PRESENT AND PERSPECTIVES OF STURGEON CONSERVATION IN THE LOWER DANUBE RIVER, ROMANIA

Transcription

1 PRESENT AND PERSPECTIVES OF STURGEON CONSERVATION IN THE LOWER DANUBE RIVER, ROMANIA Suciu R. *, Knight C.M.**, Onara D.F*., Paraschiv M.*, Taflan E.*, Iani M.*, Holostenco D.* * Sturgeon Research Group /Danube Delta National Institute (DDNI), Tulcea, Romania **Norwegian Institute of Water Research (NIVA), Oslo, Norway

2 Outline: Why conservation measures? Goals of conservation and recovery program Conservation regulation of May 2006 Preserving genetic diversity First recaptures and post stocking evaluation News on ongoing projects Discussions Perspectives

3 Why conservation measures? :10 years of intensive and uncontrolled fishing (Navodaru et. al. 1999) stellate sturgeon severely suppressed Russian and beluga sturgeon - relict status facing extinction by Alee effect (Alee 1931) Arguments: - decline of catches - disrupted age class structure - poor / lacking natural recruitment - Option to recover: build up of stocks by hatchery production and return brood stock to home system (Cowx 1999)

4 Example of Alee effect: Recession and extinction of European sturgeon (Acipenser sturio) from rivers of Western Europe Catches of European sturgeon in the Lower Elbe River during (Kinzelbach, 1997). Note that extinction occurred during only 10 years ( )

5 Decreasing of catches: A. güldenstädti ( ) Catches of Danube sturgeon recorded in Romania during [tons] Year

6 Decreasing of catches: H. huso ( ) Catches of beluga sturgeon recorded in Romania during [tone] Iron Gates I Iron Gates II No data Anul

7 Decreasing of catches: A. stellatus ( ) Catches of stellate sturgeon recorded in Romania during [tons] Under-reporting of catches Year

8 Sturgeon catches in Romania ( ) [Kg] Sturgeon landings - Romania tons 29 tons Beluga sturgeon Danube Sturgeon Stellate sturgeon Total [Kg] 17 tons 11 tons Year

9 Methods: (1) Age determination Pectoral bony fin rays collected by professional fishermen cross-sections

10 Age class structure ( ): frequ. [% (N captured = 344; N sampled = 137) Stellate sturgeon males (2003) A Age [years] Freq. [%] ( N landed = 29; N sampled = 12 ) Russian sturgeons / mixed sexes (2003) Age [years] B frequ. % (N landed = 97; N sampled = 25) beluga sturgeons / mixed sexes (2003) C Freq. [%] ( N landed = 62; N sample = 22) beluga sturgeons females (2004) D Age [years] Age [years] stellate sturgeon (A) cohort consists mainly of first time spawners (6 8 years old) Russian sturgeon (B) and beluga sturgeon (C&D) clearly lack first time spawners

11 (2)Catching larvae in the River Fishing with drift nets set at m depth in the Danube River, downstream of potential spawning sites, in years 1999, 2004, 2007 and 2008, we collected six Acipenser (?) / Huso (?) larvae (Paraschiv et al. 2007). April 28, 2007 Danube River Km 310

12 Identification of larvae captured in the Lower Danube River ( ) (Onara 2008) using cytochrome b region of mt DNA cut with MseI) May 2, 2008 May 20-21, 2004 May 29, 1999 Apr. 28, A d u l t s L a r v a e bp stellatus güldenstädti ruthenus huso R e f e r e n c e s a m p l e s

13 Methods: (3) Bottom drifting trammel net to capture YOY (90 x 1.8) m, 20 mm mesh size

14 Natural recruitment in the Lower Danube River ( ) Juvenile index (Paraschiv et al. 2007) CPUE Beluga sturgeon- Huso huso CPUE Stellate sturgeon - Acipenser stellatus Year Year CPUE Russian sturgeon - Acipenser gueldenstaedti CPUE Sterlet - Acipenser ruthenus Year Year

15 Conservation regulation of May 2006 joint Ministerial Order (May 4, 2006): - conservation of wild sturgeon populations / stocks - development of sturgeon aquaculture in Romania allows only the capture of brood fish from the wild (special authorization) for artificial propagation: - supportive stocking of the Danube River -development of sturgeon aquaculture use non-destructive artificial propagation procedures release PIT tagged wild brood fish back in the Danube River Migratory Fish Monitoring Station (Isaccea, Danube River km 100)

16 Goals of the conservation and sustainable use program (Suciu et al. 2007) Prevent population extinction Preserve genetic diversity of populations / stocks Rebuild natural age class structure by implementing of Supportive Stocking Program (SSP) Restore natural recruitment Develop sturgeon aquaculture to lower market pressure on wild populations / stocks

17 Structure of Supportive Stocking Program: catch and PIT tag of wild brood stock in limited number of sites (2) and time ( ) use minimum effective annual number of brood fish apply non-destructive artificial propagation procedure apply fertilization scheme to maximize genetic variability release all spent brood fish back in the Danube River grow offspring separately in families to a TL 15 cm tag all young sturgeons individually using CWT stock young sturgeons close to catch sites of brood fish monitor survival in the DR and the Black Sea costal waters conduct post stocking evaluation

18 Capturing of wild adult sturgeons (Suciu et al. 2007) Fishing of live wild adult sturgeons permitted only in two locations: * Km (downstream of Grindu) * Km (on the Borcea branch) Ukraine Fishing sites - surveyed day and night by the Fishery Inspection to: prevent illegal catch PIT tag the fish Iron Gates I (1974) Serbia Romania Iron Gates II (1984) Danube River Bulgaria Tulcea Give a chance to all other sturgeons to spawn naturally in the river. Black Sea

19 Catching and tagging wild adult sturgeons All brood-fish captured live and immediately PIT tagged, transported to hatcheries - kept in covered concrete tanks. All PIT serial numbers recorded - data base at NAFA Romania. Clip fins were sampled for later DNA analysis in DDNI lab.

20 Preserving genetic diversity: (i) minimal effective number of brood fish + multiple male fertilizing Ovulation - induced using Nerestin - synthetic product with soft action - avoids over maturation of brood fish. Eggs - obtained by stripping after a minor internal incision in the ovarian duct Sperm was extracted with a silicon tube attached to syringes - kept on ice for multiple male fertilization

21 YOY grown in families and tagged individually - CWT (Paraschiv et al. 2008) Tags injected alternatively in right /left pectoral fin (2005 / 2006)

22 Stocking the Danube River artificially produced young sturgeons - stocked close to locations where their parents were captured data base with CWT serial numbers of young sturgeons stocked from each family was established at DDNI and NAFA Romania.

23 Preserving genetic diversity: (ii) Releasing of wild brood fish after artificial propagation 172 wild sturgeons - captured in year 2007 for SSP: 16 beluga sturgeons; 5 - Danube sturgeons 88 stellate sturgeons; 60 - sterlets After artificial propagation 169 released back in the Danube River

24 Preserving genetic diversity: (iii) cryopreservation of sperm (Suciu et al. 2008) - to enable multiple male fertilisation in species lacking brood fish (A. güldenstädti) cryopreservation of sperm was applied for the first time in May 2007 at Isaccea hatchery -Sturgeon sperm bank - 24 ml of high quality sperm from: 2 stellate sturgeons 1 sterlet 2 Russian sturgeons

25 Preserving genetic diversity: (iv) preserve rare genotypes (Onara et al. 2007) RFLP of mtdna regions ND 5/6 and Cyt b A. stellatus brood fish having rare ND 5/6 (II - VI) and Cyt b (II - III) haplotypes migrate in the Danube in early spring Their spawning grounds are more distant from the sea and therefore were historically more vulnerable to the fishery To preserve the genetic diversity of A. stellatus rare mtdna genotypes should be used in SSP separately

26 YOY stocked into the Danube River ( ) Year Huso huso A. gueldenstaedti A. stellatus [No. of specimens] Mean [No. of specimens] Mean [No. of specimens] Mean TW [g] TW [g] TW [g] Ø Total Cost of SSP: 1 million / year Duration of SSP: Until full restoration of natural recruitment and rebuilding of natural age class structure but NOT longer than 10 years

27 Survival of tagged juveniles During experimental fishing to monitor natural recruitment, in June Sept 2007 seven CWT tagged stellate sturgeons were captured at Danube R. Km 119 and 100. Each fish had CWT tags in their left pectoral fin, showing that they were tagged and released in December 2006 on the Borcea branch ( Km 39).

28 First post stocking evaluation (June - Sept 2007) June 5, Danube Km 119 Average TL of stellate sturgeon at release (Dec. 2006): 17 cm Average TL of stellate sturgeon recaptured after: 6 month 37.75cm 8 month cm i.e. growth rates of cm / month Average annual growth rate recoded in white sturgeons stocked in the Kootenai River was 6.4 cm / year (Ireland 2002)

29 Discussion: Weaknesses of SSP: in some years stocking delayed due to difficult public acquisition process of young sturgeons (improved in 2009) lack of involvement of local fishermen communities survival evaluation survey still missing fall migrants still not propagated separately Difficulties: in some years insufficient number of brood fish of Russian sturgeon deficient enforcement of regulations (3 governments in just 3years) illegal fishing / poaching of sturgeons still present Monitoring Center Isaccea of DDBRA still not operational

30 Ongoing projects: Best Combat (RO & NO) Satellite telemetry May 2009 for the first time on the Danube River and in Europe

31 Satellite telemetry Argos satellite - first locations of tagged beluga in the Black Sea / 75d Chilia delta St. George / 65d

32 DIDSON camera First Dual Frequency Identification Sonar (DIDSON - 75,000) in Romania & lower Danube River Dan Ericson / USA Kate Hawley / NIVA- No DIDSON Marian Iani / DDNI - Ro viewing large fish in deep & turbid water / Danube River

33 Acoustic telemetry (Oct. Nov. 2009)

34 Perspectives: Assist NAFA to improve regulation enforcement ( ): (i) involving local fishermen communities; (ii) include in long-term contracts with private hatcheries guarding of fishing sites Improving SSP ( ): (i) propagate fall migrants separately; (ii) avoid late stocking during the year BestCombat project ( ): (i) present and ancient genetic diversity in beluga sturgeon - microsatellite and mtdna genes; (ii) location of essential spawning and wintering habitats in the river using up to date acoustic telemetry and DIDSON camera; (iii) finalizing survey of movements and distribution in the sea using satellite transmitters. JOP Black Sea ( ): All Black Sea survey (CWT) of survival and distribution of young sturgeons stocked in the Danube River ( ) (TR, BG, RO, UA & GE)

35 Acknowledgments: Research funded by projects: DanStur (348,000 / ) project 120 / CEEX Programme - Romanian Research Agency BestCombat (1.234 million / ) project / Norwegian Cooperation Programme for Bulgaria and Romania (85%) and Romanian Ministry of Environment (15%) The authors are grateful to Marilena & Dumitru Maereanu and to Robert Raduta for providing the fish and logistical assistance for the satellite telemetry and to Fishermen Association Fetesti for assistance in capturing beluga sturgeons for acoustic telemetry

36 THANK YOU VERY MUCH FOR YOUR ATTENTION!