius) to Bleak that may slow their establishment (Maceda-Veiga et al. 2010; Waidbacher et al. 2018). This species has a high reproductive rate and its seasonal movements from reservoirs to tributaries make it an excellent disperser (Vinyoles et al. 2007; Matano et al. 2018). Bleak’s interpopulation (Maso et al. 2016; Latorre et al. 2020) and wide trophic plasticity makes it a very successful invader (Almeida et al. 2014, 2017; Latorre et al. 2018). It can adapt to different habitats quickly, particularly those with flow regulation (weirs, reservoirs, dams, etc.) which are common throughout the Great Lakes region (Amat-Trigo et al. 2019).

Following its introduction into the Ebro basin in Spain, this species rapidly established throughout the entire Iberian Peninsula, where it is currently present in all of the major Iberian water basins and a large number of Iberian rivers, suggesting that it has the ability to adapt to a warmer climate regime (Vinyoles et al. 2007). After its establishment in Britain, Alburnus alburnus consequently spread and established in Cyprus. It is believed that the high fecundity rate of this species is responsible for its establishment. Bleak’s rapid expansion throughout the Ob River basin in Russia was attributed to human mediated and natural dispersal (Reshetnikova et al. 2017).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic

Alburnus alburnus is a superior competitor because of its high reproductive rate, its non-specific diet, and its ability to tolerate a broad range of temperatures. Alburnus alburnus exhibits large and sudden bursts in population size so it has outcompeted native species where established (Welcomme 1988; Perez-Bote et al. 2004; Vinyoles et al. 2007). Bleak has similar behavior and activity patterns to Pseudorasbora parva, another potential invader to the Great Lakes, due to major isotopic niche overlap indicating competition between the two species if resources become limited, however, they can co-exist in open systems and potentially double their trophic impact (Haubrock et al. 2019; Balzani et al. 2020). Invasive Bleak in the Iberian Peninsula have led to higher metabolic expense, reduced shelter use, and increased predation risk in the critically endangered Iberian saramugo Anaecypris hispanica (da Silva et al. 2019).

Bleak is able to hybridize with other cyprinids (Blachuta and Witkowski 1984; Crivelli and Dupont 1987; Maceda-Veiga et al. 2010). In the Iberian watershed, Alburnus alburnus has threatened endemic species (e.g. Squalius and Anaecypris spp.) through hybridizing with other cyprinids and its generally high reproductive rate (Vinyoles et al. 2007; Sousa-Santos et al. 2018). Besides impacting native fish fauna, Alburnus alburnus feeds on cladoceran and other small invertebrates that play an important role in freshwater ecosystems and may directly affect the water quality (Maceda-Veiga et al. 2010). This species exhibits a high level of plasticity in population traits and is able to adapt to a wide variety of environmental conditions.

Bleak are very active fish with fast metabolism which can lead to bioaccumulation of heavy metals and other toxins (Kolarevic et al. 2016; Jovanovic et al. 2018). 58% of Bleak muscle samples taken from the Dunajec River, Poland contained more than the human consumption limit of lead (0.3 mg Pb kg-1 dry matter) (Niemiec et al. 2018).

It is a host to the widespread eastern European parasites Paracoenogonimus ovatus (Ostrowska et al. 2019) and Nicolla skrjabini (Chunchukova et al. 2019) which can infect a wide variety of fish that inhabit the Great Lakes, including both invasive (e.g. Scardinius erythrophthalmus, Gymnocephalus cernua, Salmo trutta, and Cyprinus carpio) and native species (e.g. Esox lucius) to the Great Lakes. Bleak is also a vector for the Carp Edema Virus (Matras et al. 2019).

There is little or no evidence to support that Alburnus alburnus has the potential for significant socio-economic impact if introduced to the Great Lakes.

Alburnus alburnus may affect water quality (i.e., increased turbidity and algae/chlorophyll a concentrations) by feeding on organisms that play a direct role in water quality (Maceda-Veiga et al. 2010).

The bioaccumulation of heavy metals, including lead, in Bleak may pose a threat to the health of humans who consume them (Niemiec et al. 2018).

Alburnus alburnus has the potential for high beneficial effects if introduced to the Great Lakes.

This species may be commercially valuable as forage fish and baitfish (Pérez-Bote et al. 2004), and the artificial pearl trade (Denton and Nicol 1965). A small amount of Bleak is fished recreationally in the Tsimlyansk Reservoir, Russia, amounting to 141 kg in 2019 (0.5% total catch) (Kutsenko et al. 2020). In the Western Balakan Peninsula, catch of Bleak varies amongst lotic and lentic systems. There is a total annual catch of 65 tons - a very small proportion of the estimated population of ~5000 tons (Simic et al. 2016). In some lentic systems it's less than 1% of the catch but is between 40-70% in Skadar lake, Montenegro/Albania (Mrdak 2009).

In Europe, it has been introduced into various reservoirs to benefit the populations of exotic fish predators such as the Northern Pike (Esox Lucius), Largemouth Bass (Micropterus salmoides), Zander (Sander lucioperca), and Sheatfish (Silurus glanis) (Maceda-Veiga et al. 2010). Establishment of Alburnus alburnus may increase productivity of predator fish in the Great Lakes, especially for predatory fish that do not have specific diets.

*Ballast water regulations applicable to this species are currently in place to prevent the introduction of nonindigenous species to the Great Lakes via shipping. See Title 33: Code of Federal Regulations, Part 151, Subparts C and D (33 CFR 151 C) for the most recent federal ballast water regulations applying to the Great Lakes and Hudson River.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
Biological
There are no known biological control methods for this species.

Physical
There are no known physical control methods for this species.

Chemical
There are no known chemical control methods specific to this species. General piscicides (such as rotenone) may be used for control, but expect significant kill of non-target species.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.