Milica Jaćimović - Academia.edu (original) (raw)

Papers by Milica Jaćimović

Универзитет у Београду, Dec 28, 2015

During the last decades in the freshwater system in Serbia 32 allochthonous fish species appeared... more During the last decades in the freshwater system in Serbia 32 allochthonous fish species appeared, and they can be divided into five groups according to their region of origin: Asian, Ponto-Caspian, North American, South American, and Europe without Ponto-Caspian region. The Asian and Ponto-Caspian species are the most numerous. In the first group are representatives of fish fauna which are originally from Asia and they are intentionally introduced into open waters and aquaculture in Serbia, while the second group represents the migrants spreading their range from the Black Sea into freshwater systems. Some of these species already have established populations. Representatives of marine origin that inhabit freshwater systems in Serbia are: <em>Syngnathus abaster, Neogobius fluviatilis, Neogobius melanostomus, Babka gymnotrachelus, Ponticola kessleri, Proterorhinus semilunaris, Knipowitschia caucasica, Benthophyllus stellatus, Gasterosteus aculeatus, Morone saxatilis x Morone c...

Aquatic Conservation: Marine and Freshwater Ecosystems

Archives of Biological Sciences, 2021

In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-wes... more In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-west invaders of European inland waters, but there are insufficient data on its biology in the countries it has entered. Specimens of two sets of samples from November 2015 (n=25) and October 2016 (n=39) were caught in the Danube River channel near Veliko Gradište (Serbia) by electrofishing. Thirty morphometric and eight meristic characteristics of the collected fish were measured with the aim of describing the general body shape in more detail using the "point-to-point" method. This is the first attempt to obtain morphometric and meristic characteristics of Amur sleeper caught in Serbia. The results revealed a relatively low variability in the morphometric and meristic characters of the studied population. When compared to other studies, there was a great variability of the studied characteristics between geographically distant European populations that inhabit different water body types. Female fish had more robust bodies compared to males of the same length, while males had longer pectoral, anal and dorsal fins. Additionally, 2+ individuals had more robust heads and jaws, as well as longer anterior parts of the body compared to 1+ individuals of the same size.

Biological Invasions, May 25, 2014

Invasive species have the ability to modify their life-history traits in newly colonized areas, w... more Invasive species have the ability to modify their life-history traits in newly colonized areas, with positive shifts in specific life history traits under favourable environmental conditions. If such positive changes in their life history result in a comparably larger population growth rate, it may give them a competitive edge over native species, support faster range expansion and contribute to their invasion success. Within the present paper we hypothesized that the demographic flexibility represents an important contribution to the invasion success of exotic species, and that demographic flexibility patterns of invasive species differ from those in unsuccessful invaders. We tested this hypothesis by the use of elasticity analysis applied on simple age-structured population models of invasive fish species in the Danube River, as well as of non-native species that failed to establish or become invasive. Findings imply that the invasive fish species could have the ability to experience a more rapid population growth under favourable environmental conditions, especially those that sustain recruitment, while at the same time being more robust to changes in survival. The highest population elasticity among the assessed alien invasive species was detected in stone moroko (Pseudorasbora parva). The described approach has the potential to be used as an additional screening tool for invasive species. When combined with other invasion risk profiling methods, it can provide additional insight into characteristics of species invasions and in invasion potential of a species.

Archives of Biological Sciences, 2021

The black bullhead is an invasive species that forms dense populations and has a negative impact ... more The black bullhead is an invasive species that forms dense populations and has a negative impact on the native ichthyofauna. Recent studies indicate that it is one of the most dominant invasive fish species in Serbian waters. Feeding habits based on stomach contents of individuals caught in Lake Sava were analyzed as a first step towards evaluating its possible negative impact on the native fish fauna of the lake. The following indices for diet analysis were applied: vacuity index, frequency of occurrence, numerical abundance and prominence value. Trophic niche breadth and seasonal trophic diversity were calculated using the Shannon?s index. The diet spectrum comprised 16 different prey categories from five groups: Mollusca, Crustacea, Insecta, Teleostei and plants. Fish were the main prey in all seasons, followed by aquatic invertebrates. Plant material and terrestrial insects were used as food in relatively small quantities. Predation on fish eggs was also detected. Our research c...

The aim of this work was to compare the efficiency of two different methods for fish sampling and... more The aim of this work was to compare the efficiency of two different methods for fish sampling and to assess the influence of the twilight period on the catch of gobiids along the Danube River in Serbia. The samplings were performed by electrofishing and beach seining in inshore parts of the Danube River with water depth up to 120 cm at four locations: Novi Sad, Belgrade, Tekija, and Prahovo, in October 2012 and September 2013. At each location, the samplings were performed at 17:30, 18:30, 19:30 and 20:30. Totally, 539 gobiids were caught. The highest number of specimens (218) was registered at Tekija, while lower numbers were registered at Belgrade (192) and Prahovo (117), and only 12 specimens were caught at Novi Sad. The catch of the round goby Neogobius melanostomus and monkey goby Neogobius fluviatilis was more efficient by beach seining than by electrofishing, whereas the catch of the tubenose goby Proterorhinus semilunaris was more efficient by electrofishing. Both methods ha...

Crni američki patuljasti som (Ameiurus melas Rafinesque, 1820) je najzastupljenija i najuspešnija... more Crni američki patuljasti som (Ameiurus melas Rafinesque, 1820) je najzastupljenija i najuspešnija alohtona vrsta ribe koja naseljava kopnene vode Evrope. Istraživanja koja su sprovedena u proteklih nekoliko godina ukazuju na to da je ovo dominantna invazivna vrsta i u mnogim kopnenim vodama u Srbiji. Cilj istraživanja se odnosio na ispitivanje populacionih atributa patuljastog soma u Savskom jezeru, kao i na bioakumulaciju teških metala i mikroelemenata u različitim tkivima. Terenska istraživanja vršena su u periodu od 2009. do 2012. godine. Jedinke su uzorkovane jednom mesečno, četiri dana za redom. Laboratorijska obrada prikupljenih uzoraka obuhvatila je merenje totalne dužine tela (TL) i ukupne težine tela ulovljenih primeraka. Nakon disekcije jedinki merena je težina tela bez utrobe, kao i masa jetre i gonada.Struktura populacije utvrđena je kombinovanjem dve metode – analizom starosti jedinki i analizom dužinskih frekvencija. Starost jedinki određena je takođe uz pomoć dve meto...

Archives of Biological Sciences, 2021

In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-wes... more In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-west invaders of European inland waters, but there are insufficient data on its biology in the countries it has entered. Specimens of two sets of samples from November 2015 (n=25) and October 2016 (n=39) were caught in the Danube River channel near Veliko Gradiste (Serbia) by electrofishing. Thirty morphometric and eight meristic characteristics of the collected fish were measured with the aim of describing the general body shape in more detail using the ?point-topoint? method. This is the first attempt to obtain morphometric and meristic characteristics of Amur sleeper caught in Serbia. The results revealed a relatively low variability in the morphometric and meristic characters of the studied population. When compared to other studies, there was a great variability of the studied characteristics between geographically distant European populations that inhabit different water body types. F...

The aim of this work was to compare the efficiency of two different methods for fish sampling and... more The aim of this work was to compare the efficiency of two different methods for fish sampling and to assess the influence of the twilight period on the catch of gobiids along the Danube River in Serbia. The samplings were performed by electrofishing and beach seining in inshore parts of the Danube River with water depth up to 120 cm at four locations: Novi Sad, Belgrade, Tekija, and Prahovo, in October 2012 and September 2013. At each location, the samplings were performed at 17:30, 18:30, 19:30 and 20:30. Totally, 539 gobiids were caught. The highest number of specimens (218) was registered at Tekija, while lower numbers were registered at Belgrade (192) and Prahovo (117), and only 12 specimens were caught at Novi Sad. The catch of the round goby Neogobius melanostomus and monkey goby Neogobius fluviatilis was more efficient by beach seining than by electrofishing, whereas the catch of the tubenose goby Proterorhinus semilunaris was more efficient by electrofishing. Both methods ha...

Slovenian Veterinary Research, 2015

Distribution of 17 chemical elements in gills, muscle, and liver of the European perch (Perca flu... more Distribution of 17 chemical elements in gills, muscle, and liver of the European perch (Perca fluviatilis) and black bullhead (Ameiurus melas) from the Sava Lake (Serbia) was studied to detect bioaccumulation patterns in relation to the species’ diet and trophic level. Concentrations of Ba, Cd, Co, Cr, Li, Ni, Pb, B, and Se were below the detection limits. Concentrations of Al, Fe, Mn, Sr, and Zn were higher in gills of the black bullhead; As, Mo, and Sr were higher in liver of the European perch; Fe and Zn were higher in liver of the black bullhead. In muscle, a significant difference between species was found only for Sr. Copper was detected only in liver of the black bullhead. Similarity in elemental concentrations in both species could be explained by a relatively similar diet of these two species, while the differences, especially in gills, could be explained by different habitat preferences.

There is a lack of adequate estimates of the fish stocks in the Belgrade city area, Serbia, as we... more There is a lack of adequate estimates of the fish stocks in the Belgrade city area, Serbia, as well as of the current fishery pressure on fish diversity and of the contamination level of fish meat. These factors obstruct efforts to conduct valorisation of the current state and potential development of this resource. During 2012 and 2013, an assessment of the current state of the fish resources in Belgrade fishery waters was performed, in order to establish a good basis for the development of a monitoring system on the state of fish stocks and their exploitation. Fish were collected at ten localities in the Danube, Sava and Kolubara rivers. The fish stock composition and biomass were determined at each of the localities. The results indicate that the commercial fishery in the Danube and Sava rivers is characterised by seasonal variability regarding the amount and the composition of fish catch, while the ratio of high versus low quality fish remained relatively stable over time. In most of the analyzed fish, heavy metal concentrations remained below the prescribed maximum allowable concentrations (MAC). However, concentrations of mercury, cadmium and zinc exceeded MAC in the tissues of a number of individuals of Wels catfish, common carp, sterlet, pikeperch, European perch, ruffe, and sichel, which indicates that the meat of Danube fish species can be utilised in human diet only in limited quantities, and that it is necessary to establish permanent monitoring of heavy metal concentrations in this area. Based on the results, a system of indicators was defined and a monitoring system for the Belgrade fishery waters was proposed. Pikeperch and freshwater bream were selected as major species for fish meat quality monitoring, while the implementation of fishery monitoring program should comprise both economically important fish species and certain nonindigenous species.

Geobotany Studies

The Danube River basin represents a hotspot for the European freshwater diversity. The Danube in ... more The Danube River basin represents a hotspot for the European freshwater diversity. The Danube in Serbia is characterized by a significant level of fish diversity, as well as by economically important fish resources. However, the Danube fish fauna is facing a number of adverse anthropogenic impacts, such as unsustainable fishery, habitat loss and fragmentation, water pollution and non-native species invasions. In this chapter, the major adverse impacts on the Danube fish communities in Serbia are presented, and the critical management measures are discussed, such as those related to supportive stocking and other conservation efforts. In order to ensure adequate protection and sustainable management of fish resources in the Danube in Serbia, it will be critical to introduce effective monitoring system, to establish and enforce adequate management measures, and to intensify research efforts on critical issues related to fish management and conservation.

Fisheries Management and Ecology

Distribution of 17 chemical elements in gills, muscle, and liver of the European perch ( Perca fl... more Distribution of 17 chemical elements in gills, muscle, and liver of the European perch ( Perca fluviatilis) and black bullhead ( Ameiurus melas) from the Sava Lake (Serbia) was studied to detect bioaccumulation patterns in relation to the species’ diet and trophic level. Concentrations of Ba, Cd, Co, Cr, Li, Ni, Pb, B, and Se were below the detection limits. Concentrations of Al, Fe, Mn, Sr, and Zn were higher in gills of the black bullhead; As, Mo, and Sr were higher in liver of the European perch; Fe and Zn were higher in liver of the black bullhead. In muscle, a significant difference between species was found only for Sr. Copper was detected only in liver of the black bullhead. Similarity in elemental concentrations in both species could be explained by a relatively similar diet of these two species, while the differences, especially in gills, could be explained by different habitat preferences.

Ecology of Freshwater Fish, 2014

ABSTRACT Fishery in the Danube River basin has been characterised over the past century by increa... more ABSTRACT Fishery in the Danube River basin has been characterised over the past century by increasing fishing levels, illegal fishing practices and poor regulations. However, there is a remarkable lack of available information on the actual status of fish stocks, as well as on the trends and sustainability of fisheries, which poses a problem for the development of adequate policy and management measures. In this study, we assessed the trends in the commercial fishery in the Middle Danube in Serbia during 1969–1989 and 2006–2010 by evaluating the temporal changes in life history-related indicators that might point out unsustainable fishing pressures. Moreover, we present the approach of using the catch-weighted mean egg-per-recruit (EPR) index as a proxy for the overall resilience of fish stocks to fishing. Results indicated a marked shift towards smaller fish that mature earlier and have a shorter lifespan. Landings also shifted towards species at lower trophic levels, with a mean trophic level decline at a rate of approximately 0.16 per decade. Results indicated likely presence of the ‘fishing through the food web’ phenomenon. At the same time, catch-weighted community mean of the 20% EPR threshold ratio (EPR20%) increased by 4.2%, indicating the increase of the overall resilience to fishing of the exploited species. Obtained results indicated the importance of using such metrics for the assessments of trends in fishery. The approach and results presented here could be of interest for the scientific community and stakeholders involved in fishery management.

Biological Invasions, 2014

Универзитет у Београду, Dec 28, 2015

During the last decades in the freshwater system in Serbia 32 allochthonous fish species appeared... more During the last decades in the freshwater system in Serbia 32 allochthonous fish species appeared, and they can be divided into five groups according to their region of origin: Asian, Ponto-Caspian, North American, South American, and Europe without Ponto-Caspian region. The Asian and Ponto-Caspian species are the most numerous. In the first group are representatives of fish fauna which are originally from Asia and they are intentionally introduced into open waters and aquaculture in Serbia, while the second group represents the migrants spreading their range from the Black Sea into freshwater systems. Some of these species already have established populations. Representatives of marine origin that inhabit freshwater systems in Serbia are: <em>Syngnathus abaster, Neogobius fluviatilis, Neogobius melanostomus, Babka gymnotrachelus, Ponticola kessleri, Proterorhinus semilunaris, Knipowitschia caucasica, Benthophyllus stellatus, Gasterosteus aculeatus, Morone saxatilis x Morone c...

Aquatic Conservation: Marine and Freshwater Ecosystems

Archives of Biological Sciences, 2021

In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-wes... more In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-west invaders of European inland waters, but there are insufficient data on its biology in the countries it has entered. Specimens of two sets of samples from November 2015 (n=25) and October 2016 (n=39) were caught in the Danube River channel near Veliko Gradište (Serbia) by electrofishing. Thirty morphometric and eight meristic characteristics of the collected fish were measured with the aim of describing the general body shape in more detail using the "point-to-point" method. This is the first attempt to obtain morphometric and meristic characteristics of Amur sleeper caught in Serbia. The results revealed a relatively low variability in the morphometric and meristic characters of the studied population. When compared to other studies, there was a great variability of the studied characteristics between geographically distant European populations that inhabit different water body types. Female fish had more robust bodies compared to males of the same length, while males had longer pectoral, anal and dorsal fins. Additionally, 2+ individuals had more robust heads and jaws, as well as longer anterior parts of the body compared to 1+ individuals of the same size.

Biological Invasions, May 25, 2014

Invasive species have the ability to modify their life-history traits in newly colonized areas, w... more Invasive species have the ability to modify their life-history traits in newly colonized areas, with positive shifts in specific life history traits under favourable environmental conditions. If such positive changes in their life history result in a comparably larger population growth rate, it may give them a competitive edge over native species, support faster range expansion and contribute to their invasion success. Within the present paper we hypothesized that the demographic flexibility represents an important contribution to the invasion success of exotic species, and that demographic flexibility patterns of invasive species differ from those in unsuccessful invaders. We tested this hypothesis by the use of elasticity analysis applied on simple age-structured population models of invasive fish species in the Danube River, as well as of non-native species that failed to establish or become invasive. Findings imply that the invasive fish species could have the ability to experience a more rapid population growth under favourable environmental conditions, especially those that sustain recruitment, while at the same time being more robust to changes in survival. The highest population elasticity among the assessed alien invasive species was detected in stone moroko (Pseudorasbora parva). The described approach has the potential to be used as an additional screening tool for invasive species. When combined with other invasion risk profiling methods, it can provide additional insight into characteristics of species invasions and in invasion potential of a species.

Archives of Biological Sciences, 2021

The black bullhead is an invasive species that forms dense populations and has a negative impact ... more The black bullhead is an invasive species that forms dense populations and has a negative impact on the native ichthyofauna. Recent studies indicate that it is one of the most dominant invasive fish species in Serbian waters. Feeding habits based on stomach contents of individuals caught in Lake Sava were analyzed as a first step towards evaluating its possible negative impact on the native fish fauna of the lake. The following indices for diet analysis were applied: vacuity index, frequency of occurrence, numerical abundance and prominence value. Trophic niche breadth and seasonal trophic diversity were calculated using the Shannon?s index. The diet spectrum comprised 16 different prey categories from five groups: Mollusca, Crustacea, Insecta, Teleostei and plants. Fish were the main prey in all seasons, followed by aquatic invertebrates. Plant material and terrestrial insects were used as food in relatively small quantities. Predation on fish eggs was also detected. Our research c...

The aim of this work was to compare the efficiency of two different methods for fish sampling and... more The aim of this work was to compare the efficiency of two different methods for fish sampling and to assess the influence of the twilight period on the catch of gobiids along the Danube River in Serbia. The samplings were performed by electrofishing and beach seining in inshore parts of the Danube River with water depth up to 120 cm at four locations: Novi Sad, Belgrade, Tekija, and Prahovo, in October 2012 and September 2013. At each location, the samplings were performed at 17:30, 18:30, 19:30 and 20:30. Totally, 539 gobiids were caught. The highest number of specimens (218) was registered at Tekija, while lower numbers were registered at Belgrade (192) and Prahovo (117), and only 12 specimens were caught at Novi Sad. The catch of the round goby Neogobius melanostomus and monkey goby Neogobius fluviatilis was more efficient by beach seining than by electrofishing, whereas the catch of the tubenose goby Proterorhinus semilunaris was more efficient by electrofishing. Both methods ha...

Crni američki patuljasti som (Ameiurus melas Rafinesque, 1820) je najzastupljenija i najuspešnija... more Crni američki patuljasti som (Ameiurus melas Rafinesque, 1820) je najzastupljenija i najuspešnija alohtona vrsta ribe koja naseljava kopnene vode Evrope. Istraživanja koja su sprovedena u proteklih nekoliko godina ukazuju na to da je ovo dominantna invazivna vrsta i u mnogim kopnenim vodama u Srbiji. Cilj istraživanja se odnosio na ispitivanje populacionih atributa patuljastog soma u Savskom jezeru, kao i na bioakumulaciju teških metala i mikroelemenata u različitim tkivima. Terenska istraživanja vršena su u periodu od 2009. do 2012. godine. Jedinke su uzorkovane jednom mesečno, četiri dana za redom. Laboratorijska obrada prikupljenih uzoraka obuhvatila je merenje totalne dužine tela (TL) i ukupne težine tela ulovljenih primeraka. Nakon disekcije jedinki merena je težina tela bez utrobe, kao i masa jetre i gonada.Struktura populacije utvrđena je kombinovanjem dve metode – analizom starosti jedinki i analizom dužinskih frekvencija. Starost jedinki određena je takođe uz pomoć dve meto...

Archives of Biological Sciences, 2021

In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-wes... more In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-west invaders of European inland waters, but there are insufficient data on its biology in the countries it has entered. Specimens of two sets of samples from November 2015 (n=25) and October 2016 (n=39) were caught in the Danube River channel near Veliko Gradiste (Serbia) by electrofishing. Thirty morphometric and eight meristic characteristics of the collected fish were measured with the aim of describing the general body shape in more detail using the ?point-topoint? method. This is the first attempt to obtain morphometric and meristic characteristics of Amur sleeper caught in Serbia. The results revealed a relatively low variability in the morphometric and meristic characters of the studied population. When compared to other studies, there was a great variability of the studied characteristics between geographically distant European populations that inhabit different water body types. F...

The aim of this work was to compare the efficiency of two different methods for fish sampling and... more The aim of this work was to compare the efficiency of two different methods for fish sampling and to assess the influence of the twilight period on the catch of gobiids along the Danube River in Serbia. The samplings were performed by electrofishing and beach seining in inshore parts of the Danube River with water depth up to 120 cm at four locations: Novi Sad, Belgrade, Tekija, and Prahovo, in October 2012 and September 2013. At each location, the samplings were performed at 17:30, 18:30, 19:30 and 20:30. Totally, 539 gobiids were caught. The highest number of specimens (218) was registered at Tekija, while lower numbers were registered at Belgrade (192) and Prahovo (117), and only 12 specimens were caught at Novi Sad. The catch of the round goby Neogobius melanostomus and monkey goby Neogobius fluviatilis was more efficient by beach seining than by electrofishing, whereas the catch of the tubenose goby Proterorhinus semilunaris was more efficient by electrofishing. Both methods ha...

Slovenian Veterinary Research, 2015

Distribution of 17 chemical elements in gills, muscle, and liver of the European perch (Perca flu... more Distribution of 17 chemical elements in gills, muscle, and liver of the European perch (Perca fluviatilis) and black bullhead (Ameiurus melas) from the Sava Lake (Serbia) was studied to detect bioaccumulation patterns in relation to the species’ diet and trophic level. Concentrations of Ba, Cd, Co, Cr, Li, Ni, Pb, B, and Se were below the detection limits. Concentrations of Al, Fe, Mn, Sr, and Zn were higher in gills of the black bullhead; As, Mo, and Sr were higher in liver of the European perch; Fe and Zn were higher in liver of the black bullhead. In muscle, a significant difference between species was found only for Sr. Copper was detected only in liver of the black bullhead. Similarity in elemental concentrations in both species could be explained by a relatively similar diet of these two species, while the differences, especially in gills, could be explained by different habitat preferences.

There is a lack of adequate estimates of the fish stocks in the Belgrade city area, Serbia, as we... more There is a lack of adequate estimates of the fish stocks in the Belgrade city area, Serbia, as well as of the current fishery pressure on fish diversity and of the contamination level of fish meat. These factors obstruct efforts to conduct valorisation of the current state and potential development of this resource. During 2012 and 2013, an assessment of the current state of the fish resources in Belgrade fishery waters was performed, in order to establish a good basis for the development of a monitoring system on the state of fish stocks and their exploitation. Fish were collected at ten localities in the Danube, Sava and Kolubara rivers. The fish stock composition and biomass were determined at each of the localities. The results indicate that the commercial fishery in the Danube and Sava rivers is characterised by seasonal variability regarding the amount and the composition of fish catch, while the ratio of high versus low quality fish remained relatively stable over time. In most of the analyzed fish, heavy metal concentrations remained below the prescribed maximum allowable concentrations (MAC). However, concentrations of mercury, cadmium and zinc exceeded MAC in the tissues of a number of individuals of Wels catfish, common carp, sterlet, pikeperch, European perch, ruffe, and sichel, which indicates that the meat of Danube fish species can be utilised in human diet only in limited quantities, and that it is necessary to establish permanent monitoring of heavy metal concentrations in this area. Based on the results, a system of indicators was defined and a monitoring system for the Belgrade fishery waters was proposed. Pikeperch and freshwater bream were selected as major species for fish meat quality monitoring, while the implementation of fishery monitoring program should comprise both economically important fish species and certain nonindigenous species.

Geobotany Studies

The Danube River basin represents a hotspot for the European freshwater diversity. The Danube in ... more The Danube River basin represents a hotspot for the European freshwater diversity. The Danube in Serbia is characterized by a significant level of fish diversity, as well as by economically important fish resources. However, the Danube fish fauna is facing a number of adverse anthropogenic impacts, such as unsustainable fishery, habitat loss and fragmentation, water pollution and non-native species invasions. In this chapter, the major adverse impacts on the Danube fish communities in Serbia are presented, and the critical management measures are discussed, such as those related to supportive stocking and other conservation efforts. In order to ensure adequate protection and sustainable management of fish resources in the Danube in Serbia, it will be critical to introduce effective monitoring system, to establish and enforce adequate management measures, and to intensify research efforts on critical issues related to fish management and conservation.

Fisheries Management and Ecology

Distribution of 17 chemical elements in gills, muscle, and liver of the European perch ( Perca fl... more Distribution of 17 chemical elements in gills, muscle, and liver of the European perch ( Perca fluviatilis) and black bullhead ( Ameiurus melas) from the Sava Lake (Serbia) was studied to detect bioaccumulation patterns in relation to the species’ diet and trophic level. Concentrations of Ba, Cd, Co, Cr, Li, Ni, Pb, B, and Se were below the detection limits. Concentrations of Al, Fe, Mn, Sr, and Zn were higher in gills of the black bullhead; As, Mo, and Sr were higher in liver of the European perch; Fe and Zn were higher in liver of the black bullhead. In muscle, a significant difference between species was found only for Sr. Copper was detected only in liver of the black bullhead. Similarity in elemental concentrations in both species could be explained by a relatively similar diet of these two species, while the differences, especially in gills, could be explained by different habitat preferences.

Ecology of Freshwater Fish, 2014

ABSTRACT Fishery in the Danube River basin has been characterised over the past century by increa... more ABSTRACT Fishery in the Danube River basin has been characterised over the past century by increasing fishing levels, illegal fishing practices and poor regulations. However, there is a remarkable lack of available information on the actual status of fish stocks, as well as on the trends and sustainability of fisheries, which poses a problem for the development of adequate policy and management measures. In this study, we assessed the trends in the commercial fishery in the Middle Danube in Serbia during 1969–1989 and 2006–2010 by evaluating the temporal changes in life history-related indicators that might point out unsustainable fishing pressures. Moreover, we present the approach of using the catch-weighted mean egg-per-recruit (EPR) index as a proxy for the overall resilience of fish stocks to fishing. Results indicated a marked shift towards smaller fish that mature earlier and have a shorter lifespan. Landings also shifted towards species at lower trophic levels, with a mean trophic level decline at a rate of approximately 0.16 per decade. Results indicated likely presence of the ‘fishing through the food web’ phenomenon. At the same time, catch-weighted community mean of the 20% EPR threshold ratio (EPR20%) increased by 4.2%, indicating the increase of the overall resilience to fishing of the exploited species. Obtained results indicated the importance of using such metrics for the assessments of trends in fishery. The approach and results presented here could be of interest for the scientific community and stakeholders involved in fishery management.

Biological Invasions, 2014