Production,consumption and prey availability of northern pike (Esox lucius), pikeperch (Stizostedion lucioperca) and European catfish (Silurus glanis): a bioenergetics approach

Bioenergetics models were applied for the assessment of food consumption of northern pike, pikeperch and European catfish in drainable ponds of 0.4 ha. The ponds were stocked with known numbers of the 0⁺ predators. The prey fish consisted of naturally recruited 0⁺ cyprinids (rudd, roach and bream). The study shows that the impact of the three 0⁺ piscivores on the aquatic system differs, which is related to the feeding behaviour and habitat use of the fish. All piscivores realised part of their production on a non-fish diet.     

Impact of cyprinids on zooplankton and algae in ten drainable ponds

To study the impact of cyprinids on algae, zooplankton and physical and chemical water quality, ten drainable ponds of 0.1 ha (depth 1.3 m) were each divided into two equal parts. One half of each pond was stocked with 0 + cyprinids (bream, carp and roach of 10–15 mm), the other was free of fish. The average biomass of the 0 + fish at draining of the ponds was 466 kg ha^–1, to which carp contributed about 80%.The fish and non-fish compartments showed significant differences. In the non-fish compartments the density of Daphnia hyalina was 10–30 ind. l^–1 and that of Daphnia magna 2–4 ind. l-^–1, whereas in the fish compartments densities were c. 1 ind. l^–1. Cyclopoid copepods and Bosmina longirostris, however, showed higher densities in the fish compartments. The composition of algae in the two compartments differed only slightly, but the densities were lower in the non-fish compartments. The significant difference in turbidity was probably caused by resuspension of sediment by carp. No significant difference in nutrient concentration between the compartments was found.     

Restoration by biomanipulation of lake Bleiswijkse Zoom (The Netherlands): First results

In 1987, the Bleiswijkse Zoom, a small, shallow lake in The Netherlands, was divided into two compartments to investigate the possible use of biomanipulation as a tool for restoring the water quality of hypertrophic lakes. The density of the fish stock before restoration was about 650 kg.ha^–1, composed mainly of bream, white bream and carp. Pikeperch was the main fish predator in the lake. In April, 1987, in one compartment (Galgje) all planktivorous bream and white bream and about 85% of the benthivorous bream and carp were removed. Advanced pikeperch fry were introduced as predator during the transient period. The other compartment (Zeeltje) was used as a reference. Removal of the fish in Galgje resulted in low concentrations of chlorophyll-a, total phosphorus, nitrogen and suspended solids. The absence of bottom-stirring activity by benthivorous fish and the low chlorophyll-a concentrations led to an increase in the Secchi disk transparency from 20 to 110 cm. Within two months after removal of the fish, macrophytes, mainly Characeae, became abundant. Until July the high density of large zooplankton species caused low algal biomass. From June onwards, the zooplankton densities decreased, but the algal concentrations remained low. This is probably because of nutrient limitation or depression of algal growth by macrophytes or both. Compared with the non-treated compartment the number of fish species in the treated compartment was higher. Perch, rudd and roach, i.e. the species associated with aquatic vegetation, were found in the samples. The survival of the O⁺ pikeperch was poor. The pikeperch could not prevent the growth of young cyprinids. Within two months after the removal of the fish a habitat for northern pike was created.     

Effects of benthivorous bream (Abramis brama) and carp (Cyprinus carpio) on sediment resuspension and concentrations of nutrients and chlorophyll a

1. The effect of benthivorous bream and carp on sediment resuspension and the concentrations of nutrients and chlorophyll a were studied in sixteen experimental ponds (mean depth 1m, mean area 0.1 ha, sandy clay/clay sediment), stocked with bream or carp at densities varying from 0 to 500 kg ha^?1. Planktivorous perch (Perca fluviatilis L.) were added to some ponds to suppress zooplankton. 2. Suspended sediment concentrations increased linearly with biomass of benthivorous fish. Bream caused an increase of 46 g sediment m^?2 day^?1 per 100kg bream ha^?1 and a reduction of 0.38m^?1 in reciprocal Secchi disc depth, corresponding to an increase in the extinction coefficient of 0.34m^?1. 3. No relationship was found between size of fish and amount of resuspension, but the effect of bream was twice as great as that of carp. Benthivorous feeding was reduced in May because alternative food (zooplankton) was available. 4. Assuming a linear relationship, chlorophyll a level increased by 9.0 μgI^?1, total P by 0.03mgl^?1 and Kjeldahl-N by 0.48mgl^?1 per 100kg bream ha^?1. Silicate, chlorophyll a, total P and total N were all positively correlated with fish biomass, but orthophosphate showed no correlation.     

Effects of different fish species and biomass on plankton interactions in a shallow lake

Thirty-six enclosures, surface area 4 m², were placed in Little Mere, a shallow fertile lake in Cheshire, U.K. The effects of different fish species (common carp, common bream, tench and roach) of zooplanktivorous size, and their biomass (0, 200 and 700 kg ha^–1) on water chemistry, zooplankton and phytoplankton communities were investigated. Fish biomass had a strong effect on mean zooplankton size and abundance. When fish biomass rose, larger zooplankters were replaced by more numerous smaller zooplankters. Consequently phytoplankton abundance rose in the presence of higher densities of zooplanktivorous fish, as zooplankton grazing was reduced. Fish species were also significant in determining zooplankton community size structure. In enclosures with bream there were significantly greater densities of small zooplankters than in enclosures stocked with either carp, tench and, in part, roach. When carp or roach were present, the phytoplankton had a greater abundance of Cyanophyta than when bream or tench were present. Whilst top-down effects of fish predation controlled the size partitioning of the zooplankton community, this, in turn apparently controlled the bottom-up regeneration of nutrients for the phytoplankton community. At the zooplankton–phytoplankton interface, both top-down and bottom-up processes were entwined in a reciprocal feedback mechanism with the extent and direction of that relationship altered by changes in fish species. This has consequences for the way that top-down and bottom-up processes are generalised.     

Biomass dependent interactions in pond ecosystems: responses of lower trophic levels to fish manipulations

The effects of mature benthivorous cyprinid fish and theirrecruitment on sediment resuspension, turbidity, phyto- andzooplankton, and benthic macroinvertebrates were studied in fourexperimental ponds. The ponds were stocked with bream (Abramisbrama L.), white bream (Blicca bjoerkna L.), roach (Rutilus rutilus L.) and wild carp (Cyprinus carpio L.) of3+–5+ age classes at standing crop biomass varying from 0 to500 kg ha-1. Cyprinids caused an increase in sedimentresuspension and in turbidity, in proportion to their biomass. Meancrustacean biomass did not significantly affect phytoplanktonbiomass due to intense grazing by fish during spring. Ponds withhigh fish stocks showed reduced midge biomass and vegetation coverand increased biomass of predatory invertebrates.     

Development of fish communities in lakes after biomanipulation

Biomanipulation measures in the Netherlands are usually a combination of a drastic fish stock reduction and an introduction of pike fingerlings. In three small shallow lakes (Noorddiep, Bleiswijkse Zoom and Zwemlust) these measures resulted in a clear water state and the development of macrophytes. After the measures the fish community developed differently because of the new physical and biological conditions. Results of lake Noorddiep and lake Bleiswijkse Zoom showed that the fish community became more divers. Bream and carp became less dominant and were partly replaced by roach and perch. The importance of the main predator pike-perch was strongly reduced and replaced by pike and perch. The share of piscivorous fish in the total fish stock increased at all sites. The recruitment of young-of-the-year was similar or even higher in the clear overgrown areas than in the turbid water before the measures, but the recruitment of young-of-the-year to older fish differed between the species. Predation by pike and perch could not control the young-of-the-year cyprinids, but their predation may have contributed to the shift from bream to roach, because of selective predation on bream in the open water, while roach was hiding in the vegetation. The macrophytes provide new refugia and feeding conditions that favour roach and perch, but offer relatively poor survival conditions for bream and carp.     

Changes in the fish community and water quality during seven years of stocking piscivorous fish in a shallow lake

SUMMARY 1. Piscivores (annual stocking of 1000 individuals ha^?1 of 0+ pike and a single stocking of 30 kg ha^?1 of large 20–30 cm perch) were stocked in seven consecutive years in a shallow eutrophic lake in Denmark. The stocking programme aimed at changing food‐web structure by reducing zooplanktivorous and benthivorous fish, with resultant effects on lower trophic levels and ultimately water quality. 2. The fish community and water quality parameters (Secchi depth, concentrations of total phosphorus, chlorophyll a and suspended solids) were monitored between 1996 and 2000 and relationships were evaluated between predatory fish and potential prey and between zooplanktivorous or benthivorous fish and water quality parameters. In addition, potential consumption of piscivorous fishes was calculated. 3. The density of fish feeding on larger zooplankton or benthos (roach >15 cm, crucian carp >15 cm) declined distinctly during the study period. This effect was attributed to predation by large (>50 cm) pike. Based on scale readings, we cautiously suggest that the stocking of 0+ pike boosted the adult pike population to produce an unexpected impact in later years. Conversely, no direct impact of stocked 0+ pike was detected on 0+ roach. 4. A major decline in the recruitment strength of 0+ roach was observed in 2000. A combination of (i) the indirect effect of large pike preying on adult roach, with negative effect on roach reproduction and (ii) the direct predation effect of 0+ pike and/or 1+ and 2+ perch recruited in the lake, provides the most likely explanation of this phenomenon. 5. A marked increase in Secchi depth in 2000 and declining trends in suspended solids, chlorophyll‐a and total phosphorus concentrations were observed. These changes may also be attributable to changes in the fish community, although the relationships were not straightforward. 6. This 7‐year study indicates that piscivorous fish may be a significant structuring force in shallow eutrophic lakes, suggesting that stocking piscivores can increase predation pressure on cyprinids. However, the general lack of impact of 0+ pike points to the need of refining current stocking practices in several countries across Europe.     

Fish community structure in mesotrophic and eutrophic lakes of southern Finland: the relative abundances of percids and cyprinids along a trophic gradient

In 36 south Finnish lakes, the number of species, as well as the cyprinids:percids ratio, was dependent, not only on total phosphorus (TP), but also on lake size. Total fish biomass and cyprinid biomass increased along the TP gradient, whereas the dependence of percid biomass was less evident. Perch Perca fluviatilis and roach Rutilus rutilus strongly dominated mesotrophic lakes; in eutrophic lakes the proportion of other cyprinids and percids, such as white bream Blicca bjoerkna , bream Abramis brama , pikeperch Stizostedion lucioperca and ruffe Gymnocephalus cernuus , increased. Perch biomass was weakly related to abiotic factors but depended on roach biomass. Lake size and fish species composition are essential factors affecting fish community changes in relation to TP, and may be important as well in regulating the responses of a fish community to biomanipulation.     

In situ estimates of gut evacuation and its dependence on temperature in five cyprinids

Gut evacuation and its dependence on the temperature in bream Abramis brama , silver bream Blicca bjoerkna , roach Rutilus rutilus , gibel Carassius aurtaus gibelio and carp Cyprinus carpio , held in mesh cages in Lake Balaton, was best fitted by an exponential model in 18 of 36 trials, while in 14 and four trials, a linear and a square-root model, respectively, gave a better fit. Adjusted r ² values, however, often did not differ markedly between the three models. The shape parameter, B , was 0.36 for carp and ranged from 0.81 to 1.24 for the other four cyprinids, according to the general evacuation model expanded with the temperature variable, and fitted to whole data sets. Relationships between the food evacuation rates obtained from the exponential models and the temperature were described by exponential functions for bream, silver bream, roach and gibel.     

Fish impingement at power stations situated along the rivers Rhine and Meuse in The Netherlands

Summary Substantial numbers of predominantly O⁺ fish were impinged on the cooling water screens of Harculo, Gelderland, Merwedehaven and Amer power stations. Low numbers were impinged at the two stations located on the river Meuse (Maas and Claus). Two possible reasons for this difference are suggested,viz. a low fish density in the river Meuse and the deep position of the cooling water intakes. In comparison with Bergum power station situated on a lake the impingement rate at the river stations was more than ten times as low.Most fish were impinged during the summer months when large numbers of juvenile fish are present in the rivers. Dominating species impinged were roach, pikeperch, bream and perch. The abundance of pikeperch in the screensamples, points to a recent increase in the population of pikeperch in the rivers. The growth pattern of O⁺ pikeperch and O⁺ roach during summer seemed very similar for power stations located at different rivers. Thirty fish species and four crustacean species were collected, among whichOrconectus limosus was quite abundant at Maas and Claus power stations.     

The distribution and growth of coarse fish in gravel-pit lakes in south-east England

SUMMARY. Age and growth rates of the coarse fish of thirty-nine gravel-pit lakes in south-east England are compared. Species composition was very variable, the commonest species being roach ( Rutilus rutilus ), bream ( Abramis brama ), tench ( Tinca tinca ), perch ( Perca fluviatilis ) and pike ( Esox lucius ). Two main kinds of fish community were identifiable from the survey: (1) those consisting of a mixture of cyprinids, usually roach and bream; and (2) those in which cyprinids were rare or absent and the fish community was composed of perch and pike. The majority of the lakes fell into the first category. Comparison of growth curves derived by back-calculation showed that, in all species, variation occurred from lake to lake and from year to year. The majority of gravel-pit lake fishes had 'medium' growth rates when compared with published data by other workers on different waters. Seasonal growth of roach infected with plerocercoids of Ligula intestinalis was observed at monthly intervals. Annulus formation on the scales of these fish occurred at the onset of growth in May. The heavy Ligula burden in 89% of these fish had not caused the formation of any additional or false rings.     

Swimming, grazing and social behaviour of rohu Labeo rohita (Hamilton) and common carp Cyprinus carpio (L.) in tanks under fed and non-fed conditions

Fish behaviour was monitored in 1-m² tanks each stocked with three 67-g rohu (Labeo rohita). In addition, 80-g common carp (Cyprinus carpio) were stocked at 0, 1 or 2 fish per tank. All tanks were fertilized prior to stocking to stimulate natural food production. In addition, half of the tanks were fed a supplemental diet. Results confirm the general view that rohu mainly lives and feeds in the water column, while common carp is a bottom feeder. In the presence of common carp, rohu increased the time spend grazing on tank wall and bottom, and decreasing grazing time in the water column. Supplemental feeding had a similar, be it less pronounced effect. When both present, rohu and common carp spend 47–52% of their time together. Rohu spends more time close to the bottom in the presence of common carp than when no common carp is present, presumably to profit from increased zooplankton production, triggered by the resuspension of nutrients by burrowing common carp. This was reflected in a higher growth rate of rohu in the presence of carp. These effects were stronger with one common carp per tank than with two common carp. In this study, the results from behavioural observations in tanks nicely complemented results from a pond study analyzing growth, production and food availability. Behavioural observations in tank yielded useful additional information helpful to clarify species interactions and feeding ecology in polyculture ponds.     

Biomass of planktonic crustaceans and the food of young cyprinids in the littoral zone of Lake Balaton

The littoral zone of Lake Balaton and its periphyton-zooplankton-fish communities have been investigated intensively in recent years. Total average number of crustacean plankton varied from 36 to 126 ind l^–1, their biomass from 0.49 to 1.86 mg ww l^–1 month^–1 at different areas of the littoral zone. In general, these values for the above parameters were higher in hypertrophic areas. 23 fish species occurred in the littoral zone with cyprinids dominating. The seasonal food spectra of Y-O-Y roach (Rutilus rutilus), white bream (Blicca bjoerkna) and bream (Abramis brema) were based mainly on planktonic crustaceans and benthic/periphytic invertebrates. According to the frequency of occurrence of crustaceans and other invertebrates, the food composition of young cyprinids differed significantly in the NE and SW-basins of the lake.     

Measurement of vitellogenin,a biomarker for exposure to oestrogenic chemicals,in a wide variety of cyprinid fish

There is increasing concern about man-made chemicals in the aquatic environment that mimic oestrogens because they may disrupt reproductive function. Vitellogenin, a precursor of egg-yolk in fish and other oviparous animals, may be used as a biomarker for “oestrogen” exposure. This study investigated the use of a radioimmunoassay developed to carp (Cyprinus carpio) vitellogenin to measure vitellogenin in other species of fish, especially cyprinids that would be of value for field and laboratory studies on oestrogenic xenobiotics. Of the nine families of fish studied, only vitellogenin from cyprinids (to which the carp belongs) showed good cross-reactivity in the carp vitellogenin radioimmunoassay. Vitellogenin from cyprinids native to Europe that cross reacted in the carp vitellogenin radioimmunoassay included: bream (Abramis brama), roach (Rutilus rutilus), rudd (Scardinius erythropthalmus), gudgeon (Gobio gobio) and minnow (Phoxinus phoxinus). Vitellogenin from cyprinids used widely in ecotoxicology that cross reacted in the carp vitellogenin radioimmunoassay included: fathead minnow (Pimephales promelas), zebrafish (Brachydanio rerio) and goldfish (Carassius auratus). In the cyprinids studies, the concentrations of vitellogenin in mature females were between a few hundred and a thousand microgram per millilitre. Concentrations of plasma vitellogenin in immature females were always greater than 200 ng·m^-1, whereas in males (with the exception of the fathead minnow) plasma vitellogenin concentrations were less than 20 ng·ml^-1 (and generally, much lower). The results suggest that the structure of vitellogenin is highly conserved within the cyprinid family and that the carp vitellogenin radioimmunoassay may be used to measure the concentrations of vitellogenin in plasma from a wide variety of cyprinids.     

0+ perch predation on 0+ bream: a case study in a eutrophic gravel pit lake

SUMMARY 1. We studied the population dynamics of 0+ fish in a eutrophic gravel pit lake in which predation of 0+ Eurasian perch on other 0+ fish was suspected to influence perch growth and the structure of the fish community, with effects on the lake food web. 2. The adult fish community was dominated by piscivorous species, especially perch, and the 0+ fish community was dominated by perch and bream. Bream grew to a total length of 80 mm between May and the end of August, gradually decreased in numbers during the summer, and completely disappeared in autumn. Stomach analysis revealed that 0+ perch ≥28 mm fed on 0+ bream. 3. The initially unimodal cohort of 0+ perch gradually broadened and became bimodal by the end of July. Fish of the larger, piscivorous cohort grew faster (1.4 mm day^?1) than the smaller, zooplankton‐consuming fish (0.6 mm day^?1). Although individuals of both cohorts later consumed zooplankton and grew at similar rates (0.5 mm day^?1), only perch of the large cohort (mean TL 125 mm) were found by mid‐October. Intraspecific competition for food or cannibalism of older perch may have contributed to the disappearance of the smaller perch. 4. Early piscivory of the fast‐growing 0+ perch apparently resulted in the disappearance of 0+ bream by the end of the growing season and precocious maturation of male perch. In contrast to findings in other studies, these large 0+ perch thus avoided the juvenile bottleneck by switching to piscivory early during their ontogenetic development. 5. The observations of this study suggest that early piscivory of 0+ perch can have a long‐lasting impact on fish communities in eutrophic lakes, particularly if prey fish are abundant and the structural complexity of the lake is low. Furthermore, early piscivory of 0+ perch may help prevent the expected increase in 0+ cyprinids following reduction of adult cyprinids, which is considered important to ensure the long‐term success of biomanipulation experiments.     

Comparative study of acetylcholinesterase and butyrylcholinesterase in brain and serum of several freshwater fish: specific activities and in vitro inhibition by DDVP, an organophosphorus pesticide

A comparative study of specific activities and in vitro inhibition of brain and serum acetylcholinesterase (AChE; EC 3.1.1.7) and serum butyrylcholinesterase (BChE; EC 3.1.1.8) by DDVP, an organophosphorus pesticide, was conducted in 11 freshwater teleost species belonging to four families (Cyprinidae; common carp Cyprinus carpio, bream Abramis brama, blue bream A. ballerus, white bream Blicca bjoerkna, roach Rutilus rutilus, bleak Alburnus alburnus, ide Leuciscus idus; Percidae: perch Perca fluviatilis, pikeperch Stizostedion lucioperca; Esocidae: pike Esox lucius and Coregonidae: whitefish Coregonus albula). Specific AChE and BChE activities in brain and serum of fish were determined. Brain AChE activity varied among fish species approximately 10-fold, ranging from 192.6 to 1353.2 micromol g(-1) h(-1), respectively in perch and whitefish. All cyprinids had higher brain AChE activity than those of other fish families. Serum AChE activity was 100-fold lower than in brain. Serum BChE activity was found only in cyprinids with the exception of the common carp. It varied from 163.8 to 970.3 micromol g(-1) h(-1), respectively in roach and bleak. The bimolecular enzyme inhibition rate constants (kIIs) and pI50) values for DDVP were calculated. Sensitivity of fish AChEs both in brain and serum is similar to those of typical AChEs in mammals. The range of kIIs was 3.4-51.7 x 10(3) mol(-1) 1 min(-1) (pI50s were 5.3-6.5), respectively in white bream and ide. In contrast, fish serum BChE was more sensitive to inhibition than typical BChE and AChE in mammals. Values of kII for BChE were 1.0-2.5 x 10(7) mol(-1) 1 min(-1) (pI50 was 8.8-9.2), respectively in ide and bleak.     

一种优良淡水鱼——团头鲂(Megalobrama amblycephala)的繁殖和饲养

团头鲂原是一种野生的草食性淡水鱼类,从1960年起对它进行了一系列的观察试验,肯定它有以下六个优点:(1)在池养条件下,性腺能发育成熟;(2)以各种草类为主要食料;(3)抗病力强、成活率高;(4)容易捕捞、起水率高;(5)含肉量高,脂多、味美;(6)一年半可长至商品规格。试验结果证明团头鲂可以作为新的养殖对象,同时也提供了一套繁殖、饲养管理方法。1964年到1973年已有二十一个省市先后进行移殖饲养,有的已就地繁殖、推广。本文系历年试验和部分移殖经验的总结。       

Causes and consequences of the success of bream in Dutch eutrophic lakes

In the last decennia eutrophication has caused a shift in the species composition of fish communities in Dutch fresh waters. The changes have led to the disappearance of vegetation in lakes and ponds; zooplankton and chironomids are now the most abundant food organisms for fish. In the turbid, open waters bream and pikeperch are the dominant fish species. Only small bream is vulnerable to predation, but because bream grows much faster than the other cyprinids the time span in which the fish is vulnerable is the shortest. The large bream (>20 cm) can coexist with pikeperch since it is not vulnerable to predation and still utilizes the food organisms efficiently. Eutrophication is accelerated if both bream populations are composed of small-sized specimens preventing large-sized zooplankton to develop, and if they are composed of large-sized individuals which can efficiently stir up the bottom sediments.     

Isolation of a rhabdovirus during outbreaks of disease in cyprinid fish species at fishery sites in England

A virus was isolated during disease outbreaks in bream Abramis brama, tench Tinca tinca, roach Rutilis rutilis and crucian carp Carassius carassius populations at 6 fishery sites in England in 1999. Mortalities at the sites were primarily among recently introduced fish and the predominant fish species affected was bream. The bream stocked at 5 of the 6 English fishery sites were found to have originated from the River Bann, Northern Ireland. Most fish presented few consistent external signs of disease but some exhibited clinical signs similar to those of spring viraemia of carp (SVC), with extensive skin haemorrhages, ulceration on the flanks and internal signs including ascites and petechial haemorrhages. The most prominent histopathological changes were hepatocellular necrosis, interstitial nephritis and splenitis. The virus induced a cytopathic effect in tissue cultures (Epithelioma papulosum cyprini [EPC] cells) at 20 degrees C and produced moderate signals in an enzyme immunoassay (EIA) for the detection of SVC virus. The virus showed a close serological relationship to pike fry rhabdovirus in both EIA and serum neutralisation assays and to a rhabdovirus isolated during a disease outbreak in a bream population in the River Bann in 1998. A high degree of sequence similarity (> or = 99.5% nucleotide identity) was observed between the English isolates and those from the River Bann. Experimental infection of juvenile bream, tench and carp with EPC cell-grown rhabdovirus by bath and intraperitoneal injection resulted in a 40% mortality of bream in the injection group only. The virus was re-isolated from pooled kidney, liver and spleen tissue samples from moribund bream. The field observations together with the experimental results indicate that this rhabdovirus is of low virulence but may have the potential to cause significant mortality in fishes under stress.