Distinguishing characteristics were given in Berg (1949), Scott and Crossman (1973), Muus and Dahlstrom (1978), Wheeler (1978), and Page and Burr (1991). Identification keys that include this species and photographs or illustrations were provided in a few published state fish books (e.g., Whitworth et al. 1968; Woodling 1985; Bond 1994; Moyle 2002; Wydoski and Whitney 2003). A name used in some of the early literature for this species is Tinca vulgaris.

Potential pathway(s) of introduction: Dispersal

Tench have known reproducing populations in the St. Lawrence and Humber Rivers, both of which are connected to the Great Lakes (Avlijaš et al., 2017). In the St. Lawrence River, Tench populations are separated from Lake Ontario by the Moses Saunders Dam. However, the Humber river does not have any barriers. In October 2018 a Tench was caught by a commercial fisherman in the Bay of Quinte, Lake Ontario. Tench may be misidentified as other species and used as bait which could lead to unauthorized intentional release.

Tinca tinca has a moderate probability of establishment if introduced to the Great Lakes (Confidence level: High).
    Tench have high tolerance to a broad range of environmental conditions inlcuding low pH, low dissolved oxygen, and high temperatures (Sabapathy, 2014; Avlijaš et al., 2017). However, they do not typically inhabit water flowing faster than 0.5 m/s (Avlijaš et al., 2017). They can likely overwinter in the Great Lakes given that they have established populations in Quebec and Ontario, as well as at high elevations in Colorado (Zuckerman and Behnke, 1986). CLIMATCH analysis rates the Great Lakes region as very high (USFWS ERSS, 2014). The Tench’s broad diet mean they would also likely find appropriate food sources if introduced to the Great Lakes. However, Tench were introduced throughout the United States in the 19th century, yet are only established at a fraction of these sites today ( Avlijaš et al., 2017). Some observations indicate that the failure of the Tench to establish may be related to a biotic interaction with centrarchids (DeVaney et al., 2009), which are widely distributed in the Great Lakes Region.

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

Environmental	Socioeconomic

There is little or no evidence to support that Tinca tinca has the potential for significant Socio-Economic impacts if introduced to the Great Lakes.
    Tench are not reported to pose any threat to human health. They have not been found to damage infrastructure or affect water quality. Tench do not harm economic sectors or inhibit recreational activity.

Tinca tinca has the potential for moderate beneficial impacts if introduced to the Great Lakes.
    Tench were originally brought to the United States for use as a food and sport fish (USFWS ERSS, 2014). Tench may be mixed with other rough fish for sale  (Avlijaš et al., 2017). However there is not much demand for Tench, and their economic contribution is insignificant (Marcogliese et al. 2009). Tench are sometimes fished for recreationally, however there are already numerous sport fish established in the Great Lakes.

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

Control
    Biological
    Bass consume Tench (USFWS ERSS, 2014); restricting harvest of bass in areas where Tench have been collected may help to reduce their population.
   
    Physical
    Physical barriers such as dams may prevent dispersal of Tench
   
    Chemical
    Piscicides such as Rotenone may be effective in managing small isolated populations of Tench, however expect significant mortality in non target species.

     Other

Tench were introduced to Tasmania in the 19th century (Weatherley 1961).

DeVaney et al. (2009) performed ecological niche modeling to examine the invasion potential for tench and three other invasive cyprinids (common carp Cyprinus carpio, grass carp Ctenopharyngodon idella, and black carp Mylopharyngodon piceus). All of the current established populations of tench were in areas of predicted high suitability for this species. Interestingly, many areas where tench failed to become established or is currently extirpated (e.g., Great Lakes region) also had a moderate to high predicted suitability. DeVaney et al. (2009) attributed this potentially to negative interactions with sunfishes or unmeasured environmental factors.

Voucher specimens: Colorado (USNM 055569), Maryland (USNM 31003, 37850, 30336, 27234), Missouri (USNM 073666), New Mexico (UMMZ 118218), Virginia (USNM 30336, 31003, 37850).