The decline of Danube sturgeons is clearly documented by the rapidly decreasing catches in the last decades, and any delay of actions is highly detrimental for their survival: In Bulgaria, total annual catches fell from 63,5 t in the 1940s to 25,3 t in 1995-2002, in Romania from app. 1144 t in 1940 to less than 8 t in 1995. More information on the 6 Danube sturgeon species:
Beluga (Huso huso)
There is no research data on the Beluga populations in the Danube, only fragmented data from catches and CITES quotas until 2007. Percentage of used fishing quota in Romania is 85 % in 2002, 84 % in 2003, 46 % in 2004 and 34 % in 2005, meaning that catches declined by 50% in a 3-year period, which is one of the most rapid species population declines ever noted in nature. In 2006, Beluga fishing was banned in the Romanian Danube. In Bulgaria, Beluga fishing was legal until 2012 (with 1-year fishing bans enforced in 2007 and 2011).
IUCN Red List category: critically endangered - A2bcd - ver 3.1; population trend: declining.
Stellate Sturgeon (Acipenser stellatus)
Currently only one natural Stellate Sturgeon population exists in the Black Sea basin. The individuals migrate only along Danube river, where they are subject to overexploitation. Registered is a dramatic decline in the numbers of this species – 72.5 % for a 4-year period (2002-2005) in the Romanian Danube. For Bulgaria data is: 14,1 t in 1940, 1,7 t in 1995-2002 (Vassilev & Pehlivanov, 2003). Research with marked Stellate Sturgeons shows that 100% of marked and released individuals were caught within a few months proving significant overexploitation of this species (Kynard et al., 2002).
IUCN Red List status: critically endangered A2cde ver 3.1; population trend: declining
Russian Sturgeon (Acipenser gueldenstaedtii)
The species with highest numbers in the Danube in the past, now almost extinct, with no reliable data on numbers. Fishing data for the Danube is: in 2002 - 3726 kg; in 2003 - 1499 kg; in 2004 - 440 kg; in 2005 - 37 kg, showing 99 % decline in 4 years only (Paraschiv et al. 2006). Research on Lower Danube larvae of Russian Sturgeons shows over 90% decline in numbers (Suciu 2008, pers. comm.; Paraschiv et al. 2006; Knight et al. 2010). Vassilev & Pehlivanov (2003) present fishing data of 16.5 t in 1940, with decline to 2,6 t in 1995-2002
IUCN Red List category: critically endangered A2bcde ver 3.1; population trend: declining.
Sterlet (Acipenser ruthenus)
The smallest sturgeon species, which does not migrate to Black Sea. Statistics data is not reliable as all catchment books list smaller sturgeon specimen as Sterlet. There is only one more comprehensive research between 1958 and 1981, with catching data varying between 117 t in 1963 and 36 t in 1979 (CITES 2000). This is the only sturgeon species with a more stable population and research shows that in Romania, Hungary and Serbia above Iron Gate there are reasonable numbers of reproducing individuals (Paraschiv et al. 2006; Knight et al. 2010). There is no data though about the species status in the Bulgarian-Romanian section of the Danube below Iron Gate.
IUCN Red List category: Vulnerable A2cde ver 3.1; Population trend: declining.
Ship Sturgeon (Acipenser nudiventris)
Extinct from Lower Danube. Three male specimen were caught in Middle Danube above Iron Gate after 2000, indicating the existence of a small population which does not migrate due to migration route interruption by Iron Gate dam.
Atlantic Sturgeon (Acipenser sturio)
Extinct from Danube and Black Sea. The only natural population is at the French Atlantic coast.
WWF DCP Bulgaria is part of the global WWF network and works since 1998 to promote the conservation, restoration and sustainable management of natural resources of two of the world’s 200 most valuable ecological regions, Danube River basin and Carpathian Mountains. We run 5 main conservation programmes – Freshwater; Forests; Natura 2000 and Protected Areas; Green Public Funds, and Climate Change. We work on the national level through policy, advocacy, awareness raising, fostering stakeholder dialogue, education, training, capacity building and communications; as well as on the local level through model activities in our main program region – Bulgarian Danube river basin (Danube islands and river bank, selected Danube tributaries, Persina, Rusenski Lom and Balgarka Nature Parks). We engage with media and business partners and run national information campaigns to raise public awareness and generate public support for nature conservation issues.
As part of the Danube Carpathian Program, we contributed to the Action Plan for the conservation of sturgeons in the Danube River Basin. Work on sturgeons is a priority in our Freshwater program. As stated in the executive summary, this small grant would be complementary to our current project “Conservation of sturgeons and improving their status in Bulgaria through implementation of activities from the National Action plan on Sturgeons in the Bulgarian Aquatories of Danube River and Black Sea” (Envi OP Sturgeon project). Implementation period is January 2012 – February 2014, specific objectives are improvement of available scientific information (key habitats, spawning grounds) as a basis for design of efficient protection measures (protection of key sites, etc.); strengthening of Danube sturgeon populations through direct conservation measures (restocking), improvement of stakeholder capacity to limit negative human impact and illegal activities – work with authorities, local communities and scientists. Specific project activities include:
1. Review and improvement of the national legislation related to sturgeon conservation. Recommendations for revision of the Sturgeon Action Plan.
2. Field research of sturgeon habitats, identification of sturgeon spawning grounds along the Bulgarian Danube, ensure their effective protection.
3. Strengthening the Danube sturgeon population through restocking (breeding, marking and release) with sturgeons of Danube origin – release of at least 50,000 individuals. Preparation of methodology and program for future restocking with sturgeons of Danube origin from fish-farms
4. Preparation of tri-lateral (BG-RO-SER) management measures to ensure conservation and reproduction of sturgeons in the Danube river basin
5. Joint activities with stakeholders (authorities, scientists, local communities), involvement of authorities in main activities of project (field work, work with local communities). Forming of 2 advisory councils to the project – scientific (with participation of international experts) and inster-institutional.
6. Creation of electronic database and online portal on sturgeon – all available documentation, legislation, scientific data, analyses, reports, studies, maps, etc will be collected and uploaded there along with main project results.
This CMS small grants proposal aims to complement our Envi OP Sturgeon project by providing funding for the necessary tagging equipment (tag injector, tag detector and reading device) to mark and monitor at least 50.000 restocked sturgeons by a unified methodology for the Lower Danube. The tagging and monitoring will be done in coordination with Romanian colleagues from the Danube Delta National Institute, using their recognized longtime experience in this field.
Marking sturgeons is specific due their small size at the time that marking is usually feasible or desirable, their large size when data recovery is required, and the long period between tagging and mark recovery. The CWT method has proven to be most feasible. The Coded Wire Tag (CWT) is a small length of stainless steel wire 0.25 mm in diameter and typically about 1.1 mm in length. Double length tags are also used in some circumstances. The tag is coded with a series of factory-etched decimal numbers, which allow identification of the spool of wire (typically 10,000 tags) from which it was. The tag is cut, magnetized and implanted into suitable tissue with a Handheld Multishot Injector. Tag sites that have been used in sturgeon include the cartilage of the snout, beneath one of the dorsal or lateral scutes, within pectoral fin rays, or in the bases of the fins.
The tag is detected in live fish using magnetic detection devices like T- Wand Detector .The tag must be recovered from the fish for code identification. The tag is then “read” under a low-power microscope (20 to 40 x magnification), like MagniViewer.
The other activities, such as research, monitoring, breeding and restocking, tri-lateral measures, stakeholder networking and involvement, online database are provided for by our Envi OP Sturgeon project.
In our sturgeon work we are supported by and partner with the Ministry of Environment and Water and the Executive Fisheries Agency, and we network with the Customs Agency, scientific institutions, NGOs and the Danube Sturgeon Task Force. These stakeholders are encompassed by the above mentioned project.