THE KEY THREATS TO STURGEONS AND MEASURES FOR THEIR PROTECTION IN THE LOWER DANUBE REGION

Transcription

1 THE KEY THREATS TO STURGEONS AND MEASURES FOR THEIR PROTECTION IN THE LOWER DANUBE REGION MIRJANA LENHARDT * Institute for Biological Research, Serbia IVAN JARIĆ, GORČIN CVIJANOVIĆ AND MARIJA SMEDEREVAC-LALIĆ Center for Multidisciplinary Studies, Serbia Abstract The six native sturgeon species have been commercially harvested in the Danube Basin for more than 2,000 years, with rapid decrease in catch by mid 19th century. Additional negative effect on sturgeon populations in the Danube River was river regulation in Djerdap region, due to navigation in the late 19th century, as well as dam construction in the second half of 20th century that blocked sturgeon spawning migrations. Beside overtion in Lower Danube Region countries) and pollution all pose serious threats on sturgeon fishing and habitat loss, illegal trade, life history characteristics of sturgeon, lack of effective management (due to lack of transboundary cooperation and change in political situapopulations in Lower Danube Region. International measures established by the Convention on International Trade in Endangered Species (CITES) in late 20th century, listing of beluga (Huso huso) as an endangered species under the U.S. Endangered Species Act, as well as development of Action plan for conservation of sturgeons in the Danube River Basin, had significant impact on activities related to sturgeon protection at beginning of 21st century. These actions were aimed towards diminishment of pressure on natural sturgeon populations and aquaculture development in countries of Lower Danube Region. The main goal of the Action Plan was to raise public awareness and to create a common framework for implementation of urgent measures. Black Sea Sturgeon Management Action Group (BSSMAG) was founded as a consultative body to improve transboundary cooperation among countries in Lower Danube Region. Nevertheless, more actions are necessary in the field of basic scientific investigation, NGO involvement and better connection among all stakeholders. Everyone involved in sturgeon protection must be aware that the sturgeon recovery, as well as their extinction, is a multi-decadal affair, especially for species with * Mirjana Lenhardt, Institute for Biological Research, Despota Stefana 142, Belgrade, Serbia; lenhardt@ibiss.bg.ac.yu V. Lagutov (ed.), Rescue of Sturgeon Species in the Ural River Basin. Springer Science + Business Media B.V

2 88 M. LENHARDT ET AL. long life and late maturing like beluga. Resource users and other stakeholders must be patient enough to support recovery plans, which will allow only small-scaled sturgeon fisheries, or even fisheries that will be performed by some future generations. Keywords: Acipenseriformes, CITES, aquaculture, beluga, over-fishing Introduction For biologists, sturgeons are a group that has been extant for a quarter of a billion years, while for the public they are prized exhibits in aquaria and, of course, the source of caviar (Bemis and Findeis 1994). In spite the fact that many sturgeon species have outlived the dinosaurs and survived two Ice ages, nowadays they are on the verge of extinction, due to river regulation, dam building, pollution and market demand for their meat and well prized caviar. Sturgeons, with 27 existing species, have some characteristics that distinguish them from teleost fish and make them unique. While modern teleosts may have lost the ability to synthesize ascorbic acid since the late Triassic, sturgeon can produce ascorbic acid in the kidney (Moreau and Dabrowski 2000). Sturgeon fish sperm possess acrosin-like activity (loss in teleost fish) that shares many properties with mammalian acrosin and has some unique properties that may represent adaptations of this enzyme to the environment of external fertilization (Ciereszko et al. 1996). Sturgeons have a unique gastrointestinal tract, because the pyloric stomach wall is hypertrophied to a gizzard-like organ (Hung and Deng 2002). Bearing previous in mind, sturgeon protection is very important for biological and genetic diversity salvation. Decline in sturgeon catch Historically, five acipenserid species migrated from the Black Sea into the Danube River: beluga (Huso huso), Russian sturgeon (Acipenser gueldenstaedtii), stellate sturgeon (A. stellatus), ship sturgeon (A. nudiventris) and Atlantic sturgeon (A. sturio) (Bacalbasa-Dobrovici 1997). The freshwater sterlet (A. ruthenus) once thrived in the Danube and its tributaries. Presently, only three anadromous species occur in the Danube: H. huso, A. gueldenstaedtii and A. stellatus. Atlantic sturgeon nowadays occurs only along the Eastern coast of the Black Sea, in the area adjacent to the Inguri and Rhioni Rivers in Georgia (Bacalbasa-Dobrovici and Holcik

3 STURGEON PROTECTION IN LOWER DANUBE ). Specimens of ship sturgeon are rarely recorded, with the latest finding at 1,401 rkm of Danube (Simonovic et al. 2005), while A. ruthenus is still present in the Danube River basin. Inhabitants of the Greek colonies in the area noted the catch of sturgeon in the Lower Danube River, in 5th and 6th century B.C. By the beginning of the 16th century sturgeon catch decreased in the Middle Danube River, and in the 18th century fishing of migratory sturgeons in the Austrian stretch of the Danube River was completely abandoned. In 19th century, over-fishing and river modification became main reasons for decrease in sturgeon population, with water pollution becoming one of the most important factors in 20th century (Nikcevic et al. 2004). Sturgeon resources in the Danube River have been over-exploited since the early 1900s. Since ancient time, navigation through Djerdap sector was not safe during low water levels, due to underwater rocks that emerged from the water. Modifications of this part of river flow lasted since 1890 to 1896, and even then it became partial barrier for sturgeon upstream migrations (Petrovic 1998). But the most drastic decline of capture followed the construction of the dam (Patriche et al. 1999; Lenhardt et al. 2004a). Huge anthropogenic influence, expressed through river bottom modification, over-fishing, dam construction and pollution, lead to decrease of fish catch in Lower Danube countries. The sturgeon catches have decreased dramatically in Romania, from 1,144 t in 1940 to less than 8 t in 1995, while Ukraine catch decreased from t in 1952 to lack of catch record since 1994 (Navodaru et al. 1999). Romania was the second world major exporter of caviar, after the former Soviet Union (Patriche et al. 1999). According to data on total sturgeon catch in the Bulgarian part of the Danube River, for the period , it varied between 9.1 t and 72.4 t (Vassilev and Pehlivanov 2003). Yugoslavia catch declined from 38.5 t in 1975 to 5.2 t in 1986 (Stamenkovic 1991). Based on catch statistics for Serbian part of the Danube River, during the period , predicted extinction of Russian sturgeon was estimated to fall around the middle of this century, and of beluga approximately at middle of this millennium (Lenhardt et al. 2006d). Activities related to sturgeon protection Principal reasons that triggered action for diminishment of pressure on sturgeon natural populations and shifted attention to aquaculture were significant decrease of sturgeon species catch, political changes that took place in Lower Danube countries during the last decade of 20th century, inclusion of all sturgeon species in CITES Annexes on April 1, 1998, as

4 90 M. LENHARDT ET AL. well as United States Department of the Interior, Fish and Wildlife Service declaration (U.S. Fish and Wildlife Service 2005) on trade suspensions for Black Sea basin beluga (Huso huso) caviar and meat. CITES Quotas for sturgeon species were established since Figure 1 shows quotas for beluga, Russian sturgeon and stellate sturgeon (total for Ukraine, Romania, Bulgaria and Serbia) for period, with visible fall of quotas for all three species. In 2006 Romania declared ban on sturgeon fisheries for the following ten years. In 2007, there were no prescribed quotas for sturgeon fisheries in Black Sea basin. Figure 1. CITES catch quotas for beluga, Russian sturgeon and stellate sturgeon of the N-W Black Sea and the Lower Danube River (total quota for Ukraine, Romania, Bulgaria and Serbia) CITES, in cooperation with member countries governments, faciltitates organization of meetings for both scientists and governmental representatives. One of the meetings resulted in establishment of Black Sea Sturgeon Management Action Group (BSSMAG) consultative body of sturgeon range countries. It was formed in October 2001, during the First Regional CITES Meeting on Sustainable Management of Black Sea Sturgeons, held in Sofia, Bulgaria.

5 STURGEON PROTECTION IN LOWER DANUBE 91 Regional Strategy for the Conservation and Sustainable Management of Sturgeon Populations of the N-W Black Sea and Lower Danube River in accordance with CITES ( activities-romania2.html) was established in accordance with Resolution Conf Representatives of the Fisheries and CITES Management Authorities of N-W Black Sea and Lower Danube River countries (Bulgaria, Romania, Serbia and Ukraine) met in Tulcea, November 2003 and agreed on the Regional Strategy. The strategic goals are: improvement of knowledge on biological features of the sturgeon species, development and application of standardized assessment of all existing sturgeon species, protection of important habitats, insight in genetic structure and proper methods of artificial spawning for restocking and reintroduction, monitoring of fishery load compared to the potentials of sturgeon populations, development of stock assessment system for different sturgeon species, improvement of national legislation and ensuring enforcement mechanisms, adaptive management of sturgeon species, development of sturgeon aquaculture, development of cooperation and promotional programs for sturgeon protection and inclusion of economic and social components. Scientific research Since drastic decreases of stocks were observed in the Danube River, there is increasing demand for specific knowledge about biology and ecology of the various sturgeon species. It is surprising that there is still a significant lack of knowledge regarding species identification, migration behavior and natural reproduction (Reinartz et al. 2003). At the end of 20th and beginning of 21st century started international funding for sturgeon related projects and consequently publication of scientific papers (Finn et al. 2003; Kolarevic et al. 2004; Lenhardt et al. 2005a). International projects, related to location of essential sturgeon habitats in the Danube River and their genetic structure, were so far conducted in Romania. Research was also focused on specific species, such as stellate sturgeon (Ceapa et al. 2002a, b; Vecsei et al. 2007), beluga (Vecsei et al. 2002; Vassilev 2003), sterlet (Lahnsteiner et al. 2004; Lenhardt et al. 2004b). The impact of industrial, agricultural and domestic wastewater discharge on sterlet populations was also investigated (Lenhardt et al. 2004c; Stanic et al. 2004). Development of Action plans was also initiated (Lenhardt et al. 2005b).

6 92 M. LENHARDT ET AL. Aquaculture Private enterprises in Romania, Bulgaria and Serbia began development of sturgeon hatcheries and rearing facilities. Quotas for export of sturgeon species produced in aquaculture have increased in last two years. Nevertheless, aquaculture development can also have negative effects. Hatcheries have long been proposed as a means to sustain and restore sturgeon population, but beside the risk of inbreeding, there is also a lack of adequate understanding of artificial rearing influence on behavoiur after their release (Secor et al. 2002). However, the new trend of emerging private sturgeon hatcheries may add more problems than provide solutions, especially with respect to the intentional, incidental or accidental release or escape of exotic species, such as the accidental escape of North-American paddlefish (Polyodon spathula) from ponds into the Danube River (Lenhardt et al. 2006a, b; Simonovic et al. 2006). NGO International Association for Danube Research The International Association for Danube Research (IAD), as a nongovernmental organization that celebrated 50 years since foundation, had significant impact on Danube sturgeon species protection. As a result of its activities, IAD published a book that deals with biology and state of sturgeon species and their protection in the Danube River (Reinartz 2002). Also, former IAD president dr Jürg Bloesch initiated development of the Action Plan for the Conservation of the Sturgeons (Acipenseridae) in the Danube River Basin (Action plan 2006). Part of the IAD 2006 Congress was dedicated to sturgeon species in the Danube River (Guti 2006; Lenhardt et al. 2006c; Paraschiv and Suciu 2006; Bloesch 2006). Internet presentations In order to enable better availability of information related to sturgeon protection issues, a number of Internet presentations was developed: Sturgeons of Romania and CITES ( rosturgeons/ index1e.htm) and Sturgeons in Serbia ( However, there is a constant need for continuus input of new data.

7 STURGEON PROTECTION IN LOWER DANUBE 93 Activities that could resolve problems There is an emerging atmosphere for cooperation of all interested parties. On the other hand, there is still a lack of nongovernmental sector involvement and public awareness. Cross-sectoral cooperation is still undeveloped, especially regarding problem of fish passes which requires involvement of electrical industry and hydro-engineers. Figure 2. Flow chart presenting who makes impact on wild sturgeon populations Mutual work of all interested parties would be best to organize through projects which would, beside biological component, also include socioeconomic component. Application for project funding is currently available at the GEF (related to biodiversity), or for FP7 projects that refer to fishery, aquaculture or Water Framework Directive (WFD). In every Lower Danube Region country it is also possible to work in accordance with ideas from WFD. One of the ideas in the WFD is that there should be full recovery of costs for water services. The water users should pay what the use of water costs (Berge and Dahl-Hansen 2005). In that sense, all who impact sturgeon populations (Figure 2) could pay for sturgeon recovery in Danube.

8 94 M. LENHARDT ET AL. References Action plan, 2006, Action plan for the conservation of sturgeons (Acipenseridae) in the Danube River basin, Nat Environ 144, Council of Europe. Bacalbasa-Dobrovici, N., 1997, Endangered migratory sturgeons of the lower Danube River and its delta, Environ Biol Fish 48: Bacalbasa-Dobrovici, N., and Holcik, J., 2000, Distribution of Acipenser sturio L., 1758 in the Black Sea and its watershad, Bol Inst Esp Oceanogr 16(14): Bemis, W. E., and Findeis, E. K., 1994, The sturgeon s plight, Nature 370:602. Berge, D., and Dahl-Hansen, G., 2005, Management of freshwater fisheries on bordering rivers; EU-regulations in the field of water and fish management, NIVA report SNO , ISBN Bloesch, J., 2006, The ultimate need for implementation of sturgeon protection in the Danube River a view of 2006 and call for actions with the sturgeon Action Plan under Bern Convention, Proceedings of the 36th International Conference of IAD, Austrian Committee Danube Research/IAD, Vienna, pp Ceapa, C., Williot, P., and Bacalbasa-Dobrovici, N., 2002a, Present state and perspective of stellate sturgeon brood fish in the Romanian part of the Danube, Int Rev Hydrobiol 87: Ceapa, C., Williot, P., Le Menn, F., and Davail-Cuisset, B., 2002b, Plasma sex steroids and vitellogenin levels in stellate sturgeon (Acipenser stellatus Pallas) during spawning migration in the Danube River, J Appl Ichthyol 18: Ciereszko, A., Dabrowski, K., and Ochkur, S. I., 1996, Characetrization of acrosin-like activity of lake sturgeon (Acipenser fulvescens) spermatozoa, Mol Reprod Dev 45: Finn, R. N., Lenhardt, M., Ferrara, A., Isely, J. J., Dean, J., and Fyhn, H. J., 2003, Yolk proteins and free amino acids in Acipenseriformes, Proceedings of the 26th Annual Larval Fish Conference, Bergen, July 2002, Norway. Guti, G., 2006, Past and present status of sturgeons in Hungary, Proceedings of the 36th International Conference of IAD, Austrian Committee Danube Research/IAD, Vienna, pp Hung, S. S. O., and Deng, D. F., 2002, Sturgeon, Acipenser spp. In: Nutrient requirement and feeding of finfish for aquaculture, C. D. Webster, and C. Lim, eds., CAB International, pp Kolarevic, J., Lenhardt, M., Cakic, P., and Jaric, I., 2004, Population study of the Danube sterlet (Acipenser ruthenus L.). In: Otterstad, releasing development potentials at the Eastern Adriatic, O. Oddmund, ed., NTNU; Lahnsteiner, F., Berger, B., Horvath, A., and Urbanyi, B., 2004, Studies on the semen biology and sperm cryopreservation in the sterlet, Acipenser ruthenus L., Aquac Res 35: Lenhardt, M., Cakic, P., and Kolarevic, J., 2004a, Influence of the HEPS Djerdap I and Djerdap II dam construction on catch of economically important fish species in the Danube River, Ecohydrol Hydrobiol 4: Lenhardt, M., Cakic, P., Kolarevic, J., Mickovic, B., and Nikcevic, M., 2004b, Changes in sterlet (Acipenser ruthenus L.) catch and length frequency distribution in the Serbian part of the Danube River during the twentieth century, Ecohydro Hydrobiol 4: Lenhardt, M., Kolarevic, J., Jaric, I., Cvijanovic, G., Mickovic, B., Gacic, Z., Cakic, P., and Nikcevic, M., 2004c, Assessment concepts for river ecosystems characterization based on sterlet (Acipenser ruthenus L.) population research, Proceedings of the Fifth International Symposium on Ecohydraulics Aquatic habitats: analysis & restoration, Madrid, September, pp Lenhardt, M., Finn, R. N., Cakic, P., Kolarevic, J., Krpo-Cetkovic, J., Radovic, I., and Fyhn, H. J., 2005a, Analysis of the post-vitellogenic oocytes of three species of Danubian Acipenseridae, Belg J Zool 135(2): Lenhardt, M., Hegedis, A., and Jaric, I., 2005b, Action plan for sturgeon management in fishery waters of Republic Serbia, Institute for Biological research, Belgrade, pp AQ: Please provide publisher location.

9 STURGEON PROTECTION IN LOWER DANUBE 95 Lenhardt, M., Bloesch, J., Reinartz, R., Suciu, R., Ivanova, P., Guti, G., Pannonhalmi, M., and Tsekov, A., 2006a, The actual situation of the endangered sturgeons in the Danube River Basin, Danube News 13 14: Lenhardt, M., Hegediš, A., Mićković, B., Višnjić-Jeftić, Ž., Smederevac, M., Jarić, I., Cvijanović, G., and Gačić, Z., 2006b, First record of the North American paddlefish (Polyodon spathula Walbaum, 1792) in the Serbian part of the Danube River. Arch Biol Sci 58(3):27P 28P. Lenhardt, M, Jaric, I., Bojovic, D., Cvijanovic, G., and Gacic, Z., 2006c, Past and current status of sturgeon in the serbian part of the Danube River, Proceedings of the 36th International Conference of IAD, Austrian Committee Danube Research/IAD, Vienna, pp Lenhardt, M., Jaric, I., Kalauzi, A., and Cvijanovic, G., 2006d, Assessment of extinction risk and reasons for decline in sturgeon, Biodivers Conserv 15: Moreau, R., and Dabrowski, K., 2000, Biosynthesis of ascorbic acid by extant actinopterygians, J Fish Biol 57: Navodaru, I., Staras, M., and Banks, R., 1999, Management of the sturgeon stocks of the Lower Danube River system. In: The Delta s: State-of-art protection and management, Conference Proceedings, Tulcea, Romania July 1999, pp Nikcevic, M., Lenhardt, M., Cakic, P., Mickovic, B., Kolarevic, J., and Jaric, I., 2004, Historical review and new initiatives for sturgeon fisheries, aquaculture and caviar production in Serbia and Montenegro. In: Otterstad, releasing development potentials at the Eastern Adriatic, O. Oddmund, ed., NTNU; Paraschiv, M., and Suciu, R., 2006, Present state of sturgeon stocks in the Lower Danube River, Romania, a review, Proceedings of the 36th International Conference of IAD, Austrian Committee Danube Research/IAD, Vienna, pp Patriche, N., Pecheanu, C., and Billard, R., 1999, Sturgeon fisheries, caviar production in Romania and possible measures of rehabilitation in the Lower Danube, Rivista Italiana di Acquacultura 34: Petrovic, M., 1998, Ribarstvo [Fisheries], Zavod za udzbenike i nastavna sredstva, Belgrade [In Serbian]. Reinartz, R., 2002, Sturgeons in the Danube River, International Association for Danube Research, Vienna. Reinartz, R., Bloesch, J., Ring, T., and Stein, H., 2003, Sturgeon are more than caviar: A plea for the revival of sturgeons in the Danube River (Literature review), Arch Hydrobiol 14(Suppl Large Rivers 3 4): Secor, D. H., Anders, P. J., Winkle, W. V., and Dixon, D. A., 2002, Can we study sturgeons to extinction? What we do and don t know about the conservation of North American sturgeons, American Fisheries Society Symposium 28, pp Simonovic, P., Budakov, L. J., Maric, S., and Nikolic, V., 2005, Recent record on ship sturgeon Acipenser nudiventris in the middle Danube (Serbia), Biologia 60(2): Simonovic, P., Maric, S., and Nikolic, V., 2006, Occurence of paddlefish Polyodon spathula (Walbaum, 1792) in the serbian part of the lower River Danube, Aquatic Invasions 1(3): Stanic, B., Andric, N., Zoric, S., Grubor-Lajsic, G., and Kovacevic, R., 2004, Biochemical response of sterlet Acipenser ruthenus collected from the River Danube, Proceedings of the 35th International Conference of IAD, IAD, Vienna, pp Stamenkovic, S., 1991, Evolution des captures de troits especes d esturgeons Huso huso, Acipenser gueldenstaedtii, et Acipenser stellatus dans la partie Yougoslave du Danube. In: Acipenser, P. Williot, ed., Cemagref Publications, Bordeaux, pp U.S. Fish and Wildlife Service, 2005, Endangered and threatened wildlife and plants; special rule to control the trade of threatened beluga sturgeon (Huso huso), Federal Register 70(42): Vassilev, M., 2003, Spawning sites of beluga sturgeon (Huso huso L.) located along the Bulgarian- Romanian Danube stretch, Acta Zool Bulg 55(2): Vassilev, M., and Pehlivanov, L., 2003, Structural Changes of Sturgeon Catches in the Bulgarian Danube Section, Acta Zool Bulg 55: AQ: Please confirm if publisher name and location are correct.

10 96 M. LENHARDT ET AL. Vecsei, P., Sucui, R., and Peterson, D., 2002, Threatened fishes of the world: Huso huso (Linnaeus, 1758) (Acipenseridae), Environ Biol Fish 65: Vecsei, P., Peterson, D., Suciu, R., and Artyukhin, E., 2007, Threatened fishes of the world, Acipenser stellatus, Pallas, 1771 (Acipenseridae), Environ Biol Fish 78(3):