Juvenile Perch Research Articles

First evidence of the possible implication of the 11-deoxycorticosterone (DOC) in immune activity of Eurasian perch (Perca fluviatilis, L.): Comparison with cortisol

Cortisol, the main corticosteroid in fish, is frequently described as a modulator of fish immune system. Moreover, 11-deoxycorticosterone (DOC) was shown to bind and transcriptionally activate the mineralocorticoid receptor and may act as a mineralocorticoid in fish. Immune modulations induced by intraperitoneal injections of these two corticosteroids were assessed in Eurasian perch juveniles. Cortisol and DOC were injected at 0.8mgkg−1 and 0.08mgkg−1 body weight respectively. Cortisol increased plasma lysozyme activity 72h post-injection, C-type lysozyme expression in spleen from 1 to 72h post-injection, and favoured blood neutrophils at the expense of a mixture of lymphocytes and thrombocytes. Moreover, 6h after injection, cortisol reduced expression levels of the pro-inflammatory cytokine TNF-α in spleen. DOC had no effects on the immune variables measured in plasma, but increased expression levels of C-type lysozyme and apolipoprotein A1 mRNA in both gills and spleen. Meanwhile, DOC stimulated its putative signalling pathway by increasing expression of mineralocorticoid receptor and 11β-hydroxysteroid dehydrogenase-2 in spleen. These results confirmed the role of cortisol as an innate, short term immune stimulator. For the first time, DOC is described as a possible immune stimulator in fish.

Entrainment and impingement of juvenile silver perch, Bidyanus bidyanus, and golden perch, Macquaria ambigua, at a fish screen: effect of velocity and light

AbstractEntrainment and impingement of two non‐salmonid species susceptible to entrainment at irrigation diversions, silver perch, Bidyanus bidyanus (Mitchell), and golden perch, Macquaria ambigua (Richardson), were examined at an experimental intake screen in a laboratory flume under a range of velocities and light levels. The presence of an intake screen significantly reduced entrainment, in some cases reducing mortality from over 90% (unscreened) to less than 2% (when screened). Although some differences in behaviour existed between species, approach velocities (measured 8 cm in front of the screen) up to 0.4 m s−1 effectively reduced entrainment, with very little injury or mortality resulting from incidental screen contacts or impingement. Both species used visual cues to negotiate the screen face, thereby increasing their ability to avoid contact at higher velocities. In the absence of these visual cues, positive rheotactic behaviour was enhanced and fish mostly avoided approaching the screen. These results demonstrate that fish screens operated at approach velocities of up to 0.4 m s−1 have great potential for the protection of silver perch and golden perch juveniles at irrigation intakes.

Whole body and egg amino acid composition of Nile perch, Lates niloticus (Linnaeus, 1758) and prediction of its dietary essential amino acid requirements

Eggs and tissue of Nile perch juveniles were analysed in order to derive the essential amino acid dietary requirements for Nile perch larvae and juveniles, using the A/E ratio. Results revealed the presence of both essential and non-essential amino acids in Nile perch. A significant difference (p < 0.05) between the amino acids (AA) composition in the eggs and tissue and amongst the four class sizes of juveniles was observed. Estimates of the amino acid dietary requirements revealed that Nile perch has high arginine, leucine, threonine, valine and isoleucine dietary requirements. Key words: Nile perch, amino acids, dietary requirements, larvae, juveniles.

Twin-screw Extrusion Processing of Vegetable-based Protein Feeds for Yellow Perch (Perca flavescens) Containing Distillers Dried Grains, Soy Protein Concentrate, and Fermented High Protein Soybean Meal

&lt;span style="color: #800000; font-family: Times New Roman; font-size: small;"&gt; &lt;/span&gt;&lt;p class="MsoNormal" style="margin: 0in 0in 4pt; line-height: 12pt; mso-line-height-rule: exactly;"&gt;Changing to alternative protein sources supports production of more economic aquafeeds. Two isocaloric (3.06 kcal/g) and isonitrogenous (40% db) experimental feeds for juvenile yellow perch were formulated with incorporation of fermented soybean meal (FSBM) and soy protein concentrate (SPC), each of which were at two levels (0 and 20% db), along with constant amounts of high protein distillers dried grains (DDG) (~30% db), and appropriate amounts of other ingredients. Using a pilot scale twin-screw extruder, feed production was performed in two replications for each diet at conditioner steam levels of 0.11 to 0.16 kg/min, extruder water of 0.11 to 0.19 kg/min, and screw speeds of 230 to 300 rpm. The effects of SPC and FSBM&lt;ins datetime="2012-07-09T13:59" cite="mailto:k"&gt; &lt;/ins&gt;inclusion on extrudate physical properties were compared with those of a control diet (which contained 20% fishmeal and ~30% DDG). Inclusion of 20% FSBM and 20%SPC resulted in a substantial decrease in unit density by 9.2 and 24%, but an increase in lightness, greenness, yellowness, and expansion ratio of the extrudates by 7, 27, 14, 7, 17, 34, 15, and 16.5%, respectively. SPC inclusion led to a considerable increase in water absorption, thermal resistivity, and thermal diffusivity by 17.5, 6.3, and 17.6%, respectively, whereas no significant change was observed for these properties with incorporation of 20% FSBM. Additionally, all extruded products had high durability. Taken together, using ~30% DDG with20% FSBM or20% SPC as alternative protein sources resulted in viable extrudates with properties appropriate for yellow perch production. A future study investigating the effect of extrusion processing conditions on the production of complete vegetable-based protein feeds for yellow perch species would be appropriate.&lt;/p&gt;&lt;span style="color: #800000; font-family: Times New Roman; font-size: small;"&gt; &lt;/span&gt;

Diel and temporal habitat use of four juvenile fishes in a complex glacial lake

Weber NJ, Brown ML. 2012. Diel and temporal habitat use of four juvenile fishes in a complex glacial lake. Lake Reserv Manage. 28:120-129. Juvenile fishes may use multiple habitats during early life stages, and habitat use may change based on diel period, temporally, or ontogenetically, with patterns of habitat use being species specific. To better understand habitat use of juvenile fishes, we evaluated relative abundance of juvenile black crappie (Pomoxis nigromaculatus), bluegill (Lepomis macrochirus), yellow perch (Perca flavescens), and common carp (Cyprinus carpio) among nearshore open water, emergent vegetation, submergent vegetation, flooded timber, and open water offshore habitats in a glacial lake. In August, catch rates of common carp were highest in emergent vegetation, yellow perch and black crappie catch rates were highest in submergent vegetation, and bluegill catch rates were highest in nearshore open water, submergent vegetation, and flooded timber. In September, submergent vegetation was no longer available due to senescence, and catch rates of all species did not differ among habitats, except for common carp where catch rates were highest in emergent vegetation and flooded timber. Within a species, fishes were generally of similar size among habitats. Abundance of invertebrate prey was highly variable and was generally similar among habitats. Our results provide information about the habitat use of juvenile fishes that can be useful to the management of these species and aquatic habitat conservation.

Do Juvenile White Perch Morone americana Grow Better in Freshwater Habitats of the Blackwater River Drainage (Chesapeake Bay, MD, USA)?

Increasing rates of freshwater habitat loss in the Chesapeake Bay (and elsewhere) have renewed interest in the role of freshwater in population integrity for euryhaline fishes. Freshwater habitats may be important nurseries for juveniles of anadromous species. Using length–weight residuals and scales, we determined if body condition and growth of juvenile (<120 mm total length) white perch Morone americana (a semi-anadromous species) differed between brackish and freshwater tributaries within the Blackwater River drainage (Chesapeake Bay Watershed, U.S.A.). We then examined how monthly variation in body condition varied with monthly variation in selected environmental factors. Body condition differed between tributaries and was greater in freshwater (specific conductivity <0.45 mS) than brackish water when water temperature was greater than 9.6°C. White perch growth rates did not differ between tributaries, except for a short time during summer or early fall. Some anadromous fishes may spawn in freshwater to promote greater body condition, thereby ensuring a quality contingent of individuals for the population. With continued loss or impairment of freshwater habitat, the availability of nurseries for juvenile white perch will be reduced and reduce the number of quality juveniles recruiting to the adult population.

The effect of dipeptide, Lys-Gly, supplemented diets on digestive tract histology in juvenile yellow perch (Perca flavescens)

The aim of the present study was to evaluate the effects of three formulated diets: wheat-gluten-protein-based diets supplemented with Lys-Gly dipeptide (LG) or free lysine and glycine (FL), a control diet without lysine supplementation (C) and commercial starter Bio Oregon (BO) for on the growth and digestive system morphology of yellow perch. After 48 days of experimental feeding, fish fed LG diet showed the highest body mass. Fish fed LG diet showed the highest number of gastrin/cholecystokinin positive cells and the lowest number of CD3-positive cells. The brush border of anterior intestine was the most PepT1 immunopositive in fish fed LG diet, the weakest in fish fed C diet. The largest hepatocytes were observed in fish fed BO, while the smallest in those fed FL diet, the difference being statistically significant. Relative hepatocyte cytoplasm volume occupied by lipids was higher in fish fed BO and FL compared to those fed C and LG. Number of proliferating cell nuclear antigen-positive hepatocyte nuclei did not significantly differ among experimental groups. These results indicate that wheat-gluten-protein-based diets supplemented with dipeptide Lys-Gly (LG) were appropriate for yellow perch.

Preserving young-of-the-yearPerca fluviatilisin ethanol, formalin, or in a frozen state and the consequences for measuring morphometrics

Summary As it is often not possible to immediately analyse individuals sampled in the field, captured fish are preserved and stored for later investigation. The objective of this study was to assess the effects of various preservation methods on subsequent changes in morphometric parameters while also providing correction factors to re-calculate the original body dimensions when sampled fish are measured at a later date. In this study, juvenile perch (Perca fluviatilis, 66.5 ± 10.2 mm total length) were measured directly after capture, then either frozen at )20� C, preserved in 70% ethanol, or in 4% formalin. They were again measured after 24 h, 3 days, 7 days, and thereafter on a weekly basis for 8 weeks. Ethanol-preserved perch greatly decreased length and weight; formalin preservation also led to a comparable length reduction, but increased the weight of the perch. In contrast, frozen perch showed less shrinkage and only moderate weight loss. Of the three preservation methods, freezing clearly caused the fewest distortions. Hence, freezing is recommend as the most preferable preservation method, especially in multi-disciplinary studies on fish ecology; for all other preservation methods the correction factor over time will have to be pre-determined for each species and size class.

Variation in vertical distribution of sand dollar larvae relative to haloclines, food, and fish cues

Larvae of marine invertebrates may vertically position themselves in locations where conditions favor growth, development, and survival. Areas in stratified water columns with favorable salinities, concentrated food, or low predation may increase the probability for larvae to reach settlement. We examined the vertical distribution of three developmental stages of the echinoid Dendraster excentricus in response to haloclines, food cues, and predator cues in laboratory microcosms. Embryos, 4-arm plutei, and 8-arm plutei responded similarly to haloclines by swimming upward through haloclines when the bottom layer was at salinity 31 (ambient) and the top layer was at 27 or 23. The centers of larval mass for all stages were near the halocline when the top layer was at salinity 19 or 15. We tested the tolerance of each stage to prolonged exposure to each of these salinities and found sublethal effects under salinity 23, suggesting costs for concentrating in low salinity environments. To test the response of 4-arm larvae to food patches, we constructed a food layer composed of cells or supernatant of one of three species of algae (Dunaliella tertiolecta, Isocrysis galbana, Rhodomonas sp.). The larvae distributed above the food layer in the presence of two algal species, D. tertiolecta and Rhodomonas sp., but distributions were similar to controls when I. galbana was tested. Finally, larvae significantly changed their distributions in response to cues from a potential predator (juvenile perch), showing an avoidance behavior. The observed larval behaviors in response to haloclines, algae, and a potential predator suggest that D. excentricus plutei behaviorally respond to their environment and likely change position in response to environmental cues in the field.

Oligotrophication from wetland epuration alters the riverine trophic network and carrying capacity for fish

Submerged aquatic vegetation (SAV) constitutes a major component of fish habitat, providing support for epiphytes and invertebrates as well as shelter from predators. The effects of wetland epuration from a mesotrophic to a nearly oligotrophic state were examined over a 15 km long reach of the St. Lawrence River under the direct influence of major farmland tributaries. We hypothesized that the nutrient-enriched zone would support a higher biomass of SAV, epiphytes, macroinvertebrates and fish than the nitrogen-deficient epurated zone located downstream of the wetland. Predictions included that the enriched habitat would support a richer fish assemblage, with higher biomass and growth of juvenile yellow perch than found in the epurated zone. Results supported these hypotheses, demonstrating the chain of effects of nutrient reduction on the biomass of SAV (fourfold drop), invertebrate prey (ninefold), small (threefold) and large (1.5-fold) fish between the two zones. In addition to the reduction in SAV biomass, the replacement of filamentous chlorophytes by benthic mats of filamentous cyanobacteria in the epurated zone resulted in a less complex 3-D habitat structure and a low invertebrate availability for fish. Oligotrophication by wetland epuration exerted negative effects on fish habitat quality, food quantity and availability, with an impairment of juvenile perch growth and recruitment. A generalized model of the changes in habitat carrying capacity occurring with epuration (oligotrophication) or eutrophication is presented, with examples of other aquatic systems in which strong linkages between trophic status, SAV, invertebrates and fish productivity were also demonstrated.

Physiological and proteomic evidences that domestication process differentially modulates the immune status of juvenile Eurasian perch ( Perca fluviatilis) under chronic confinement stress

The current study aimed to evaluate the influence of domestication process on the stress response and subsequent immune modulation in Eurasian perch juveniles ( Perca fluviatilis) submitted to chronic confinement. Briefly, F1 and F4 generations were confined into small-size tanks and sampled 7 and 55 days after stocking. Cortisol and glucose levels as well as lysozyme activity and immunoglobulin level were evaluated in the serum. Spleen Somatic Index and spleen ROS production were also measured. A proteomic analysis was performed on serum sampled on day 7. Finally, both generations were genetically characterized using a microsatellite approach. Globally, results revealed that chronic confinement did not elicit a typical stress response but resulted in a prolonged immune stimulation. Proteomic results suggested that domestication process influenced the immune status of perch submitted to chronic confinement as the F1 confined fish displayed lower abundance of C3 complement component, transferrin and Apolipoprotein E. Microsatellite data showed a strong genetic drift as well as reduced genetic diversity, allelic number and heterozygosity along with domestication process. The present work is the first to report that fish under domestication can develop an immune response, assessed by a combined approach, following recurrent challenges imposed by captive environment despite a reduced genetic variation.

CATCH ME IF YOU CAN-PREDATION AFFECTS DIVERGENCE IN A POLYPHENIC SPECIES

Predation is a major driving force in evolution. Predation has been shown to select for size, morphology, and camouflage. Many animals use camouflage to reduce predation risk. In some cases, individuals can adjust their pigmentation, enabling them a higher survival in a heterogeneous environment. Here, we show that the difference in pigmentation between juvenile perch individuals (Perca fluvuiatilis) occupying different environments (open water and vegetated habitats of lakes) is likely a consequence of predator selection. Lightly pigmented individuals have a higher chance of survival in open water whereas darker pigmented individuals survive better in vegetation. As a response to predators, individuals forced into the vegetation by predators developed darker skin whereas the skin of individuals forced into open water became lighter. In a common garden experiment, in the absence of predation, we found that pigmentation in juvenile perch is only due to plasticity and not to genetic variation. However, contrary to predictions, individuals raised in open water developed darker skin compared to individuals raised in vegetation. This may be a response to UV-stress. Overall, our results suggest that predation can be a strong selective agent on pigmentation differences among conspecifics occupying different habitats.

Persistence of malachite green and leucomalachite green in perch (Lateolabrax japonicus)

The persistence of malachite green (MG), and its metabolite leucomalachite green (LMG), in fish tissues is still unclear, leading to many trade disputes. In this research, we established and evaluated an HPLC method that could detect MG and LMG simultaneously, and then investigated the persistence of these two toxins in the tissues of juvenile perch (Lateolabrax japonicus) post sub-chronic MG exposure at 1.0 mg/L. Exposure lasted for 2 h everyday and was repeated six times. The perch were then placed in MG-free seawater for 100 d to eliminate the toxins. Results show that MG accumulated in the tissues, including the gills, liver, muscle, blood and viscera, and then was metabolized rapidly to LMG. The concentrations of these two toxins increased significantly with the accumulation process. In general, the highest concentrations of MG and LMG in all tissue exceeded 1 000 μg/kg, except for MG in the muscle. The order of accumulation levels (highest to lowest) of MG was gill>blood>liver>viscera>muscle, while that of LMG was liver>blood>gill>viscera>muscle. High levels of MG or LMG could persist for several hours but decreased rapidly during the elimination process. The concentration of LMG was much higher than that of MG during the experiment, especially in the gill, liver and blood. Therefore, the three tissues play important roles in toxin accumulation, biotransformation, and elimination. Although the MG and LMG concentrations in muscle were much lower than in other tissues, the content still exceeded the European minimum required performance limit (MRPL), even after 2 400 h (100 d) of elimination. This demonstrates that it is extremely difficult to eliminate MG and LMG from tissues of perch, and therefore use of these toxins is of concern to public health.

Feeding, development, and growth of juvenile perch perca fluviatilis in mesocosms in the presence of filter-feeding zebra mussel Dreissena polymorpha pallas

6360 specimens/m 2 , and the biomass was 3.73 kg/m 2 (Perova, 2004). At the same time, the maximum abun� dance of zebra mussel in Lake Erie (United States) reached 700000 specimens/m 2 (Primak, 2002). An abrupt increase in the abundance of zebra mussel in water bodies can lead to changes in the trophic chains of ecosystems. Even a lower abundance of zebra mus� sel leads to the poor food supply of zooplankton; to changes in the structural and functional relationships in bacterial, phytoplankton, zooplankton, and benthic communities; and to changes in the food supply for fish and in the fish productivity of the water body. The rapid invasion of the zebra mussel in Europe and the United States stimulated intensive investigations into the potential effect that this organism may have on the resident components of water biotopes (Dgebuadze,

Diet partitioning, habitat preferences and behavioral interactions between juvenile yellow perch and round goby in nearshore areas of Lake Erie

Ecological interactions between native and non-indigeneous species depend on interspecies dietary and habitat overlap and species-specific behavior. In the Great Lakes, the exotic round goby ( Apollonia melanostoma) is very abundant in littoral areas used by the native yellow perch ( Perca flavencens). We examined yellow perch-round goby interactions using multiple approaches. Field surveys analyzing dietary overlap among three size classes of yellow perch and round goby detected significant overlap only between juvenile perch (< 95 mm TL) and gobies (< 60 mm TL). Laboratory experiments using juvenile stages tested for habitat preference differences (open sand, macrophytes and dreissenids) in solitary, intraspecific (2 perch) and interspecific (1 perch, 1 goby) treatments. In macrophyte and dreissenid habitats, we tested for treatment differences in fish behavior (intraspecific vs. interspecific) and yellow perch growth (solitary, intraspecific and interspecific). Round goby consistently preferred complex habitats. Yellow perch showed diurnal preference of complex habitats, but increased nocturnal use of sand in the solitary and interspecific treatments. Activity was greater in dreissenid than macrophyte habitat, but prey attacks showed the opposite trend. Activity and prey attacks were greater in the intraspecific than interspecific treatments. The trend was due to lower prey attacks executed by round goby. In macrophytes, individual yellow perch growth was lower in the intraspecific than in the solitary and interspecific treatments. In dreissenids, intraspecific and interspecific competitors equally decreased yellow perch growth. Our results suggest differences in diet, habitat preference and behavior between juvenile round goby and yellow perch may allow their coexistence in nearshore areas.

Assessment of dietary lysine requirement for silver perch ( Bidyanus bidyanus) juveniles

A 10-week rearing trial was conducted to assess the lysine requirement of juvenile silver perch, and to evaluate the effects of dietary lysine levels on the morphological measurements, body composition, hematological traits and muscle carnitine status of the fish. Seven isonitrogenous and isolipidic diets were formulated to contain multiple intact proteins and pre-coated crystalline amino acids. l-lysine HCl was supplemented to the experimental diets at the expense of a dispensable amino acid mixture to achieve lysine levels from 0.90 and 2.70% of dry diet. Each diet was randomly assigned to triplicate groups of 10 fish and was fed to apparent satiation five times daily. At the end of the trial, percent weight gain increased with increasing dietary lysine from 0.90% to 2.10%, then the value decreased slightly. A similar trend was observed in the feed efficiency, protein efficiency ratio, productive protein value and daily protein deposition. The condition factor, hepatosomatic index, intraperitoneal fat and viscerosomatic index were markedly affected by the dietary lysine level. Crude protein contents of the whole body, muscle and liver were significantly depressed in the fish fed lysine-deficient diets, while the whole body lipid content was higher in these fish. The hematocrit value, hemoglobin concentration and free lysine levels in plasma were lower in the silver perch given lower lysine diets. Although muscle carnitine status was not clearly affected by the dietary lysine level, the values of free carnitine and acid soluble carnitine tended to be lower in the fish fed lower lysine diets. Based on the quadratic broken-line model, the dietary lysine requirement for maximum growth of the silver perch juveniles was satisfied at 2.32% lysine in the dry diet, corresponding to 5.96% of the dietary protein. Furthermore, 2.06% of chemically available lysine in the diet (equivalent to 5.30% dietary protein) was required for the optimal growth of the fish.

Does the consumption of divergent resources influence risk taking behaviour in juvenile perch (Perca fluviatilis L.)?

Heynen M, Heermann L, Borcherding J. Does the consumption of divergent resources influence risk taking behaviour in juvenile perch (Perca fluviatilis L.)? Ecology of Freshwater Fish 2011: 20: 1–4. © 2010 John Wiley &amp; Sons A/S

Shoaling preference and evidence for maintenance of sibling groups by juvenile black perch Embiotoca jacksoni

Group sizes in free-living juvenile black perch Embiotoca jacksoni were quantified and predictions of the hypothesis that such groups comprise sibling brood-mates were tested. Group sizes in the field were within the range of female brood sizes and often occurred close to each other but did not merge. In captivity, juveniles formed groups immediately after birth. In laboratory experiments, they also associated significantly more with chambers containing familiar members of their own brood than empty chambers but did not associate more with chambers containing similar-sized juveniles from a different brood. Juvenile E. jacksoni also associated significantly more with chambers containing familiar brood-mates than with chambers containing unfamiliar members of a different brood. The strength of this preference increased with the number of days fish had been together since birth. When two broods were placed in a large outdoor tank, all individuals from both broods directed significantly more aggressive acts towards members of the other brood than towards members of their own brood. While the relative effects of familiarity and relatedness cannot be completely separated in this viviparous species, associating with familiar individuals would facilitate the maintenance of sibling groups in the field.

Effect of Wetland Enhancement on Parasites of Juvenile Yellow Perch

Impoundments and dams are frequently used in wetlands to stabilize water levels and maintain breeding habitat for waterfowl. The objective of the study was to examine the effect of reduced water level fluctuations and connectivity on fish parasitism in wetlands caused by the installation of such structures. We compared parasites of juvenile yellow perch (Perca flavescens) from two enhanced wetlands where water level is regulated and where connection with the main channel occurs only during spring flood (enhanced wetlands) to parasites of juvenile perch living in seasonally flooded wetlands where connection with the main channel is continuous (natural wetlands). Parasite species richness and Shannon diversity index were higher in natural than in enhanced wetlands. Jaccard similarity index revealed a higher similarity in parasite assemblages within than between each type of wetlands. Glochidia and parasites that include clams in their life cycle were absent from the two enhanced wetlands. Our study suggested that local factors such as water level fluctuation and connectivity in enhanced wetlands may limit the establishment of bivalves and that the use of impoundments and dams in wetlands areas may have an impact on some components of the food web.

The impact of introduced Ponto-Caspian amphipods and mysids on perch (Perca fluviatilis) diet in Lithuanian lakes

Ponto-Caspian amphipods and mysids were introduced into inland waters of Lithuania in 1960–1961, attempting to enhance production of commercially important fish. It was assumed that fish species would specialize to feed on introduced peracaridans. The impact of introduced species on perch diet was tested in seven lakes which differed by the presence and abundance of introduced species. Juvenile perch consumed introduced amphipods and mysids from the first year of age in the lakes wherein these peracaridans were abundant. However, the abundance of introduced crustaceans had no impact on the breadth of perch feeding niche, although perch underwent an earlier diet shift from zooplankton to macroinvertebrates in the lakes with numerous populations of Ponto-Caspian mysids because of availability of this prey and probable reduction in the littoral zooplankton abundance. Our results suggest that juvenile perch generally did not selectively feed on introduced species, although some selectivity for mysids, when th...