U ovom radu se potvrđuje prisustvo dva odrasla primerka kečige, nađenih 20 km jugoistočno od Zagreba u reci Savi. Familija Acipenseridae spada među najstarije zrakoperke. Populacija kečige u reci Savi je doživela značajan pad u toku XX veka, a u delovima reke Dunav koji prolaze kroz Austriju i Nemačku, ova vrsta je skoro izumrla i njen opstanak zavisi samo od kontinuiranog poribljavanja. Tokom marta 2011. godine dva odrasla primerka kečige veličine 431 i 570 mm su ulovljeni u reci Savi. Analizirano je šesnaest morfometrijskih i tri merističke karakteristike. Starost kečiga je procenjivana korišćenjem delova pektoralnog peraja, dok je za analizu crevnog sadržaja korišćena prva trećina ukupne dužine creva. Procena crevnog sadržaja je urađena koristeći frekvenciju pojavljivanja (F%) i brojnost (N%) raličitih komponenti hrane. Iz crevnog sadržaja je evidentno da su glavna hrana vrste Acipenser ruthenus, Chironomidae, kao i različite larve insekata, pre svih Trichoptera i Odonata

Matulic, Daniel

Piria, Marina

Sprem, Nikica

Tomljanovic, Tea

Zanella, Davor

English

CaSA NaRA

326 VI INTERNATIONAL CONFERENCE “WATER & FISH” - CONFERENCE PROCEEDINGSFINDING OF STERLET (acipenSer ruTHenuS)  IN THE SAVA RIVER NEAR ZAGREBTEA TOMLJANOVIĆ1, MARINA PIRIA1, NIKICA ŠPREM1, DANIEL MATULIĆ1, DAVOR ZANELLA21University of Zagreb, Faculty of Agriculture, Department of Fisheries, Beekeeping, Game Management and Special Zoology, Svetošimunska 25, 10 000 Zagreb, Croatia2University of Zagreb, Faculty of Science, Department of Zoology, Roosveltov trg 6, 10 000 Zagreb, CroatiaNALAZ KEČIGE (ACIPENSER RUTHENUS) U RIJECI SAVI KOD ZAGREBAApstraktU ovom radu se potvrđuje prisustvo dva odrasla primerka kečige, nađenih 20 km jugoistočno od Zagreba u reci Savi. Familija Acipenseridae spada među najstarije zrakoperke. Populacija kečige u reci Savi je doživela značajan pad u toku XX veka, a u delovima reke Dunav koji prolaze kroz Austriju i Nemačku, ova vrsta je skoro izumrla i njen opstanak zavisi samo od kontinuiranog poribljavanja. Tokom marta 2011. godine dva odrasla primerka kečige veličine 431 i 570 mm su ulovljeni u reci Savi. Analizirano je šesnaest morfometrijskih i tri merističke karakteristike. Starost kečiga je procenjivana korišćenjem delova pektoralnog peraja, dok je za analizu crevnog sadržaja korišćena prva trećina ukupne dužine creva. Procena crevnog sa-držaja je urađena koristeći frekvenciju pojavljivanja (F%) i brojnost (N%) raličitih komponenti hrane. Iz crevnog sadržaja je evidentno da su glavna hrana vrste Aci-penser ruthenus, Chironomidae, kao i različite larve insekata, pre svih Trichoptera i Odonata.Ključne riječi: kečiga, Acipenser ruthenus, Sava, HrvatskaKeywords: sterlet, Acipenser ruthenus, Sava, CroatiaINTRODUCTIONThe sturgeons (family Acipenseridae) are among the most ancient ray-finned fishes. This extremely endangered group of animals should be the object of biological VI INTERNATIONAL CONFERENCE “WATER & FISH” - ZBORNIK PREDAVANJA   327conservation programmes (Birstein, 1993) which, to be efective, require preliminary study of the specific status of sturgeons in the diferent regions of their distribution area. Sterlet (Acipenser ruthenus L.) is a fluvial fish which inhabits rivers and their tributaries (Vostradovsky, 1974). Occurs in large rivers, usually in the current and in deep water.  In the first place, sterlet is potamodromous (Lucas and Baras, 2001) and moves to flooded areas for feeding (Kottelat and Freyhof, 2007). Like other sturge-ons, it aggregates in bottom holes in winter and exhibit little activity. In spring, when ice breaks, it rises from the bottom holes and moves upstream for spawning. Spawns in habitats with strong-current on gravel, rarely on gravel-sand bottom or in flooded sites. Juveniles stay in riverine habitats during their first summer. This species is cla-ssified as endangered. Populations of sterlet in the Sava River have experienced serious decline during the 20th century (Ristić, 1969), and sterlet has been almost extirpated from the German and Austrian section of the Danube River, where its presence depends on continuous stoc-king efforts (Reinartz, 2002). It has a limited distribution in the basin of the Middle and the Lower Danube (Guti and Gaebele, 2009), and there are ongoing stocking activities with the majority of fish released by Hungary, and to a small extent by Slovakia and Bulgaria (Holčik et al., 2006). In Serbia there is a captive broodstock of A. ruthenus at the Danube river, upon which controlled reproduction has been successfully performed since 1988. Specimens of this stock have been imported to Danube river. The objective of the present study is to confirm the occurrence A. ruthenus in a Sava river. MATERIALS AND METHODSDuring the March 2011, two adult specimens of A. ruthenus, ranging from 431 to 570 mm total length (TL), were captured by local fishermen using hook in a water body about 20 km southeast of Zagreb City. Specimens were examined and identified according to Kottelat and Freyhof (2007). All morphometric and meristic characters were taken following Copp and Kováč (2003) and measurements recorded to the lowest millimetre using a digital calliper, as shown in table 1. All morphometric measurements related to the head region as a proportion relative to head length, and those not related to the head region as proportions of the standard length. Sterlet age determination was performed using pectoral fin spine sections according to Stevenson and Secor (1999). Briefly, we cut the spines with a laboratory saw and then polished it with emery paper, until sections were transparent enough for microscopic observation. Age was estimated by counting annuli in the fin ray sections. For the anal-ysis of stomach contents the anterior third of the gut was used, with the food organisms still recognizable, weighed and fixed in 4% formaldehyde. When possible, the different food items in the gut were identified to the family or genus level. The identification and the counting were made using a binocular microscope.Assessment of the diet was based on the frequency of occurrence (F%) and numeri-cal frequency (N%) of the different diet components, using the following formulas:2006). In Serbia there is a captive broods ock of A. ruthenus at the Danube river, upon which controlled reproducti  has been successfully performed since 1988. Specimens of this stock have been imported to Danube river. The objective of the present study is to confirm the occurrence A. ruthenus in a Sava river.   MATERIALS AND METHODS  During the March 2011, two adult specimens of A. ruthenus, ranging from 431 to 570 mm total length (TL), were captured by local fishermen using hook in a water body about 20 km southeast of Zagreb City. Specimens were examined and identified according to Kottelat and Freyhof (2007). All morphometric and meristic charact rs were taken following Copp and Kováč (2003) and measurements recorded to the lowest millimetre using a digital calliper, as shown in table 1. All morphometric measurements related to the head region as a proportion relative to head length, and those not related to the head region as proportions of the standard length.  Sterlet age determination was performed using pectoral fin spine sections according to Stevenson and Secor (1999). Briefly, we cut the spines with a laboratory saw and then polished it with emery paper, until sections were transparent enough for microscopic observation. Age was estimated by counting annuli in the fin ray sections. For the analysis of stomach contents the anterior third of the ut was used, with the fo d organisms still recognizable, weighed and fixed in 4% formaldehyde. When possible, the different food items in the gut were identified to the family or genus level. The identification and the counting were made using a binocular microscope. Assessment of the diet was based on the frequency f occurrence (F%) and numerical frequency (N%) of the different diet components, using the following formulas: %F100xfif  fi = number of stomachs containing each prey items and Σf = total number of stomachs with food; 100% xniNn ni = total number of one food item, Σn = total number of food items consumed by the fish (Hyslop, 1980).  RESULTS  Morphometric and meristic traits are given in table 1. A. ruhtenus exhibited the following set of characterists: narrow and pointed snout with four long and fringed barbels. Back and flanks are beige. Five rows of scutes, first dorsal scute not fused with head. Ventrals and laterals are very light-colored, nearly white. Inferior lip clearly slit.         fi = number of stomachs co taining each prey items and Σf = total nu  f stomachs with food;328 VI INTERNATIONAL CONFERENCE “WATER & FISH” - CONFERENCE PROCEEDINGS2006). In Serbia there is a captive broodstock of A. ruthenus at the Danube river, upon which controlled reproduction has been successfully performed since 1988. Specimens of this stock have been imported to Danube river. The objective of the present study is to confirm the occurrence A. ruthenus in a Sava river.   MATERIALS AND METHODS  During the March 2011, two adult specimens of A. ruthenus, ranging from 431 to 570 mm total length (TL), were captured by local fishermen using hook in a water body about 20 km southeast of Zagreb City. Specimens were examined and identified according to Kottelat and Freyhof (2007). All morphometric and meristic characters were taken following Copp and Kováč (2003) and measurements recorded to the lowest millimetre using a digital calliper, as shown in table 1. All morphometric measurements related to the head region as a proportion relative to head length, and those not related to the head region as proportions of the standard length.  Sterlet age determination was performed using pectoral fin spine sections according to Stevenson and Secor (1999). Briefly, we cut the spines with a laboratory saw and then polished it with emery paper, until sections were transparent enough for microscopic observation. Age was estimated by counting annuli in the fin ray sections. For the analysis of stomach contents the anterior third of the gut was used, with the food organisms still recognizable, weighed and fixed in 4% formaldehyde. When possible, the different food items in the gut were identified to the family or genus level. The identification and the counting were made using a binocular microscope. Assessment of the diet was based on the frequency of occurrence (F%) and numerical frequency (N%) of the different diet components, using the following formulas: %F100xfif  fi = number of stomachs containing each prey items and Σf = total number of stomachs with food; 100% xniNn ni = total number of one food item, Σn = total number of food items consumed by the fish (Hyslop, 1980).  RESULTS  Morphometric and meristic traits are given in table 1. A. ruhtenus exhibited the following set of characterists: narrow and pointed snout with four long and fringed barbels. Back and flanks are beige. Five rows of scutes, first dorsal scute not fused with head. Ventrals and laterals are very light-colored, nearly white. Inferior lip clearly slit.         ni = total number of one food item, Σn = total number of food items consumed by the fish (Hyslop, 1980).RESULTSMorphometric and meristic traits are given in table 1. A. ruhtenus exhibited the fo-llowing set of characterists: narrow and pointed snout with four long and fringed bar-bels. Back and flanks are beige. Five rows of scutes, first dorsal scute not fused with head. Ventrals and laterals are very light-colored, nearly white. Inferior lip clearly slit.Table 1. Morphometric measurements and meristic counts and age of A. ruhtenus from Sava river Morphometric andmeristic traits Specimen 1 Specimen 2Total length (mm) 431,00 570,00Standard length  (mm) 348,00 453,00Fork length (mm) 108,82 109,49Preanal length (mm) 74,70 73,28Predorsal length (mm) 75,88 77,483Prepectoral length (mm) 27,05 24,94Pectoral fin length (mm) 19,70 17,21Head length (mm) 25,88 26,04Preorbital length (mm) 50,00 50,84Preoral length (mm) 62,50 61,016Prebarbel length (mm) 39,77 40,67Mouth width (mm) 15,90 16,94Distance between eyes (mm) 28,40 31,35Maximum head width (mm) 51,13 43,22Head width at barbel base (mm) 25,00 23,72Head width at mouth level (mm) 35,22 34,74No. of dorsal scutes 11 12No. of lateral scutes 61 60No. of ventrolateral scutes 15 13Age (years) +5 +8From the stomach content it is evident that Chironomidae and various insect larvae are primarily food of Acipenser ruthenus, of which are important Trichoptera and Odo-nata. Since the specimens were caught on earthworms (Lumbricus terrestris), the same one were found in the stomachs of the analyzed samples (Table 2).VI INTERNATIONAL CONFERENCE “WATER & FISH” - ZBORNIK PREDAVANJA   329Table 2. The frequency of occurrence (F%), numerical frequency (N%), pergentage of weight of stomach content (W%) of Acipenser ruthenus from Sava riverTaxa F% N% W%Chironomidae 100,00 51,09 1,93Lumbricus terrestris 50,00 1,09 1,84Other Insecta 100,00 33,70 5,42Trichoptera larvae 50,00 10,87 8,85Odonata anisoptera 50,00 2,17 9,74Bivalvia 50,00 1,09 0,01detritus - - 72,20DISCUSSIONThe fish from family Acipenseridae are economically extremely valuable and threa-tened by overfishing. Unreasonable fishing in the Danube River, based on the catch of the younger age categories that are not sexually mature, presents a serious risk for from this family. The major factor driving unsustainable legal and illegal sturgeon fisheries in this region is the fact that beluga caviar is one of the most prized fish products worldwi-de (Nikčević et al., 2003). Changes in natural habitats caused by human activity, such as pollution, sand digging and regulation of water flows adversely affected the natural sturgeon population. It was noted that the construction of dams and reservoirs affects the propagation of sturgeon because of the population increase in the number of elderly individuals that do not reproduce (Mrakovčić et al., 2006). Also, dams block access to many sturgeon-spawning grounds and, therefore, are considered to be one of the main reasons for the decline of their stocks (Lenhardt et al., 2004). A. ruthenus is consider endangered by IUCN Red List (Gesner et al., 2010) in Croa-tia, and listed as vulnerable by the Red book of Freshwater Fish of Croatia (Markovčić et al., 2006).Nowadays in Croatia a relatively good conditions exist for a start of common action among state representatives, scientists, holders of fishing rights, fishermen and private sturgeon hatcheries to solve the problem of sturgeon extinction risk. REFERENCESBirstein, V.J (1993): Sturgeons and paddlefishes: threatened fishes in need of conser-vation. Conservation Biology, 7, 773-787.Copp, G.H., Kováč, V. (2003): Biometric relationships between body size and bone lengths in fish prey of the Eurasian otter Lutra lutra: chub Leuciscus cephalus and perch Perca fluviatilis. Folia Zoologica, 52, 109–112.Gesner, J., Freyhof, J., Kottelat, M. (2010): Acipenser ruthenus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. www.iucnredlist.org Downloa-ded on 10 May 2013Guti, G., Gaebele, T. (2009): Long-term changes of sterlet (Acipenser ruthenus) popula-tion in the Hungarian section of the Danube. Opuscula Zoologica Budapest, 40, 2, 17–25.Holčik, J., Klindova, A., Masar, J., Meszaros, J. (2006): Sturgeons in the Slovakian rivers of the Danube river basin: an overview of their current status and proposal for their conservation and restoration. Journal of Applied Ichthyology, 22, 1, 17–22.330 VI INTERNATIONAL CONFERENCE “WATER & FISH” - CONFERENCE PROCEEDINGSHyslop, E. J. (1980): Stomach content analysis – a review of methods and their application. Journal of Fish Biology, 17, 411–429.Kottelat, M., Freyhof, J. (2007): Handbook of European freshwater species. Cornol, Switzerland: Berlin, Germany. 55 ppLenhardt, M., Cakić, P., Kolarević, J. (2004): Influence of the HEPS Djerdap I and Djerdap II dam construction on catch of economically important fish species in the Da-nube River. Ecohydrology and Hydrobiology, 4, 4, 499–502.Lucas, M.C., Baras, E. (2001): Migration of freshwater fishes. Oxford: Blackwell Science. 440 p.Mrakovčić, M., Brigić, A., Buj, I., Ćaleta, M., Mustafić, P., Zanella, D. (2006): Cr-vena knjiga sltakovodnih riba Hrvatske. Državni zavod za zaštitu prirode, Republika Hrvatka. 110 ppNikčević, M., Lenhardt, M., Cakić, P., Mićković, B., Kolarević, J., Jarić, I. (2003): Historical review and new initiatives for sturgeon fisheries, aquaculture and caviar pro-duction in Serbia and Montenegro. In: Otterstad Oddmund (ed.), Releasing Develo-pment Potentials at the Eastern Adriatic.Reinartz, R. (2002): Sturgeons in the Danube river. Vienna: International Associati-on for Danube Research. Ristić, M. (1969): Osobenosti rasta kečige (Acipenser ruthenus L.) iz Dunava, Save i Tise. Ribarstvo Jugoslavije, 24, 2, 21-31.Stevenson, J.T., Secor, D.H. (1999): Age determination and growth of Hudson River Atlantic sturgeon, Acipenser oxyrinchus. Fisheries Bulletin, 97, 153-166.Vostradovsky, J. (1973): Freshwater fishes. The Hamlyn Publishing Group Limited, London. 252 pp

Nalaz kečige (acipenser ruthenus) u rijeci Savi kod Zagreba

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Nalaz kečige (acipenser ruthenus) u rijeci Savi kod Zagreba

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