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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Shimofuri Goby

Synonyms and Other Names: shimofuri shimahaze [Japanese]

Taxonomy: available through www.itis.gov

Identification: Akihito and Sakamoto (1989) resurrected this species after over 50 years of synonomy with T. trigonocephalus. They provided details on distinguishing characteristics, and also provided color photographs for both species. Distinguishing characteristics were also summarized by Matern and Fleming (1995). According to Matern and Fleming (1995), some published reports of T. trigonocephalus in California (e.g., Raquel 1988; Meng et al. 1994) actually refer to T. bifasciatus. Species of Tridentiger can be distinguished from all North American native gobies by the presence of tricuspid (three-lobed) teeth in the outer row of the jaw. This species can be separated from T. trigonocephalus primarily by coloration patterns (white spots on lower portion of head, orange/red margin and no conspicuous stripes on 2nd dorsal and anal fins in T. bifasciatus; no white spots on lower portion of head, white margin and consipicuous stripes on 2nd dorsal and anal fins in T. trigonocephalus), and from T. barbatus by the presence of barbels on the head on the latter species.

Size: 11 cm.

Native Range: Fresh and brackish water. Asia, including Japan, Korea, China, Taiwan, and the former Soviet Union (Akihito and Sakamoto 1989).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: The shimofuri goby is primarily feeds on benthic invertebrates, including ostracods, copepods, isopods, amphipods, oligochaetes, polychaetes, and mysids (Matern 1999; Matern and Brown 2005). Other introduced species, including the hydroid Cordylophora caspia and cirri of the barnacle Balanus improvisus, comprise a large portion of the diet of T. bifasciatus (Matern and Brown 2005).

Shimofuri gobies can tolerate a wide range of temperature and salinity values. They exhibit thermal tolerances greater than those of most native fishes in the San Francisco Estuary, and exhibit salinity tolerances well-suited to salinities found throughout most of the San Francisco Estuary (Matern 1999, 2001).

Spawning in the shimofuri goby generally occurs from March to September in oligohaline (up to 19 ppt.) to fresh water (Matern 1999; Wang 2011). Males build and guard nests inside of cavities with hard interior surfaces, such as oyster shells, crevices, logs, or cans/bottles (Matern 1999; Wang 2011). Reproduction occurs multiple times throughout the season (Matern 1999). Maturity is reached in 1 year, with a maximum longevity of 2 years (Matern 1999).

Means of Introduction: Probably introduced via ballast water circa 1985 (Matern and Fleming 1995).

Status: Based on trawl samples, this species was the most abundant adult fish in Suisun Marsh by 1989 (Meng et al. 1994, as T. trigonocephalus; Matern and Fleming 1995), and the third most abundant larval fish (Matern and Fleming 1995). They were the most abundant larvae by 1990 (Matern and Fleming 1995).

Impact of Introduction: A study conducted by Meng et al. (1994) found that yellowfin gobies prey on the eggs and larvae of the introduced chameleon goby Tridentiger trigonocephalus. However, their research was conducted in Suisun Bay, an area known to be in the range of the shimofuri goby and not the chameleon goby (Fleming, personal communication). Therefore, it is actually the shimofuri goby that eats the eggs of the chameleon goby. Meng et al. (1994) also suggested this goby may be responsible, at least in part, for the chamelon goby's decline in the San Francisco Bay estuary. However, Fleming (personal communication) disagrees. He believes it is unlikely the shimofuri goby has been in the Bay long enough to have and impact on the chameleon goby's population.

Shimofuri gobies likely compete with native species for Corophium amphipods, which are seasonally abundant in winter and comprise a major prey item of tule perch (Hysterocarpus traski), Sacramento sucker (Catostomus occidentalis), prickly sculpin (Cottus asper), staghorn sculpin (Leptocottus armatus), and starry flounder (Platichthys stellatus) (Feyrer et al. 2003). While Young et al. (2017) found that Shimofuri Goby are habitat generalists in the San Francisco Estuary, they claim the gobies do not have a high impact on the native Prickly Sculpin due to a lack of habitat overlap.

Remarks: The shimofuri goby may compete with the federally endangered tidewater goby Eucyclogobius newberryi if the two come in contact. The two species are very similar in habitat and dietary preferences (Matern and Fleming 1995). One potential scenario that would cause the two species to become sympatric is introduction of the shimofuri goby into Lake Cachuma in southern California via the California Aqueduct, and then into the Santa Ynez River (Matern and Fleming 1995). Tridentiger bifasciatus, although often sympatric with T. trigonocephalus in its native range, apparently prefers brackish to freshwater habitats (less than 22 ppt) and has never been taken in normal marine salinities, whereas T. trigonocephalus prefers more saline habitats and is rarely found in salinities less than 22 ppt. (Matern and Fleming 1995). Both species are found in brackish water. This species, like the chameleon goby, is capable of rapidly changing color (Matern and Fleming 1995). Voucher specimens: California (CAS 81588, 81582, 82361).

References: (click for full references)

Akihito and K. Sakamoto. 1989. Reexamination of the status of the striped goby. Japanese Journal of Ichthyology 36(1):100-112.

Feyrer, F., B. Herbold, S.A. Matern, and P.B. Moyle. 2003. Dietary shifts in a stressed fish assemblage: consequences of a bivalve invasion in the San Francisco Estuary. Environmental Biology of Fishes 67:277-288.

Matern, S.A. 1999. The invasion of the shimofuri goby (Tridentiger bifasciatus) into California: establishment, potential for spread, and likely effects. Doctoral dissertation. University of California, Davis, CA.

Matern, S.A. 2001. Using temperature and salinity tolerances to predict the success of the shimofuri goby, a recent invader into California. Transactions of the American Fisheries Society 130:592-599.

Matern, S.A., and L.R. Brown. 2005. Invaders eating invaders: exploitation of novel alien prey by the shimofuri goby in the San Francisco Estuary, California. Biological Invasions 7:497-507.

Matern, S.A., and K.J. Fleming. 1996. Invasion of a third Asian goby species, Tridentiger bifasciatus, into California. California Fish and Game 81(2):71-76.

Meng, L., P.B. Moyle, and B. Herbold. 1994. Changes in abundance and distribution of native and introduced fishes of Suisun Marsh. Transactions of the American Fisheries Society 123:498-507.

Raquel, P.F. 1988. Record of the chameleon goby, Tridentiger trigonocephalus, from the Sacramento-San Joaquin Delta. California Fish and Game 74(1):60-61

Sommer, T, B. Harrell, M. Nobriga, R. Brown, P. Moyle, W. Kimmerer, and L. Schemel. 2001. California's Yolo Bypass: Evidence that flood control can be compatible with fisheries, wetlands, wildlife, and agriculture. Fisheries 26(8):6-16.

Swift, C.C., T.R. Haglund, M. Ruiz, and R.N. Fisher. 1993. The status and distribution of the freshwater fishes of southern California. Bulletin of the Southern California Academy of Science 92(3):101-167.

Wang, J.C.S. 2011. Fishes of the Sacramento-San Joaquin River delta and adjacent waters, California: a guide to early life histories. Tracy Fish Collection Facility Studies, vol. 44. U.S. Bureau of Reclamation, Mid-Pacific Region and Denver Technical Service Center.

Young, M.J., K.A. Berridge, T. O'Rear, P.B. Moyle, and J.R. Durand. 2017. Habitat partitioning by native and alien fishes and decapods in novel habitats of the upper San Francisco Estuary. Biological Invasions 19(9):2693-2710. https://link.springer.com/article/10.1007/s10530-017-1477-2.

Other Resources:
California Fish Species

US Fish and Wildlife Service Ecological Risk Screening Summary for Tridentiger bifasciatus

Author: Leo Nico, Pam Fuller, and Matt Neilson

Peer Review Date: 11/26/2012

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.