Gobiosoma bosc - Naked goby
The Naked goby originates from North America, where it thrives along the West Atlantic coast from Massachusetts to the Gulf of Mexico [2-4].
First observation in Belgium
The first Belgian specimen of the Naked goby was caught in September 2018 during an anchor seine campaign in the Sea Scheldt, near Steendorp, at a depth of 6.5 meters [5,6].
Distribution in Belgium
The presence of the Naked goby was confirmed several times between 2018 and 2023 in the Sea Scheldt near Steendorp and Doel [7,8], as well as in the moat surrounding the Fort of Lillo [9] (see also observations on waarnemingen.be).
Distribution in neighbouring countries
The first report of the Naked goby in Western European was in 2009, when about seven specimens were found in the River Weser (Germany) [10]. In March 2017, the first specimen was found in the Dutch part of the North Sea Canal, marking its first appearance in the Netherlands [6], followed by a second specimen in October 2018 [11].
The fact that the species has consistently been found along international shipping routes in proximity to international ports (Amsterdam, Antwerp, Bremen) in Western Europe suggests that the exchange of ballast water by transoceanic ships is likely responsible for the introductions in Europe [6,10].
Based on the limited number of observations, it is currently difficult to assert that the species is successful in our region, although there is a chance that the fish is underreported due to its small size and cryptic nature [12]. However, despite the Naked goby often being categorised as a tropical species with a temperature range between 11 and 33°C [13], it is also found in temperate latitudes in the western Atlantic Ocean [12].
Genetic research on specimens caught in Germany revealed that these fish could be linked to Atlantic populations (Florida, Mid-Atlantic) and showed no connections with populations from the Gulf of Mexico [12]. This suggests that the ancestors of the specimens found in the North Sea area already possessed phenotypic traits related to adaptation to the prevailing climatic conditions at the northern boundary of the species' natural distribution range [7].
Despite adult Naked gobies having a demersal lifestyle, their larvae undergo a planktonic phase [12], which allows them to easily end up in ballast water and be transported over long distances [14].
The Naked goby is characterised as being strongly dependent on estuarine conditions [15]. The species inhabits various shallow estuarine habitats (sandy and muddy substrates, marshes, oyster reefs, tidal pools) [16-20] and exhibits a high tolerance to salinity variations (0-45 psu) [21], although it appears more frequently in estuaries with lower to moderate salinity levels [16]. Despite its temperature tolerance down to at least 11°C [13], a minimum temperature of 18 to 20°C is required for reproduction [16,22], with the fish preferring complex and scattered microhabitats (e.g., oyster reefs) for shelter [12]. The northernmost natural reproduction in the western Atlantic Ocean was observed in Chesapeake Bay [23], where the larvae are the most common species in the ichthyoplankton (collective term for fish eggs and larvae) [24].
Based on the available information regarding temperature, salinity, depth, substrate, and the presence of oyster reefs, the invasion risk for the North Sea under current climate conditions is assessed as ‘low-medium’ [7]. However, it is expected that the potential invasion risk will increase in the future based on climate change scenarios [7,25]. The actual impact of the Naked goby on native species and ecosystems is currently not well understood [26].
There are no specific measures known related to the management or control of this species. However, in 2004, under the auspices of the International Maritime Organization (IMO), the International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWMC) was adopted, which entered into force in 2017. This convention aims to prevent the spread of (invasive) aquatic organisms from one region to another by establishing standards and procedures for the management and control of ships' ballast water and sediments.
The Naked goby reaches a maximum length of about 6 cm and is characterised by the absence of scales, which immediately explains its name [6,2]. The coloration varies from yellow to brown but is highly variable. In living specimens, the color dorsally ranges from greenish to dark, and ventrally it is pale, with the neck and sides marked by 9 to 10 very narrow pale transverse stripes. The pectoral fin is greenish, while the other fins tend towards black [27]. The tail fin is slightly lighter than the dorsal fins, and a black spot appears on the anterior part of the dorsal fin [2,27]. Generally, male specimens are slightly darker than females [27]. A comprehensive species description can be found in the literature [6].
In its natural distribution range, the Naked goby primarily feeds on polychaetes and small crustaceans [18,28]. The larval and juvenile Naked gobies, in turn, prey on zooplankton, including larvae of bivalves [18,29,30]. The abundant food resources for larval Naked gobies around oyster beds enhance their growth rate and shorten their planktonic stage, reducing predation risks from predators [31,32].
[1] World Register of Marine Species (WoRMS) (2024). Gobiosoma bosc (Lacepède, 1800). https://www.marinespecies.org/aphia.php?p=taxdetails&id=159767 (2024-10-18).
[2] Robbins, C.R.; Ray, G.C. (1986). A field guide to Atlantic Coast fishes of North America. Peterson Field Guide Series, 32. Houghton Mifflin: Boston. ISBN 978-0395318522. 512 pp. [https://www.vliz.be/en/imis?module=ref&refid=381618]
[3] Van Tassell, J.L. (2011). Gobiidae of the Americas, in: Patzner, R.A. et al. (Ed.) The biology of gobies. pp. 139-176. [https://www.vliz.be/en/imis?module=ref&refid=208949]
[4] Hubbs, C.; Edwards, R.J.; Garrett, G.P. (1991). An annotated checklist of the freshwater fishes of Texas, with keys to the identification of species. Texas J. Sci. 53(4): 2-87 [https://www.vliz.be/en/imis?module=ref&refid=381619]
[5] Breine, J.; Galle, L.; Lambeens, I.; Maes, Y.; Terrie, T.; Van Thuyne, G. (2019). Monitoring van de visgemeenschap in het Zeeschelde-estuarium. Ankerkuilcampagnes 2018. Rapporten van het Instituut voor Natuur- en Bosonderzoek, 2019(7). Instituut voor Natuur- en Bosonderzoek (INBO): Brussel. 68 pp. [https://www.vliz.be/nl/imis?module=ref&refid=306377]
[6] Verreycken, H.; Galle, L.; Lambeens, I.; Maes, Y.; Terrie, T.; Van den Bergh, E.; Breine, J. (2019). First record of the naked goby, Gobiosoma bosc (Actinopterygii: Perciformes: Gobiidae), from the Zeeschelde, Belgium. Acta Ichtyol. Piscat. 49(3): 291-294. [https://www.vliz.be/nl/imis?module=ref&refid=316778].
[7] Dodd, J.A.; Copp, G.H.; Tidbury, H.J.; Leuven, R.S.E.W.; Feunteun, E.; Olsson, K.H.; Gollasch, S.; Jelmert, A.; O’Shaughnessy, K.A.; Reeves, D.; Brenner, J.; Verreycken, H. (2022). Invasiveness risks of naked goby, Gobiosoma bosc, to North Sea transitional waters. Mar. Pollut. Bull. 181: 113763. [https://www.vliz.be/nl/imis?module=ref&refid=353699]
[8] Bauwens, F.; Van den Neucker, T. (2023). Een speurtocht naar niet-inheemse soorten in het Galgeschoor en het Doeldok te Antwerpen. De Strandvlo 43(2): 39-50. [https://www.vliz.be/nl/imis?module=ref&refid=380571]
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[10] Thiel, R.; Scholle, J.; Schulze, S. (2012). First record of the naked goby Gobiosoma bosc (Lacepède, 1800) in European waters. Bioinvasions Records 1(4): 295-298. [https://www.vliz.be/en/imis?module=ref&refid=381258]
[11] Van Emmerik, W.; Beelen, P. (2018). Eerste hengelvangst Naakte grondel. Kijk op Exoten 7(2): 11-11. [https://www.vliz.be/en/imis?module=ref&refid=381620]
[12] Moore, C.S.; Ruocchio, M.J.; Blakeslee, A.M.H. (2018). Distribution and population structure in the naked goby Gobiosoma bosc (Perciformes: Gobiidae) along a salinity gradient in two western Atlantic estuaries. PeerJ 6: e5380. [https://www.vliz.be/en/imis?module=ref&refid=381257]
[13] Darcy, G.H. (1980). Comparison of ecological and life history information on gobiid fishes, with emphasis on the southeastern United States. NOAA Technical Memorandum, NMFS-SEFC-15. NOAA: USA. 53 pp. [https://www.vliz.be/en/imis?module=ref&refid=381621]
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[15] Able, K.W. (2005). A re-examination of fish estuarine dependence: Evidence for connectivity between estuarine and ocean habitats. Est., Coast. and Shelf Sci. 64: 5-17 In: Estuarine, Coastal and Shelf Science. Academic Press: London; New York. ISSN 0272-7714; e-ISSN 1096-0015 [https://www.vliz.be/en/imis?module=ref&refid=208085]
[16] Dahlberg, M.D.; Conyers, J.C. (1973). An ecological study of Gobiosoma bosc and G. ginsburgi (Pisces, Gobiidae) on the Georgia coast. Fish. Bull. 71(1): 279-287. [https://www.vliz.be/en/imis?module=ref&refid=381411]
[17] Crabtree, R.E.; Dean, J.M. (1982). The structure of two South Carolina estuarine tide pool fish assemblages. Estuaries 5(1): 2-9. [https://www.vliz.be/en/imis?module=ref&refid=381274]
[18] Breitburg, D.L. (1999). Are three-dimensional structure and healthy oyster populations the keys to an ecologically interesting and important fish community?, in: Luckenbach, M. et al. Oyster reef habitat restoration: a synopsis and synthesis of approaches. Proceedings from the symposium, Williamsburg, Virginia, April 1995. pp. 239-250. [https://www.vliz.be/en/imis?module=ref&refid=381450]
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[21] Dawson, C.E. (1969). Studies on the gobies of Mississippi Sound and adjacent waters II. An illustrated key to the gobioid fishes. Wilkes Printing Company: Mississippi. 60 pp. [https://www.vliz.be/en/imis?module=ref&refid=391060]
[22] Bechler, D.L. (1996). Reproductive strategies in a population of Gobiosoma bosci (Osteichthyes: Gobiidae) with slow and fast maturing individuals. Gulf Res. Rep. 9(3): 177-182. [https://www.vliz.be/en/imis?module=ref&refid=381413]
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[28] Breder, C.M. (1948). Field book of marine fishes of the Atlantic Coast from Labrador to Texas. G. P. Putnam’s Sons: New York. xxxvii, 332 pp. [https://www.vliz.be/en/imis?module=ref&refid=381415]
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[32] Hunter, J.R. (1981). Feeding ecology and predation of marine fish larvae, in: Lasker, R. (Ed.) Marine fish larvae: morphology, ecology, and relation to fisheries. pp. 33-77. [https://www.vliz.be/en/imis?module=ref&refid=393473]
VLIZ Alien Species Consortium (2024). Gobiosoma bosc – Naked goby. Introduced alien species of the Belgian part of the North Sea and adjacent estuaries anno 2024. Flanders Marine Institute (VLIZ). 6 pp.