Biologia, Bratislava, 60/2: 1—, 2005
1 Short communication
Recent record of the ship sturgeon Acipenser nudiventris in the middle Danube (Serbia) ´1, Ljiljana Budakov2, Vera Nikolic ´1 & Saša Maric ´1 Predrag Simonovic 1
Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia and Montenegro; e-mail:
[email protected] 2 Nature Protection Bureau of Serbia, Department Novi Sad, Radnička 20, 21000 Novi Sad, Serbia and Montenegro
Abstract: An old male ship sturgeon Acipenser nudiventris caught in the middle Danube River at the river km 1390 near Apatin, Serbia is the first reliable record of the species since 1989 in the whole river basin. Key words: Ship sturgeon, new record, Danube basin.
Introduction Prior to the building of the Djerdap (i.e., the Iron Gate) dam system in 1970s, ship sturgeon Acipenser nudiventris Lovetzky, 1828 migrated to spawn far upstream in the Slovakian section of the Danube River, e.g., at Komárno (river km 1766) and even Bratislava (river km 1869) (SOKOLOV & VASIL’EV, 1989; HENSEL & HOLČÍK, 1997). There are also records of occasional catches of the ship sturgeon in the Drava, Sava and Tisa rivers (SOKOLOV & VASIL’EV, ´ (1994) considered the ship stur1989). Recently, JANKOVIC ´ geon rare in the lower Danube of Serbia, and SIMONOVIC (2001) classified this species as endangered (EN) national status according to the IUCN (2003). The Serbian national fisheries legislation (Ministry for Natural Resources and Environment Protection of Serbia, 2003) therefore proscribes a total ban on ship sturgeon fishing in Serbia. The ship sturgeon has been considered extinct or very rare in Romanian Danube since 1960s (BACALBASA-DOBROVICI, 1997; UNEP/GRID-ARENDAL, 2003). It is considered critically endangered (CR) in Bulgaria (KARAPETKOVA et al., 1995), Hungary and Romania (IUCN, 1996). The most recently reported record of ship sturgeon in the middle Danube basin is that from the Drava River in 1989 (CITES Management Authority of Hungary, TRAFFIC Europe, 13 September, 2000). The most recent record of this rare and endangered sturgeon species in the middle section of the Danube River is reported in this brief paper.
Material and methods The length of fish, and mensural characters necessary for diagnostics of this species according to HOLČÍK et al. (1989) were taken using a measuring tape to the nearest millimetre, and the mass was measured using a fishmonger’s scale to the nearest kilogram. The photographs were taken using a Nikon Coolpix 4500 digital camera. The identification
was accomplished using the key for the genus Acipenser of ´ (2001). SOKOLOV & VASIL’EV (1989) and SIMONOVIC Results and discussion The male ship sturgeon Acipenser nudiventris (Fig. 1) was recorded in the Serbian/Croatian section of the Danube River in the early morning in the area of the city of Apatin (river km 1390) (Vojvodina Province, Serbia) on 31 October 2003. It was caught by commercial fishermen, using a bottom drifting gill net of mesh size 40 mm, of 1.80 m in depth and 50 m in length. The fish was of 1.76 m in standard length and of 56.2 kg in mass. The landing was reported on the same day to both the fisheries and nature protection authorities as a catch of young beluga. According to the national legislation (Ministry for Natural Resources and Environment Protection of the Republic of Serbia, 2003), the reported beluga had to be returned to the Danube as soon as possible, because it was smaller than the proscribed landing limit of 2.5 m standard length. On arrival at the landing site, the fish was found in excellent condition, housed in a small pool with oxygenation. The only noticeable mark on the body was one healing wound of about 3 cm in length on the rear part of the right flank. The fish was taken from the pool using a blanket wrap and laid on the ground for some quick photographs, and after 15 minutes it was released into the Danube River. The positive identification of the species was determined by the distinctive external morphological characters. The mouth gap was moderately wide and the lower lip was continuous (Fig. 2). The fringed barbels, half the distance between the upper lip and tip of the snout, barely reached the front edge of the upper lip, and were round in cross section (Fig. 2). The gill cover membranes were clearly separated by isthmus (Fig. 2) on the ventral side of the head. The head length was 24.1% of the total length (Tl ), the body depth H was 18.9% of Tl, the snout length s-m was 37.6% of the head length (lc) and the first barbel on the
2
Fig. 1. The male ship sturgeon Acipenser nudiventris Lovetzky, 1828 from the middle Danube in Serbia.
by Dr. R. SUCIU (pers. commun.), who reported that this record of ship sturgeon is the first competent, i.e., reliable identification of this species in last 30 years. The discovery of this old fish upstream of the two Djerdap dams indicates that the ship sturgeon is not yet ex˘ NA ˘ RESCU (1964) tinct in the Danube basin. Although BA and HOLČÍK (1995) stated that the non-migratory morph of the ship sturgeon occurs in the Danube, the occurrence of a wound on the flank indicates that this male passed the two Djerdap dams on the upstream migration in the autumn migration wave of 2003, since the cork-lifted hooking gears that most probably made the wound have not been used upstream of the Djerdap II Hydropower Plant dam at least for last 30 years. Acknowledgements Dr. R. SUCIU (Danube Delta Biosphere Research Institute, Tulcea, Romania) confirmed the identification.
References
Fig. 2. Ventral side of the head of ship sturgeon caught at middle Danube.
right side was 16.6% of lc. There were 56 scutes in the lateral row and 39 rays in the dorsal fin. The values for the head length lc and body depth H are greater compared to the values reported for the ship sturgeon from the Caspian Sea and for other characters they are within the expected variation range of the species (BORZENKO, 1950, in SOKOLOV & VASIL’EV, 1989). Weak rows of barely visible dorsal and ventral extensions, instead of true bony scutes, with their apices embedded below the skin, (Fig. 1) indicated that the fish is old. According to the age – length relationship (SOKOLOV & VASIL’EV, 1989), the released male is of age about 23+. The identification of the ship sturgeon was confirmed
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