Apr 28, 2007 - free migration route in the LDR. Locating the potential spawning sites along Danube. 1999-2000: The river shoreline areas between Galati (rkm ...
International Conference on Conservation, Recovery and Sustainable Use of Danube River Sturgeons 29th of March - 2nd of April 2011, TULCEA, ROMANIA
Contributions to Understanding the Spawning Ecology of Sturgeons in the Lower Danube River, Romania
Dalia Onără, Radu Suciu, Marian Paraschiv, Marian Iani, Daniela Holostenco, Elena Taflan Danube Delta National Institute, Tulcea, Romania
Sturgeon species of Lower Danube River:: Huso huso Acipenser gueldenstaedti A. stellatus A. ruthenus
Objectives : Elucidate timing of spawning of sturgeons in the Lower Danube River (LDR), Identify and confirm the natural spawning sites and establish protection measures in particular areas, Analyze antropic influence during the last century on timing / sites of spawning of beluga in the LDR.
Spawning habitats scattered over 863 km long free migration route in the LDR Locating the potential spawning sites along Danube 1999-2000: The river shoreline areas between Galati (rkm 150) and Turnu Măgurele (rkm 600) to determine the riverine substrate type and presence of sturgeon ELS (Kynard, Suciu & Horgan, 2002 ).
Galati
Ukraine St George
Romania Iron Gates Dam I Turnu Margurele
Iron Gates Dam II Rkm 594-599 r km 863
Serbia Bulgaria 500 km
Black Sea
Sampling sites on the Lower Danube River Vacareni, rkm 123
Chilla Br.
Galatz, rkm 150 Sulina Br. Isaccea rkm 100
Camp 1999
Tulcea rkm 70
St. George Br.
Camp 2004 YOY monitoring site (1999 - 2010 )
Harsova, rkm 238
Black Sea
Migratory fish monitoring Station - Isaccea Rocky Cliffs / Spawning Conditions Survey Drift Net Site for Early Life Stages
Red Rock, rkm 310
Oltenita rkm 430 100 km
Methods: D-Shaped Drift Net to capture ELS
Bottom-set, 6-m long, 0.4 m2 mouth, 2-mm mesh
Catching larvae in the River Fishing with drift nets set at 12 – 15 m depth in the Danube River, downstream of potential spawning sites, in years 1999, 2004, 2007, 2008 and 2010, we collected seven Acipenser / Huso larvae.
April 28, 2007 Danube River Km 310
The spawning success was assessed every year using a bottom drifting trammel net to capture YOY (90 x 1.8) m, 20mm mesh
Acoustic telemetry study of adult beluga sturgeons downstream post-spawning movement in the Danube River (Borcea branch - Nov. 2009 – May 2010)
Methods to estimate timing for capturing larvae:
•Danube water temperature and levels / discharge in Tulcea (1997 - 2010) & (1935 - 1965) •MS Excell / MS Office 2000 for plotting of graphs •Water temperature dependent duration of incubation, post-embrional and larval development taken from Ivanov (1987)
Day length [h, min]
Results:
12,45
370
13,13
13,44
14,09 14,12
15,01 15,02
14,39
15,2
25
19.05.1997
1997
20
310
* Graph : - water level - temperature - date of capture of ELS / YOY -back calculated time of hatching and spawning
10 r Km 310: 22 July / TL = 21 cm
190
20
1999
15
0
2000
28.04.2000
15
250
10 r Km 118: 12 July / TL = 23,5 - 29 cm
190
[cm]
370
2001
20 15
250
10
level in Tulcea
190 370
r Km 118: 26 June /–TL = 14,5
Anul
5
16 cm
2002
20
310
15
250 190 370
10 5
r Km 118: 19 June / TL = 14 – 19,3 cm
2003
20
310
15
250
10
r Km 118: 9 July / TL = 18 cm (hybrid)
190 370
5 2004
20
310
15
250
10
190 370
5
r Km 118: 22 June / TL = 11 cm
mean daily water level values
max.= 274cm / 2 May1935-1965 287cm / 2 May 1985-2005
310
250
2004
5
310
1935-1965
1985-2005
10
20
April
2003
20
310
130
2002
5
r Km 118: 30 June / TL = 14,5 – 17,5 cm
30
10
20
31
May
da te, location & TL (cm) of first YOY captu red by us in th at year capture of 10 da ys old belu ga larva e in ELS net ap ro x. hatching date o f larvae / YOY captured by us in tha t year ap ro x. spa wning da te o f paren ts of la rvae/ YOY captured by us in that year
Water temperature Suitability window (9 – 16,5 ºC)
370
190
8 7 6 5 4 3 2 1 0
10
190
Daily water
Multianual (1935 – 1965 & 1985 - 2005 ) Mean maximum water level in Tulcea
250
Daily mean water temperature [ºC]
310
Morun- Huso huso
2001
5
370
CPUE
2000
* Analysis :
15
250
Best spawning: close to 2 May
Spawning: 1) T > 9 º C 2) post-peak Lack of spawning : T
