Tomislav Treer

Genetic composition of the Jadro softmouth trout following translocation into a new habitat

Genetic founder effects of a historical translocation (1965; app. 12 generations ago) of endangered softmouth trout from the only remaining indigenous population to an adjacent uninhabited river were investigated.A comparison of 15 microsatellites from contemporary samples in both the source and re-established populations indicated a very low level of genetic diversity within the two populations. Furthermore, considerable differences in estimates of variability and effective population sizes were detected between populations, but no recent bottlenecks were evident. Our data suggest that the re-established population has lost variation due to genetic drift associated with founder effects following the translocation. Accordingly, in relation to management, we suggest that the re-established population could serve as a secondary source of individuals to buffer possible extinction due to demographic events. Finally, conservation initiatives to enhance the census population size and increase levels of variability in the re-established population are proposed.

Ichthyofauna of the River Sava System

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 A 0.232, fits well into the range common for large catchments in 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 rhithron fish communities cluster distinctly from those belonging to the middle rhithron, within which several subgroups of fish communities were distinguishable. Fish communities of the middle rhithron character in streams and small rivers 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 rhithron fish community in larger rivers (e.g., those in the Rivers Una and Sana) that resemble more to the fish communities common in middle rhithron streams. Fish communities in the middle section of the River Sava in Croatia and in the bordering area with Bosnia and Herzegovina mainly belong to the lower rhithron, 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 pattern of fish community classification, though with the more sharp delimitation between those belonging to the upper and middle rhithron on one and to the lower rhithron and potamon on the other side. That was supported by the determination of fish communities belonging to the upper rhithron 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 rhithron were determined mainly with chub Squalius cephalus and spirlin Alburnoides bipunctatus, whereas brook barbel Barbus balcanicus and stone loach Barbatula barbatula occurred in both upper rhithron and middle rhithron. Nase Chondrostoma nasus were associated with both middle and lower rhithron fish communities. The most common fish species that determine the lower rhithron 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 rhithron 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 rhithron 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 both long-term and recent stocking with alien hatchery-reared brown trout strains and rainbow trout in the upper rhithron 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 riverbed modifications, especially the damming, were seen the most prominent threatening factors for fish diversity.

Past and present of and perspectives for the Danube huchen, Hucho hucho (L.), in the Danube basin

Abstract Huchen, Hucho hucho (L.), also known as Danube salmon, is an iconic, endemic species inhabiting the Danube basin of Central Europe. Historically, the Danube huchen inhabited a significant portion of the Danube drainage basin stretching to the Iron Gate and the majority of large and medium-sized tributaries. Larger populations in the natural zoogeographical distribution of Danube huchen were once found in Austria, Bavaria, the former Yugoslavia, Slovakia, and western Ukraine. Currently, the species is severely fragmented within the Danube drainage, where most populations exclusively depend on stocking and natural reproduction is very limited due to habitat alterations and flow regime changes. In the Czech Republic and Poland, Danube huchen occurrence is the result of introducing the species to several rivers in the Baltic Sea and North Sea drainage basins. Danube huchen is a threatened species throughout is range of occurrence, and, according to IUCN criteria, it is classified as endangered (EN). Habitat degradation is the most serious negative factor impacting huchen populations. Dam construction, pollution, and river regulation have led to loss and degradation of spawning sites. Detailed research on population abundance and structure is greatly needed to help identify the populations which are most threatened and to help to develop the best protection systems.

Comparative proteomics analysis of teleost intermuscular bones and ribs provides insight into their development

BackgroundIntermuscular bones (IBs) and ribs both are a part of skeletal system in teleosts, but with different developing process. The chemical composition of fish IBs and ribs as well as the underlying mechanism about their development have not been investigated. In the present study, histological structures showed that one bone cavity containing osteoclasts were existed in ribs, but not in IBs of Megalobrama amblycephala. We constructed the first proteomics map for fish bones including IBs and ribs, and identified the differentially expressed proteins between IBs and ribs through iTRAQ LC-MS/MS proteomic analysis.ResultsThe proteins extracted from IBs and ribs at 1- to 2-year old M. amblycephala were quantified 2,342 proteins, with 1,451 proteins annotated with GO annotation in biological processes, molecular function and cellular component. A number of bone related proteins as well as pathways were identified in the study. A total of 93 and 154 differently expressed proteins were identified in comparison groups of 1-IB-vs-1-Rib and 2-IB-vs-2-Rib, which indicated the obvious differences of chemical composition between these two bone tissues. The two proteins (vitronectin b precursor and matrix metalloproteinase-2) related to osteoclasts differentiation were significantly up-regulated in ribs compared with IBs (P < 0.05), which was in accordance with the results from histological structures. In comparison groups of 1-IB-vs-2-IB and 1-Rib-vs-2-Rib, 33 and 51 differently expressed proteins were identified and the function annotation results showed that these proteins were involved in regulating bone development and differentiation. Subsequently, 11 and 13 candidate proteins in comparison group of 1-IB-vs-1-Rib and 1-IB-vs-2-IB related to bone development were validated by MRM assays.ConclusionsOur present study suggested the different key proteins involved in the composition of fish ribs and IBs as well as their growth development. These findings could provide important clues towards further understanding of fish skeletal system and the roles of proteins playing in regulating diverse biological processes in fish.

Variation of wild boar reproductive performance in different habitat types : implications for management

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.

Are the dinaric mountains a boundary between continental and mediterranean wild boar populations in Croatia

Wild boar is the most important large game species in Croatia, with populations subjected to hunting/management programs. There are indications from previous analyses of morphological variation and reproductive performance that population structure of wild boar in Croatia is strongly influenced by the Dinaric mountain range that separates Croatia in two biogeographic regions: Continental and Mediterranean. Of the two main wild boar haplogroups found in Europe, the most widespread is the E1 clade (present from Portugal to Russia), while the E2 clade is found within the Italian peninsula and on Sardinia. Outside Italy, the E2 clade has to date been found only in archaeological samples from the Mediterranean region of Croatia. The aims of this study were to investigate the hypotheses that (i) the Dinaric Mountains act as a natural boundary separating the Continental and Mediterranean wild boar subpopulations in Croatia; and (ii) the mtDNA E2 clade is present in Croatian wild boar. A total of 14 unlinked microsatellite loci were examined in 264 geo-referenced individuals, and the 486-bp fragment of the mtDNA control region sequence was examined in 69 individuals. The results suggest that the region of the Dinaric Mountains. represents a weak boundary between the Continental and Mediterranean subpopulations, and that the predominant factor causing the observed genetic structuring is isolation by distance. Based on these results, it can be proposed that the Croatian wild boar population in the mainland should be managed as a whole. Three variable sites and four haplotypes were obtained from the mtDNA sequences, all of which belonged to the major European clade (E1).

A review of introduction of common carp Cyprinus carpio in Pakistan: origin, purpose, impact and management

Abstract Common carp Cyprinus carpio was introduced from Thailand to Pakistan in 1964 for the purpose of aquaculture. Due to its high tolerance to temperature and turbidity, and prolific pond breeding habit, it was established promptly in most of natural inland waters, including rivers, lakes, streams, canals, wetlands and even village ponds of the country. Although common carp became one of the most abundant cyprinid species in inland waters and important food fish in Pakistan, its impact is not well documented. Fish farming of common carp has been carried out in Pakistan since 1970; initially it grew slowly but now it is playing an important role in the economy of the country by employing more than 400,000 people. Nowadays, farming of freshwater carps is present throughout Pakistan, especially in the provinces of Punjab and Sindh. There is a huge potential in common carp farming and it could help increase the livelihood of people and gross domestic product (GDP) of the country as well. Still, there is a need to improve the fish farming practice to meet the world-class demands that could only be possible by the keen interest of policy makers and stake holders with better management.

First record of palmetto bass (Morone saxatilis x M. chrysops) in the Croatian part of the river Danube

On October 19, 2010, a male specimen of palmetto bass (Morone saxatilis x M. chrysops) was caught by commer- cial fishing net in the Croatian section of the river Danube (302 mm TL and 331 g). It was in its third year of age (2+). A condition factor of 1.20 was based on the total length. Six specimens of prey fish were found in its gut (22.97 g altogether). Morphometric and meristic traits of this palmetto bass are presented and its possible threat to the fish community is dis- cussed.

Microsatellite-based genetic variability and differentiation of hatchery and feral common carp Cyprinus carpio L. (Cyprinidae, Cypriniformes) populations in Croatia.

Common carp production has an important status in Croatian aquaculture. In addition, the sport fishing of common carp in open waters is very popular, but it is often based on stocking from fish farms. Using fifteen microsatellites, 243 individuals from 5 hatchery and 5 feral populations have been analyzed. A total number of 148 alleles were recorded. However, the mean number of alleles per locus was remarkably low. Pairwise FST values (0.026-0.130) were significant (P<0.01), demonstrating differentiation among populations. The Markov chain method test showed that all the popula- tions deviated from HWE (P <0.05). After sequential Bonferroni correction only the Vrana lake was in HWE in all the loci but MFW20. The factors that may result in genetic divergence and significant reduction of the observed heterozygosity are discussed. AMOVA results for 10 populations indicate that the percentage of the variation among populations was 6.26%, which is lower than the variation within populations (91.04%).

The common carp Cyprinus carpio in Croatia (Danube and Adriatic basins): a historical review

This review provides the first historical account of the ecology and biology of common carp Cyprinus carpio in the Danube and Adriatic basins of Croatia, and emphasises the species’ economic relevance and management implications. As a semi-native species that is native to the Danube but translocated across the Adriatic Basin, carp plays an important role for aquaculture, recreational and artisanal fisheries. However, original strains have now disappeared, and because of genetic pollution in inland waters there is an increasing demand for restoring populations of the now rare and threatened wild carp, making conservation measures a priority. Translocations of carp across water bodies of the Adriatic Basin mostly for food supply did not prove successful in the long term, as the resulting ecological impacts may have been higher than the expected economic advantages. Measures for the prevention of further (uncontrolled) carp re-stocking are therefore necessary and this will require closer collaboration between scientists and environmental managers.