Neogobius melanostomus (Pallas 1811)

AUTHOR: Dr. Krzysztof E. Skora
AUTHOR’S ADDRESS: Hel Marine Biological Station, 84-150, Hel, P.O. Box 37,
tel.: +48 58 750836, fax: +48 58 750420,
e-mail: sekhel@halina.univ.gda.pl
CITATION OF THIS ENTRY: Skora, K., E. 1997. Neogobius melanostomus. In: Baltic Sea Alien Species Database. S. Olenin, E. Leppakoski and D. Daunys (eds.).
INTERNET: http://www.ku.lt/nemo/mainnemo.html

TAXONOMY

Subspecies (?) in the Caspian Sea ­ Neogobius melanostomus affinis Eischwald

• Common synonyms:

Gobius melanostomus Pallas 1811,
Gobius (Apollonia) melanostomus Pallas 1811

• Common names:

Trevno popche (Bu), Schwarzmundgrundel, Kruglyak ­ Grundel (D), Round goby, Black spotted goby (En), Gobie ā taches noires (Fr), Babka bycha, babka okragla (Pl), Guvid, Stronghil, Babca neagrā (Ro), Bychok ­ kruglyak, Chornorotyj bychok (Ru), Gobio pintato (Sp)

IDENTIFICATION

• Diagnosis:

After Miller (1986) ­ nape scaled completely, scales cycloid on middle and anterior nape. Head depth 0.9 ­ 1.2 width. Inter ­ orbit four ­ fifths to almost equalling eye diameter. Angle of jaws below anterior quarter of eye. Snout 1.1 ­ 1.4 orbit. Upper lip narrowing slightly to rear, with about half lateral preorbital area. Pelvic disc 0.6 ­ 0.8 abdomen length, anterior membrane width very shallow, rounded, lateral lobes, if evident at all. Caudal peduncle depth about two ­ thirds own length. D1 VI (V­VII); D2 I + 14­16 (13­16): A I + 11­13 (11­14); P 18­19 (17­20). Scales in lateral series 49­55 (45­57). Vertebrae 32­33 (31­34). Colour: yellowish­grey, with lateral blotches; first dorsal fin with large black spot in posterior part; breeding males are black, with median fins white­edged. Size: to 22 cm. (24.6 cm Lt, in Gulf of Gdańsk)

Fig.1 Neogobius melanostomus (Pallas 1811) from the Gulf of Gdansk (Lt 185 mm).
The figure does not show the changeable colour and pattern of the fish.

Fig.2 Larvae and juvenile Neogobius melanostomus affinis (after Koblickaja 1981)

• Species already present in the Baltic Sea, with which an introducent have similar features, and therefore may be mixed up

Fig.3 Gobius niger

Fig.4 Gobiusculus flavescens

Fig.5 Pomatoschistus microps

Fig.6 Pomatoschistus miutus

INTRODUCTION AND DISTRIBUTION

• First record from the Baltic Sea (year, area, reference):

Year ­ 1990,
Area ­ Gulf of Gdańsk (Hel),
Reference ­ Skóra K. E., Stolarski J. 1993 "New fish species in the Gulf of Gdansk Neogobius sp [cf. Neogobius melanostomus (Pallas 1811)]", in: Notes Bulletin of the Sea Fisheries Institute 1 (128): 83.

• Established:

in the entire Baltic Sea ­ No
in the area of primary introduction ­ Yes

• Primary or secondary introduction into the Baltic:

Primary, probably before 1987, into the harbours or shipyard basins of Gdynia (Gulf of Gdansk) because the first individual of this species, caught in 1990 in Hel, was age 3 or 4 according to scale readings.

• Present distribution in the Baltic:

In the Gulf of Gdańsk:

In the entire Puck Bay:

• in the harbours of: Gdynia, Hel, Jastrania, Puck and out of them (data from Hel Marine Station);
• in the coastal zone, of thr above harbours, and near the fishery villages: Kuźnica, Chałupy, Swarzewo, Rzucewo, Osłonino, Rewa, Mechelinki, Gdyni­Oksywie, Gdynia­Orłowo and Gdynia­ Redłowo (data from Hel Marine Station),
• shoal area of Ryf Mew (data from Hel Marine Station)
• position 54° 31, 39 N and 18° 50, 47 E at depth =31­34 m (data from Sea Fisheries Institute, Gdynia).

Outside the Puck Bay:

• in the area of Gdańsk­Brzeźno, Gdańsk­Westerplatte (data from Sea Fisheries Institute and Hel Marine Station).

Outside of the Gulf of Gdańsk:

• near Dębki. (data from Sea Fisheries Institute, Gdynia).

• Primary introduction (in Europe): a route of introduction:

The first transfer of this species outside its native biogeographic range occurred in the Aral Sea (Miller 1986). However, the species died out because of increasing salinity in this body of water (A. Neelov, personal comm.).
N. melanostomus could have found its way into the Gulf of Gdansk by means of ballast waters of vessels sailing along the line connecting the Caspian and Black Seas with the Baltic, or directly through rivers: from the Black Sea through the Dnieper, Pripet, Pina, Kanal Krolewski, Bug, and Vistula. It is also possible that they reached the Baltic by a longer route from the Sea of Azov through the Don to theVolga or from the Caspian Sea through the Volga, Rybinskoe Reservoir, the Onega and Ladoga Lakes and the Gulf of Finland. This second longer route seems more likely. This is supported by the fact that N. melanostomus was observed in the river Moskva (Sokolov et al. 1989). So far the presence of these fish in other parts of the Baltic has not been observed; the Gulf of Gdansk is their only habitat. Transport of eggs or larvae with ballast waters seems more likely than the migration of fish. This species is not a good "swimmer" and it is difficult to imagine the fish covering such a long distance, leading mostly upstream.

Fig.7 Hypothetical route of N. melanostomustransfer from its native habitat into the Gulf of Gdansk.

ABIOTIC PREFERENCES AND BIOLOGY

In the area of origin

Inshore, on coarse gravel, shelly and sandy bottom, to a depth of 20 m (50-60 m in winter, off Varna, Bulgaria); also lower and middle reaches of rivers, in only slightly brackish to freshwater (Miller 1986).

In the Baltic

In the Gulf of Gdansk: on sandy­stony bottom, among mussel beds, marine structures (piers, wharves), sunken objects. In the Puck Lagoon, which is a part of the Puck Bay, juvenile stages inhabit muddy­sandy humus­containing bottom, overgrown with bethic flora.

• Reproduction, physiology, feeding strategy, mobility level, etc.

After Miller (1986) ­ Reproduction: April to end of September (Varna), May­June (Romania), early April to August (Strait of Kerch) but ending by July in Sea of Azov; repeat spawning, up to six times, every 18­20 days in captivity. Eggs ovoid, with sharp apex, about 3.9 x 2.2 mm, deposited under or between stones. Fecundity 328­5221 at 7­13 cm. Sexually mature at 3­4 years (males), 2­3 years (females).
Lifespan: up to 4 years, but males after the spawning season.
Food: chiefly bivalves, crustaceans (corophiid amphipods, decapods) and polychaetes; also, small fish and chironomid larvae.
Based on the observation from two years (very warm seasons in 1994 and 1995), it was concluded that the spawning season of N. melanostomus in the Gulf of Gdansk extended from the end of April until the end of August/beginning of September. In captivity at water temperatures of 18­19°C the incubation lasted from 17 to 19 days (Skora, unpublished). Fecundity values, calculated by Kuczynski (1995) for two 15 cm long females were 2700 and 3000 eggs/individual.

• Effects of introduction

a) positive and/or negative social and economic effects

The consequences of the growth of this species population in the Gulf of Gdañsk may be commercially favourable for local fishery and anglers because­in a situation when many of traditionally caught species disappear­ it may compensate for their absence.
This species has cobstituted most of gobiid catches in the Sea of Azov, Romanian and Bulgarian waters (Miller 1986).
According to Svietovidow (1964) in the `30s and `40s in the Aral Sea the catches of this species ranged from 2 to 35 thousand tons, while in 1956, they amounted to almost 50 thousand tons. In the northern Black Sea annual catches fluctuated at the level of 3 to 4 thousand tons (Fig.8). Catch rates vary widely because of the stock size, predation by pike perch and mortality due to the summer oxygen deficiency in water.

 

Fig.8 Cans with Round Goby in the Russian supermarket (Photo by S. Olenin)

It is uncertain whether the stock of N. mealnostomus will be that numerous; food resources (abundance of mollusks) and lack of predators are to the species advantage. For a year N. melanostomus has bee sold in fish markets at 1.5 PLN/kg (0.6 $/kg). By­catch rates of this species during eel­directed catches with traps reach up to 50 kg/day/boat. This fish becomes more and more often the main sporting species, particularty in the Gdynia area.

b) impact on the ecosystem (physical displacement of, or predation on native species; changes in autochtonous communities and food chains; others)

An increase in the number of N. melanostomus may bring about far­reaching changes in the ecosystem. This species may become a serious competitor for food with other species of ichthyofauna of coastal zone (especially crustaceans and molluscs feeders). Its hiding places will overlap with those occupied by Zoarces viviparus and Gobius niger. N. melanostomus, being abundant and accessible, will become a new food item for other fish and birds. This will probably result in reduced preying intensity on traditionally consumed major species (sand eels, sprat, large crustaceans).

• Abundance in study area: quantitative data on density/biomas and comparison to autochtonous species of the same taxonomic/ecological group.

The abundance of N. melanostomus in the Gulf of Gdansk should be considered as high and widespread. In the habitats optimal for this species (among constructions reinforcing the beach, made of rocks) the presence of even several individuals per 1 m2 od surface area was reported (Redlarski A., Samsel J., viedeo films).
The remaining autecological features reveal that this species has found adequate living condition in the Gulf of Gdansk. Its propagation in our waters is aided by the food base, abundant in molluscs, which are the main food component for this species. In the areas of its natural habitat molluscs constitute from 46 to 98% of its diet (Svetovidov 1969). Not without significance is also its optimum spawning strategy (caring for the eggs, absence of the pelagic phase during the larval stage), protecting embryos and juvenile stages against predation by stickleback, dominant in the coastal zone. Besides, the disappearance of large predators (cod, pike, eel, seals) in the coastal zone nullifies the threat to adult individuals. Another factor, which probably favourably influences the ability of this pontocaspian species to settle in the Baltic, are symptoms of the global warming.

REFERENCES

1. Crossman, E.J. Holm E., Cholmondeley R., Turininga K., 1992 First record for Canada of the rudd Scardinus erythrophthalmus, and notes on the introduced round goby, Neogobius melanostomus Can. Field. Nat 106, 2: 206­209.
2. Jude D.J., Reider R.H., Smith G.R., 1991 "First evidence of Gobiidae in the Great Lakes basin. Conf. of the Int. Assoc. for great Lakes Res. June 2­5 1991.
3. Jude D.J., Reider R.H., Smith G.R. 1992 "Establishment of Gobiidae in the Great Lakes Basin" Can. J. Fish. Aquat. Sci. Vol. 49, 2: 416­421.
4. Jude D.J., Jamssen J., Crawford G., (in press) Ecology distribution and impact of the newly introduced round and tubenose gobies on the biota of St. Clir and Detroit Rivers" In M. Munawar, T. Edsall and J. Leach (eds) The lake Huron Ecosystem: Ecology, Fisheries and Management. Ecovision World Monograph Series, S.P.B. Academic Publishing, The Netherlands.
5. Grygiel W. 1995 Występowanie nowego gatunku babki Neogobius melanostomus (Pallas 1811) w polskicj obszarach morskich. Notatka w Zakladzie Biologii i Ochrony Zasobów MIR, Gdynia.
6. P.J. Miller 1986 "Gobiidae" in: "Fishes of the North­eastern Atlantic and the Mediterranen", Vol III, P.J.P. Whitehead at al (ed): 1019­1086.
7. Müller H. 1983 "Fische Europeas" Neuman Verlag, Leipzig; 320.
8. Koblickaja A.F. 1981 "Opredielitiel molodii priesnowodnyh ryb" Moskva. Legkaja i pischevaja promyslennost. 208.
9. Kuczyński J. 1995 Babka krągła Neogobius melanostomus (Pallas 1811) ­ emigrant z Basenu Pontokaspijskiego w Zatoce Gdańskiej. Bull. SFI, Gdynia, 2(135): 68­71.
10. Kuzancejev E.N. 1981 "Ryby Kaspijskogo morija" Moskva, Legkaja i pischevaja promyslennost.
11. Skóra K.E., Stolarski J. 1993 New fish species in the Gulf of Gdansk Neogobius sp [cf. Neogobius melanostomus (Pallas 1811), in: Notes Bulletin of the Sea Fisheries Institute 1(128): 83.
12. Skóra K.E., Stolarski J., 1993 "Neogobius melanostomus (Pallas 1811) a new immigrant species in the Baltic Sea" Proceedings of Second Estuary Symposium on Biology of Estuarine Species. Gdańsk, Poland Oct. 18­22 1993. AMBER (in press).
13. Skóra K.E., Stolarski J. 1994 "Neogobius melanostomus (Pallas 1811) ­ new fish in the Baltic Sea". Poster, communicat (abstrakt), The VIII European Congress of Ichthyology "Fishes and their environment". Sep 25­ Oct 2, 1994 Oviedo, Spain.
14. Skóra K.E., Stolarski J., 1995 "Round goby ­ a fishy invader" WWF Baltic Bulletin 1/95, :46­47.