Sturgeon Research News and Publications Lower Danube River (Romania)
Dr. Radu Suciu
Head Sturgeon Research Group, Danube Delta National Institute (Tulcea);
Lecturer in Fish Genetic, Lower Danube University ( Galatz);
CITES S.A. for Acipenseriformes of ROMANIA.
Mail: Str. Babadag 165 Ro - 820 112 TULCEA Romania
Timing of natural spawning of Beluga Sturgeon (Huso huso)
In 2004, spawning timing of Great Sturgeon (H. huso ponticus) and Beluga Sturgeon were predicted from water level and temperature by SRG. In 2005, SRG staff will repeat the experiments to verify their findings.
In 2004, Beluga Sturgeon larvae drifting downstream of potential spawning site were captured (using a special D-frame bottom set of 6 m long, drift nets, with 0.4m 2 mouth openings and 2 mm mesh openings).
Observations of the last 7 years show that spawning of Beluga Sturgeon in the LDR systematically occurs 1 - 2 days after the water level has reached a peak when temperature is suitable, between 9 - 16 ºC.
ELS behavioural study
As part of the GEMS project, SRG / DDNI Tulcea is preparing to conduct the first ELS behavioural study in sturgeons of LDR (April - June 2005). It is expected that the results of the studies, conducted from 2005 - 2007, will enable improvement of monitoring of ELS and juveniles in the LDR.
SSG member Dr. Boyd Kynard (kynard@forwild.umass.edu), CAFC Turnners Falls MA, has provided essential support on logistics and equipment for this study, including: a professional video recorder and DAGE camera, digital weekly time switch, AC motor and SCR thyristor motor control as well as a submerged AC water pump. An endless oval channel, a vertical movement experimental column and illumination/substrate aquaria, constructed by SRG staff using methods developed by Kynard, Henyey & Horgan (2002), will be installed in the Isaccea Hatchery of Marilena & Dumitru Maereanu (mae.kav@xnet.ro) (Tulcea Branch of Kaviar House Ltd. Bucharest).
Fertilized eggs of Beluga Sturgeon (Huso huso) and/or Stellate Sturgeon (Acipenser stellatus) as well as water and electricity supply for the experiments will be provided by the hosting hatchery.
Marking & recapture of YOY (young of the year) Beluga Sturgeon (Huso huso)
Since the summer of 2000, from May - July SRG staff has been monitoring the downstream migration and abundance of young of the year (YOY) sturgeons at Danube River Km 118 (downstream of Reni, Ukraine) on an annual basis. A preliminary juvenile index was established. In June - July 2004 all 73 YOY Beluga Sturgeons captured with Floy Fingerling Tags were marked and their abundance and aggregation in space and time were evaluated (Paraschiv & Suciu, 2005, in Press). Marking and recapture will continue in 2005, enabling the group to gather valuable information to be used in the planing of activities at the future Monitoring Station (to be constructed at River Km 100 / Isaccea).
Recent SRG / DDNI Publications :
PARASCHIV M., SUCIU R. (2005) First results of marking and recapturing young of the year beluga sturgeons (Huso huso) in the lower Danube River. Scientific Annals of Danube Delta Institute, Tulcea, vol. 11 (in press)
ABSTRACT:
Marking and recapture was used for the first time to study timing of migration, abundance, aggregation and specific growth rate of young of the year (YOY) Beluga Sturgeons while moving downstream at Danube River Km 118. Recapture of 13 YOY tagged by fin clipping and Floy tags indicated strong group behaviour of juveniles. During June - July 2004, the maximum abundance of 3 successive groups of YOY was estimated at 46 individuals/4 ha x 12 hours, using the Jolly - Seber method. One YOY Beluga Sturgeon recaptured after 7 days had a specific growth rate of 8.57 % /day.
Key words: Huso huso, young of the year, mark & recapture, Floy fingerling tag, migration behaviour, Jolly - Seber method, abundance, specific growth rate.
Suciu R., Tudor D., Paraschiv M., Suciu M. (2005) Heavy metal bio-accumulation in tissues of sturgeon species of the lower Danube River, Romania. Scientific Annals of Danube Delta Institute, Tulcea, vol. 11 (in press)
ABSTRACT:
Bio-accumulation of heavy metals in tissues of sturgeons of the Western Black Sea and Lower Danube River (LDR) was examined in this study. Samples (of 10 - 30 g) of liver, muscle, fat, gonads and skin tissues were collected in October 2003 from 21 adult specimens of three sturgeon species: Acipenser stellatus (10), A. gueldenstaedti (2), and Huso huso (9) and analyzed for content in Cd, Cu, Zn, Pb, Mn, Fe and Ni, using VARIAN SpectraA 100. The highest concentrations of Zn, Cu and Cd were found in the liver and the smallest in muscles of sturgeons. The highest heavy metal content was detected in tissues of Stellate Sturgeon (Acipenser stellatus) , followed by Russian Sturgeon ( A. gueldenstaedti ). In all three species the Cd and Cu content of the liver surpasses the admitted limits for human consumption ( Cd - 0,1; Zn - 50; Cu - 5,0; Pb - 0,5 [mg/kg FWT] ). It is strongly recommended that human consumption of liver of sturgeons captured in the LDR be avoided.
In the case of Cd, a bio-accumulation phenomenon with growing age of fishes was visible. In all species males seem to accumulate more heavy metals in their tissues than females. This can be explained as an effect of more frequent spawning migration of males in the LDR, the major contamination source. Beluga Sturgeon showed less heavy metal bio-accumulation of tissues. According to classification of Wachs (1998) it was concluded that within the ecological index, the LDR and the Black Sea near the mouth of the river are mostly classified as waters medium (II - III) to highly (IV) contaminated with heavy metals.
Next page > Photo Gallery
