Tridentiger bifasciatus - Shimofuri goby

The Shimofuri goby Tridentiger bifasciatus is native to the northwestern part of the Pacific Ocean, specifically around Japan, China, and South Korea ^[2].

First observation in Belgium

In November 2022, two specimens of the Shimofuri goby were caught in the Ghent-Terneuzen Canal during a fishing competition. This was described as the first observation in Europe ^[3], but it soon became apparent that these fish belonged to the same species as the 'unknown gobies' found near Biervliet (the Netherlands) in August 2022 ^[4].
 

Distribution in Belgium

To date, the species has been found multiple times in the Ghent-Terneuzen Canal ^[5], and in March 2024, two Shimofuri gobies were detected in the Scheldt near Doel ^[6]. The fact that multiple individuals have been caught in Flanders as well as near Biervliet (Netherlands) suggests that this species may have established itself in the region ^[4].
 

Distribution in neighbouring countries

Due to the cryptic lifestyle of the Shimofuri goby (living on the bottom) and its morphological similarity to native goby species, it is possible that this species is present in other European river systems but has not yet been identified as such ^[3]. In the Netherlands, this goby was first observed in August 2022 in the Uitwateringskanaal Nol Zeven near Biervliet ^[4].

Prior to the observation in Belgium in 2022, this species had only been recorded outside Asia in California, where it was introduced in the mid-1980s and has been established since the 1990s ^[7].

The goby was likely introduced to the Ghent-Terneuzen Canal through ballast water exchange by trans-oceanic ships ^[3]. The brackish water of the Western Scheldt allows the Shimofuri goby to thrive in the estuary, which may have facilitated its natural spread from the Ghent-Terneuzen Canal to Biervliet ^[4]. The recent detection of the Shimofuri goby in the Scheldt near Doel suggests that there may have been multiple introduction sites in Belgium ^[6].

The Shimofuri goby can survive temperatures up to 37°C ^[8]. Although the lower temperature tolerance limit is not known, based on the climatic conditions in its natural range, it can be inferred that this fish can survive in Belgian waters and other parts of Western Europe ^[3]. The species occurs in both freshwater and brackish environments and can tolerate salinities up to 17 psu ^[8]. However, for successful reproduction, the water must have a maximum salinity of 5 psu ^[7].

Global climate change could play a facilitating role in the establishment of this species outside its natural range ^[3].

The Shimofuri goby inhabits the same habitat as the non-native and already established Round goby (Neogobius melanostomus). Further research is needed to determine whether the Shimofuri goby has established itself and whether both goby species can coexist ^[3]. The species is a generalist predator, primarily feeding on benthic invertebrates such as ostracods, copepods, isopods, amphipods, oligochaetes, polychaetes, and scavenging shrimp ^[9,10]. Additional studies are required to assess whether this goby could have a significant negative impact on native fauna in the future ^[4].

Currently, there are no known measures for managing the Shimofuri goby.

The Shimofuri goby has a relatively short life cycle. The species reaches maturity within a year and has a maximum lifespan of 1 to 2 years ^[9,11]. This goby can grow up to 12 cm in length ^[12]. Depending on the location, spawning events occur once a year (in China) ^[11] or multiple times a year (in the USA) ^[9]. Eggs are laid in sheltered areas and are guarded by the male ^[9].

Typical color features of the Shimofuri goby include the orange edge of the second dorsal fin, the yellow edge of the anal fin, white spots on the ventral side of the jaw, and a striped-marble pattern on the lateral side of the jaw and operculum. Additionally, the goby caught in Belgium had a dark line with white spots on its flank, but this coloration can also occur in the Chameleon goby (Tridentiger trigonocephalus), which is not yet present in Western Europe ^[3]. Color patterns can vary between populations and even among individuals, complicating identification ^[3,4]. There are also black and striped variants ^[2], but these have not yet been found in Belgium ^[3].

Due to its cryptic lifestyle and strong morphological similarities with other gobies, targeted monitoring using eDNA techniques may provide better insights into the distribution of this species outside its original range ^[3,13].

[1]          World Register of Marine Species (WoRMS) (2024). Tridentiger bifasciatus Steindachner, 1881. https://www.marinespecies.org/aphia.php?p=taxdetails&id=283045 (2024-10-18).

[2]          Akihito [Emperor]; Sakamoto, K. (1989). Reexamination of the status of the striped goby. Jap. J. Ichthyol. 36(1): 100-112. [https://www.vliz.be/en/imis?module=ref&refid=393647] 

[3]          Verhelst, P.; Verreycken, H. (2023). First record in Europe of the Asian gobiid, Shimofuri (marbled) goby Tridentiger bifasciatus Steindachner, 1881. J. Fish Biol. 102(5): 1253-1255. [https://www.vliz.be/nl/imis?module=ref&refid=363466] 

[4]          Vos, M.; Verhelst, P.; Verreycken, H.; van Broekhoven, B.; Patijn, N. (2023). Nieuwe exotische vis ontdekt in Nederland: de Shimofurigrondel. Kijk op Exoten 43: 18-19. [https://www.vliz.be/nl/imis?module=ref&refid=366716] 

[5]          waarnemingen.be. Tridentiger bifasciatus Steindachner, 1881. https://waarnemingen.be/species/796604/ (2024-04-02).

[6]          Verreycken, H. (INBO). Persoonlijkemededeling. (2024-04-04)

[7]          Matern, S.A.; Fleming, K.J. (1995). Invasion of a third Asian goby, Tridentiger bifasciatus, into California. Calif. Fish Game 81(2): 71-76. [https://www.vliz.be/en/imis?module=ref&refid=393646]  

[8]          Matern, S.A. (2001). Using temperature and salinity tolerances to predict the success of the Shimofuri goby, a recent invader into California. Trans. Am. Fish. Soc. 130(4): 592-599. [https://www.vliz.be/en/imis?module=ref&refid=393645] 

[9]          Matern, S.A. (1999). The invasion of the Shimofuri goby (Tridentiger bifasciatus) into California: Establishment, potential for spread, and likely effects. PhD Thesis. University of California: Davis. xvi, 167 pp. [https://www.vliz.be/en/imis?module=ref&refid=393644] 

[10]        Matern, S.A.; Brown, L.R. (2005). Invaders eating invaders: exploitation of novel alien prey by the alien Shimofuri goby in the San Francisco Estuary, California. Biological Invasions 7: 497-507. [https://www.vliz.be/nl/imis?module=ref&refid=203309] 

[11]        Jiao, Q.; Miao, X.; Meixiang, J.; Fei, C.; Lei, Z.; Victor, S.; Jian, L.; Songguang, X. (2020). Combined opportunistic and equilibrium life-history traits facilitate successful invasions of the Shimofuri goby (Tridentiger bifasciatus). Aquat. Invasions 15(3): 514-528. [https://www.vliz.be/en/imis?module=ref&refid=393642] 

[12]        Froese, R.; Pauly, D. (2024). FishBase. World Wide Web electronic publication. www.fishbase.org, version (02/2024).

[13]        Everts, T.; Halfmaerten, D.; Neyrinck, S.; De Regge, N.; Jacquemyn, H.; Brys, R. (2021). Accurate detection and quantification of seasonal abundance of American bullfrog (Lithobates catesbeianus) using ddPCR eDNA assays. NPG Scientific Reports 11(1): 11282. [https://www.vliz.be/en/imis?module=ref&refid=393641]

VLIZ Alien Species Consortium (2024). Tridentiger bifasciatus – Shimofuri goby. Introduced alien species of the Belgian part of the North Sea and adjacent estuaries anno 2024. Flanders Marine Institute (VLIZ). 5 pp.