freshwater sculpin, Miller's thumb, Vit sculpin, Cottus affinis, Cottus ferrugineus, Cottus haemusi

Nonindigenous Occurrences: Cottus gobio is widespread in Europe. This species is nonindigenous in the south-eastern Pyrenees watershed (Mann et al. 1984, Vila-Gispert et al. 2005). Cottus gobio has been reported to occur in habitats that were once considered inhabitable for the species in the Lower Rhine in the Netherlands and Germany (Cazemir 1988, De Nie 1997, Lelek and Köhler 1993, Nolte et al. 2005, Schleuter 1991, Van der Brink et al. 1990).

It is reported to have a geographical distribution covering northern Spain to southern Scandinavia and Wales to the eastern limits of Europe (Lelek 1987); however, it is not specified whether it is non-indigenous in this case.

Cottus gobio feeds on benthic invertebrates and its diet changes seasonally (Smyly 1957). During the winter, Gammarus amphipods were a large component of their diet (Mills and Mann 1983). Peak consumption of Plecoptera nymphs occurred in the summer. Brown trout (Salmo trutta), Pike (Esox lucius), eel (Anguila anguila), chub (Leuciscus cephalus), and perch (Perca fluviatilis) prey on Cottus gobio (Tomlinson and Perrow 2003). Piscivorous birds such as the grey heron (Ardea cinerea), kingfisher (Alcedo atthis), and the dipper (Cinclus cinclus) also prey on Cottus gobio.

Reproduction occurs over a single long brood cycle from February to June (Fox 1978, Marconato et al. 1993) and females produce 1-4 egg batches per year (Mills and Mann 1983). Males construct a nest by digging a cavity in the sand (Morris 1954). The males guard the nest, sitting at the entrance. Once a female is near the entrance, the male bites her and moves her into the nest. The female lays her eggs on the underside of the roof of the nest. The male exhibits parental care for the eggs for about 1 month by fanning to ventilate the nest. During the term of parental care, the males lose on average 13.5 - 18.8% of their weight, and were observed to cannibalize on their own eggs if their chance of obtaining other food items was low (Marconato et al. 1993).

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

Cottus gobio does not occur near waters connected to the Great Lakes. It is not known to hitchhike or foul. Cottus gobio is not stocked, commercially cultured, or sold in the Great Lakes region. This species occurs in ports that have direct trade connections with the Great Lakes (NBIC).  Cottus gobio may survive ballast tank environments; however, ballast water exchange regulations that require flushing with full-strength seawater are likely to prevent its introduction due to its salinity tolerance. Cottus gobio may be introduced to the Great Lakes via ships declaring “No Ballast on Board” (NOBOB), which are exempt from ballast water exchange. The majority of ships entering the Great Lakes are NOBOB vessels and 43% of these ships contain residual water with less than 10‰ salinity (NOAA Final Report 2005). In the study, the temperature of the residual water from the vessels sampled ranged from -0.7 to 23.9°C; thus Cottus gobio is likely to survive the salinity and temperature of the NOBOB ballast water.

Cottus gobio has a low probability of establishment if introduced to the Great Lakes (Confidence level: Moderate).

Kolar and Lodge (2002) predicted that Cottus gobio would spread quickly if introduced.The native and introduced ranges of Cottus gobio have similar climatic and abiotic conditions as the Great Lakes (Grigorovich et al. 2003, Reid and Orlova 2002, US EPA 2008). This species can tolerate the temperature of the Great Lakes during the winter, however, as an oxyphilic species, may not be capable of overwintering in waters with low-oxygen levels. Evidence suggests that increased water temperatures due to climate change may negatively impact reproductive physiology of Cottus gobio. Gonadal maturation for male and female fish was disrupted when water temperature was raised 8°C, reflecting complete reproductive failure (Dorts et al. 2012). Reyjol et al. (2009) conducted a study on the effects of temperature on life-history traits of Cottus gobio and predict that a mean air warming of 3.7°C is enough to negatively affect their populations. This fish commonly inhabits cold, well-oxygenated streams and lakes, but has been found in large stagnant water bodies as a nonindigenous species (Nolte et al. 2005). Appropriate habitats are somewhat available in the Great Lakes. Hybrids of 2 Cottus gobio populations are thought to have greater potential to adapt to new habitats.

The diet of Cottus gobio is flexible, and changes seasonally. The prey types in its diet are present in the Great Lakes.  However, there is no indication that Cottus gobio is a strong competitor. In the River Great Ouse, Britain, a crayfish native to North America, Pacifastacus leniusculus (Dana), competes with Cottus gobio for shelter, and reduces its abundance (Guan and Wiles 1997). Pacifastacus leniusculus does not currently occur in the Great Lakes. Cottus gobio may be preyed on by some fish that occur in the Great Lakes including Salmo trutta and Esox lucius (Fuller 2014, Fuller et al. 2014). 

Cottus gobio has moderate fecundity (Hänfling and Weetman 2006, Vila-Gispert et al. 2005). It requires large stones to make nests in order to reproduce (Smyly 1957); it is unlikely that the reproductive strategy of this species will aid its establishment in the Great Lakes.

There is little or no evidence to support that Cottus gobio has the potential for significant socio-economic impacts if introduced to the Great Lakes.

It has not been reported that Cottus gobio poses a threat to human health or water quality. There is no evidence that this species negatively impacts infrastructure, economic sectors, recreational activities and associated tourism, or the aesthetic appeal of the areas it inhabits.

There is little or no evidence to support that Cottus gobio has the potential for significant beneficial impacts if introduced to the Great Lakes.
It has not been indicated that Cottus gobio can be used for the control of other organisms or improving water quality. There is no evidence to suggest that this species is recreationally or medically valuable. It does not have significant positive ecological impacts. Cottus gobio can be eaten or used as live bait for large fish (Tomlinson and Perrow 2003).

*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.