N AT U R A M O N T E N E G R I N A, P o d g o r i c a , 1 0 ( 2 ) : 1 1 5 - 1 2 4 STATUS OF GOBIID ICHTHYOFAUNA (Gobiidae) IN BULGARIA: TAXONOMICAL, CONSERVATIVE, ECOLOGICAL AND SOCIAL ASPECTS Milen V A S S I L E V 1 , Apostolos A P O S T O L O U 1 , Boris V E L K O V 1 , Petya I V A N O V A 2 , Marina P A N A Y O T O V A 2 , Dobrin D O B R E V 1 , Luchezar PEHLIVANOV1 1 Institute of Biodiversity and Ecosystem Research, BAS, 2 Gagarin Str., 1113 Sofia, Bulgaria, E-mal: m.vv@abv.bg. 2 Institute of Oceanology, BAS, 40 Parvi May Str., P.O.Box 152, 9000 Varna, Bulgaria. SYNOPSIS Key words: Gobiidae, Ichthyofauna, Benthic Fish, Black Sea basin, Ponto-Caspian relicts, immigrants. At present the Bulgarian ichthyofauna includes 24 Gobiid species inhabiting the Black Sea, its rivers and coastal lakes, Danube River and its tributaries, rivers Maritsa and Tundzha (Aegean watershed). Six species live in the Bulgarian Danube section and its tributaries and 2 species are established in the Bulgarian sector of Maritsa River and its major tributary - Tundzha. The Black Sea Gobiid fauna is specific: fourteen species are brackish and freshwater autochthonous Ponto-Caspian relicts and 10 – Mediterranean immigrants. Seventeen species of conservation significance are enlisted in different national and international documents. Alterations in the spatial distribution of some species in Bulgarian waters occur recently. The main commercial target species from catches for the Bulgarian market has occurred to be Neogobius melanostomus. INTRODUCTION Globally, the Gobiid fish family (Gobiidae) includes more than 1500 species, which are grouped in 230 genera ( H OESE et al., 2006). They are mostly small-size fishes living in marine, brackish and fresh waters in temperate, subtropical and tropical areas. Most of them are demersal species inhabiting the coastal areas. Bulgarian Black Sea basin, according to S VETOVIDOV (1964) and M ILLER (2004), is inhabited with approximately 26-29 of Gobiid species. The most characteristic Natura Montenegrina 10(2) morphological feature of the family is the adhesion of the two ventral fins in one pelvic disc. Sexual dimorphism is present. During the breeding season, males build nest and take care of eggs during the incubation period. Their diet consists primarily of bottom invertebrates (crustaceans, molluscs, worms), eggs and small fish. In turn, Gobies represent a substantial food item for the bottom predators (sharks, rays, sturgeons, etc.) and also for dolphins ( S VETOVIDOV , 1964). Recently a significant increase of some Black Sea Gobiid species has been established, especially in the Lower and Middle Danube. Five species (Proterorhinus marmoratus, Neogobius gymnotracheilus, N. kessleri, N. melanostomus and N. fluviatilis) have expanded their areas westwards to the Upper Danube and some tributaries, in Serbian, Hungarian, Slovakian, Czech and even Austrian and German territory. N. melanostomus and Pr. marmoratus are distributed in even greater distance outside their original area – to the Aral and Baltic Seas and to the North American Great Lakes. In the North American Great Lakes, these two species have been acclimatized successfully and cause serious damages by finishing off or displacing the local fish fauna. In some regions the Gobies acquire even economic value after their invasion. In Europe the Gobies are of commercial significance for the countries continuous to the Black and Azov Seas. The official statistics for the fishing on Gobies in Bulgaria are incomplete and the total catches can be considered lower than the actual ones mainly because the catches of anglers and the spear fishermen, as well as a significant part of commercial catches, are not taken into account. Although Gobies are not of the most valuable fish species, in Bulgaria their catcheshave kept the second/third place during the last two decades. Studies on the Gobies in Bulgaria started with the development of the ichthyological science in the country, at the beginning of last century. They are mainly of faunistic and taxonomic nature and are associated with the names of following Bulgarian scientists: C HICHKOFF (1912), and D RENSKY (1923,1931). Untiill the 50’s it was known, that a total of 16 gobiid species was inhabiting Bulgarian Black Sea coast, coastal lakes and rivers and some inland rivers. Significant contribution to the study of species composition and their distribution along the Bulgarian Black Sea coast and coastal lakes was given by G HEORGIEV (1966). During the 60’s he reported 23 species for the Bulgarian ichthyofauna. This number and species composition was accurate until very recently. Other Bulgarian ichthyologists who contributed to the establishment of the gobiid species composition and some aspects of their biology in the Black Sea, Black Sea rivers and lakes, the Danube and its tributaries are: P ESHEV (1970), M ARINOV (1978), K ARAPETKOVA (1976), V ASSILEV & P EHLIVANOV (2005) and others. In the 90’s D OBROVOLOV & P INCHUK , (1993), D OBROVOLOV et al. (1995) used and developed genetic and biochemical methods to establish specific differences in this complex taxonomic group. The spatial distribution and 116 Vassilev et al: S T A T U S O F G O B I I D I C H T H Y O F A U N A ( G o b i i d a e ) I N B U L G A R I A . . . abundance of invasive gobiid species inhabiting the upper and middle Danube was rrecently studied by P OLAČIK et al. (2008). This investigation was aimed to establish the recent species composition of Gobies in the Bulgarian waters, commercial and recreational catches, and to specify their conservation status. MATERIAL AND METHODS Field studies were carried out from 2006 to 2010 covering various sites almost all along Bulgarian Black Sea coast: from Durankulak in north (43 o 41’55”N, 28 o 34’17”E) to Sinemorets in south (42 o 03’13”N, 27 o 59’15”E) at depths up to 15m and in inland waters: Danube and its tributaries, Black Sea Rivers and Rivers of the Aegean watershed. Fish were sampled mainly by different types of nets and spearfishing. In shallow wadable fresh water bodies portable electrofishing equipment is used for sampling as more appropriate. Moreover in coastal sea waters underwater direct species determination and underwater photos have been also accomplished. Bottom trawl survey was carried out at depths between 15 and 100 m. Altogether 24 hauls with duration of 90 minute each were accomplished in the investigated area. To establish the biomass index of N. melanostomus in front of the Bulgarian Black Sea coast a standard methodology for stratified sampling was employed ( G ULLAND , 1966; S PARRE & V ENEMA , 1998; S ABATELLA & F RANQUESA , 2004 ). A part of the material was fixed in 4% formaldehyde solution, 95% ethanol or frozen in -20 o C on dependance of the folowing analysis. The rest of the caught fish, after species identification and counting in situ, were released back in the water at the same place. Information has also been colected from local fishermen by questionairies and by direct observations of the local market. The taxonomic determination was accomplished according to G HEORGIEV (1966), M ILLER (2004), and V ASSIL ’ EVA (2007). RESULTS AND DISCUSSION Twenty four species of Gobies were identified inhabiting in whole variety of the studied marine, brackish and fresh waters on the territory of Bulgaria during the present study (Table 1). Two species (N. syrman, Chromogobius quadrivittatus) reported only once in the references ( G HEORGIEV , 1966) were not found in the present study. Their recent status is not entirely clear, since over the past 40 years their presence has not been confirmed again. Three new species for the Bulgarian ichthyofauna were found in the studied waters: N. eurycephalus, Pomatoschistus marmoratus and P. bathi. 117 Natura Montenegrina 10(2) According to our data the species N. platyrostris, reported by G HEORGIEV (1966), is not presented in Bulgarian waters. This species is typical for the North-Eastern part of Black Sea, and obviously it was reported in the past as a result of misidentification instead of N. cephalargoides. The same author ( G HEORGIEV , 1966) wrongly described also P. marmoratus as P. microps. The last one is known in the Atlantic Ocean but not in the East Mediterranean, including Black Sea ( M ILLER , 2004). Two groups of species were distinguished according their historical origin. The first group, including brackish and freshwater autochthonous Ponto-Caspian relict, is presented by 14 species and the second one including mediterranean immigrants by 10 species. The highest species richness was recorded in the Black Sea and adjacent inland waters (coastal lakes and some rivers inflowing directly into the sea). The Black Sea Gobiid fauna, which consists of 21 species, is quite specific. This complex includes originally freshwater, brackish and marine elements (Tab. 1). Gobiid fauna in the Bulgarian stretch of the Danube and its tributaries is presented by 6 freshwater and euryhaline species. Only two freshwater species are found in the Bulgarian sector of Maritsa River (Aegean Sea basin) and its major tributary – Tundzha River (N. fluviatilis and Pr. Marmoratus). Seventeen species of the established Bulgarian Gobiid fauna are of conservation significance according to different national and international documents. Seven species of that number are enlisted in the new Bulgarian Red Book (in press), 11 species - in the Black Sea Red Book (1999) and 8 are included in the IUCN Red List (Tab. 1). Three marine species of gobies (A. minuta, G. bucchichi, P. minutus) are considered rare in the near shore sea zone according to the results of the present study. A very rare species B. brauneri was reported previously only in Shabla Lake ( G HEORGIEV , 1966). It was not detected again over the past 40 years until July 2010, when a single specimen was caught in the Ezerets – a lake connected with the Shabla by an artificial channel. Another very rare species K. longecaudata was described in 1960’s only in the Beloslav Lake ( G HEORGIEV , 1966). The current investigation showed that recently this species inhabits all three coastal lakes located on the Northern Bulgarian Black Sea coast (north from the Kamchia River): Durankulak, Shabla-Ezerets and Beloslavsko (or Varna Lake). Results about Gobiid abundance and biomass, obtained from bottom trawl surveys in Bulgarian Black Sea area during the period 2006 - 2009, show presence of the following species in hauls: N. melanostomus, G. niger, M. batrachocephalus, G. cobitis and N. cephalargoides, distributed at depths between 15 and 100 m. The most abundant species in offshore areas are N. melanostomus and G. niger. Spatial distributions of these two species during a recent study in autumn-winter season of 118 Vassilev et al: S T A T U S O F G O B I I D I C H T H Y O F A U N A ( G o b i i d a e ) I N B U L G A R I A . . . 2009 show higher abundance of N.melanostomus at depths between 45 and 60 m in front of Kamchia River mouth and in Burgas Bay (Fig.1). Higher numbers of G. niger was observed in deeper areas – between 55 and 75 m off Varna, Burgas and Ahtopol. Table 1: Gobiid species composing the Bulgarian fish fauna. Habitat Species Origin Locality Type Conservation status Aphya minuta (Risso,1810) Mediterranean Black Sea Marine, pelagic Benthophiloides brauneri (Beling & Iljin, 1927) PontoCaspian Shabla/Ezerets Lake Freshwater, benthic BRB, BSRB, IUCN Benthophilus stellatus (Sauvage, 1874) PontoCaspian Danube Freshwater, benthic BRB Chromogobius quadrivittatus (Steindachner, 1863) Mediterranean Black Sea Marine, benthic BSRB Gobius bucchichi (Steindachner, 1870) Mediterranean Black Sea Marine, benthic BSRB Gobius cobitis (Pallas, 1814) Mediterranean Black Sea Marine, benthic BSRB Gobius niger (Linnaeus, 1758) Mediterranean Black Sea Marine, benthic - Gobius paganellus (Linnaeus, 1758) Mediterranean Black Sea Marine, benthic - Knipowitschia caucasica (Berg, 1916) PontoCaspian Black Sea Rivers Estuaries Brackish, benthic BRB Knipowitschia longecaudata (Kessler, 1877) PontoCaspian Coastal Lakes Brackish, BRB, BSRB Mesogobius batrachocephalus (Pallas, 1814) PontoCaspian Black Sea, Veleka River Eurihaline, benthic BSRB, IUCN Neogobius cephalargoides (Pinchuk, 1976) PontoCaspian Black Sea Brackish, benthic - Neogobius eurycephalus (Kessler, 1874) ‫٭‬ PontoCaspian Black Sea Brackish, benthic - 119 Natura Montenegrina 10(2) Neogobius fluviatilis (Pallas, 1814) PontoCaspian Black Sea Rivers, Danube and tributaries, Tundzha Eurihaline, benthic R., Black Sea IUCN Neogobius gymnotrachelus (Kessler, 1857) PontoCaspian Black Sea Rivers, Danube and tributaries, Freshwater, benthic IUCN Neogobius kessleri (Günther, 1861) PontoCaspian Danube and tributaries Freshwater, benthic BRB, IUCN Neogobius melanostomus (Pallas, 1814) PontoCaspian Black Sea, Black Sea Rivers, Danube and tributaries Eurihaline, benthic IUCN Neogobius platyrostris (Pallas, 1814) ‫٭٭‬ PontoCaspian Not inhabiting the Bulgarian coast Brackish, benthic Neogobius ratan (Nordmann, 1840) PontoCaspian Black Sea Brackish, benthic BRB, BSRB Neogobius syrman (Nordmann, 1840) PontoCaspian Mandra Coastal Lake Freshwater, benthic BRB, BSRB, IUCN Pomatoschistus bathi (Miller, 1982) ‫٭‬ Mediterranean Black Sea Marine, benthic - Pomatoschistus marmoratus (Risso, 1810) ‫٭‬ Mediterranean Black Sea Marine, benthic - Pomatoschistus microps (Krøyer, 1838) ‫٭٭‬ Mediterranean Not inhabiting the Bulgarian coast Marine, benthic - Pomatoschistus minutus (Pallas, 1770) Mediterranean Black Sea Marine, benthic BRB Proterorhinus marmoratus PontoCaspian Black Sea Rivers and Coastal lakes, Danube and tributaries, Maritsa and Tundzha R., Freshwater, benthic BSRB Zostericola ophiocephalus (Pallas, 1811) Mediterranean Black Sea Marine, benthic BSRB, IUCN BRB – Bulgarian Red Book, BSRB– Black Sea Red Book, IUCN – World’s Red Book; ‫ ٭‬new species for the Bulgarian ichthyofauna, ‫ ٭٭‬reported before, but recently not inhabiting Bulgarian water basins. Market observations in 2009 indicate that the commercial catch (accomplished with nets and lines) is divided into two groups: catch realized and not realized in the market. Both consist of the following species: G. cobitis, G.niger, M. batrachocephalus, N. cephalargoides, N. eurycephalus, and Z. ophiocephalus. In 120 Vassilev et al: S T A T U S O F G O B I I D I C H T H Y O F A U N A ( G o b i i d a e ) I N B U L G A R I A . . . view to their comparatively lower economic value and their availability, Gobiid catches are of social significance for the local societies. Figure 1: Distribution of N.melanostomus and G.niger in autumn-winter season of 2009. The target species for the Bulgarian fisheries is N. melanostomus. The biomass of round goby was estimated at 33.58 t for the areas between 15 and 100 m amounted at a surface of 8010 km 2 . This area is planimetric and does not take into account the bottom relief. Two well distinguished maximums in biomass index were observed in the areas in front of Kamchia River mouth and Burgas Bay at depths up to 50 m (Fig. 2). It is evident, that the main stock of N. melanostomus is situated in shallower areas up to 50 m. Observed high densities of Gobiid species in offshore areas are usually associated with availability of mussel beds, which form appropriate habitat with good food availability due to high biodiversity of different taxa. 121 Natura Montenegrina 10(2) Figure 2: Biomass Index of Neogobius melanostomus in autumn-winter season of 2009. CONCLUSION The established alterations in the species composing the Bulgarian Gobiid fauna result from contemporary changes in taxonomy on one side, and the more intensive investigations provided with modern methods in a wider area on the other. The human factor impacts rather the quantity of the commercial species, as well as the populations of some rare species. Protection of Gobiid habitat together with 122 Vassilev et al: S T A T U S O F G O B I I D I C H T H Y O F A U N A ( G o b i i d a e ) I N B U L G A R I A . . . sustainable use of their stocks are important issues related to the conservation and management of this valuable resource for the Bulgarian Black Sea region. AKNOWLEDGEMENTS The investigation and preparation of the manuscript was performed under the support of the project DO 02-201 funded by the National Research Fund to MEYS. REFERENCES: Black Sea Red Data Book (edited by H. J. D UMOND ) 1999. - United Nations Office for Project Services, New York, 413 pp. C HICHKOFF , G. 1912. Contribution l’etude de la faune de la Mer Noire. Animaux recoltes sur les cotes Bulgares. - Arcives de Zoologie experimental et general, Paris, 10: 39 pp. D OBROVOLOV I., P INCHUK V. 1993. Genetic divergence in Black Sea Goby fish group Ponticola, as evaluated by biochemical markers. - Vestnik Zooogii, 2: 58-63. [in Russian with English summary]. D OBROVOLOV I., G HEORGIEV Z., D OBROVOLOVA S. 1995. Comperative elctrophoretic investigations of the species of the family Gobiidae (Pisces) in the Bulgarian sector of the Black Sea. - Proceedings of the Research Institute of Fisheries and Oceanography, Varna, 23: 48-68. D RENSKY P. 1923. On the fauma of Black Sea. - Natural History and Geography, Sofia, 8(3): 87-93 [in Bulgarian]. D RENSKY P. 1931. To the knowledge of Bulgarian Black Sea ichthyofauna. - Agriculture Reports, Sofia, 12: 3-42 [in Bulgarian]. G HEORGIEV Z. 1966. Composition d’espèce et charactèristique des gobiidès (Pisces) en Bulgarie. - Proceedings of the Research Institute of Fisheries and Oceanography, Varna, 7: 159-227 [in Bulgarian with French summary]. G ULLAND J. 1966. Manual of sampling and statistical metods for fisheries biology. Part I: Sampling metods. - FAO Manuals in Fisheries Science, Rome, 3: 87pp. H OESE , D., B RAY D., R AXTON J., A LLEN G. 2006. Fishes. In: Beasley O. & A. Wells (Eds), Zoological Catalogue of Australia. - ABRS & CSIRO Publishing, Australia, Part 1, 24, 670 pp. K ARAPETKOVA M. 1976. Composition and characteristic of ichthyofauna in the Bulgarian Black Sea Rivers. - Hydrobiology, Sofia, BAS, 4: 52-59 [in Bulgarian with Russian and French summaries]. M ARINOV B. 1978. Ichthyofauna of the Bulgarian Danube River section and its economic importance- In: Limnology of the Bulgarian Danube River section. - Bulgarian Academy of Sciences, Sofia, 201-228 [in Bulgarian with Russian and German summaries]. 123 Natura Montenegrina 10(2) M ILLER P. 2004. (Editor.) The freshwater fishes of Europe. Freshwater Fishes of Europe, Gobiidae 2 (8/2), 477 pp. P ESHEV I. 1970. Ichthyofaunistical review of some rivers in the Eastern Bulgaria. Proceedings of the National Museum, Varna 5(20): 213-220 [in Bulgarian with French summary]. P OLAČIK M., T RICHKOVA T., J ANÁČ M,. V ASSILEV M., J URAJDA P. 2008. The Ichthyofauna of the Shoreline Zone in the Longitudinal Profile of the Danube River, Bulgaria. - Acta Zoologica Bulgarica, 60(1): 77-88. S ABATELLA E., R. F RANQUESA , 2004. Manual for fisheries sampling surveys: Methodologies for estimation of socio-economic indicators in the Mediterranean sea. General Fisheries Commission for the Mediterranean - Studies and Reviews, FAO Rome, 73: 38 pp. S PARRE P., S. C. V ENEMA , 1998. Introduction to tropical fish stock assessment. Part I: Manual. - FAO Fisheries Technical Paper, 306/1, rev.2, DANIDA, Rome FAO. 407p. S VETOVIDOV , A. N. 1964. Rîbî Chernogo Morya. [The fishes of the Black Sea]. Opred. Faune SSSR, Nauka Publishing, Moscow, 550 pp. [in Russian]. V ASSILEV M., P EHLIVANOV L. 2005. Checklist of Bulgarian fershwater fishes. - Acta Zoologica Bulgarica, 57 (2): 161-190. V ASSIL ’ EVA E. 2007. Fishes of the Black Sea. Key to marine, brakish-water, eurihaline and anadromous species with color illustrations collected by S. V. Bogorodsky. - VNIRO Publishing, Moscow, 238 pp. Received: 21 October 2010. 124