Preliminary Plan for Conservation of

Transcription

1 International Conference on Conservation, Recovery and Sustainable Use of Danube River Sturgeons Tulcea, March 3-31, 211 Preliminary Plan for Conservation of Sturgeon Populations in the Middle Danube Gábor Guti Danube Research Institute Hungarian Academy of Sciences Budapest

2 Historical sturgeon fishery 7-9 years ago, Paleolithic Age cent. fishery flourished Buda & Pest sturgeon fishing site 17 th century Husonum piscario Great sturgeon (Huso huso) sturgeon fishing site Danube Budapest d.s. 17th century (Marsigli) 2633 ind. within 3 years ( ), 77 ind. in one day at one site (1553)

3 Decline of sturgeon catch in Hungary 18th century. Regular sturgeon fishery ended in the Hungarian Danube section 2th century. anadromous sturgeon species are at risk of extinson ,192, ,198,199, ,1944,1953,1955,1956, ,1911,1912, ,1954,1957, , ind. in 1 years (2th cent.) Difference: 5-6 order of magnitude 77 ind. in one day at one site (1553) Paks, May 16, 1987

4 Occurrence of 3 sturgeon species in the 2th century Acipenser gueldenstaedti , , , , ind. 18 sites Dunakiliti,1999 Acipenser nudiventris ,1922, 1929,1932, ind. 18 sites 1989 Mohács Acipenser stellatus ?? (<195) ind. 6 sites 1965 Tiszajenı,

5 Occurrence of Acipenser ruthenus in Hungary from database of the Hungarian fish fauna annual catch (1 kg) országos kecsegefogás (t) összes kecsege fogás (kg) fogás max t median min. 5.5 t

6 Conservation measures Species are on verge of extinction High economic value caviar price: /kg Development of breeding and farming technologies Stocking actions are applied Popular events Efficiency for rehabilitation?

7 Main reasons of decline of sturgeon populations Overfishing Habitat degradation, fragmentation Population, decline of genetic integrity Regulation and control of fishery Decline Fromstarted secondin half theof 16th Started thecent. 2th incent. the 19th cent. Higher Introduction in the Middle of non-native Danube Typicalsturgeons problems High bynumber uncontrolled of fishing stocking sites change of bedload transport Hybridization bed incision intense sedimentation Fragmentation of migratory way Habitat protection, restoration, continuity Species and population conservation

8 Main reasons of decline of sturgeon populations Overfishing Habitat degradation, fragmentation Population, decline of genetic integrity Regulation and control of fishery Habitat protection, restoration, continuity Species and population conservation

9 Sturgeon conservation in consideration of holistic approach Fish fauna indicator of environmental changes 2 out of 522 of Europe s freshwater fish species are at risk for extinction 6% of riverine species are endagered Frequency of endangered fish sp. Frequency of extirpateded fish sp. Kottelat & Freyhof 27 Kottelat & Freyhof 27 frequency of endangered fish species is positively related to indicators of human activity - GDP, - population density, - percentage of urban area Sturgeons are best indicator of ecological integrity of the Danube Consider as flagship species in assessment of ecological status Develop a benchmarking system to complement biotic evaluations of the WFD

10 Social and economic benefits of large rivers Land use in floodplain Navigation way Domestic water Hydropower Industrial water Irrigation

11 Human activity decline ecological integrity of rivers interruption of lateral fragmentation of longitudinal connectivity channelization connectivity damming river bed incision increasing floodplain sedimentation pollution (eutrophication, pesticides, heavy metals ) invasion of non-native species

12 Sustaining of ecosystem integrity By recognition of human dependence on ecosystems (Millennium Ecosystem Assessment 25) Restoring ecological integrity policy goal Human population density restoring pristine state is impossible Integrative policy is needed with consideration: Degradation of ecosystems Economic needs of growing human population Social needs of human population What types of measures can provide sustainable ecosystem integrity, in the context of balancing social, economic and environmental needs?

13 Restoration strategy of large rivers (according to Jungwirth et al. 22) Status quo assessment Water management Flood protection Navigability improvement River engineering, Ecology Hydro-morphology Landscape, habitats Flora, fauna, EU WFD Status quo evaluation Assessment of ecosystem deficits Historical reference conditions Pre-regulation system, ecology Target vision Delineation environmental objectives Consideration existing constraints Restoration program Monitoring program Evaluation of restoration or rehabilitation measures Framework conditions Land use Water utilization Urban areas Legal aspects Water Framework Directive, FFH Directive,

14 Iron Gate Dam fragmentation of river system Insurmountable barrier to upstream turbines Generate high mortality of migratory fish to downstream direction - particularly for large adult fish

15 Iron Gate Dam Rehabilitation of longitudinal connectivity emphasized goal, high priority measure in significant action plans SAP - 25 DRBMP - ICPDR 26 8 m 3 m Ship lock as fish lock

16 Iron Gate Dam Prediction of impact of fish pass Historical catch of great sturgeon Are there any migrating specimens at the Iron Gate? High priority measure? Lower Danube has priority in conservation of anadromous species 16th century 2633 ind./3 year 18th century End of regular sturgeon fishery 2 order 18th century 25 ind./year 4 years before Iron Gate dam 193s 2 ind./1 year 193s 3 order >5 t/year 3 order

17 Estimation of impact of sterlet stocking in Hungary Artificial propagation was developed in the 197s and 198s Stocking of juveniles in the 198s (regular): Stocking in the 199s (became occasional): Stocking from 2 (regular): Stocking does not have significant impact on recruitment ind./year ind./year ind./year L (mm) growth tonna (Kovrižnych Sterlet ) catch age group influence of stocking can be estimated by population dynamical parameters 1 age distribution (Jankovic 1958) survival rate: S=.54 N = 1246 ind Data from Jankovic 1958 age group Etimated biomass of recruitment Stocking of 1. ind. juv. (L=1mm) protected species 1973 Cost of surplus: 12 /kg 1975 fishery size limit biomass: 175 kg yield: 35 kg (25-55) (M F =.2) kor (év) 1977 stocking Succes story?

18 Long-term seasonal water level fluctuation of the Danube at Budapest monthly average Nov Sze Júl Máj Már Jan seasonal water level fluctuation is a key factor of the fish production in the large lowland rivers

19 Long-term seasonal water level fluctuation and annual sterlet catch in the Hungarian section of the Danube ( ) Duna vízállás Bp. (cm) Water level Jan Feb Már Ápr Máj Jún Júl Aug Sze Okt Nov Dec Sterlet kecsege catch fogás (kg) (kg) - fishermen - halászat 1

20 Relationship between monthly water levels and annual catch analysed by cross-correlation ( ) Danube, fishermen: water level Jan./a.catch Danube, fishermen: water level Feb./a.catch Danube, fishermen: water level Mar./a.catch Correlation Correlation Correlation Correlation Danube, fishermen: water level Apr./a.catch Lag Danube, fishermen: water level Jul./a.catch Lag Danube, fishermen: water level Oct./a.catch Lag Lag Correlation Correlation Correlation Jan. Feb. Mar Lag Danube, fishermen: water level May/a.catch Apr. May Jun Lag Danube, fishermen: water level Aug./a.catch Jul. Aug. Sep. Correlation Lag Danube, fishermen: water level Nov./a.catch Oct. Nov. Dec Lag Correlation Correlation Correlation Correlation Danube, fishermen: water level Jun./a.catch Lag Danube, fishermen: water level Sep./a.catch Lag Lag Danube, fishermen: water level Dec./a.catch Lag sign. negative correlation annual catch monthly water lev. in previous 1-4 y. negative retarded effect of floods on sterlet catch reproductive succes depends on water level, incresing bed shear stress

21 Correlation: 5 year average of monthly mean water levels 5 year average of commercial catch 3 2,7 2,4 Carp Szigetköz ( ) R =,8684 catch of com. fishery (ton) 1,28 1,12,96,8,64,48,32 Sterlet Szigetköz ( ) R = -,779 catch of com. fishery (ton) 12,8 11,2 9,6 8 6,4 4,8 3,2 1,6 Barbel Szigetköz ( ) R = -, ,2 18,4 18,6 18, ,2 19,4 19,6 19,8 water level (m a.s.l.) catch of com. fishery (ton) 2,1 1,8 1,5 1,2,9,6,3 18,2 18,4 18,6 18, ,2 19,4 19,6 19,8 water level (m a.s.l.) 6,4 Pike Szigetköz ( ) R =,9557,16 18,2 18,4 18,6 18, ,2 19,4 19,6 19,8 water level (m a.s.l.) catch of com. fishery (ton) 5,6 4,8 4 3,2 2,4 1,6,8 18,2 18,4 18,6 18, ,2 19,4 19,6 19,8 water level (m a.s.l.)

22 Habitat degradation Szigetköz case study Anabranching system Historical spawning habitat Szigetköz floodplain 18th century 19 th century: River engineering navigation way, flood protection works 1992 Discharge diversion (85%), Hydrower station main arm (end 19 th c.) floodplain sidearms Gabčikovo hydroelectric power station (1992) bypass canal (end 2 th c.) Intense human modifications dike (end 19 th c.)

23 Sterlet catch - Szigetköz (195-25) Acipenser ruthenus 2 16 catch (kg) water quality improvement Sterlet spawning site Danube diversion Bagoméri side arm ( ) former spawning habitat aggradation sedimentation bed incision erosion 4. m 3 soft sediment accumulated in a 4 km long section sterlet important indicator of the habitat change

24 Improvement of habitats key element of rehabilitation Reliable information need to target vision localisation of key habitats - telemetry 2D and 3D hydraulics models Sonar image processing Description of local hydromorphological processes sand, silt gravel seepage Bedrock or impermeable material Delineation of environmental objectives for habitat restorations

25 EU Danube Region Strategy Improvement of habitat quality is relevant to EDRS EU Danube Black Sea Central Asia New opportunities for development of sectoral policies socio-economic development competitiveness environmental management modernisation of transport corridor Decline of biodiversity Alteration of natural ecosystem Environmental protection Sustainable utilization approach To achieve goal of sustainable utilization Need to investment in environmental research to identify new tools for improvement ecosystem integrity reduce human pressure on river ecosystem

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27 Principle of ecological restoration (according to Williams et al. 1997) increasing ecosystem function Replacement replaced function but not structure ecological husbandry restoration historic condition restored system rehabilitation existing condition degraded system degradation Replacement replaced structure but not function ecological gardening increasing ecosystem structure