FAO Regional Conference on River habitat restoration for inland fisheries in the DRB and adjacent Black Sea areas. 13-15 November 2018, Bucharest, Romania Habitats of sturgeons in the Lower River and the North Western Black Sea: status of knowledge and perspectives for restoration

Radu Suciu – DSTF and IAD Romania Marian Paraschiv, Marian Iani, Stefan Honţ – National Institute (DDNI) Tudor Ionescu – Lower Danube University Galați Content: Photo credits: Marian Paraschiv /DDNI

1. Sturgeons of the Danube River 2. Peculiarities and importance of riverine and marine habitats for the survival of sturgeons 3. Wintering habitats in the Black Sea and in the Lower Danube River (LDR) 4. Spawning habitats 5. Nursery habitats 6. Feeding habitats for juveniles, subadults and adults in the Black Sea 7. Impact of ongoing hydrotechnical works, for the improvement of conditions for navigation in the LDR, on sturgeon habitats 8. Restoration of longitudinal connectivity at Iron Gate dams to provide access to historical habitats 1. Sturgeons of the Danube River: historically 6 species; now only 5 species

Beluga Sturgeon

Stellate Sturgeon

Russian Sturgeon

Photo R. Suciu / DDNI Juveniles captured in the Black Sea coastal waters / Ciotica (Sept, 1995) Young of the year captured in the LDR at rKm 123 on June 16, 2005 Sterlet (Acipenser ruthenus)

Russian Sturgeon (A. gueldenstaedti)

Beluga Sturgeon (Huso huso)

Photo: R. Suciu /DDNI Adult Stellate sturgeon (Acipenser stellatus )

Russian sturgeon (A. gueldenstaedtii)

Young of the year (YOY) Sterlet (Acipenser ruthenus) Photo: Vasile Otel / DDNI The only sturgeon species left in the Middle and Upper Danube River (and some tributaries) Beluga sturgeon (Huso huso)

Photos by Marian Paraschiv / DDNI Tulcea Beluga sturgeon (Huso huso)

Beluga sturgeon female TW≈ 210 Kg TL = 2.95 m Location: Isaccea Hatchery of Kaviar House Ltd Isaccea Date: April 2006 Photo: Radu Suciu / DDNI Ship sturgeon (Acipenser nudiventris) possibly extinct in the LDR but survives in the MDR, and Mura Rivers (?)

Photo: Mikhail Cebanov Sturgeon Live GenBank of the Russian Federation Krasnodar (2001)

Photo: Marieta Suciu

Photo: Predrag Simonovic Serbia: Danube River Km 1390 - Apatin, Oct. 31, 2003

Donauinsel , BOKU Life Sterlet Project, 10 Sept. 2017 2. Peculiarities and importance of riverine and marine habitats for the survival of sturgeons

• All sturgeons are long-living freshwater fish adapted to live in deep water, on the bottom of rivers, i.e. they almost never swim at the surface of water; • many species adapted to feed as juveniles and adults in the sea; • all their life stages in the river and in the sea are bound to habitats located in deep water; • most sturgeons are lithophilic / hard substrate spawners, i.e. they lay their eggs on hard substrate and after hatching their free embryos hide in crevices; • some are litho-pelagophylic, i. e. they lay their eggs on hard substrate but their free embryos are pelagic; • all sturgeons are migratory fish, i.e. at sexual maturation they migrate in rivers to spawn on the same grounds were they were borne (phenomenon called homing); • blocking the access of adult sturgeons to their home ranges for spawning is causing severe declines of populations / declines of catches and even extinction; • the process of adaptation to other / new spawning sites is presumed to be possible but it may be hampered by the innate behavior / survival strategy of their early life stages. Case study: Damming the Danube River at Iron Gates

• 1974 – Iron Gates I / R Km 943

• 1984 – Iron Gates II / R Km 863 The impact of damming the Danube at Iron Gates H. husoCatches(1920 of beluga - 2005) sturgeon recorded in Romania during

1000 1920 - 2005

900

800

700

600

500 Iron Gates I

400 [tonnes] 300 Iron Gates II

200 No data 100 Year

0

1920 1922 1924 1926 1928 1930 1934 1938 1940 1942 1944 1946 1948 1950 1952 1956 1960 1962 1964 1966 1968 1970 1972 1974 1978 1982 1984 1986 1988 1990 1992 2000 2004 1932 1936 1954 1958 1976 1980 2002 3. Wintering habitats in the Black Sea and in the Lower Danube River

∆H = 12.5m

3D bathymetric survey

Borcea Branch Km 49 / “Devils Bend” Wintering site of adult Beluga sturgeons in the NW Black Sea, Karkinyt Bay

Karkinyt Bay As tracked by satellite transmitters MK 10 - PAT

Beluga male 95710 (70 Kg / 209 cm) 59 days

from Suciu et al. 2015 Wintering habitat at Km 7.7 on Danube branch Bala ΔH = 4 m

3D bathymetric survey

from Suciu et al. 2012 Grounds with hard substrate are found were the river meets rocky banks, 4. Spawning habitats which often deviate the current and cause counter currents / eddy

Spawning habitat for beluga and sterlet at RKm 100.5 / Noviodunum confirmed by capturing larvae in 2008, 2013, and 2015

Longitudinal section through the waiting site downstream of the spawning habitat at Noviodunum

3D bathymetric map of the spawning habitat for sturgeons atLDR Km 100.5 / Noviodunum (Isaccea) Location of potential spawning grounds - were the river meets rocky banks

1000 m Narrowing effect of rocky banks 750 m

Noviodunum, D Km 100.5

Red Rock, D Km 311

22 July 2000 Spawning habitat for beluga 21 Febr. 2017 and sterlet at RKm 311, “The Red Rock”, confirmed by capturing fertilized eggs and Medium water level larvae in 2004, 2007, and (27 May 2000) 2009 Photo: Marian Paraschiv / DDNI

Waiting place before spawning

Low water level (22 July 2000)

LDR Km 311

3 D bathymetric map and profile by Global Mapper v.13.00 Photos: Radu Suciu / DDNI Confirming spawning habitats by capturing larvae : Typical setup of floats at the anchor and the D-shaped drift net

Setting drift nets at water dept of 12m At D K 100.3 12 - 14 day old feeding larvae captured at: (16 Apr. 2015)

Sterlet (29. April 2009) Beluga sturgeon (13 May 2013) D Km 310.8 D Km 100.3 5. Nursery habitats Location can be demonstrated by capturing YOY sturgeons and extracting their stomach content

Feeding / nursery site for YOY sturgeons at Danube Km 309

Stomach content of YOY sterlets captured on nursery habitat at D Km 123 Nursery habitats are ideal locations to monitor annual recruitment from the wild Capturing YOY: Fishing gear: bottom drifting trammel net

YOY beluga of June 2013

Timing: June – July (5d / week) 6. Feeding habitats for juveniles, sub-adults and adults in the Black Sea

86.5 % of all YOY and juvenile sturgeons

captured during year 2012 in 10 marine areas of

theDanube Delta Biosphere Reserve were

captured in areas 8-SAHALIN and 7- ZATOANE Sahalin

Zatoane most important feeding habitats for young sturgeons on the Black Sea continental shelf in Romania

Holostenco et al. 2013 Feeding habitats for juveniles, sub-adults and adults in the Black Sea

Locations of feeding habitats in the NW Black Sea continental shelf were YOY and juvenile sturgeons (N = 1627) were captured during 2014 - 2016

Ionescu et al. 2017 Feeding habitats for adult Danube beluga sturgeon in the Black Sea Swimming depth of beluga male / ID 95719, during May – July 2009

Hunting for pray fish Depth Depth [m]

- 25m

Diving for pray

June July

Date

Beluga male ID 95710 (TW =70 Kg ; TL =209 cm)

from Suciu et al. 2015 7. Impact on sturgeon habitats of hydrotechnical works for the improvement of conditions for navigation in the LDR

• Blocking of main migration route: submerged sill constructed on the Bala arm km (2015)

• Siltation of wintering holes: St. George arm km 67; Bala arm Km 7.7 • Deepening or straightening the fairway by dredging is perceived by migrant sturgeons as unsafe / threatening: Saint George arm / 2003 • Moving the channel for navigation purposes can affect flow conditions on nearby spawning grounds

To avoid or reduce to the minimum the impact on sturgeon habitats the ongoing navigation project FAST DANUBE (D Km 375 - 862): - has conducted 3D bathymetric survey of all 12 critical points; - technical solutions for each critical point have been studied by 3D modelling; - is willing / keen to adopt solutions less impacting for sturgeon habitats.

DDNI Tulcea is providing assistance on assessment of potential habitat for sturgeon, including spawning, wintering and nursery habitats; currently CH2m / Halcrow is considering to prolong the duration of the survey to a whole year to allow completing the survey in all 12 critical point reaches of the river. Case study: The impact of cutting in year 1985 meanders of the St. George Danube branch on the wintering hole at Km 67 / Uzlina Survey of November 2000: • deep hole with abrupt front stair (Δ H≈7m) • very low water velocity (0.13 m/s) at 15.8m • in the LDR these holes are produced by the Coriolis Effect / Force • Survey repeated in January 2003 found the hole totally silted Two adult stellate sturgeons tagged by us in September with acoustic transmitters were captured there by angler / fishermen in late fall of 1999 (Kynard 2002) Case study: submerged sill on Bala arm Km 9

Bala arm, April 22, 2015

Start

Longitudinal depth profile [m] at the submerged sill, on Bala arm Km 9 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800

-5

-10 -10 Reduction of water depth by 8 m -10.5 -15 -14

-16.2 -15.8 -16.2 -15.9 -16.7 -17 -16.6 -18 -17.6 -20 -18.3 -18.6 -19 -19 -19.2 -18.9 -20 -20 -21 -21.2 -21.2 -22.5 -22.1 -23.3 -23 -23 -25 -23.9 -23.7 -25.5 -25.5 -25.3 -25.4 -26.1 -27 -27.7 -30 Water velocity survey on Bala arm: April 22, 2015

water Water Location velocity depth [m] [m/sec] 0.1 at the surface 1.22 4.5 1.22 10 1.14 13.5 near bottom 0.65

water Water Location velocity Second half of April – migration period of stellate sturgeons depth [m] [m/sec] Admissible maximum water velocity for medium size 0.1 at the surface 2.2 sturgeons (like the stellate sturgeon): 1.5 m/sec for 2 minutes 7.5 2.16 (Peake et al. 1997) 23 near bottom 1.72 8. Restoration of longitudinal connectivity at Iron Gate dams to provide access to historical habitats

• Completion in year 1974 of the Iron Gate I dam at R Km 943 (without any fish passage) has reduced by half essential spawning and rearing habitats for anadromous sturgeons in the Danube River; • This dam was followed by a second, Iron Gate II, completed in year 1984 at D Km 863; • In May 2011 FAO has organized a technical support expert mission (5) to the Iron Gates dams, in RO and SERB, which concluded that construction of fish passages at IG is possible; • In year 2014, on behalf of the EC, the EIB of Luxemburg commissioned DDNI Tulcea to conduct a preparatory study for a large scale fish behavior study at the Iron Gate dams; • In September 2018 EC -DG Regio has announced a grant to ICPDR Vienna, DDNI Tulcea and the Sinisa Stancovic Institute of to conduct the large scale fish behavior and hydraulic study needed for the feasibility study on fish passages at the Iron Gate dams. 3D bathymetric map d/s Iron Gate II HP dam at D Km 863 / March 2015

General bathymetric map of the LDR reach d/s Iron Gate II Romania HPP, with main characteristic water depth values (survey of DDNI, March 2, 2015)

Serbia

From Suciu et al. 2015 Case study: concentration of migratory fishes at Djerdap II dam

Serbian fishermen capturing > 100 nase (Chondrostoma nasus) in one 50 m long gillnet (24 Sept. 2015)

Photo: courtesy of Mirjana Lenhardt / IMSI Belgrade Thank you for your attention !

Novel Hydro – Fishlift receiving the Goldmedal of the German Federal Ministry of Environment / 2015

Operational on the Argen River in Allgäu / DE (ΔH=5m)

http://hydro-fischlift.de/funktionsprinzip-hydro-fischlift-de/