Salmonids are an extensively hatchery-reared group of fishes that have been introduced worldwide ... more Salmonids are an extensively hatchery-reared group of fishes that have been introduced worldwide mainly for their high commercial and recreational value. The Balkan Peninsula (south-eastern Europe) is characterised by an outstanding salmonid diversity that has become threatened by the introduction of nonnative salmonids whose potential risk of invasiveness in the region remains unknown and especially so under predicted climate change conditions. In this study, 13 extant and four horizon non-native salmonid species were screened for their risk of invasiveness in the Danube and Adriatic Basins of four Balkan countries. Overall, six (35%) of the screened species were ranked as carrying a high risk of invasiveness under current climate conditions, whereas under predicted conditions of global warming, this number decreased to three (17%). Under current climate conditions, the very high risk ('top invasive') species were rainbow
Knowledge and Management of Aquatic Ecosystems, 2021
Brown trout is a salmonid fish with a natural range extending throughout western Eurasia and Nort... more Brown trout is a salmonid fish with a natural range extending throughout western Eurasia and North Africa. Due to its commercial value, it has also been introduced worldwide. In continental Croatia, introduced trout of the Atlantic lineage hybridizes with native trout of the Danubian lineage, threatening the native genetic diversity. The geometric morphometrics approach was used in this study to analyse changes in shape between native trout, introduced trout and their hybrids, classified a priori by molecular phylogenetic analyses. A total of 19 landmarks and semi-landmarks were used to capture the shape of 92 trout individuals belonging to two lineages and their hybrids. Canonical variate analysis and discriminant function analysis were used to analyse and describe shape variation. A significant difference was found between the shape of the Atlantic lineage trout and both Danubian lineage trout and hybrids, with the most prominent differences in body depth, head length and eye size. No statistically significant shape differences were observed between Danubian lineage trout and the hybrids. The observed significant differences in shape could be the result of genetic diversity or trout phenotypic plasticity. Further studies are needed to clarify the origin of this variation in shape.
Fundamental and Applied Limnology / Archiv für Hydrobiologie, 2020
During recent intensive research, monitoring and inventory programmes in the large, inland waters... more During recent intensive research, monitoring and inventory programmes in the large, inland waters of Croatia, 72 specimens of the racer goby Babka gymnotrachelus were collected at eight locations in 2016 and 2018, and of these, 61 were juveniles. This confirms the establishment of a self-sustaining population in the main channel of the Danube in Croatia, and a small tributary, the Baranjska Karašica River. However, no progress of this species in the main tributaries, i.e. the Drava and Sava Rivers, has been observed to date. Future research should be focused on tributaries, channels and backwaters to confirm their localization only to the Danube River and its northwestern tributaries in Croatia.
Background. The molecular diversity of brown trout, Salmo trutta Linnaeus, 1758, has been poorly ... more Background. The molecular diversity of brown trout, Salmo trutta Linnaeus, 1758, has been poorly studied in Croatia. The control region of mitochondrial DNA (CR mtDNA) is in addition to other molecular markers a reliable for identifying phylogenetic lineages (haplogroups) and haplotypes of brown trout. Based on analyses of the control region of mitochondrial DNA several major brown trout phylogenetic lineages were identified of which the Danubian (DA) haplotypes, though not all, are considered native to Croatian rivers belonging to the Danube basin. The introduction of allochthonous haplotypes into natural streams seriously threatens the genetic diversity of this species. Therefore, the aim of this study was to map brown trout populations inhabiting Croatian rivers of the Danube River basin and to investigate their molecular diversity and phylogeographic patterns of the established haplotypes. Materials and methods. Anal fin tissue was taken from 141 specimens of brown trout in 14 localities in the protected areas of Croatia, situated in the mountainous regions of Gorski Kotar, Žumberak, as well as Mountain Papuk in the western Slavonia. The total DNA was extracted and then the amplification of the mtDNA control region was carried out using primers Trutta-mt-F and HN20. Amplification of the 440 bp long region of the LDH-C1 gene locus was done using primers Ldhxon3F and Ldhxon4R. Amplified LDH-C* fragments were used for Restriction Fragment Length Polymorphism (RFLP) analysis using BselI restriction enzyme. Results. Analysis of the CR mtDNA revealed the presence of two phylogenetic lineages, the DA and the Atlantic (AT). Haplotypes Da1, Da2, and Da22 were recorded within the DA lineage and At1 was recorded within the AT haplogroup. Two new haplotypes were described for the first time in this study and are named Da1f and Da1g. Restriction analysis of the lactate dehydrogenase gene locus revealed a high degree of hybridization between brown trout of DA and AT haplogroups. Conclusion. The results of this study confirmed the complex molecular diversity of brown trout and the high degree of the introduction of non-native haplogroups into rivers of the Danube basin in Croatia. Conservation of native brown trout populations has become evident, as introduced allochthonous DA and AT haplogroups severely disrupt the indigenous brown trout stock.
Fish introductions, particularly in areas of high biological diversity and endemism, represent a ... more Fish introductions, particularly in areas of high biological diversity and endemism, represent a major threat for biodiversity. In the Balkan Peninsula, 60 fish species have been introduced to date, of which 36 have become naturalized in inland waters. Since the Balkans are one of the world's 35 biodiversity hot spots, this large presence of alien fish species poses a serious threat for the stability of freshwater ecosystems and the survival of the native ichthyofauna and of aquatic biodiversity in general. The motivation for the introductions, and the historical timeline, varies among the Balkan states. Despite recent attempts to implement and align legislation aimed at preventing the introduction of potentially invasive species, and the implementation of rigorous controls of introductions and increased protection of open waters, the majority of
Invasive alien species (IAS) are a significant and growing problem worldwide. In Europe, some asp... more Invasive alien species (IAS) are a significant and growing problem worldwide. In Europe, some aspects of IAS have been addressed through existing legal instruments, but these are far from sufficient to tackle the problem comprehensively. The FINS II Conference considered the relevance of Top 20 IAS issues (Top 10 threats and opportunities) for Europe determined at the 1st Freshwater Invasiveness – Networking for Strategy (FINS I) conference held in Ireland in 2013. Using a similar format of sequential group voting, threats from FINS I (lack of funding, of awareness and education; poor communication) and several new threats (lack of lead agencies, of standardized management and of common approach; insufficient monitoring and management on private property) were identified by 80 academics, applied scientists, policy makers and stakeholders from 14 EU and three non-EU countries (including 10 invited speakers) during four workshop break-out sessions (legislation remit in both EU/non-EU countries; best management and biosecurity practice for control; data management and early warning; pathways of introductions and citizen science). Identified opportunities include improved cooperation and communication, education and leadership to enhance public awareness and stakeholder participation, systems establishment for early detection, rapid response, monitoring and management of IAS using standardised methods of data collection, storage and usage.The sets of threats and opportunities identified underline the importance of international cooperation on IAS issues in communication, education and funding as priorities, as well as in standardization of legislation, control methods and best practise of research.
The part of the River Danube basin in the Western Balkans region (11 sampled localities and 57 in... more The part of the River Danube basin in the Western Balkans region (11 sampled localities and 57 in total with using of published data) revealed the remarkable diversity of brown trout assessed using the Control Region (CR) of mitochondrial DNA (mtDNA) as a molecular marker. The greatest number of brown trout populations holds brown trout of the Da1 haplotype. Particular distinct haplotypes are limited to isolated brown trout stocks. There are haplotypes of Danubian (Da), and those of Atlantic (At), Adriatic (Ad) and marmoratus (MA) lineages introduced there.Phylogenetic relationships inferred between them implicate the 22 plesiomorhic character of Da*Vr, Da*Dž and Da-s6 haplotypes that were resolved as ancestral clades, with the intermediate position between clades holding haplotypes of the non-Danubian lineage and more advanced haplotypes of the Danubian lineage. A uniform rate of evolution was found for all clades. The recent widespread distribution and exclusivity of Da1 haplotype imply its ancestral character among advanced Danubian haplotypes. Populations in the Sava, Drava, Una and Drina revealed an expansion, whereas those in the Kupa and Zapadna Morava catchments revealed both stability in size and great differentiation. Gene flow between stocks was found to be negligible.
Sampling was undertaken, with the same fishing gear and along the Sava River, from its source to ... more Sampling was undertaken, with the same fishing gear and along the Sava River, from its source to its confluence, in September 2014 and September 2015. In total, 44 fish species were identified, of which 37 were native species and 7 were alien. Fish samples revealed independence in terms of both species composition and their abundance under different hydrological conditions. During flooding and high water levels in 2014, pelagic fish species were sampled in greater proportion than at lower water levels in 2015 when benthic fish species were more abundant. The flood wave in 2014 was accompanied by catch of common carp, Cyprinus carpio, a typical lower rhithron fish species in the upper course, and of tench, Tinca tinca, a typical potamon fish species of backwaters, in the main channel of the lower Sava River. One specimen of bighead goby, Ponticola kessleri, which is common in the potamon fish community, was caught during the 2015 sampling close to the boundary between the upper and middle sections of the Sava. This is the first record of Ponto-Caspian gobies in the inland waters of Slovenia. Its finding far upstream indicates a strong effect of an as yet unidentified stress along the Sava River up to the spot where the bighead goby was sampled. Finally, these results indicate that pelagic fish species are more resistant to the stressful effect of flooding than benthic species, and that the structure of fish communities is influenced/affected by flooding as a short-term stressor. The progressively increasing number of alien fish species downstream in the Sava River point to the effects of long-term human-induced stressors in the area.
Data about the mitochondrial DNA haplotypes of brown trout Salmo trutta L. in the area of the Riv... more Data about the mitochondrial DNA haplotypes of brown trout Salmo trutta L. in the area of the River Danube basin in Bosnia and Herzegovina have not been hitherto published. Brown trout from the River Una drainage area was assessed for the first time using the Control Region of the mitochondrial DNA. Anal fin clips of 43 brown trout were sampled from four sites in the headwater section and in two tributaries joining the Una River in the middle section. In total, three CR haplotypes were recorded: Da2 and Da22 from the Danubian and At1 from the Atlantic brown trout lineage. Da22 haplotype was inferred the native one in the River Una drainage area from its most frequent and most upstream dispersal in the headwater section. The other two haplotypes were found with the native one only in one or two tributaries joining the River Una in the middle section and they are considered alien. They were most likely introduced there by stocking with hatchery reared brown trout fingerlings. Occurrence of several trout hatcheries in the area poses strong risk for introduction of alien haplotypes into the headwater section and consequential breakdown in local native brown trout.
The aim of this study was analyze reproductive performance of wild boar in different habitat over... more The aim of this study was analyze reproductive performance of wild boar in different habitat over a 7-year period (2006-2012). A total of 468 pregnant females and 2,819 fetuses were analyzed, the mean number of fetuses was 6.02 (median=6) per animal (4.62 per juvenile, 6.39 per yearling and 6.77 per adult). In litters, male-biased fetuses occurred significantly more often than female, the overall fetal sex ratio is 1:0.86. Positive reproductive traits increased up to 90 kg of live body weight and then decreased. The reproductive parameters observed in our study reflect a relatively high reproductive capacity compared to the populations in southern and northern Europe, but are comparable with some populations in central Europe. Concerning habitat conditions, it is obvious that they influence the reproductive performance of females, and therefore must be included in management plans.
Danubian spinned loach, Cobitis elongatoides, is a species of loach distributing in the watershed... more Danubian spinned loach, Cobitis elongatoides, is a species of loach distributing in the watershed of the Danube basin, Europe, and its populations are quite stable. This species is widespread in all small rivers of the Sava and Drava tributaries in Croatia. Cobitidae and its phylogenic analysis are of importance in elucidating evolutionary adaptations in freshwater fishes in Asia and Europe. The complete mitochondrial genome of C. elongatoides was sequenced with the aim of obtaining genetic information essential to inferring its evolution and genetic identity and phylogenetic analysis of Cobitidae fish. The genome was 16,540 bp in length, and contains 22 transfer RNA genes, 13 protein-coding genes (PCGs), two ribosomal RNA genes, a displacement loop region (D-loop). The mitogenomes from C. elongatoides and other loaches like Cobitis sinensis, Paramisgurnus dabryanus, and Misgurnus bipartitus have 89%, 88% and 91% nucleotide sequence identity, respectively.
The barbel population (Barbus peloponnesius) was studied in the Sava River at Medsave from July t... more The barbel population (Barbus peloponnesius) was studied in the Sava River at Medsave from July to October 2001. The main objective of the study was to obtain data on diet composition of this species in natural biotopes with relation to food availability in the river. In the spring, the dominant food items of barbel were Chironomidae, Oligochaeta and Cladocera. In the summer, they preferred Chironomidae, Ephemeroptera, and Trichoptera with a combination of plant foods Bacillariophyceae and Chlorophyceae. The main foods of this species in the autumn were larvae of Insecta and Bacillariophyceae. Smaller barbel preferred animal prey and less plant items, while larger sizes of this species preferred only animal prey. Diet selectivity with relation to food availability in the environment was diverse in various investigated period. Positive selectivity in June was found for Xantophyceae and makroavertebrates, in July for Chlorophyceae, Bacillariophyceae and macroinvertebrates and in Octob...
The water quality of the Sava river in its barbel zone in Croatia improved since the beginning of... more The water quality of the Sava river in its barbel zone in Croatia improved since the beginning of 1990’s, as the result of Slovenia’s abandonment of heavy industry and mining during the transition period. Ichthyofaunal changes followed. The aim of this work was to investigate trends since 2001. The fish were caught 15 times by electric gear in spring, summer and fall from 2003 to 2006. Catch per unit effort (CPUE) was expressed by the mass of fish in grams caught along the 100 m of the river course. The overall CPUE continued to vary around 3 kg (2773.4 g average). Throughout the last three decades, Leuciscus cephalus has always remained an outstandingly dominant species. Its CPUE is responsible for about half of the overall CPUE, varying between 44.1 % over 1991-1994 period and 54.5 % in 2001. Other significant constantly present species in the same period have been Barbus barbus, Alburnus alburnus, Cobitis spp. and Silurus glanis. Two other typical species, Alburnoides bipuncatatu...
The growth of grayling (Thymallus thymallus L.) was analyzed on specimen of 98 fish, caught whit ... more The growth of grayling (Thymallus thymallus L.) was analyzed on specimen of 98 fish, caught whit sport-fishing equipment in upper part of the Kupa river, northwest Croatia. The research was conducted in 2002 fishing season, monthly from May to November. The total length of caught grayling ranged from 17.0 to 41.0 cm, and weight from 40 to 700 g. The growth in total length of this population could be expressed by the following von Bertalanffy expression: Lt= 69.77(1 – e-0.1214(t-1.25)). The overall growth performance (Φ') has minimum variance, and average value of our population is Φ'=6.38±0.14. Weight express a negative allometric growth (b=2.643).
During the last decades several species of Ponto-Caspian gobies (Pisces, Gobiidae) have expanded ... more During the last decades several species of Ponto-Caspian gobies (Pisces, Gobiidae) have expanded upstream from their native distributions and invaded most of Europe, albeit their reported distributions vary greatly. Three invasive Ponto-Caspian species have so far been reported in Croatia: bighead goby Ponticola kessleri (Neilson and Stepien, 2009), monkey goby Neogobius fluviatilis (Pallas, 1814) and round goby Neogobius melanostomus (Pallas, 1814). Their distribution, abundance and condition from the River Sava were analyzed over a three-year period (2010-2012). Distribution and condition of monkey goby in tributaries of the River Sava (Kupa, Kupčina, Korana and Ilova) were also presented. CPUE values (number of fish per 100 m shoreline) were calculated and compared between the sites. A total of 246 specimens of monkey goby, 141 specimens of round goby and 21 specimens of bighead goby were analysed. In terms of distribution, monkey goby was found along the entire longitudinal prof...
Appendix for paper: Piria, M., Jakšić, G., Jakovlić, I., Treer, T. (2015): Dietary habits of inva... more Appendix for paper: Piria, M., Jakšić, G., Jakovlić, I., Treer, T. (2015): Dietary habits of invasive Ponto-Caspian gobies in the Croatian part of the Danube River basin and their potential impact on benthic fish communities. Science of Total Environment, in press doi:10.1016/j.scitotenv.2015.05.125
Between 2007 and 2009, a total of 181 individual wild boar were scored using nineteen morphologic... more Between 2007 and 2009, a total of 181 individual wild boar were scored using nineteen morphological measurements from three geograp-hical regions to describe morphological variety of the population throughout Croatia. In some regions we found phenotypical variability of the wild boar population based on hybridization The results of ANOVA show that some va-riables were significantly different (body weight, tail length, trunk length) but some of them were not homogenous for all age classes (circumference of shin, the most caudal point of scapula, circumference at chest) and were unable to highlight differences among the areas. The redundancy analysis (RDA) sho-wed a connection of sampling sites with some morphological trait. Results of cluster analysis using TREE procedure indicate separation on the two subpo-pulations and suggesting the existence of morphological differences. Overall the results confirmed that different morphotypes of wild boar are detectable in some different areas ...
Recreational and professional fishermen often argue against each other. Therefore the aim of this... more Recreational and professional fishermen often argue against each other. Therefore the aim of this research was to compare the official data of both kinds of fishing on the Danube in the three neighbouring countries.
Being of a great socio-economic importance, recreational freshwater fishing is one of the most po... more Being of a great socio-economic importance, recreational freshwater fishing is one of the most popular pastimes in many countries, Croatia included. As the fishing pressure is constantly increasing, the monitoring of the fish stock is crucial for effective fisheries management. One of the reliable evaluations on the current state of the freshwater fish communities is based on the catch of the anglers. The aim of this study was to provide an overview of the monitoring of freshwater fish community in Croatia by anglers’ data over the six year period (2004-2009). The current quantity of fish species in Croatian freshwaters is evaluated by catch per unit effort (CPUE). The evaluated CPUE parameter was highest in 2006 (18.42 kg/per angler), and lowest in 2009 (15.43 kg/per angler). During the study period the number of anglers oscillated minimally. The yearly average number of anglers was 36,612 while the yearly average of total catch was approximately 618.656 kg. The results on the tota...
Salmonids are an extensively hatchery-reared group of fishes that have been introduced worldwide ... more Salmonids are an extensively hatchery-reared group of fishes that have been introduced worldwide mainly for their high commercial and recreational value. The Balkan Peninsula (south-eastern Europe) is characterised by an outstanding salmonid diversity that has become threatened by the introduction of nonnative salmonids whose potential risk of invasiveness in the region remains unknown and especially so under predicted climate change conditions. In this study, 13 extant and four horizon non-native salmonid species were screened for their risk of invasiveness in the Danube and Adriatic Basins of four Balkan countries. Overall, six (35%) of the screened species were ranked as carrying a high risk of invasiveness under current climate conditions, whereas under predicted conditions of global warming, this number decreased to three (17%). Under current climate conditions, the very high risk ('top invasive') species were rainbow
Knowledge and Management of Aquatic Ecosystems, 2021
Brown trout is a salmonid fish with a natural range extending throughout western Eurasia and Nort... more Brown trout is a salmonid fish with a natural range extending throughout western Eurasia and North Africa. Due to its commercial value, it has also been introduced worldwide. In continental Croatia, introduced trout of the Atlantic lineage hybridizes with native trout of the Danubian lineage, threatening the native genetic diversity. The geometric morphometrics approach was used in this study to analyse changes in shape between native trout, introduced trout and their hybrids, classified a priori by molecular phylogenetic analyses. A total of 19 landmarks and semi-landmarks were used to capture the shape of 92 trout individuals belonging to two lineages and their hybrids. Canonical variate analysis and discriminant function analysis were used to analyse and describe shape variation. A significant difference was found between the shape of the Atlantic lineage trout and both Danubian lineage trout and hybrids, with the most prominent differences in body depth, head length and eye size. No statistically significant shape differences were observed between Danubian lineage trout and the hybrids. The observed significant differences in shape could be the result of genetic diversity or trout phenotypic plasticity. Further studies are needed to clarify the origin of this variation in shape.
Fundamental and Applied Limnology / Archiv für Hydrobiologie, 2020
During recent intensive research, monitoring and inventory programmes in the large, inland waters... more During recent intensive research, monitoring and inventory programmes in the large, inland waters of Croatia, 72 specimens of the racer goby Babka gymnotrachelus were collected at eight locations in 2016 and 2018, and of these, 61 were juveniles. This confirms the establishment of a self-sustaining population in the main channel of the Danube in Croatia, and a small tributary, the Baranjska Karašica River. However, no progress of this species in the main tributaries, i.e. the Drava and Sava Rivers, has been observed to date. Future research should be focused on tributaries, channels and backwaters to confirm their localization only to the Danube River and its northwestern tributaries in Croatia.
Background. The molecular diversity of brown trout, Salmo trutta Linnaeus, 1758, has been poorly ... more Background. The molecular diversity of brown trout, Salmo trutta Linnaeus, 1758, has been poorly studied in Croatia. The control region of mitochondrial DNA (CR mtDNA) is in addition to other molecular markers a reliable for identifying phylogenetic lineages (haplogroups) and haplotypes of brown trout. Based on analyses of the control region of mitochondrial DNA several major brown trout phylogenetic lineages were identified of which the Danubian (DA) haplotypes, though not all, are considered native to Croatian rivers belonging to the Danube basin. The introduction of allochthonous haplotypes into natural streams seriously threatens the genetic diversity of this species. Therefore, the aim of this study was to map brown trout populations inhabiting Croatian rivers of the Danube River basin and to investigate their molecular diversity and phylogeographic patterns of the established haplotypes. Materials and methods. Anal fin tissue was taken from 141 specimens of brown trout in 14 localities in the protected areas of Croatia, situated in the mountainous regions of Gorski Kotar, Žumberak, as well as Mountain Papuk in the western Slavonia. The total DNA was extracted and then the amplification of the mtDNA control region was carried out using primers Trutta-mt-F and HN20. Amplification of the 440 bp long region of the LDH-C1 gene locus was done using primers Ldhxon3F and Ldhxon4R. Amplified LDH-C* fragments were used for Restriction Fragment Length Polymorphism (RFLP) analysis using BselI restriction enzyme. Results. Analysis of the CR mtDNA revealed the presence of two phylogenetic lineages, the DA and the Atlantic (AT). Haplotypes Da1, Da2, and Da22 were recorded within the DA lineage and At1 was recorded within the AT haplogroup. Two new haplotypes were described for the first time in this study and are named Da1f and Da1g. Restriction analysis of the lactate dehydrogenase gene locus revealed a high degree of hybridization between brown trout of DA and AT haplogroups. Conclusion. The results of this study confirmed the complex molecular diversity of brown trout and the high degree of the introduction of non-native haplogroups into rivers of the Danube basin in Croatia. Conservation of native brown trout populations has become evident, as introduced allochthonous DA and AT haplogroups severely disrupt the indigenous brown trout stock.
Fish introductions, particularly in areas of high biological diversity and endemism, represent a ... more Fish introductions, particularly in areas of high biological diversity and endemism, represent a major threat for biodiversity. In the Balkan Peninsula, 60 fish species have been introduced to date, of which 36 have become naturalized in inland waters. Since the Balkans are one of the world's 35 biodiversity hot spots, this large presence of alien fish species poses a serious threat for the stability of freshwater ecosystems and the survival of the native ichthyofauna and of aquatic biodiversity in general. The motivation for the introductions, and the historical timeline, varies among the Balkan states. Despite recent attempts to implement and align legislation aimed at preventing the introduction of potentially invasive species, and the implementation of rigorous controls of introductions and increased protection of open waters, the majority of
Invasive alien species (IAS) are a significant and growing problem worldwide. In Europe, some asp... more Invasive alien species (IAS) are a significant and growing problem worldwide. In Europe, some aspects of IAS have been addressed through existing legal instruments, but these are far from sufficient to tackle the problem comprehensively. The FINS II Conference considered the relevance of Top 20 IAS issues (Top 10 threats and opportunities) for Europe determined at the 1st Freshwater Invasiveness – Networking for Strategy (FINS I) conference held in Ireland in 2013. Using a similar format of sequential group voting, threats from FINS I (lack of funding, of awareness and education; poor communication) and several new threats (lack of lead agencies, of standardized management and of common approach; insufficient monitoring and management on private property) were identified by 80 academics, applied scientists, policy makers and stakeholders from 14 EU and three non-EU countries (including 10 invited speakers) during four workshop break-out sessions (legislation remit in both EU/non-EU countries; best management and biosecurity practice for control; data management and early warning; pathways of introductions and citizen science). Identified opportunities include improved cooperation and communication, education and leadership to enhance public awareness and stakeholder participation, systems establishment for early detection, rapid response, monitoring and management of IAS using standardised methods of data collection, storage and usage.The sets of threats and opportunities identified underline the importance of international cooperation on IAS issues in communication, education and funding as priorities, as well as in standardization of legislation, control methods and best practise of research.
The part of the River Danube basin in the Western Balkans region (11 sampled localities and 57 in... more The part of the River Danube basin in the Western Balkans region (11 sampled localities and 57 in total with using of published data) revealed the remarkable diversity of brown trout assessed using the Control Region (CR) of mitochondrial DNA (mtDNA) as a molecular marker. The greatest number of brown trout populations holds brown trout of the Da1 haplotype. Particular distinct haplotypes are limited to isolated brown trout stocks. There are haplotypes of Danubian (Da), and those of Atlantic (At), Adriatic (Ad) and marmoratus (MA) lineages introduced there.Phylogenetic relationships inferred between them implicate the 22 plesiomorhic character of Da*Vr, Da*Dž and Da-s6 haplotypes that were resolved as ancestral clades, with the intermediate position between clades holding haplotypes of the non-Danubian lineage and more advanced haplotypes of the Danubian lineage. A uniform rate of evolution was found for all clades. The recent widespread distribution and exclusivity of Da1 haplotype imply its ancestral character among advanced Danubian haplotypes. Populations in the Sava, Drava, Una and Drina revealed an expansion, whereas those in the Kupa and Zapadna Morava catchments revealed both stability in size and great differentiation. Gene flow between stocks was found to be negligible.
Sampling was undertaken, with the same fishing gear and along the Sava River, from its source to ... more Sampling was undertaken, with the same fishing gear and along the Sava River, from its source to its confluence, in September 2014 and September 2015. In total, 44 fish species were identified, of which 37 were native species and 7 were alien. Fish samples revealed independence in terms of both species composition and their abundance under different hydrological conditions. During flooding and high water levels in 2014, pelagic fish species were sampled in greater proportion than at lower water levels in 2015 when benthic fish species were more abundant. The flood wave in 2014 was accompanied by catch of common carp, Cyprinus carpio, a typical lower rhithron fish species in the upper course, and of tench, Tinca tinca, a typical potamon fish species of backwaters, in the main channel of the lower Sava River. One specimen of bighead goby, Ponticola kessleri, which is common in the potamon fish community, was caught during the 2015 sampling close to the boundary between the upper and middle sections of the Sava. This is the first record of Ponto-Caspian gobies in the inland waters of Slovenia. Its finding far upstream indicates a strong effect of an as yet unidentified stress along the Sava River up to the spot where the bighead goby was sampled. Finally, these results indicate that pelagic fish species are more resistant to the stressful effect of flooding than benthic species, and that the structure of fish communities is influenced/affected by flooding as a short-term stressor. The progressively increasing number of alien fish species downstream in the Sava River point to the effects of long-term human-induced stressors in the area.
Data about the mitochondrial DNA haplotypes of brown trout Salmo trutta L. in the area of the Riv... more Data about the mitochondrial DNA haplotypes of brown trout Salmo trutta L. in the area of the River Danube basin in Bosnia and Herzegovina have not been hitherto published. Brown trout from the River Una drainage area was assessed for the first time using the Control Region of the mitochondrial DNA. Anal fin clips of 43 brown trout were sampled from four sites in the headwater section and in two tributaries joining the Una River in the middle section. In total, three CR haplotypes were recorded: Da2 and Da22 from the Danubian and At1 from the Atlantic brown trout lineage. Da22 haplotype was inferred the native one in the River Una drainage area from its most frequent and most upstream dispersal in the headwater section. The other two haplotypes were found with the native one only in one or two tributaries joining the River Una in the middle section and they are considered alien. They were most likely introduced there by stocking with hatchery reared brown trout fingerlings. Occurrence of several trout hatcheries in the area poses strong risk for introduction of alien haplotypes into the headwater section and consequential breakdown in local native brown trout.
The aim of this study was analyze reproductive performance of wild boar in different habitat over... more The aim of this study was analyze reproductive performance of wild boar in different habitat over a 7-year period (2006-2012). A total of 468 pregnant females and 2,819 fetuses were analyzed, the mean number of fetuses was 6.02 (median=6) per animal (4.62 per juvenile, 6.39 per yearling and 6.77 per adult). In litters, male-biased fetuses occurred significantly more often than female, the overall fetal sex ratio is 1:0.86. Positive reproductive traits increased up to 90 kg of live body weight and then decreased. The reproductive parameters observed in our study reflect a relatively high reproductive capacity compared to the populations in southern and northern Europe, but are comparable with some populations in central Europe. Concerning habitat conditions, it is obvious that they influence the reproductive performance of females, and therefore must be included in management plans.
Danubian spinned loach, Cobitis elongatoides, is a species of loach distributing in the watershed... more Danubian spinned loach, Cobitis elongatoides, is a species of loach distributing in the watershed of the Danube basin, Europe, and its populations are quite stable. This species is widespread in all small rivers of the Sava and Drava tributaries in Croatia. Cobitidae and its phylogenic analysis are of importance in elucidating evolutionary adaptations in freshwater fishes in Asia and Europe. The complete mitochondrial genome of C. elongatoides was sequenced with the aim of obtaining genetic information essential to inferring its evolution and genetic identity and phylogenetic analysis of Cobitidae fish. The genome was 16,540 bp in length, and contains 22 transfer RNA genes, 13 protein-coding genes (PCGs), two ribosomal RNA genes, a displacement loop region (D-loop). The mitogenomes from C. elongatoides and other loaches like Cobitis sinensis, Paramisgurnus dabryanus, and Misgurnus bipartitus have 89%, 88% and 91% nucleotide sequence identity, respectively.
The barbel population (Barbus peloponnesius) was studied in the Sava River at Medsave from July t... more The barbel population (Barbus peloponnesius) was studied in the Sava River at Medsave from July to October 2001. The main objective of the study was to obtain data on diet composition of this species in natural biotopes with relation to food availability in the river. In the spring, the dominant food items of barbel were Chironomidae, Oligochaeta and Cladocera. In the summer, they preferred Chironomidae, Ephemeroptera, and Trichoptera with a combination of plant foods Bacillariophyceae and Chlorophyceae. The main foods of this species in the autumn were larvae of Insecta and Bacillariophyceae. Smaller barbel preferred animal prey and less plant items, while larger sizes of this species preferred only animal prey. Diet selectivity with relation to food availability in the environment was diverse in various investigated period. Positive selectivity in June was found for Xantophyceae and makroavertebrates, in July for Chlorophyceae, Bacillariophyceae and macroinvertebrates and in Octob...
The water quality of the Sava river in its barbel zone in Croatia improved since the beginning of... more The water quality of the Sava river in its barbel zone in Croatia improved since the beginning of 1990’s, as the result of Slovenia’s abandonment of heavy industry and mining during the transition period. Ichthyofaunal changes followed. The aim of this work was to investigate trends since 2001. The fish were caught 15 times by electric gear in spring, summer and fall from 2003 to 2006. Catch per unit effort (CPUE) was expressed by the mass of fish in grams caught along the 100 m of the river course. The overall CPUE continued to vary around 3 kg (2773.4 g average). Throughout the last three decades, Leuciscus cephalus has always remained an outstandingly dominant species. Its CPUE is responsible for about half of the overall CPUE, varying between 44.1 % over 1991-1994 period and 54.5 % in 2001. Other significant constantly present species in the same period have been Barbus barbus, Alburnus alburnus, Cobitis spp. and Silurus glanis. Two other typical species, Alburnoides bipuncatatu...
The growth of grayling (Thymallus thymallus L.) was analyzed on specimen of 98 fish, caught whit ... more The growth of grayling (Thymallus thymallus L.) was analyzed on specimen of 98 fish, caught whit sport-fishing equipment in upper part of the Kupa river, northwest Croatia. The research was conducted in 2002 fishing season, monthly from May to November. The total length of caught grayling ranged from 17.0 to 41.0 cm, and weight from 40 to 700 g. The growth in total length of this population could be expressed by the following von Bertalanffy expression: Lt= 69.77(1 – e-0.1214(t-1.25)). The overall growth performance (Φ') has minimum variance, and average value of our population is Φ'=6.38±0.14. Weight express a negative allometric growth (b=2.643).
During the last decades several species of Ponto-Caspian gobies (Pisces, Gobiidae) have expanded ... more During the last decades several species of Ponto-Caspian gobies (Pisces, Gobiidae) have expanded upstream from their native distributions and invaded most of Europe, albeit their reported distributions vary greatly. Three invasive Ponto-Caspian species have so far been reported in Croatia: bighead goby Ponticola kessleri (Neilson and Stepien, 2009), monkey goby Neogobius fluviatilis (Pallas, 1814) and round goby Neogobius melanostomus (Pallas, 1814). Their distribution, abundance and condition from the River Sava were analyzed over a three-year period (2010-2012). Distribution and condition of monkey goby in tributaries of the River Sava (Kupa, Kupčina, Korana and Ilova) were also presented. CPUE values (number of fish per 100 m shoreline) were calculated and compared between the sites. A total of 246 specimens of monkey goby, 141 specimens of round goby and 21 specimens of bighead goby were analysed. In terms of distribution, monkey goby was found along the entire longitudinal prof...
Appendix for paper: Piria, M., Jakšić, G., Jakovlić, I., Treer, T. (2015): Dietary habits of inva... more Appendix for paper: Piria, M., Jakšić, G., Jakovlić, I., Treer, T. (2015): Dietary habits of invasive Ponto-Caspian gobies in the Croatian part of the Danube River basin and their potential impact on benthic fish communities. Science of Total Environment, in press doi:10.1016/j.scitotenv.2015.05.125
Between 2007 and 2009, a total of 181 individual wild boar were scored using nineteen morphologic... more Between 2007 and 2009, a total of 181 individual wild boar were scored using nineteen morphological measurements from three geograp-hical regions to describe morphological variety of the population throughout Croatia. In some regions we found phenotypical variability of the wild boar population based on hybridization The results of ANOVA show that some va-riables were significantly different (body weight, tail length, trunk length) but some of them were not homogenous for all age classes (circumference of shin, the most caudal point of scapula, circumference at chest) and were unable to highlight differences among the areas. The redundancy analysis (RDA) sho-wed a connection of sampling sites with some morphological trait. Results of cluster analysis using TREE procedure indicate separation on the two subpo-pulations and suggesting the existence of morphological differences. Overall the results confirmed that different morphotypes of wild boar are detectable in some different areas ...
Recreational and professional fishermen often argue against each other. Therefore the aim of this... more Recreational and professional fishermen often argue against each other. Therefore the aim of this research was to compare the official data of both kinds of fishing on the Danube in the three neighbouring countries.
Being of a great socio-economic importance, recreational freshwater fishing is one of the most po... more Being of a great socio-economic importance, recreational freshwater fishing is one of the most popular pastimes in many countries, Croatia included. As the fishing pressure is constantly increasing, the monitoring of the fish stock is crucial for effective fisheries management. One of the reliable evaluations on the current state of the freshwater fish communities is based on the catch of the anglers. The aim of this study was to provide an overview of the monitoring of freshwater fish community in Croatia by anglers’ data over the six year period (2004-2009). The current quantity of fish species in Croatian freshwaters is evaluated by catch per unit effort (CPUE). The evaluated CPUE parameter was highest in 2006 (18.42 kg/per angler), and lowest in 2009 (15.43 kg/per angler). During the study period the number of anglers oscillated minimally. The yearly average number of anglers was 36,612 while the yearly average of total catch was approximately 618.656 kg. The results on the tota...
Considering huchen globally endangered (E), and the largest, endemic salmonid fish species, threa... more Considering huchen globally endangered (E), and the largest, endemic salmonid fish species, threatened severely by high dams construction, there is a strong need for stopping of its recent decline. Contradiction about the huchen migratory behavior and consistent records about their lacking from the fish ladders impose considering other solutions compensating the deleterious effects (decline in reservoir sections due to comprehensive alteration of environment; suppression of natural spawning in downstream sections due to hydropeaking; river bed siltation by flushing of reservoirs and decrease in general productivity of the riverine ecosystem; river bed erosion, sinking of the river bed and destroying of gravel bars and send banks, the habitats and spawning grounds) of high dams on them. Establishment of hatcheries revealed only limited success due to making them feral instead of native and due to decrease of genetic variability in fragmented populations. Still remains the strong need for extensive research about the type of fish ladder, slope, flow rate and quality of feeding water and hydraulic signals appropriate for huchen to enter into the ladder in downstream and upstream directions. However, it is also necessary to think about the preconditions that constructors of future high dams and those who runs the recent ones should fulfil to make them more environment-friendly. Those preconditions are related to minimal length of flowing riverine stretches, the least number of tributaries there appropriate for huchen natural spawning, as well as the management measures that are to be applied to minimize the harmful effects of high dams (e.g., accessibility to spawning sites in tributaries, providing of sufficient amount of the water of appropriate quality in them during the spawning season, catch of young-of-the-year huchen and the way of their dispersal throughout the catchment in concern, etc.).
On the survey of the recent records, the fish and lamprey fauna of the River Sava catchment consi... more On the survey of the recent records, the fish and lamprey fauna of the River Sava catchment consists of 74 species, 15 of which being considered alien. The indigenous species diversity, explained using the relation N = 0. 546 A0.232, fits well into the range common for large catchments in the Europe. Both taxonomic and ecological diversity, as well as the character of fish communities in streams and rivers are strongly correlated with the stream order. On the relative abundance of species in fish communities, the upper rithron fish communities cluster distinctly from those belonging to the middle rithron, within which several sub-groups of fish communities were distinguishable. Streams and small rivers of fish communities of the middle rithron character stand distinctly apart from those belonging to particular sections of large rivers (e.g., the Rivers Sava, Drina, Vrbas and Bosna), with the transitional type of middle rithron fish community in larger rivers (e.g., those in the Rivers Una and Sana) that resemble more to the fish communities common for middle rithron streams. Fish communities in the middle section of the River Sava in Croatia and in the bordering area with the Bosnia and Herzegovina mainly belong to the lower rithron, attaining the character of potamon in the most downstream, Serbian section. River Sava’s fish communities strongly interact with the ones occurring in the most downstream sections of their largest tributaries, e.g., the Rivers Una, Vrbas, Bosna, Drina and Kolubara, which makes them very similar in structure in the areas of river mouths. Classification of fish communities based solely on the presence and absence of species revealed similar general pat-tern of fish communities classification, though with the more sharp delimitation between those belonging to the upper and middle rithron on one, and to the lower rithron and potamon on the other side. That was supported by determination of fish communities belonging to the upper rithron with brown trout Salmo cf. trutta, European bullhead Cottus gobio and minnow Phoxinus phoxinus as the most common fish species. Fish communities belonging to the middle rithron were de-termined mainly with chub Squalius cephalus and spirlin Alburnoides bipunctatus, whereas brook barbel Barbus balcanicus and stone loach Barbatula barbatula occurred in both upper and middle rithron. Nase Chondrostoma nasus were associated with both middle and lower rithron fish communities. The most common fish species that determine the lower rithron fish communities were common bream Abramis brama, ide Idus idus and bleak Alburnus alburnus, with the northern pike Esox lucius, Balon’s ruffe Gymnocephalus baloni and racer goby Neogobius gymnotrachelus as significant species explaining fish communities of both lower rithron and potamon. The level of production of fish in the River Sava varies remarkably within the sections with the similar ecological features, as well as between the sections that differ for the type of fish community. The greatest biomass and annual natural production were recorded in the sections homing the potamon and lower rithron fish communities, especially in the flooding areas of side arms and oxbows which serve as spawning areas and nurseries. A total of 15 alien fish species was recorded in the River Sava catchment, the Prussian carp Carassius gibelio and brown bullhead Ameiurus nebulosus being assessed the most invasive in the areas with the potamon fish community. A strong impact from the both long-term and recent stocking with alien hatchery reared brown trout strains and rainbow trout in upper rithron fish communities was recently recognized. Mudminnow Umbra krameri and huchen (or Danube salmon) Hucho hucho are considered the two most threatened fish species of the River Sava catchment, where various types of river bed modifications, especially the damming, were seen the most prominent threatening factors for fish diversity.
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Papers by Marina Piria
worldwide. In continental Croatia, introduced trout of the Atlantic lineage hybridizes with native trout of the Danubian lineage, threatening the native genetic diversity. The geometric morphometrics approach was used in this study to analyse changes in shape between native trout, introduced trout and their hybrids, classified a priori by molecular phylogenetic analyses. A total of 19 landmarks and semi-landmarks were used to capture the shape of 92 trout individuals belonging to two lineages and their hybrids. Canonical variate analysis and discriminant function analysis were used to analyse and describe shape variation. A significant difference was found between the shape of the Atlantic lineage trout and both Danubian lineage trout and hybrids, with
the most prominent differences in body depth, head length and eye size. No statistically significant shape differences were observed between Danubian lineage
trout and the hybrids. The observed significant differences in shape could be the result of genetic diversity or trout phenotypic plasticity. Further studies are needed to clarify the origin of this variation in shape.
Materials and methods. Anal fin tissue was taken from 141 specimens of brown trout in 14 localities in the protected areas of Croatia, situated in the mountainous regions of Gorski Kotar, Žumberak, as well as Mountain Papuk in the western Slavonia. The total DNA was extracted and then the amplification of the mtDNA control region was carried out using primers Trutta-mt-F and HN20. Amplification of the 440 bp long region of the LDH-C1 gene locus was done using primers Ldhxon3F and Ldhxon4R. Amplified LDH-C* fragments were used for Restriction Fragment Length Polymorphism (RFLP) analysis using BselI restriction enzyme.
Results. Analysis of the CR mtDNA revealed the presence of two phylogenetic lineages, the DA and the Atlantic (AT). Haplotypes Da1, Da2, and Da22 were recorded within the DA lineage and At1 was recorded within the AT haplogroup. Two new haplotypes were described for the first time in this study and are named Da1f and Da1g. Restriction analysis of the lactate dehydrogenase gene locus revealed a high degree of hybridization between brown trout of DA and AT haplogroups.
Conclusion. The results of this study confirmed the complex molecular diversity of brown trout and the high degree of the introduction of non-native haplogroups into rivers of the Danube basin in Croatia. Conservation of native brown trout populations has become evident, as introduced allochthonous DA and AT haplogroups severely disrupt the indigenous brown trout stock.
addressed through existing legal instruments, but these are far from sufficient to tackle the problem comprehensively. The
FINS II Conference considered the relevance of Top 20 IAS issues (Top 10 threats and opportunities) for Europe determined
at the 1st Freshwater Invasiveness – Networking for Strategy (FINS I) conference held in Ireland in 2013. Using a similar
format of sequential group voting, threats from FINS I (lack of funding, of awareness and education; poor communication)
and several new threats (lack of lead agencies, of standardized management and of common approach; insufficient monitoring
and management on private property) were identified by 80 academics, applied scientists, policy makers and stakeholders
from 14 EU and three non-EU countries (including 10 invited speakers) during four workshop break-out sessions (legislation
remit in both EU/non-EU countries; best management and biosecurity practice for control; data management and early warning;
pathways of introductions and citizen science). Identified opportunities include improved cooperation and communication,
education and leadership to enhance public awareness and stakeholder participation, systems establishment for early detection,
rapid response, monitoring and management of IAS using standardised methods of data collection, storage and usage.The sets
of threats and opportunities identified underline the importance of international cooperation on IAS issues in communication,
education and funding as priorities, as well as in standardization of legislation, control methods and best practise of research.
worldwide. In continental Croatia, introduced trout of the Atlantic lineage hybridizes with native trout of the Danubian lineage, threatening the native genetic diversity. The geometric morphometrics approach was used in this study to analyse changes in shape between native trout, introduced trout and their hybrids, classified a priori by molecular phylogenetic analyses. A total of 19 landmarks and semi-landmarks were used to capture the shape of 92 trout individuals belonging to two lineages and their hybrids. Canonical variate analysis and discriminant function analysis were used to analyse and describe shape variation. A significant difference was found between the shape of the Atlantic lineage trout and both Danubian lineage trout and hybrids, with
the most prominent differences in body depth, head length and eye size. No statistically significant shape differences were observed between Danubian lineage
trout and the hybrids. The observed significant differences in shape could be the result of genetic diversity or trout phenotypic plasticity. Further studies are needed to clarify the origin of this variation in shape.
Materials and methods. Anal fin tissue was taken from 141 specimens of brown trout in 14 localities in the protected areas of Croatia, situated in the mountainous regions of Gorski Kotar, Žumberak, as well as Mountain Papuk in the western Slavonia. The total DNA was extracted and then the amplification of the mtDNA control region was carried out using primers Trutta-mt-F and HN20. Amplification of the 440 bp long region of the LDH-C1 gene locus was done using primers Ldhxon3F and Ldhxon4R. Amplified LDH-C* fragments were used for Restriction Fragment Length Polymorphism (RFLP) analysis using BselI restriction enzyme.
Results. Analysis of the CR mtDNA revealed the presence of two phylogenetic lineages, the DA and the Atlantic (AT). Haplotypes Da1, Da2, and Da22 were recorded within the DA lineage and At1 was recorded within the AT haplogroup. Two new haplotypes were described for the first time in this study and are named Da1f and Da1g. Restriction analysis of the lactate dehydrogenase gene locus revealed a high degree of hybridization between brown trout of DA and AT haplogroups.
Conclusion. The results of this study confirmed the complex molecular diversity of brown trout and the high degree of the introduction of non-native haplogroups into rivers of the Danube basin in Croatia. Conservation of native brown trout populations has become evident, as introduced allochthonous DA and AT haplogroups severely disrupt the indigenous brown trout stock.
addressed through existing legal instruments, but these are far from sufficient to tackle the problem comprehensively. The
FINS II Conference considered the relevance of Top 20 IAS issues (Top 10 threats and opportunities) for Europe determined
at the 1st Freshwater Invasiveness – Networking for Strategy (FINS I) conference held in Ireland in 2013. Using a similar
format of sequential group voting, threats from FINS I (lack of funding, of awareness and education; poor communication)
and several new threats (lack of lead agencies, of standardized management and of common approach; insufficient monitoring
and management on private property) were identified by 80 academics, applied scientists, policy makers and stakeholders
from 14 EU and three non-EU countries (including 10 invited speakers) during four workshop break-out sessions (legislation
remit in both EU/non-EU countries; best management and biosecurity practice for control; data management and early warning;
pathways of introductions and citizen science). Identified opportunities include improved cooperation and communication,
education and leadership to enhance public awareness and stakeholder participation, systems establishment for early detection,
rapid response, monitoring and management of IAS using standardised methods of data collection, storage and usage.The sets
of threats and opportunities identified underline the importance of international cooperation on IAS issues in communication,
education and funding as priorities, as well as in standardization of legislation, control methods and best practise of research.