Search

Spawning strategies of lowland river fishes include single spawning, where reproduction generally occurs in early spring to provide 0+ fish with an extended growth season through the summer, but with a high risk of stochastic mortality events occurring, such as early summer floods. This risk can be reduced by multiple or protracted spawning strategies, where 0+ fish are produced over an extended period, often into mid-summer, but with the trade-off being a shorter growth season. The spawning strategies of cypriniform fish were explored in the River Teme, a spate river in Western England, which has non-indigenous European barbel Barbus barbus present. Sampling 0+ fish in spring and summer and across three spawning periods, B. barbus, chub Squalius cephalus and minnow Phoxinus phoxinus always revealed multiple spawning events, with 0+ fish of < 20 mm present in samples collected from June to August. Fish below 20 mm in August remained relatively small by the end of their growth season (October). For dace Leuciscus leuciscus, only single spawning events were evident, but with 0+ dace always being relatively large. Therefore, multiple spawning appears to be a common strategy that provides resilience in 0+ fish against stochastic mortality events in lowland rivers.

Determining where fish are distributed across days and seasons is valuable for understanding their ecology, evolution and conservation. The results presented here provide insight into the spatial and temporal distribution of brown trout (native salmonid species) and dace (invasive cyprinid species) in an artificially impounded section of lowland river, demonstrating that both species remain relatively local to their release point and do not exhibit wide-ranging movements from late summer into winter. Commonalities in the movement patterns were observed between the species despite their contrasting life histories, but there were also important differences observed both in their home range and activity patterns over the duration of the study. In general dace were much more active than trout. Both trout and dace exhibited clear crepuscular peaks in movement with higher displacement rates being observed during dawn and dusk periods which remained consistent over the duration of the study. Both species exhibited a high residency which may be a direct result of the artificial barrier present, promoting residency. Trout showed a significant increase in displacement rates and a drop in residency in November which may represent putative spawning behaviour. In general home range sizes remained stable over the tracking period for both species. Home range size was affected by fish length for both species, with larger individuals being more localised then smaller individuals. We propose that the diel patterns observed are primarily driven by foraging activity and opportunity which changes with seasonal influences and onset of potential spawning period and/or overwintering behaviour. This study demonstrates how data derived from telemetry studies can reveal movement behaviours of fish species associated with undertaking basic ecological requirements (feeding, shelter etc.) which are regulated by variation in the environment. Understanding the interplay between the environment and an animal’s behaviour is important from a conservation management perspective with increasing environmental pressures and predicted regime changes. From a fishery management viewpoint these data can feed into stock status monitoring in difficult to monitor impounded lowland riverine habitat and also increase our understanding of how potential human induced changes affect fish populations.

This study compares the effectiveness and representativeness of electrofishing, snorkelling, seining, baited lift netting, multi-mesh gillnetting, baited fish traps, fyke netting, angling and longline fishing, considering three typical lentic flood-plain habitats at different times of day. Electrofishing was by far the most effective method yielding highest species richness, species trait representation and catch per unit of effort (CPUE), followed by seining. For single species like dace Leuciscus leuciscus, European ruffe Gymnocephalus cernua, common bream Abramis brama and silver bream Blicca bjoerkna, seining was more effective than electrofishing. With both methods, some species were more consistently caught during night, dusk or dawn than during daylight. All other methods tested cannot be generally recommended for fish community assessments in shallow backwaters due to their low representativeness of species inventory and generally low CPUE. Based on these results, electrofishing of 30 m transect replicates at different times of day for monitoring the fish community in shallow backwaters, can be recommended, enabling the maximum possible comparability to adjacent river habitats. Seining should be considered as an alternative if accessibility of habitats is restricted or electrofishing is prohibited. The 25 species detected in the backwaters also suggest that these habitats contribute a large proportion of fish diversity and should be included in standard assessments of river ecological status.

The results of a study on some parameters of innate immunity and oxidative processes in hepatopancreas of the chub Leuciscus cephalus (L.) inhabiting the river ecosystems of Krasnodar krai and Abkhasia subjected to different degrees of anthropogenic load are presented. Antimicrobial properties of blood serum, the content of nonspecific immune complexes in the liver, and the level of total lipids and antioxidant activity have been studied. It is determined that the portion of immunodeficient specimens is higher in samples from polluted waters than from unpolluted areas. Fishes caught in the river subjected to high anthropogenic load contained higher concentrations of products of lipid peroxidation and immune complexes and had lower levels of antioxidants.

© 2018 John Wiley & Sons A/S. Quantifying feeding interactions between nonindigenous and indigenous fishes in invaded fish communities is important for determining how introduced species integrate into native food webs. Here, the trophic interactions of invasive 0+ European barbel Barbus barbus (L.) and the three other principal 0+ fishes in the community, Squalius cephalus (L.), Leuciscus leuciscus (L.) and Phoxinus phoxinus (L.), were investigated in the River Teme, a River Severn tributary in Western England. B. barbus has been present in the River Teme for approximately 40 years. Analyses of stomach contents from samples collected from three sites between June and September 2015 revealed that, overall, fishes displayed a generalist feeding strategy, with most prey having low frequency of selection. Relationships of diet composition versus body length and gape height were species-specific, with increasing dietary specialisms apparent as the 0+ fishes increased in length and gape height. The trophic niche size of invasive B. barbus was always significantly smaller than S. cephalus and L. leuciscus and was significantly smaller than P. phoxinus at two sites. This was primarily due to differences in the functional morphology of the fishes; 0+ B. barbus were generally restricted to foraging on the benthos, whereas the other fishes were able to forage on prey present throughout the water column. Nevertheless, the invasive B. barbus were exploiting very similar prey items to populations in their native range, suggesting these invaders were strongly pre-adapted to the River Teme and this arguably facilitated their establishment and invasion.

The values of pH in the digestive tracts of 20 freshwater fish species inhabiting various Russian Federation waterbodies were studied. Only in six species (Coregonus lavaretus, Coregonus migratorius, Catostomus catostomus, Carassius gibelio, Rutilus rutilus, Leuciscus leuciscus) out of 20 species, the differences in pH values between different regions of the intestine were significant. Feeding habits, feeding frequency, and gut fullness in fish affected pH values. Temperature was one of the most important factors affecting pH values. During cold seasons (spring and fall; average water temperature: 8–10 and 5–6○C, respectively), the pH values in fish guts were higher than that in the summer seasons(water temperature 22–25°C) for C. gibelio, Perca fluviatilis, Cyprinus carpio, L. leuciscus, and R. rutilus from the Chany Lake. Similar results (lower pH values in intestine at higher water temperatures) were also obtained for C. gibelio in warmer years in comparison to colder years in the same waterbody and in L. leuciscus and P. fluviatilis in the different waterbodies with different water temperatures. It is hypothesized that dependence of pH in fish gut on temperature may serve as a regulatory mechanism for maintaining the activities of hydrolytic enzymes at the required level for their successful functioning. info:eu-repo/semantics/acceptedVersion

Feeding habits and the activity of digestive enzymes (total alkaline proteases, α-amylase and lipase) from dace Leuciscus leuciscus, roach Rutilus rutilus, Prussian carp Carassius auratus gibelio, perch Perca fluviatilis and pikeperch Sander lucioperca fry were studied in the Malye Chany Lake–Kargat Estuary (western Siberia, Russia). The diet of fry from all studied species was mainly composed of chironomid larvae and zooplanktonic organisms (i.e. cladocera and copepoda), whereas carnivorous species such as P. fluviatilis and S. lucioperca also preyed on fry from other fishes while detritus and microalgae were also important in the diet of ommivorous species. When comparing diet similarity (Sorensen–Dice index, QS) among fry at different stages of development, both omnivorous and carnivorous species showed a high level of similarity (0·67

The effect of two commercial preparations containing different GnRH analogues with dopamine antagonists on quantitative and qualitative parameters of semen from chub Leuciscus cephalus L. collected in artificial conditions were examined. Semen was collected after the application of [(D-Ala6, Pro9 NEt)-mGnRH + metoclopramide] (Ovopel, n = 9), [(D-Arg6, Pro9 Net)-sGnR + domperidone] (Ovaprim, n = 9) and from the control group (0.9% NaCl, n = 9). Afterwards, semen volume, sperm concentration, total sperm production and semen pH were determined. Osmolality and pH of seminal plasma were also determined. Using the Computer-assisted sperm analysis system (CASA), selected sperm parameters such as sperm motility (MOT %), progressively motile sperm (PRG, %), curvilinear velocity (VCL, μm s−1), straight-line velocity (VSL, μm s−1), movement linearity (LIN, %), wobbling index (WOB, %), amplitude of lateral head displacement (ALH, μm) and beat cross frequency (BCF, Hz) were analysed. While Ovopel can also be used to stimulate chub spermation, the application of Ovaprim was much more effective for obtaining higher amounts of semen.

The effects of number of fish that are aged and scale sub-sampling strategies on the precision of estimates of mean age-length increments from populations of Rutilus rutilus, Leuciscus leuciscus and Leuciscus cephalus were tested. Analyses used data derived from river fish communities in eastern England, U.K.. Regarding the number of fishes analysed in each age group, for each species and mean fork-length increment at age, significant relationships were detected between sample size (n) and the coefficient of variation of the mean (Z) and mean length increment x‾ and measured variance (s(2)). This enabled calculation of the number of scales for producing a mean length increment at age according to n=ax‾(b(-2))Zx‾(-2). Outputs indicated that the number of scales requiring ageing increased substantially as precision increased, but with little variation between species per age category. Ageing between seven and 12 scales per age group would thus provide estimates at 10% precision. As the ages of fishes are not known in advance of scale ageing, the effect of scale sub-sampling regime on precision was also tested using randomized strategies of 10 fish per 5 mm, five per 5 mm, three per 5 mm, 10 per 10 mm, five per 10 mm and three per 10 mm. These were applied to the datasets and the consequences of their reduction in the number of scales for precision were determined using Z=a(0.5)x‾((b/2)(-1))n(-0.5). When compared to no sub-sampling, three per 10 mm always significantly reduced data precision, whereas 10 per 5 mm never significantly reduced precision. These outputs can thus be applied to the design of fish sampling protocols where age and growth estimates are required, with the randomized sub-sampling likely to be the most useful strategy.

Large year-to-year variability in different fish species recruitment has been confirmed by previous studies while diurnal patterns of occupation in two basic reservoir habitats (pelagic and littoral) by different age-0 fish species in late summer are still unclear. Data collected over an 11-year period regarding late-summer age-0 fish assemblages in pelagic and littoral habitats of a reservoir were used to test the recruitment instability and to investigate diurnal habitat use. Trawling was conducted in the pelagic habitat at night while beach seining was conducted in the littoral habitat during day and night. Fluctuations in age-0 fish abundance and species composition were observed with both sampling methods; however, the following spatio-temporal patterns were relatively stable in most investigated years: (1) pelagic species (pikeperch; Sander lucioperca, small perch; Perca fluviatilis, bream; Abramis brama at night), (2) littoral species (large perch, asp; Leuciscus aspius, dace; Leuciscus leuciscus), (3) migratory species likely performing diel horizontal migrations (bleak; Alburnus alburnus), (4) species abundant in the littoral habitat both during day and night and also in pelagic habitat at night (roach; Rutilus rutilus) and (5) species detected in both habitats exclusively at night (ruffe; Gymnocephalus cernuus).

Summary An updated, corrected checklist of both native and established alien freshwater fish species in Italy is given based on molecular, morphological and biogeographical data. Some 12 native species, reported as conspecific with transalpine species in official Italian ichthylogical literature, are in fact endemics. Previous taxonomic confusion has resulted in the introduction of several alien species, either with official stockings or mixed in as impurities. Rehabilitated species include the cyprinids Scardinius hesperidicus, Scardinius scardafa and Telestes savigny from northern Italy, as well as Squalius ruffoi and the Telestes comes from southern Italy. Squalius albus is a junior synonym of S. squalus. The endemic gudgeon, previously assigned to the genus Romanogobio, is returned to the genus Gobio (G. benacensis). Phoxinus lumaireul is a junior synonym of P. phoxinus. Among the Salmonidae, Salmo cenerinus is a junior synonym of S. marmoratus, while Salmo farioides represents the trout species of the Adriatic lineage for which a neotype is designated. Thymallus aeliani represents the endemic lineage of grayling of the Adriatic populations. The esocid Esox cisalpinus is an endemic pike species and Esox flaviae is a junior synonym; the extensive exportation as well as the presence of this species throughout Europe is possibly due to humans. Among sculpins, Cottus scaturigo and C. ferrugineus are junior synonyms of C. gobio. The International Union for Conservation of Nature (IUCN) categories for native species of Italy are updated. At present, 52 native freshwater fish species are listed: 2 are extinct (Acipenser sturio and Huso huso), 12 are critically endangered, 7 endangered, 10 vulnerable, 3 near-threatened, 15 low concern and 3 data-deficient; 35 species are the result of human transfers. Among the 51 introduced species, 6 are recently established (Leuciscus leuciscus, Oreochromis niloticus, Poecilia reticulata, Xiphophorus helleri, Amatitlania nigrofasciatus, Hemichromis sp.), 37 are already established, 5 are probably established and 3 are non-established Chinese carp, maintained in the wild by intensive stockings. The family most involved is the Cyprinidae, with 22 alien and 20 native species.

Summary Anglers' records of fish weight (ARFW) were analysed in Poland for the periods 1965–1989 (successive increases in inland water pollution), and 1990–2010 (considerable improvements in water quality). For the initial ARFW analysis, the entire study was divided into nine intervals of 5 years each; the period that followed was divided into three catchments: the Vistula, Oder and Pomeranian rivers, whereby 10 species were chosen to represent obligatory riverine and facultative species. With a few exceptions, the investigated species showed unexpected and varying reactions to the changes in water quality. The ARFW of obligatory riverine barbel Barbus barbus (L.) decreased during the first periods (1965–1989), then increased significantly from 1990 to 2010. For obligatory riverine ide Leuciscus idus (L.), tendencies were less clear but as significant. However, other obligatory riverine species have not shown a relationship between ARFW and water quality. Discrepancies were also recorded in the facultative riverine pike (Esox lucius L.) and brown trout (Salmo trutta L.). Considering the number of medals recorded, there were some interesting tendencies related to the decline or improvement in the water quality, although not in all investigated species. The species displaying a decrease in medals awarded from 1966 to 1989 and increasing after 1990, was chub Leuciscus cephalus (L.), but only until 2005. Species which showed successive increases in awards from 1989 to 2010 were: pike, perch (Perca fluviatilis L.), ide, and wels (Silurus glanis L.). However, for species in the period when the water quality actually deteriorated (1966–1990), the number of medals awarded increased: barbel, brown trout (S. trutta L.), and grayling Thymallus thymallus (L.).

In the Rybinsk Reservoir (Upper Volga basin), a sharp decrease in the occurrence of Apophallus muehlingi (Jagerskiold) parthenites was found in the population of the Ponto-Caspian snail Lithoglyphus naticoides Pfeiffer in 2009–2010. In the muscles of cyprinid underyearlings (ide Leuciscus idus (L.) and dace Leuciscus leuciscus (L.)), interspecific differences in protein content were revealed following their infection by metacercariae in the experimental environment. The helminth infection caused an increase in glycogen content in both fish species. A reduction of motor activity induced by muscle damage might be the main reason for the observed changes in biochemical characteristics.

Summary The effect of selected hormonal preparations, i.e. [(D-Ala6, Pro9-NEt)-mGnRH+metoclopramide] (Ovopel), [(D-Arg6, Pro9-NEt)-sGnRH+domperidone] (Ovaprim), luteinizing hormone releasing hormone (LHRHa), human chorionic gonadotropine (hCG) and carp pituitary extract (CPE) on the total volume of milt (TVM, ml), volume of milt per kg of body weight (VOM, ml kg−1 b.w.), sperm concentration (×109 ml−1) and total sperm production (TSP, ×109) of dace Leuciscus leuciscus (L.) has been examined. The control group (Control) included fish which milt was taken after 0.9% NaCl injection. The parameters of sperm movement were analysed with the CASA system and included: sperm motility (MOT, %), progressive motility (PRG, %), curvilinear velocity (VCL, μm s−1) and straightlinear velocity (VSL, μm s−1) of sperm, linearity of movements (LIN = 100 × VSL/VCL,%), wobbling (WOB, %), amplitude of lateral head displacement (ALH, μm) and beat cross frequency (BCF, Hz). Milt was taken from all fish (n = 12 per group) 48 h after hormonal stimulation and selected milt and sperm parameters were determined. The best results in volume of milt was found after Ovaprim treatment and TVM and VOM values were statistically higher compared to the values recorded in the Control (P 0.05). The highest VCL and VSL values were recorded after LHRHa treatment but there was no statistical differences between Control, Ovaprim and CPE groups. Significant differences in ALH parameter were recorded only between LHRHa and hCG (P

Aquatic Sciences, 75 (2), ISSN:1015-1621, ISSN:1420-9055

This study addresses a fish species discrimination method based on normalised elliptic Fourier descriptors applied to acoustic shadows derived by Dual‐frequency Identification Sonar (DIDSON). Acoustic shadows of templates (20, 30, 40 and 50 cm) and live fish of four species [bream, Abramis brama (L.); barbel, Barbus barbus (L.); chub, Leuciscus cephalus (L.); and trout, Salmo trutta (L.)] were projected on a plate in an experimental set‐up and tested on suitability for species discrimination. Twenty‐centimetre templates were correctly classified in 97.5% of the cases, indicating a size threshold. The larger templates reached values of 100% correct classification based on cross‐validated discriminant function analysis. It was also possible to classify moving fish based on screenshots of their acoustic shadows with a certainty of 83.9%. Extended field tests are required to evaluate the method for use in practical monitoring applications in multispecies river environments.

Scales collected during a maximum of seven fish population surveys over a 25-year period (1983–2008) in the River Wensum, a lowland river in Eastern England, enabled temporal analysis of the growth rates of roach Rutilus rutilus, dace Leuciscus leuciscus and chub Leuciscus cephalus. Across the study period, all species showed temporal variability in their growth patterns. Roach showed a significant temporal decrease in their growth, where rates recorded in surveys in 2005 and 2008 were significantly slower those recorded in surveys between 1983 and 1994. This change in growth rate was significantly associated with the implementation of phosphate stripping in the catchment’s sewage treatment works that reduced nutrient inputs (specifically orthophosphate). Prior to the implementation, temperature patterns explained most of the annual growth variability; following implementation and a consequent shift to the less eutrophic conditions, this relationship was lost, with changes in annual phosphate loadings now explaining most of the annual growth variation. This suggests that the changes in roach growth rates were related to shifts in river productivity resulting from water quality improvements.

The efficiency of individual genetic tagging was determined by using passive integrated transponders (PIT) as a comparative conventional tagging method. Fifty-five common dace Leuciscus leuciscus were captured in the wild, PIT tagged and fin clipped (for DNA analysis). Thirty fish were recaptured on three occasions and tissue samples were collected. Using 18 microsatellite loci, 79-94% of the recaptures were correctly assigned. Experience with scoring L. leuciscus microsatellites led to more individuals correctly assigned. Allowing matches that differed by one or two alleles resulted in 100% of all recaptures successfully assigned irrespective of the observer. Reducing the set of loci to five to six loci appropriately selected did not affect the assignment rate, demonstrating that costs can be subsequently reduced. Despite their potential benefits, the application of genetic tags for teleosts has been limited. Here, it was demonstrated that genetic tagging could be applied, and a clear guideline (flowchart) is provided on how this method can be developed for teleosts and other organisms, with subsequent practical applications to ecology, evolutionary biology and conservation management.

Summary Immediate mortality induced by electrofishing and handling of young-of the-year (YOY) fish of five cyprinid species (bitterling Rhodeus amarus, chub Leuciscus cephalus, bleak Alburnus alburnus, barbel Barbus barbus, roach Rutilus rutilus) was quantified during routine YOY fish monitoring (point abundance sampling with backpack electrofisher, in situ identification and measurement). Sampled, identified and measured fish were held in screened containers immersed in the river for 5 h after electrofishing. Bleak exhibited significantly higher mortality (17%) than all other species (1–3%). Mortality decreased significantly with fish length; fish

Acute toxicity of ammonia was investigated in four life stages of juvenile chub, Leuciscus cephalus (cyprinid fish): 1, 10, 20 and 30 days after the first feeding. The fish used for the toxicity test were reared intensively in a closed recirculation system. Each acute toxicity test duration was 96 h and lethal concentration LC1 , LC50 and LC99 values were calculated for 24, 48, 72 and 96 h. The susceptibility of chub to acute ammonia toxicity decreased linearly with age and stage of development. The LC50 (48 h) values ranged from 0.62 mg L-1 of unionized ammonia nitrogen for one day after first feeding larvae to 1.73 mg L-1 for 30 days after first feeding ones. A significant linear relationship between chub larvae susceptibility to ammonia toxicity and both body weight and length was found. The critical level of unionized ammonia nitrogen for chub larvae was suggested as 0.49 mg L-1 .

The Neretva River Delta in Croatia is under constant threat of pollution from various sources along the river watercourse, such as the aluminium industry and bauxite mining, intensive agriculture and untreated sewage from towns. The area is also an important fishing ground and food source for the local residents, whereby the suitability of fish for human consumption is always in question. In this paper the presence of arsenic from six sources was analysed: in water, sediment and fish organs (kidneys, liver, muscles and gonads) of 11 fish species: Lepomis gibbosus, Carassius auratus gibelio, Cyprinus carpio, Anguilla anguilla, Ameiurus nebulosus, Mugil cephalus, Leuciscus svallize, Oncorhynchus mykiss, Salmo trutta, Tinca tinca and Scardinius plotiza. The research showed that arsenic concentrations varied significantly from one source to another in the water, sediment and organs of different fish species. Average concentrations in water and sediment were 18.1 μg L−1 and 32.7 μg kg−1, respectively. Average arsenic levels in the fish organs were 115.9, 105.8, 76.1 and 61.9 μg kg−1 in muscles, kidneys, gonads and livers, respectively. These values are below legally permitted concentrations, although individuals with higher than average concentrations were recorded.

An invasive species is defined as an alien (or introduced or non-native) species whose establishment and spread threaten ecosystems, habitats or species with harm. Such threats to UK lake fish communities have long been appreciated and this review assembles case histories, including new data, from the largest lakes of Scotland, Northern Ireland, Wales and England to examine the hypothesis that at least some of these introductions have become invasive. Loch Lomond in Scotland has experienced six introductions [chub (Leuciscus cephalus), common bream (Abramis brama), crucian carp (Carassius carassius), dace (Leuciscus leuciscus), gudgeon (Gobio gobio) and ruffe (Gymnocephalus cernuus)], of which the most significant has been that of the percid ruffe, which has been implicated in a recent decline of the native coregonid whitefish (Coregonus lavaretus). In Northern Ireland, the introduction of the cyprinid roach (Rutilus rutilus) to Lough Neagh has apparently had a negative impact on some overwintering waterfowl, although the native coregonid pollan (Coregonus autumnalis) remains abundant. Llyn Tegid in Wales has received three introductions [rudd (Scardinius erythrophthalmus), ruffe and silver bream (Blicca bjoerkna)], although no impacts on the native whitefish or other fish populations have been observed. In England, individuals of at least 12 native and non-native fish species have been brought to Windermere for the purpose of live-baiting, although only those of the cyprinids roach and common bream have established abundant populations. At the same time, the native salmonid Arctic charr (Salvelinus alpinus) has declined markedly while the native esocid pike (Esox lucius) has shown changes in abundance, distribution and individual condition, although these developments have not been shown to be causally linked. None of these introductions were sanctioned by appropriate fisheries or other regulatory bodies and almost all of them probably arose from the release or escape of live-bait used by pike anglers. Of the 10 species introductions documented here, four (common bream, gudgeon, roach and ruffe) have established abundant populations and two of these (roach and ruffe) have apparently caused or currently threaten harm, supporting the hypothesis that at least some of these introductions have become invasive.

This paper gives the first detailed data on the number and body part related distribution of superficial neuromasts in twelve common European Cypriniform species and examines whether such anatomical variables can be related to rough scale habitat occurrence. The fishes (Barbatula barbatula, Barbus barbus, Chondrostoma nasus, Cobitis taenia, Leuciscus cephalus, Leuciscus leuciscus, Phoxinus phoxinus, Rutilus rutilus, Rhodeus sericeus, Scardinius erythrophthalmus, Tinca tinca, Vimba vimba) were classified in two generalized ‘ecological guilds’, 1) rheophilic and 2) limnophilic or indifferent, based on literature data. The total number of superficial neuromasts was consistent within each species, but differed considerably between species. Lowest numbers of superficial neuromasts were found in Barbatula barbatula (21 ± 4.9 superficial neuromasts per cm body length) (mean ± SD), highest numbers in Vimba vimba (233 ± 36.1). Both species can be classified as rheophilic. Over all no relationship was found between the total number of superficial neuromasts and large scale habitat occurrence. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Two rehabilitation projects were compared to determine their feasibility for successfully improving habitat for fish in urban waters. The first re-meandering project involved channel reconstruction in the Muggelspree upstream of Berlin to create an aesthetically pleasing, stable, meandering channel. The second project addressed a typical habitat bottleneck for fish found in urban waterways; that of nursery habitats lost due to river engineering works. Rehabilitated and control sites were sampled before and after in the Muggelspree and once in the urban Spree River. A total of 30 303 fish belonging to 27 species were collected. The fish assemblage was dominated by generalist species with 81% roach, Rutilus rutilus (L.), and perch, Perca fluviatilis L. Species diversity did not improve in either the rural or urban stretch. In the Muggelspree, the loss of riverine habitats was mirrored by significant declines in the densities of chub, Leuciscus cephalus (L.), ide, Leuciscus idus (L.), gudgeon, Gobio gobio (L.), rheophilic and lithophilic species. By contrast, densities of rheophilic species around the artificial structures created in the urban Spree River, although the main effect was an overwhelming increase in roach and perch. The results suggest that if underlying bottlenecks can be identified, artificial structures can provide functional fish habitat that replaces the natural equivalent in urban river stretches. Consequently, even the most heavily degraded waters provide opportunities to improve fish diversity and fisheries using artificial habitat structures.

The efficiency of portable passive integrated transponder (PIT) telemetry at detecting five fish species in a small river was evaluated under different environmental and tracking conditions. Significant differences between species were apparent, with detection efficiency varying between 0·7% (Leuciscus leuciscus) and 43·1% (Salmo trutta). Conditions of reduced flow and tracking in a downstream direction significantly increased detection efficiency for salmonids, while time of day had no significant effect for any species.

Valuable biological information can be obtained by monitoring the movement of organisms. However, the choice of monitoring method becomes highly restricted when following small organisms (

Summary In the years 2000–2001, specimens of two Ponto-Caspian gobiids (racer goby Neogobius gymnotrachelus and monkey goby Apollonia fluviatilis) were recorded for the first time in the lower Vistula River, which is a part of the central inland corridor used by Ponto-Caspian species to migrate in Europe. In 2004, seine net surveys were made in the river course to examine relative abundance of the non-indigenous gobiids in the local small-fish community. Altogether 4420 specimens with total lengths ranging from 10 to 340 mm (mostly

Karyotypes of six species of Cypriniformes from the water bodies of Armenia—blackbrow Acanthalburnus microlepis, white bream Blicca bjoerkna transcaucasica, chub Leuciscus cephalus orientalis, stone moroco Pseudorasbora parva, mursa Barbus mursa, and Angora stone loach Barbatula angorae were studied. The karyotype of A. microlepis is represented by 50 chromosomes (2n = 50), 10M + 28SM + 12STA, NF = 88; of B. bjoerkna transcaucasica, by 2n = 50, 12M + 24SM + 14STA, NF = 86; of L. cephalus orientalis, by 2n = 50, 12M + 18SM + 20STA, NF = 80; of P. parva, by 2n = 50, 8M + 16SM + 26STA, NF = 74; of B. mursa, by 2n = 100, 6M + 36SM + 58STA, NF = 142; and of B. angorae, by 2n = 50, 8M + 24SM + 18STA, NF = 86. The intraspecific and interspecific chromosome polymorphism of species of the genera Blicca, Leuciscus and Pseudorasbora is described.

Summary Retention and mortality associated with visible implant elastomer (VIE) and passive integrated transponder (PIT) tagged juvenile chub [Leuciscus cephalus (L.)], dace [Leuciscus leuciscus (L.)] and roach [Rutilus rutilus (L.)] were evaluated. PIT tag retention (96.6–100%) was higher than VIE over the 6-month duration of the experiment. VIE retention was significantly better in the head (96.3–98.8%) than in the fins (78.8–90.9%) the first month after tagging, but the opposite was found after 6 months (head = 21.5–57.5%; fins = 77.2–88.8%). Survival was not significantly different from controls for any treatment, except dace tagged with 23-mm PIT (significantly influenced by mass of fish at tagging) and sham PIT tagged dace, because of initial losses. PIT tags are recommended as the most suitable method for tagging individual juvenile chub, dace and roach based on high retention and survival. VIE implantation in the head (studies 30 days) could provide a cheap, batch-marking alternative, provided retention rates are monitored.

Barbus pectoralis Heckel, 1843 is widely distributed in lakes and river systems of the west-, south-, and southeast Anatolia, Syria, Iran, and Iraq (Coad 1991, Geldiay and Balik 2007). Populations of this species are commonly found in a few rivers (Gediz, Bakircay, Buyuk Menderes, Aksu, Goksu, Orontes, Euphrates, Tigris) of Turkey, in rather cool running waters. Barbus pectoralis (formerly identified as B. capito pectoralis) is one of the nine barbel species inhabiting Turkish freshwaters and it is commonly known in the country as ‘biyikli balik’. B. pectoralis can be adapted quite easily to water regime changes. It is a benthopelagic species inhabiting both lentic and lotic environments and it has an economic value since it is commercially fished in reservoirs, lakes, and rivers (Geldiay and Balik 2007). Furthermore, it is a commercially important species also in Anatolia because of its wide distribution, its body size (max 40.4 cm, 700.0 g; Colak 1982) and its tolerance to different environmental regimes. There are several studies on the biology and ecology of B. pectoralis from several water bodies in Anatolia (Balik 1980, Colak 1982, Ergene 1998, Ikiz et al. 1998, Topkara and Balik 2004). In this paper, we provide new information on the age and growth of B. pectoralis from Kemer Reservoir. This may contribute to the species conservation and the management of its fisheries in the study area. Study area. The Kemer Reservoir is located in the city of Aydin, in west Anatolia (lat 37°32'N, long 28°32'E). The reservoir has an area of 14.75 km2 with a maximum depth of 52 m (April 2005). It was constructed on the Akcay Stream, one of the important tributary of the Buyuk Menderes River (Fig 1). The reservoir has an oligo-mezotrophic character (Ozyalin 2007). The fish species such as: Acanthobrama mirabilis, Chondrostoma meandrense, Capoeta bergamae, Silurus glanis, Carassius gibelio, Lepomis gibbosus, Cyprinus carpio, Petroleuciscus smyrnaeus, and Leuciscus cephalus are also present in Kemer Reservoir.

Mark-recapture and fixed-station passive integrated transponder (PIT) telemetry were used to compare movements, distribution and survival of stocked juvenile chub Leuciscus cephalus and roach Rutilus rutilus with those of wild conspecifics. Daily activity of wild fish activity was affected by a combination of river flow and temperature, whereas stocked fishes were not influenced by environmental factors. PIT telemetry recorded exploratory movements of stocked L. cephalus immediately after stocking, a substantial number of stocked fish moved both downstream and upstream during periods of elevated flow, and proportionally more stocked fish moved during the first 6 weeks after release than later on. Proportionally more stocked fish than wild fish moved through PIT antennae, stocked L. cephalus moved greater distances than wild L. cephalus and were more widely distributed than wild fish. Minimum estimates of survival after 5 months were 50.5% for stocked R. rutilus and 28.0% for stocked L. cephalus. Ultimately, stocked cyprinids appeared to be able to cope with elevated flows and most remained in the river section local to the stocking location.

An increase in individual growth rate of chub Leuciscus cephalus along a longitudinal river gradient of the Rhône River basin was observed and supported by significant differences between mean growth rates of successive river size groups. The potential implications of the results for studies on species traits variability along large-scale environmental gradients are discussed.

Stocking is a widespread management activity in inland fisheries, but the efficacy of such fishery enhancement measures is poorly understood. Radio-telemetry was used to compare the movements and habitat selection of stocked, juvenile chub, Leuciscus cephalus (L.), with those of wild individuals in a small river in Eastern England. Thirty-two wild juvenile chub (total for 2005 and 2006 combined) and 12 stocked, 1+ chub (2006) were surgically implanted with radio-tags and tracked once per day for 1 month. Stocked chub did not disperse immediately after release, there was no evidence of reduced survival of stocked chub, and neither wild nor stocked chub were permanently displaced downstream of the study reach by high flows. Linear ranges of wild chub were, however, smaller than for stocked chub, movements were more frequent and larger for stocked fish (particularly during elevated flows), and differences in habitat use were found. The short-term success of stocking cyprinids was demonstrated, whilst emphasising behavioural (movements and habitat use) differences between hatchery fish and wild counterparts, and the necessity for long-term monitoring.

Large-scale migratory patterns of adult rheophilic fish [barbel, Barbus barbus (L.), chub, Leuciscus cephalus (L.), ide, Leuciscus idus (L.), nase, Chondrostoma nasus (L.)] were studied in relation to habitat quality and possible migration barriers in the lower rivers Meuse and Rhine, the Netherlands, using a telemetry system with transponders and detection stations based on inductive coupling. Most fish moved over short distances (

Inmanyaquaticenvironmentselevatedlevelsoftraceelements occur due to anthropogenic activities. Waterorganismscanbepreciseindicatorsinestimatingthestatusofpollutionofwaterenvironments.Amongthemseveralspeciesoffishhavebeenwidelyused(Hakanson1984,Chevreuiletal.1995,Andresetal.2000,Falandyszetal.2000,PerkowskaandProtasowicki2000,Řehulka2001,WagnerandBoman2003,Polechonski2004,Szarek-GwiazdaandAmirowicz2006).Accumulationoftraceelementsinthetissuesoffishlivinginaquaticenvironmentdependsonmanyfactors(JezierskaandWiteska2001).Thesefactorsinclude metal contents in water and food organisms,exposuretime,environmentconditions(e.g.,pH,alkalin-ity, salinity), feeding habit, age, and size of fish(Protasowicki1991,Masonetal.2000,Řehulka2001,Jezierskaetal.2002,WiteskaandBaka2002,Dobickiand Polechonski 2003, Łuczynska and Brucka-Jastrzebska2005),andthedifferencesinmetallothionein(MT)geneinductionbyvariousspeciesoffish(OlssonandKille1997,DeBoecketal.2003).Chevreuiletal.(1995)andAndresetal.(2000)—tonamejustafew—indicatedthattheomnivorousroach,whichiscommonandoftenabundantincentralEuropeaninlandwaters,isausefulspeciesinmonitoringstudies.Roachcanaccumulatecertaintraceelementsinconsider-ableamounts,greaterthanotherspeciesinhabitingthesamewaterbodies.Andresetal.(2000),Spurnýetal.(2002),Demiraketal.(2006),andYilmazetal.(2007)usedotheromnivorousfishi.e.,chub

The chub is a freshwater fish of the family Cyprinidae, which is widely distributed throughout Europe. Prior to 2001 there were no reports of chub being present in Ireland. In 2001 and again in 2004 it was reported that an angler had caught chub in a section of the River Inny. On neither occasion were live specimens retained for authentication. In 2005 a number of live, angler-caught chub from this river were formally identified. In order to determine the status of this non-native and potentially invasive fish species in this renowned Irish coarse, game and pike fishery, an electric fishing survey was conducted in 2006. Seventeen chub were captured during this operation. All were taken from one relatively short (c. 0.8 km), shallow (≤0.5 m) and moderately fast flowing section of river. The fish ranged in fork length from 15 to 41 cm and in age from III+ to X+ years old. Among the fish captured, there were two immature fish, six females and nine males. The stomach contents revealed a diet of insect, fish, plant material and detritus. A relatively fast growth rate was recorded. While relatively few chub were captured during the survey, those examined were healthy and most were in spawning condition. It is considered that the chub were introduced to the river by anglers in an effort to increase the diversity of coarse angling species available in Ireland. The potential impact of the chub on natural biodiversity and on the community composition of native and naturalised fish species in the river is discussed.

Research into arti¢cial reproduction of chub was stu-died during three subsequent reproductive seasons.Chubreproductionwasconductedintwodiierentvar-iations. In the ¢rst experiment diierent hormonalagentsweregivento¢sh,suchasCPE,hCG,oranana-logue of GnRH with dopamine antagonist (ovopel). Inthe second one, the optimum moment of applying ofarti¢cial reproduction was sought and the ¢sh wereonlyobtained an analogue of GnRH in diierent peri-ods.Theresultsobtainedintwo¢rstseasonsindicatedthat ovopel is the mosteiective agent for the arti¢cialreproduction of chub. Consequently, it was decidedthat the ¢sh would obtain only this agent in the ¢nalyear of research. In last year (experiment II), chubspawnersweretakentothehatcheryundercontrolledconditions every few weeks from February to thebeginningofJune.Periodically,thematurityofoocyteswas checked. As soon as the oocytes had achievedstage 2^3 of maturity, ¢sh were obtained ovopel. Itwas noted that there was no problem with collectingsemen. Obtaining oocytes was much more di⁄cult.Most frequently, they were not obtained at all orobtained in very small amounts. It was also observedthat the administration of hormones caused a veryquickmaturationofgonadsandtheirover-maturation.Keywords: chub Leuciscus cephalus,arti¢cialspawning, wildpopulation, gametesqualityIntroductionUnder hatchery conditions, ¢sh reproduction isconducted primarilyduetothe use of hormonalaids(Kucharczyk 2002). Until quite recently, injections ofa suspension of homogenized pituitary glands werethe only way of inducing ovulation in females andspermiationinmales.Nowadays,manydiierenthor-monal agents are available, which are slowly repla-cing the pituitary gland suspension (Brzuska A Brzuska 2000; Kucharczyk, Kujawa,Mamcarz, TargonŁska, Krejszei & Wyszomirska2007).Stimulationofpubescenceis possibleat diier-ent levels: hypothalamus, stipule and gonads. At thelevel of the hypothalamus, stimulation is executedmostly by a change of environmental parameters,mainly temperatureand daylighttime, whereas hor-monal agents are used in stimulationat other levels:pituitarygland^naturalorsyntheticgonadoliberins;gonads^ ¢shorhumangonadotropins (Yaron1995).To develop a reproduction biotechnology, varioushormonal agents are checked. The agents and thedoses in which they will be used depend onthe spe-ciesandthetypeofspawn.Onlyafewpapersonarti-¢cial reproduction of the chub Leuciscus cephaluisL.have been published before the beginning of thisstudy (Kucharczyk 2002). The following hormonalagents have been used for hormonal stimulation:hCG (human chorionic gonadotropin) and CPE (ex-tract of carp pituitary glands) (Kucharczyk, Kujawa,Mamcarz, Skrzypczak& Wyszomirska1998).Chubhasnogreatereconomicimportance,butitisvalued in recreational ¢shery. As a reophilic species,it is also important as a live component of environ-ment (Bzachuta 1998; Penczak, Kruk & Koszalin ski1998). It is one of the most widely distributed fresh-water ¢sh in Europe, although in recent years it hasdisappeared from manyhabitats and has become an

The winter diets of 0+ year juvenile dace Leuciscus leuciscus and roach Rutilus rutilus in the lower River Trent, England, were dominated by aufwuchs. There were no significant changes in the relative condition of either fish species over the winter.

The profitability of rearing larval asp, Aspius aspius (L.), ide, Leuciscus idus (L.), and dace, Leuciscus leuciscus (L.), was assessed in a system of 12 aquaria with a combined volume of 600 dm 3 . Two feeding variants were used: a) natural feed exclusively; b) natural feed plus formulated feed after seven days of rearing. All rearing variants were profitable and posed relatively low financial risks. The variant in which only natural feed was used was the most profitable. The savings incurred by the addition of formulated feed did not offset the profit lost from lower larval stock survival rates. In light of profitability, the most important aspect of larval rearing was the price of the stocking material, which was 250% higher for asp than for ide or dace. In both feeding variants, asp rearing was the most profitable and the values of the indices used to describe profitability were the best.

Myxobolus gayerae sp. n. and M. leuciscini Gonzalez-Lanza & Alvarez-Pellitero, 1985 (Myxozoa: Myxobolidae) have been described and re-described from European chub Leuciscus cephalus L. from the Hungarian stretch of the river Danube. The ellipsoidal plasmodia of M. gayerae sp. n. were found in the mucosa of the intestinal wall, whereas the large, elongated plasmodia of M. leuciscini infected the afferent arteries of the gill filaments. The spores of M. gayerae sp. n. are relatively large, slightly oval and almost rectangular in shape. On the basis of spore morphology and 18S rDNA sequences, the most similar species was M. cycloides Gurley, 1893, but the 2 species differed in host and tissue tropism as well as in the size of the spores. The spores of M. leuciscini from L. cephalus, having no intercapsular appendix or occasionally a very small one, showed a high morphological similarity to spores collected from L. cephalus cabeda, Chondrostoma polylepis and Rutilus arcasi in Spain and described as M. leuciscini Gonzalez-Lanza & Alvarez-Pellitero, 1985.

To address a lack of information on topmouth gudgeon Pseudorasbora parva introduced to watercourses, the microhabitat use of this non-native cyprinid and co-existing native species was assessed in a small stream located in southern England. Overall, microhabitat use was size-structured and significant associations were observed between topmouth gudgeon and native species, including brown trout Salmo trutta, chub Leuciscus cephalus, European bullhead Cottus gobio and stone loach Barbatula barbatula. Significant associations with environmental variables, however, were more frequent in native species than in topmouth gudgeon. Topmouth gudgeon demonstrated few habitat preferences, which were weak and limited to small specimens, emphasizing the species broad, plastic breadth of microhabitat use. This is expected to facilitate the species’ successful invasion of novel aquatic systems.

The fork length (LF) of individual chub Leuciscus cephalus in English riverine populations at the end of their first growth season varied considerably, ranging from 70 mm. This had a significant influence on the subsequent growth of individuals over their lifetime. Chub of small LF at age 1 year generally produced smaller annual growth increments throughout life than those of longer LF at age 1 year, although they had the potential to attain greater ultimate LF. This variability in LF at age 1 year resulted, at least in part, from multiple spawning events over a protracted period, that caused variation in the growing seasons for 0 year group chub of the same year class. Since the adult population contained individuals that only attained LF of

Summary Changes in the behaviour of cyprinids belonging to different ecology groups were observed below a weir that was restricting their upstream migrations during the spawning period May–July. Positions of chub Leuciscus cephalus (L.), Prussian carp Carrasius auratus gibelio (Bloch 1783), bream Abramis brama (L.) and white bream Blicca bjoerkna (L.) were recorded every 12 min over a 24-h period using an automatic data logger (ALS) in the upper Elbe River, Czech Republic. For all observed species, two activity peaks occurred; however, the interspecies timing of these peaks differed. Peak times for chub, bream and white bream occurred at night and during daylight, whereas Prussian carp was active mostly at night. Specimens belonging to the rheophilous group suggested more efficient behavioural tactics in passing the weir, staying below the obstacle one month longer than did eurytopic species.

A spatially based approach was used to analyse the response of fish-based metrics to human impacts in the Iberian Peninsula. A fish-based typology was established that distinguished one salmonid type (fish assemblages dominated by Salmo trutta fario L.), two mixed types (S. trutta fario associated with different cyprinids) and six cyprinid types (dominated by different species of barbel (Barbus spp.), nase (Chondrostoma spp.) or chub (Leuciscus spp.)). These types broadly correspond to different forms of ecosystem functioning, ranging from the cold, northern and high altitude sections to warmwater, lowland and southern sections. Twenty metrics were identified that responded to disturbance - four to 14 per fish type. The highest correla- tions were )0.795 for abundance of Squalius sp. and segment (localised) disturbance and 0.754 for abundance of limnophilic specimens and water quality disturbance. Disturbance of segment, habitat and hydrological regime yielded more metric responses in western Iberian fish types, while that of habitat and water quality gave more in north-eastern Iberian fish types. Global (catchment scale) disturbance generally gave more responsive metrics and higher correlations than partial disturbances. All guilds were represented and a number of metrics were responsive across fish types - namely native species, alien abundance, water column (natives), eurytopic and invertivorous (natives). However, several metrics were only reactive in one or a few types, such as benthic and S. trutta fario in north-western mixed fish type. Different trends in metric reaction occurred for total abundance in north-western mixed fish type, and for eurytopic and phytophilic (natives) in the north-eastern fish types.

We investigated interspecific differences in the downstream drift of seven species of young-of-the-year cyprinids over a 2-year period in two central European rivers, using a comparison of drifting fish with fish collected from nurseries at the same time and the same site as the drift samples. Species varied in the utilisation of the drift; Rutilus rutilus, Gobio spp., Abramis brama and Carassius auratus gibelio drifted abundantly, while Leuciscus cephalus and Alburnus alburnus were abundant in nurseries, but drifted at low densities. Abramis bjoerkna was equally represented among drifting and resident fish. Generally, fish drifted at two major developmental intervals; L3 stage and the stage at transition between larval and juvenile periods (L6/Juv), with interspecific differences in the ontogenetic timing of drifting. The propensity to drifting of certain developmental stages was also reflected in body size comparisons between drifting and resident fish. The stage-dependent drifting may be attributed to major changes in fish morphology, behaviour and swimming ability.

Summary 1. Climatic effects are increasingly being recognised as an important factor causing inter-annual variability in organism abundances in aquatic and terrestrial ecosystems. This study investigated the relationships between water temperature (cumulative degree-days >12 °C), river discharge (cumulative discharge-days above basal discharge rate), the position of the North Wall of the Gulf Stream (NWGS), and the 0+ growth (September mean length) and recruitment success (year-class strength, YCS) of three species of cyprinid fishes in two contrasting English lowland rivers, using a 21-year dataset. 2. Contrary to the majority of studies on 0+ fishes, growth in the Yorkshire Ouse was most significantly correlated with river discharge, with water temperature of less importance. By contrast, temperature was more influential than discharge in the River Trent, possibly because of its regulated hydrological regime, although none of the relationships were statistically significant for this river. 3. Year-class strength of roach (Rutilus rutilus) was positively correlated with the position of the NWGS, and there was evidence of synchrony in recruitment success between rivers, but the relationships were poorer for chub (Leuciscus cephalus) and dace (Leuciscus leuciscus). The strongest relationships between YCS and discharge during specific time periods were for when the fish were in their early (especially larval) developmental stages, although none of the relationships were statistically significant because of inter-annual variations in river discharge relative to the timing of fish hatching. 4. Fishes are key predators in the majority of aquatic ecosystems and, as such, fluctuations in their abundances can have implications for ecosystem functioning as a whole. This study has demonstrated an underlying influence of broad-scale climatic effects on the recruitment of riverine fishes, in spite of local variations in biotic and abiotic conditions. The relative importance of various abiotic factors on the recruitment success of riverine cyprinid populations varies spatially and temporally. For example, river discharge is likely to be of relatively greater importance in poorly-structured rivers or those that are prone to large and rapid fluctuations in flow, while temporal variations occur because of inter-annual differences in river discharge relative to the timing of fish hatching. Biotic factors may also be important determinants of fish recruitment success, especially in rivers with stable and predictable flow regimes.

The Dice Snake (Natrix tessellata) is an aquatic colubrid that is known for having a basically piscivorous diet and a female-biased sexual size dimorphism (larger females). The feeding habits of three populations of N. tessellata from Mediterranean streams in central Italy were studied. The three streams differed in terms of their water regimes, one being seasonal and two being perennial. More than 2,000 snake individuals were handled for food items, and 1,200+ prey items were collected. The percent of fed snakes was significantly influenced by the study area and by the interaction term between study area and season (i.e., by the hydric regime). Fishes accounted for over 90% of the snake diets at all study areas, the most common prey species being cyprinids. Overall, the three snake populations had similar taxonomic diet composition. There was a significant ontogenetic change in diets in all populations. There were also significant intersexual differences in prey composition, with the females taking more Scardinius erythrophtalmus fishes and more anurans, and the males more Leuciscus s. muticellus. The various fish species found at the three study areas (15 species) were classified in terms of six independent ecological characteristics in order to investigate what factors make a given prey species suited or not for Dice Snakes. It appeared that N. tessellata selected mainly fish species that were gregarious, small to medium sized, active foraging, diurnal, and not using mud as preferred substratum. We also found that the seasonal desiccation of the stream-bed of one study area caused a shift in the diet composition of these snakes, with males and juveniles being the categories where the seasonal dietary shift was more evident. Males preyed especially on the fishes S. erythrophtalmus and Leuciscus cephalus, and the juveniles preyed upon Leuciscus s. muticellus, whereas in spring their primary prey was Alburnus a. alborella.

Understanding intraspecific variability in fish somatic growth rates is important as growth is a key life history trait that plays a fundamental role in many biological and ecological processes. Here, the influence of environmental and chemical parameters was tested on intraspecific variability in growth rates of the cyprinid fishes roach Rutilus rutilus, chub Squalius cephalus and dace Leuciscus leuciscus across 13 rivers in England, and also compared with those for barbel Barbus barbus from the same rivers. Outputs indicated that growth rate responses to the parameters were species-specific, with more significant effects generally detected on juvenile growth than lifetime growth. For R. rutilus and S. cephalus, latitude (as a surrogate of temperature) was the most significant predictor of their growth rates, with growth rates decreasing as latitude increased. Contrary to prediction, aspects of degraded water quality accelerated the growth rates of these fishes, except in B. barbus, although concentrations of nitrogenous compounds were below toxicity thresholds. This emphasizes the ability of populations of these cyprinid fishes to tolerate some environmental disturbances and, in entirety, suggests that the intraspecific variability in the growth rates of these fishes is significantly influenced by abiotic parameters and their association with levels of anthropogenic disturbance.