Historical Distribution, current Situation and future Potential of Sturgeons in Austrian Rivers Thomas Friedrich Supervisor: O.Univ.Prof. Dr.phil. Mathias Jungwirth 812.084 Masterseminar BOKU - University of Natural Resources and Applied Life Sciences Institute of Hydrobiology and Aquatic Ecosystem Management Vienna, Austria Contents - Current situation and objective - Method - Historical distribution, current situation and potential in Salzach & Inn system Danube in upper Austria Danube in lower Austria Thaya & March system other tributaries Drava Mur - Summary - Conclusions & open questions 2 Current situation and objective - Very little existing knowledge about actual historic distribution of various sturgeon species in Austrian waters. - The last remaining sturgeon species in Austria is highly endangered. - Increased stocking and catch reports of native and non-native sturgeon species in recent years. - Further intensification of sturgeon aquaculture will increase this trend. - Successrate of stocking is unknown. - Little knowledge about habitat use in Austrian rivers. Objective: A synopsis containing as much available data about sturgeons in Austria as possible 3 Method - Analysis of historical texts, catch reports and sturgeon preparates of the NHM - Search for recent reports of sturgeon catches and stocking through fishing shops, governmental institutions, fishing magazines, internet platforms, private fish ecologists, fishermen and scientific organizations - Determination of species and origin of stocked/caught fish in the various catchments - Interpretation of gained data 4 Inn & Salzach Historic records - Reports of catches from A. ruthenus (1890 - 1952) in the Inn upstream to Rosenheim (MAIER, 1908; MARGREITER, 1927; FISCHER, 1952; BROD 1980; STREIBL). - A catch of A. gueldenstaedtii is reported for the area around Ering in the year 1746 (BROD, 1980). - Around the year 1800 there are records for a specimen of H. huso near Reichersberg (FREUDLSPERGER, 1936). - A. ruthenus is claimed by some authors to occur rarely in the Salzach (AIGNER, 1859; PEYRER, 1874), while others say it occured often (FREUDLSPERGER, 1936). There is one reported catch in the area around Laufen (SIEBOLD, 1863). - One reported catch of H. huso around Tittmonig and one questionable catch of A. gueldenstaedtii in the same area (FREUDLSPERGER, 1936; HOCHLEITHNER, 1996; RATSCHAN & SCHMALL, 2011). 5 Inn & Salzach Stocking & Catch Inn above PP Stammham Inn below PP Stammham Mouth of Salzach A. transmontanus 2002 1 2003 1 A. baerii 2004 2 A. gueldenstaedtii 2004 1 species unknown 2003/2004 2 6 Inn & Salzach Potential 14,2km 12,6km 13km 44 + 14,3km 16,4km - The lower Inn has many powerplants and is therefore very smallfragmented. - Rhithralization through hydromorphological changes in the Salzach downstream of Laufen. - All recent catches occured in the most upstream section of the Inn. 7 Danube Historic records - A. nudiventris was said migrate up to Komorn and to only seldom enter the Austrian Danube (FITZINGER & HECKEL, 1836). There is a reported catch near Vienna in the year 1936 (ZAUNER, 1997) and another catch near Regensburg, Bavaria (F & H, 1836), however the exact species of this specimen remains doubtful (SIEBOLD, 1863). - A. gueldenstaedtii is reported as rare in the Austrian Danube, the farthest upstream record being a specimen near Regensburg 1679 (F & H, 1836). - A. stellatus seems to have been the rarest sturgeon species in Austria (F & H, 1836; MOHR, 1952). SIEBOLD (1863) mentions the only record of the species in Bavaria in the Isar. 8 Danube Historic records - A. ruthenus is stated as frequent in the lower Austrian Danube (F & H, 1836) with many catches near Vienna 1831 – 1960. In upper Austria and Bavaria some authors claim that it was a common species (F & H, 1836; HECKEL & KNER, 1857; KINZELBACH, 1994) while others say it was rare (LORI, 1871; KERSCHNER, 1956). Reports from catches range up to Ulm, the earliest record being in 1430 (F & H, 1836; SIEBOLD, 1863; JÄCKEL, 1864; KERSCHNER, 1956; WACHA, 1956; KINZELBACH, 1994; STREIBL). - H. huso was said to be rare in the Austrian Danube by F & H (1836), however they point out that there were plenty of them in the middle ages. GAMLITSCHEK (1897) mentions catches near Tulln, other reports of single specimen come from Straubing in 1692 (F & H, 1836) and Vilshofen in 1605 (WACHA, 1956). 9 Danube upper Austria Stocking & Catch Aschach Ottensheim Abwinden-Asten Wallsee-Mitterkirchen Ybbs-Persenbeug A. gueldenstaedtii 1996 unknown qty. 1984 1 1997 4 2002 3 2005 1 A. ruthenus 2006 4 2007 4 2008 2 2011 8 unknown 1 hybrid 2003 1 2006/07 5 1999 1 A. baerii 2006/07 1 1993 1 Polyodon spathula 2003 1 2002 1 species unknown 2010 1 2011 1 1 10 Danube upper Austria Stocking & Catch 11 Danube upper Austria Potential 27 + 4km 26,9 + 3,2km 15,7km 23,5 + 3,1km 40,1km 33,8km - The impoundment Aschach is the home of the only self-sustaining population of A. ruthenus in Austria, with most catches directly below the powerplant Jochenstein. - Hybridization with A. baerii poses a threat to autochthonous sterlet populations. - Only small fragments of the tributaries are still connected to the Danube. - Recent catch of 2 sterlet specimen stocked in Germany (Schwarze Laber ~150km upstream) 12 Danube lower Austria Stocking & Catch Melk Altenwörth Greifenstein Freudenau National Park Area unknown unknown qty. 1994 700 1700 A. ruthenus 2001 1000 2002-2005 7000 3000 2010 5 A. gueldenstaedtii 2005 300 unknown 1 1980 1 1986 1 1888 1 A. ruthenus 1990 2 1999 2 2000 6 2003 1 2011 1 hybrid 2002 1 unknown 1? 2005 1 A. baerii 2008 1? 2011 1 A. gueldenstaedtii 2001 1 2002 1 2005 1 species unknown 2009/2010 1 1 9 2011 1 3 13 Danube lower Austria Stocking & Catch 14 Danube lower Austria Potential 30,3km 57,7km 27,8km 22,1 + 3km 98,6 + 104,8km - Most reported catches below the powerplants Altenwörth (mostly alien species) and Freudenau (mostly sterlets). - No catch reports above Freudenau after intensive stocking. - Middle to late 80s catch of a few small specimen of A. ruthenus near Klosterneuburg (before construction of PP Freudenau). - No reports about sterlet catches from the Hungarian section upstream of Gabcikovo (GUTI, pers. comm.). - Still high potential in the National Park/March/Thaya system. 15 March & Thaya Historic records - Both A. gueldenstaedtii, A. ruthenus and H. huso are reported in the March and Thaya upstream to Lundenburg/Landshut (HEINRICH, 1856; JEITTELES, 1864; KRAFT, 1874; REMES 1902). - MAHEN (1927) states that H. huso was rare in the March. - Catches of H. huso in the area around Landshut are recorded by REMES (1902) and ZBORIL & ABSOLON (1916). 16 March & Thaya Potential 31,5 + 73,3 + 98,6km - Both epi- and metapotamal character offer a greater possibility of habitat- availability for all life stages. - Longest connected, freeflowing river system in Austria. - Relatively few human impacts on the hydromorphology. 17 Other Tributaries Historic records | Stocking & Catch | Potential - A. ruthenus was stated to rarely occur in the mouth of the river Enns (ANONYMOUS, 1884). - No reports of other rivers could be found except for a few stocked fish in the river Vienna (FRAUENFELD, 1871). Aschach Enns 1996 1 Polyodon spathula unknown 1 - Only very small stretches of Traun, Enns and Ybbs are still connected to the Danube. - Many powerplants and other barriers in the lower sections of these rivers, therefore very small fragmented. - Rhithralization through hydromorphological changes. 18 Drava Historic records | Stocking & Catch - A. ruthenus was stated to occur in the Drava by MOJSISOVICS (1897) and HECKEL & KNER (1857), although its exact distribution within the Drava remains unknown. Rosegg Feistritz Ferlach Annabrücke Völkermarkt Schwabegg Lavamünd 1982 130 130 1983 150 1987 70 300 A. ruthenus 1991 111 1995 90 2005 50 2010 300 A. gueldenstaedtii 2010 unknown qty. 1982 - 1993 3 2 5 11 17 4 3 A. ruthenus 1994 - 2003 1 1 species unknown 1994 - 2008 1 8 58 2 3 - Various oral reports by fishermen about juveniles in the impoundment Annabrücke (HONSIG-ERLENBURG & FRIEDL, 1999). - Discovery of a head capsule of a 5cm specimen 1998 in the impoundment Völkermarkt (HONSIG-ERLENBURG & FRIEDL, 1999). 19 Drava Potential 16,3km 6,1km 9,6km 10km 23,8km 13,4km 14,2km 10,2km - As the various stretches are very short and the existing free-flowing sections are even shorter the Austrian Drava is rather unlikely to support a self- sustaining population of sterlet. - Possible exceptions: impoundments Annabrücke, Völkermarkt and Lavamünd. - It is not sure that A. ruthenus ever occured in the Austrian Drava. 20 Mur Historic records | Stocking & Catch - A. ruthenus was stated by MOJSISOVICS (1897) to occur in the Mur as far upstream as Graz (one reported catch in the Andritzbach 1890). - A. gueldenstaedtii was stated for the area around Legrad (GLOWACKI, 1885). Murau Graz Spielfeld species unknown 2001 unknown qty. (A. ruthenus?) 2005 1 A. baerii 2010 2 21 Mur Potential 6,7km 4,2km 7,5km 3,9km 5,3km 4,7km 5,5km 21 + 110km 2,6km 12,3km - Many powerplants and other barriers therefore very smallfragmented. - Rhithralization through hydromorphological changes in the area around Graz. - High density of aquaculture and fishing lakes in catchment. - Last stretch on the Austrian - Slovenian border offers a total lenght of ~130km and is connected to the Drava. 22 Summary Historic catches A. gueldenstaedtii A. nudiventris A. ruthenus A. stellatus H. huso species unknown 23 Summary Recent catches 1980 - 2011 Danube Total 80 ind. 221 ind.