STUDIU DE FEZABILITATE PENTRU SOLUŢII TEHNICE ALTERNATIVE/COMPLEMENTARE PRIVIND LUCRĂRILE CE SE VOR EXECUTA ÎN PUNCTUL CRITIC 01 BALA DIN CADRUL PROIECTULUI ÎMBUNĂTĂŢIREA CONDIŢIILOR DE NAVIGAŢIE PE DUNĂRE ÎNTRE CĂLĂRAŞI ŞI BRĂILA, KM 375 KM 175 WORKSHOP #2 Sturgeon Analysis Bucharest 1
A General Sturgeon Context B Sturgeon Analysis C Solutions 2
Chapter A General sturgeon context 3
A I General Sturgeon Context A1. General Sturgeon Context Sterlet Sturgeon Vulnerable Stellate Sturgeon Critically Endangered Russian Sturgeon Critically Endangered Beluga Sturgeon Critically Endangered 0 100 km Lower Danube is the only and last chance to natural reproduction of sturgeon in the region of the Black Sea 4
Chapter B Sturgeon Analysis 1. 2. 3. 4. Sturgeon Swimming Performances Bottom Flow Velocity Key questions: Can Sturgeons Pass the Sill? Sturgeons Habitats in Bala-Borcea System / Risks 5
B1. Sturgeon Swimming Performances 1 - Increased pressure drag 2 - Reduced thrust ability 3 Low routine metabolism limits the amount of energy available for high speed swimming and endurance Swimming performances classified 3 categories (Clay 1995): - Cruising speed: could be maintained > 200 minutes - Sustained speed: maintained between 20 seconds and 200 minutes Ok - Burst speed: maintained less than 20 seconds (anaerobic) CLAY, CH., 1995. Design of fishways and other fish facilities. Boca Raton: CRC Press. 248 p. 6
B1. Sturgeon Swimming Performances 120 cm 45 cm 15 cm According to Reinartz (2002) Peake et al (1996) Russian sturgeon 40 min at 0.95 m/s Stellate and Sterlet sturgeon 30 min at 0.95 m/s Stellate sturgeon 10 min at 1.1 m/s 2 minutes at 1.5 m/s speed before resting 7
B1. Sturgeon Swimming Performances 1.5 m/s (during 2 min before resting period) Bottom Flow 1.0 m/s Upstream Migration delta «effective» speed : 0.5 m/s 2 minutes swimm: 60 m upstream progression Bala Sill Bottom 0 B.S.C Level is more than 150 m long (precise length??) : 3 runs interrupted with resting periods needed to overcome Conclusion: Favourable Bottom Flow velocity < 1.5 m/s (closer to 1.0 is better) Threshold upper speed limit = 1.8 m/s 8
B1. Sturgeon Swimming Performances Detection experiments between August 2013 10th and 28th with tags 3m deep: - Establishing sturgeons swimming velocity - Testing detection range 9
B1. Sturgeon Swimming Performances Experiments not representative from field conditions during spawning migration: 1 Spawning migration in Spring means - higher discharge; - higher turbidity - lower detection range (150 m spring vs 420 m summer see Deak et al 2014) 2 Sturgeons stand deeper than 3 m (5-15 m) Intense monitoring design not fully adequate / reliable for spring conditions 10
B1. Sturgeon Swimming Performances On the whole presented area there are vortices which may hamper acoustic signals transmission. The vortices may appear due to hydrotechnical constructions, but also due to river bed with deep pits. (Deak et al 2014) Vortices (uncertain origin) are an aggravating factor vs signal detection efficiency Swimming speed estimation = not a key element 11
B2. Bottom Flow Velocity Key element for sturgeon migration and success to pass the sill all over the year Dark Zone 0 1 m over the bottom with ADCP Field Measurements upstream / over / downstream the sill needed Must wait the end of ongoing works to ease model confrontation Essential to know if bottom flow velocities are suitable or not to overcome the sill i.e. < 1.5 m/s (threshold 1.8 m/s) 12
B2. Bottom Flow Velocity 1 - Bala km 7.5 & km 9.5 do not correspond to the sill (Bala Km 10 10.5) 2 - Maximum flow velocity not representative from bottom flow conditions We can say with a high level of trust that Beluga sturgeon in this case, overcome by different methods (still unsolved) the stream speeds comprised between 2.2-2.5 m/s. Final conclusion extracted from the Synthesis Report (September 2013) Not suitable to conclude on Sturgeons ability to pass the sill 13
B3. Can Sturgeons Pass the Sill? Sturgeons monitoring studies start in Spring 2011 Works on Sill still in progress to reach the Bottom 0 B.S.C level stage Sturgeons catch and tag session in Spring and Autumn each year We have to transpose results from Sterlet and Stellate sturgeon? Handling time is very long High % of drop back behaviour (Kynard et al 2002) Loss of useful Potential data on sill overcoming 14
B3. Can Sturgeons Pass the Sill? Intense monitoring system of sturgeons in the critical point 01 area. Installed July August 2013 period Detection range is Spring: 150; Summer: 420 m Station Name and location River width (m) Station depth (m) Upper Borcea Km 69, left bank 140 3.9 Bala Branch Km 4, left bank 340 10.3 Borcea Branch Km 64, right bank 393 8.8 Old Danube Km 348, right bank 560 10.9 Old Danube Km 347, left bank 715 9.2 Bala Branch Km 7 310 10.2 Epuraşu 440 4.4 Old Danube Km 350, right bank 680 4.1 Old Danube Km 350, left bank 680 4.1 Old Danube Km 252 480 2.6 Borcea Branch Km 42 430 8.8 Borcea Branch Km 16.5 320 9.1 Caleia Branch, right bank 330 12.8 Cravia Branch, right bank 170 12.4 Danube Km 180.8 left bank 630 8.5 Danube Km 187 right bank 230 17 Danube Km 177.5 290 12.1 15
B3. Can Sturgeons Pass the Sill? Detection range is Spring: 150; Summer: 420 m Station with possible detection «blank zone» 16
B3. Can Sturgeons Pass the Sill? List of some sturgeons that have overcome the Bala sill 17
B3. Can Sturgeons Pass the Sill?, s i s the r o p Hy clea No ord rec is, s e oth ar p y H cle o N ord rec 18
B3. Can Sturgeons Pass the Sill? - 8 sturgeons (5 Beluga + 3 Stellate) overcome the sill between Nov 2011 May 2014-134 sturgeons (51 Beluga + 83 Stellate) tagged between Spring 2011 Autumn 2013 Approx 6 % success while sustainable populations need at least 70 % (80 %) of success among specimens who try to overcome the sill Q = 3840 Q = 5530 Bottom near velocity defavourable to Sturgeon migration Equal or over to the threshold upper limit (1.8 m/s ) According to all these elements: Bala bottom Sill = disrupting element for sturgeon migration 19
B4. Sturgeons Habitats and Risks - Fine sediments deposits Risks - Filling - Flow change 20
B4. Sturgeons Habitats and Risks Risks are hard to predict Risk related to Bottom sill vs risks related to complementary solution? Modelling needed on whole Bala-Borcea System + Old Danube Special focus on critical habitats areas New conditions = new habitats in Old Danube?? New conditions = Branch attractivity for migration?? 21
Chapter C Solutions 22
C. Sturgeon Analysis C1. Solutions (preliminary) Priority must be given to solution without impacts on sturgeons critical habitats and to solution preserving migration possibilities: - Avoid impacts as far as possible on habitats - Prevent migration disruption (Sill lowering / partial decommission?) - Reduce / mitigate impacts that can not being suppressed (adapt seasons of works or try alternative solutions.) - Compensate any significant remaining impacts by different solutions like the building of a fish pass or the creation of artificial spawning grounds, with all the technical difficulties it includes (Flow attractivity, discharge, size, slope.) - As far as possible, compensation (like fish pass) must be avoided and should be considered as the last solution to consider. The issues and opportunities related to sturgeons monitoring will be considered in the consortium monitoring program as part of the solution. 23
Thank You for your attention 24