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      Neogobius melanostomus (Photo: Eric Engbretson, U.S. Fish and Wildlife Service, www.forestryimages.org) - Click for full size   Neogobius melanostomus - close up of head (Photo: U.S. Fish and Wildlife Service, www.forestryimages.org) - Click for full size   Neogobius melanostomus (Photo: Center for Great Lakes and Aquatic Sciences Archives, University of Michigan, www.forestryimages.org) - Click for full size
    Taxonomic name: Neogobius melanostomus (Pallas, 1814)
    Synonyms: Apollonia melanostoma Iljin, 1927, Gobius affinis Eichwald, 1831, Gobius cephalarges Pallas, 1814, Gobius chilo Pallas, 1814, Gobius exanthematosus Pallas, 1814, Gobius lugens Nordmann, 1840, Gobius melanio Pallas, 1814, Gobius melanostomus Pallas, 1814, Gobius sulcatus Eichwald, 1839, Gobius virescens Pallas, 1814, Gobius weidemanni Kessler, 1874, Neogobius cephalarges Vasil'yeva & Vasil'ev, 1994, Neogobius cephalarges Berg, 1949, Neogobius melanostomus affinis Berg, 1949, Neogobius melanostomus Berg, 1949
    Common names: babca neagrâ (Romanian), babka bycha (Polish), babka okragla (Polish), black spotted goby (English), bychok kruglyak (Russian), chornorotyj bychok (Russian), gobie â taches noires (French), gobio pintato (Spanish), grundel (German), guvid (Romanian), Kruglyak (German), round goby (English), Schwarzmundgrundel (German), stronghil (Romanian), trevno popche (Bulgarian)
    Organism type: fish
    Neogobius melanostomus is a bottom dweller found in rivers and near the shore of lakes, preferring rocky habitats with many places to hide. It preys on small fish, such as darters and the eggs of lake trout, and many other fish. Adult Neogobius melanostomus aggressively defend spawning sites and will occupy prime spawning areas, preventing native species from utilising these sites. This fish may out-compete native fish for food resources, due to its ability to feed in darkness. Neogobius melanostomus often eats bivalves that filter water and becomes a vector of bioaccumulation, with contaminants becoming passed on to the larger game fish or humans that eat them. There is little information on successful management options for this species.
    Description
    Charlebois et al. (1997) state that, "N. melanostomus is a small, soft-bodied fish. It is most readily distinguished from all other freshwater fish in North America by the presence presence of a fused pelvic fin that forms a suction disk on the ventral surface. The body is brownish gray with dark brown lateral spots. Mature males are completely black during spawning and nest guarding, with yellowish spots on the body and median fins fringed in yellow or white. A large, oblong, black spot is usually present at the end of the first dorsal fin, beginning at the fifth ray. This spot is distinct but not unique, as sculpins often have a dark mark in this location. N. melanostomus without this spot have been found in Lake Erie (Cavender, Ohio State University, pers. comm.). Juveniles have a light border around the black spot."

    Charlebois et al. (1997) describe N. melanostomus in detail as, "scaled on the parietal region, nape, back (all), throat (all or most), abdomen, pectoral fin peduncles, and one quarter of the gill covers. Scales on the middle and anterior nape are cycloid (as are scales on the greater part of the gill covers and throat, pectoral peduncles, and part of the abdomen [Rudnicka, personal communication]). The head is as wide as or wider than deep; depth is 0.9-1.2 times the width. Head length is 22-23% of total body length. There are usually six, rarely seven, transverse suborbital series of pit organs. Ventral fins reach or almost reach the vent. The pelvic disk is 0.6-0.8 times the abdomen length. If present, the anterior membrane width is very shallow, with rounded, lateral lobes. The caudal peduncle depth is about two-thirds its length. The anterior dorsal fin has five to seven spines, usually six, and the posterior dorsal fin has one spine and 13-16 soft rays. The anal fin has one spine and 11-14 soft rays, and the pectoral fins have 17-20 soft rays N. melanostomus possesses upper and lower pharyngeal teeth, and the posterior teeth are smaller than anterior teeth (Pinchuk, 1992; Ghedotti et al., 1995). N. melanostomus lacks a gas bladder and chemoreceptors."

    Occurs in:
    lakes, marine habitats, water courses
    Habitat description
    Neogobius melanostomus is a bottom dweller in the nearshore region of lakes and in rivers, and prefers rocky habitat that provides lots of hiding opportunities. Although juvenile and adult round goby prefer rocky substrates, the fish also is found in fine gravel and sandy substrates in which they may burrow (Ray and Corkum 2001, in The Animal Diversity Web, 2002). Successful maintenance of all stages of the round goby in the laboratory requires vigorous aeration and a flow-through system (Corkum, personal observation). Steingraeber et al. (1996) report that, "N. melanostomus prefer to reside among macrophytes or rocky substrate in littoral areas (Jude et al. 1992; Jude et al. 1995) but are not restricted to these habitats (Jude and DeBoe, 1996)."

    Charlebois et al. (1997) go into great detail on the specific habitat preference of N. melanostomus. The authors state that, "N. melanostomus occur on coarse gravel, shell, and sand in inshore areas to depths of 20m in the Black Sea and the Sea of Azov (Miller, 1986). In the Caspian Sea, N. Melanostomus occur to 70 m, and are often associated with eelgrass (Zostera sp.) (Moskal'kova, 1996). In the Kuybyshev Reservoir, N. Melanostomus occur in silted sand at depths of 5-10m and in river beds to 30m (Tsyplakov, 1974). N. Melanostomus also occur in lower and middle reaches of rivers, but only in slightly brackish or fresh water (Miller, 1986, but see "Physiology" section). During spring-autumn in the Black Sea, N. Melanostomus is found in slowly flowing rivers, lagoons, and brackish coastal water to 20m (Jude and DeBoe, 1996), but it migrates to deeper water (50-60 m) in winter (Miller, 1986). During spring, N. Melanostomus migrates to inshore areas of the northern Caspian Sea even while these areas are still partially frozen (Nikol'skii, 1954). N. Melanostomus prefers littoral areas where wave action maintains high dissolved oxygen levels and reduces the amount of decaying material. In the Gulf of Gdansk, N. Melanostomus is associated with stone/sand areas, mussel beds, marine structures, and sunken objects. In Puck Bay, Gulf of Gdansk, N. Melanostomus inhabits areas with a humus/mud/sand substratum overgrown with benthic flora (Skora, 1996)".

    Charlebois et al. (1997) state that in its introduced range, "In the St. Clair River, N. Melanostomus are associated with large cobble to depths of 3m and macrophytes (e.g., Elodea canadensis, Myriophyllum spp. And Potamogeton spp.) in depths of 1.5-4.6 m. They also have been impinged on industrial screens at 6m depth (Jude et al. 1992; Jude et al. 1995; Jude and DeBoe, 1996). Fry were collected in Chara beds presumably where spawning occurred (Jude et al. 1995). Macrophytes and cobble provide large interstices for refuge and spawning (Jude and DeBoe, 1996), but N. Melanostomus apparently is not restricted to these habitats (Jude et al. 1992; Jude and DeBoe, 1996; MacInnis and Corkum, 2000). In Calumet Harbor (Illinois), N. Melanostomus were abundant on both cobble and sand, although adults were less abundant on sand than juveniles. N. Melanostomus also will move onto sandy beaches to feed at night (Jude et al. 1992). In the St. Clair River, there is an inverse relationship with depth and number of N. Melanostomus, but a direct relationship with depth and length of individuals, which may be due to gear bias (Jude et al. 1995). N. Melanostomus were not collected in shallow near shore areas of Lake St. Clair until May 8 in 1993 (T. Water =7.8ºC), but were abundant from shore to 5m on November 5, and in December trawls at 3, 5, and 7 m."

    General impacts
    For details on the impacts of Neogobius melanostomus of this species please see general impacts
    Uses
    Neogobius melanostomus is fished commercially in the Black and Caspian seas. The species also is used as a bait fish, although this practise is often not permitted in regions where the fish is non-indigenous.
    Geographical range
    Native range: Asia and parts of Europe (ANSRP, 2003)
    Known introduced range: North America (ANSRP, 2003) and parts of Europe (Baltic Sea Alien Species Database, 2004)
    Introduction pathways to new locations
    Ship ballast water: Morrison et al. (2000) state that, "N. melanostomus was probably deposited in the Great Lakes during ballast water exchange (Crossman, 1991)."


    Local dispersal methods
    Boat: Fuller et al. (2005) state that, "N. melanostomus spread to Lake Superior by freighters operating within the Great Lakes."
    Nutrition
    The Animal Diversity Web (2002) states that, "N. melanostomus are voracious feeders, with a penchant for stealing the worms off an angler's hook. They also prey on zebra mussels, another Great Lakes exotic from the same native region. Young and eggs of other fishes, and even their own, as well as aquatic insects and invertebrates are choice prey. A complete lateral line system (a sensory system) allows them to feed in complete darkness."

    Charlebois et al. (1997) state that, "N. melanostomus is a benthic feeder. Its diet is composed primarily of crustaceans and molluscs, including zebra mussels. Polychaetes, small fish, goby eggs, and chironomid larvae also are eaten (Berg, 1949; Miller, 1986). In the Sea of Azov, N. melanostomus was the primary consumer of benthos, consuming up to 13% of the annual production. Its diet during the primary feeding period (spring-fall) was 90% molluscs, and during winter was 11-41.8% fish (mainly Clupeonella; Skazkina and Kostyuchenko, 1968). N. melanostomus of all sizes eat molluscs and crustaceans. Small- and medium-sized N. melanostomus also eat worms (presumably polychaetes), but only larger individuals eat other fish (Skazkina and Kostyuchenko, 1968; Kovtun et al. 1974). In North America, N. melanostomus also primarily consume benthic organisms. Other items in the stomachs were Gammarus, Ceratopogonidae, Ephemeroptera (Caenis, Stenonema, Ephemera, Hexagenia , Baetis), Odonata (Macromia), Diptera (Atherix pupae and larvae), Oligochaeta, Ostracoda, Decapoda (crayfish), and Trichoptera. Larger fish contained more chironomids and zebra mussels than smaller fish. N. melanostomus ingests zebra mussels intact; divers in the St. Clair River have observed N. melanostomus wresting zebra mussels from the substratum and swallowing them whole (Johnson and Lashbrook, 1993). N. melanostomus generally crushes the zebra mussels with its pharyngeal teeth, and shells are discarded before the soft body is swallowed (Ghedotti et al. 1995)."

    Reproduction
    Murphy et al. (2001) state that, "Males migrate from deeper waters to spawning areas in the spring, establish territories prior to arrival of females, defend a nest site to which females are attracted for spawning, and care for single or multiple batches of eggs (Moiseyeva and Rudenko, 1976; MacInnis and Corkum, 2000). As with other male gobiids [e.g., Bathygobius soporator (Tavolga, 1956)], male round gobies use visual displays (colouration changes and posturing) and acoustical signals when courting females (Protosov et al. 1965; Moiseyeva and Rudenko, 1976)." The Animal Diversity Web (2002) states that, "Female N. melanostomus spawn repeatedly (approximately every 20 days) from April until September while males guard the eggs and young." The authors go on to state that, "Five hundred to three thousand eggs are deposited by the female on a hard substrate and are then guarded by the male until hatching." Pheromone signalling is crucial to mating behaviour in N. melanostomus (Corkum, 2004). Gill ventilation by reproductive males in response to steroids and to gonadal extracts from gravid females is dependent upon olfactory sensory input (Belanger et al. 2003). Accessory nasal sacs have the capacity to "regulate the flow of odorant molecules over the sensory surface of the olfactory sensory neurons, possibly through a pump-like mechanism driven by opercular activity associated with gill ventilation" (Belanger et al. 2003). Arbuckle et al. (2005) discovered that 5-ß-reduced androgens are produced in the islets of steroid-synthesizing glandular tissue of male round goby testes. The male round goby releases a sex attractant to which gravid females respond (Belanger et al. 2004). In a laboratory flume, gravid females spent significantly more time than non-reproductive females near the source of the reproductive male donor water (Belanger et al. 2004).
    Lifecycle stages
    The Animal Diversity Web (2002) states that, "Female N. melanostomus mature by 1-2 years of age and males at 3-4 years." Studies have shown that newly colonized round gobies in brackish waters and lakes are smaller, mature earlier, have a male biased sex ratio and are more short-lived compared with round gobies from marine (native) habitats (Corkum et al. 2004).
    Reviewed by: Dr. Lynda D. Corkum, Professor Department of Biological Sciences University of Windsor Canada
    Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
    Last Modified: Thursday, 27 April 2006


ISSG Landcare Research NBII IUCN University of Auckland