Pikeperch Larvae Research Articles

Effect of size sorting on the survival, growth and cannibalism in pikeperch (Sander lucioperca L.) larvae during intensive culture in RAS

The aim of the experiment was to determine the impact of sorting on the growth, survival, and cannibalism of pikeperch larvae during intensive culture in recirculation systems. Larvae aged 48 days post-hatch (DPH) were reared in three groups – small specimens (group S – average body weight 40 mg), large specimens (group L – average body weight 76 mg), and unsorted ones (group U – average body weight 55 mg). After three weeks of rearing, there were no statistically significant differences in specific growth rates among the groups. However, increases in biomass were higher in the sorted groups. Survival exceeded 50% in the sorted groups and 39% in group U. Higher cannibalism was noted in group U than in the sorted groups. Significant differences among the sorted groups were observed in cannibalism, which was higher in group L, and in natural and manipulation losses, which were higher in group S (P < 0.05). During the first two weeks of rearing, the lowest cannibalism rates were observed in group S, the difference between groups S and U was statistically significant (P < 0.05). The results of the experiment indicate that the sorting of pikeperch larvae has a positive impact on the survival rate, however, it has no impact on growth during their rearing in the RAS.

Effect of different sources and levels of dietary phospholipids on performances and fatty acid composition of pikeperch (Sander lucioperca) larvae

The aim of this study was to evaluate the effects of dietary phospholipids (PL) sources (fish gonad G-PL and soybean lecithin S-PL) and levels (50 and 90 g kg−1 dry matter) on the performances and fatty acid (FA) composition of pikeperch larvae. From day 10 to day 34 posthatching (p.h.), larvae were fed with three isoproteic and isolipidic microdiets. The best results of growth and skeletal development were related to a high phospholipid level regardless of their origin and FA profile. Jaw deformities seemed associated with high dietary highly unsaturated FA (HUFA) level. The optimal level of eicosapentaenoic acid and docosahexaenoic acid (EPA + DHA) for pikeperch larvae appeared to be around 12 g kg−1 (dry matter) associated with a PL level around 90 g kg−1. FA composition of diets and larvae revealed a better incorporation of arachidonic acid, EPA and DHA into PL fraction especially in larvae fed with soybean PL. Moreover, 34-day-old pikeperch larvae may have capability of converting 18 carbon n-3 FA into the n-3 HUFA. Hence, for pikeperch larvae, PL from plant origin were as efficient as those from marine fish origin.

The effects of dietary long-chain essential fatty acids on growth and stress tolerance in pikeperch larvae (Sander lucioperca L.)

The nutritional requirements of pikeperch larvae have been sparsely examined. Dietary polyunsaturated fatty acids, arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may affect growth and physiological stress response in marine fish larvae, but these mechanisms have not received as much attention in freshwater fish. Pikeperch larvae were reared on Artemia from day 3 until 21 days posthatch. Artemia were enriched with six formulated emulsions, with inclusion of either fish oil, pure olive oil (POO) or olive oil supplemented with various combinations of ARA, EPA and DHA. Larval tissue FA was significantly related to the content in the diets, but larval growth was similar for all treatments. When exposed to stress by confinement in small tanks with culture tank water or saline water (15 g L−1.), mortality in larvae treated with POO was significantly higher than in the remaining treatments while tissue cortisol contents in these fish seemed lower. The findings of a lower stress response in larvae fed POO may be related to the lower tissue content in these larvae of essential fatty acids especially DHA but also EPA and ARA.

Diel vertical migrations of age 0+ percids in a shallow, well-mixed reservoir

The distribution of age 0+ percids (perch, Perca fluviatilis and pikeperch, Sander lucioperca) was investigated in a shallow, wellmixed reservoir during a 24-h period in late May, using acoustic and netting methods. Diel vertical migrations (DVMs) were acoustically recorded between the layers close to the bottom and the whole water column. The netting data showed a high abundance of larvae and juveniles at night (nearly 1 ind m-3, or 6 ind m-2), whereas negligible numbers of age 0+ percids were present in the water column during the day (3% of night abundance). Age 0+ percids remained during the day in the layer very close to bottom. Smaller pikeperch larvae dominated the pelagic age 0+ fish assemblage during daylight, while larger perch prevailed at night. A strong difference between day and night abundances along with a clear pattern discerned by acoustic methods revealed the DVM of age 0+ percids. Analyses of the fish digestive tract contents indicate that DVM was not governed by feeding behaviour, but rather a defensive strategy against predation. This is in agreement with the size distribution of age 0+ percids, since they were smaller in water column during the day as opposed to the night.

Differential protein expression profile in the liver of pikeperch ( Sander lucioperca) larvae fed with increasing levels of phospholipids

A comparative proteomic approach was used to assess the protein expression profile in the liver of 34 days old pikeperch larvae fed from day 10 post hatching, with three isoproteic and isolipidic formulated diets varying by their phospholipid (PL) contents (% dry diet weight): 1.4% (PL1), 4.7% (PL5) and 9.5% (PL9). Using 2D-DIGE minimal labelling of liver extracts, we were able to show 56 protein spots with a differential intensity ( p < 0.05) depending on the dietary PL content. Among these spots, 11 proteins were unambiguously identified using nanoLC-MS/MS tandem mass spectrometry. In the PL9 larvae, our results indicate that the glycolytic pathway could be down-regulated due to the under-expression of the fructose biphosphate aldolase B and the phosphoglucomutase 1. Meanwhile, propionyl coenzyme A carboxylase (a gluconeogenic enzyme) was under-expressed. In addition, another gluconeogenic and lipogenic enzyme, pyruvate carboxylase, was identified in 3 different spots as being under-expressed in fish fed with the intermediate PL level (PL5). A high PL content increased the expression of sarcosine dehydrogenase, an enzyme involved in methionine metabolism, along with vinculin, a structural protein. Moreover, several stress proteins (glutathione S-transferase M, glucose regulated protein 75 and peroxiredoxin-1) were modulated in response to the dietary PL level and fatty acid composition. In the larvae fed with the lowest dietary PL content (PL1), over-expression of both GSTM and GRP75 might indicate a cellular stress in this experimental treatment, while the under-expression of Prx1 might indicate a lower defence against oxidative stress . In conclusion, this nutriproteomic approach showed significant modifications of protein expression in the liver of pikeperch larvae fed different PL contents, highlighting the importance of these nutrients and their influence on metabolism processes and on stress response.

Effect of dietary phospholipid levels on performance, enzyme activities and fatty acid composition of pikeperch (Sander lucioperca) larvae

This study was carried out to evaluate the effects of dietary phospholipid on the development and rearing performance of pikeperch (Sander lucioperca) larvae. From day 10 post-hatching, fish larvae were weaned onto three isoproteic and isolipidic formulated diets with different phospholipid (PL) levels: 1.4 (PL1), 4.7 (PL5) and 9.5% (PL9) of dry matter, as soybean lecithin. Neutral lipid (NL) with inversed gradient was incorporated in diets. Survival, growth and deformities were monitored until day 34 post-hatching, as well as intestinal enzyme activities, leucine alanine peptidase (leu-ala), aminopeptidase N (AN) and alkaline phosphatase (AP), which were used as indicators of digestive tract maturation. This study showed that PL supplementation significantly improved growth but not survival. The increase in dietary PL from 1.4 to 9.5% led to a 50% increase in larval final weight suggesting that high PL levels are needed during larval stages of pikeperch. The incidence of deformities was not affected by dietary phospholipid level. The specific activity of brush border membrane enzymes (AN and AP) increased with dietary phospholipid levels, indicating an earlier or more efficient maturation of digestive structures. A gut maturation index based on the ratio of segmental activity of the brush border membrane enzyme AP related to segmental activity of a cytosolic enzyme, leu-ala, was significantly higher in PL5 and PL9 groups compared to PL1 group indicating that 1% phospholipid incorporation in diet was not sufficient to induce good enterocyte maturation. Diet fatty acid composition was affected by phospholipid incorporation, dietary n−3 HUFA concentration decreasing with the incorporation of PL. Fatty acid composition in larvae reflected that of corresponding diet. The best results in growth and development obtained in the PL9 group seemed related to the PL entity, independently of its fatty acid composition. The results of this study indicate that pikeperch larvae have a relatively high PL requirement (at least 9.5% of the diet, dry weight).

Effects of weaning age and diets on ontogeny of digestive activities and structures of pikeperch (Sander lucioperca) larvae

Growth and ontogeny of digestive function were studied in pikeperch (Sander lucioperca) larvae weaned on artificial food at different ages. Three weaning treatments initiated respectively on day 9 (W9), day 15 (W15) or day 21 (W21) post-hatching (p.h.) were compared with a control group, fed Artemia nauplii from first feeding until the end of the rearing trial on day 36 p.h. The digestive enzyme activities and the ontogeny of digestive structures were investigated using enzymatic assays and histological methods. Growth of pikeperch larvae was significantly affected by precocious weaning. Pancreatic (trypsin and amylase) and intestinal (leucine-alanine peptidase, leucine aminopeptidase N and alkaline phosphatase) enzyme activities were detected from hatching onwards, increased at the moment of first feeding and then decreased. Pepsin secretion occurred at day 29 p. h. only, concurrently with the stomach development and differentiation of gastric glands. In the early weaning group (W9) the maturation process of intestinal enterocytes seems to be impaired and/or delayed and several signs of malnutrition were recorded. Except for alkaline phosphatase activity, no differences in enzyme activities and development of digestive structures were observed among the control, W21, and W15 groups. Moreover, at the end of the experiment, no differences in proteolytic activities were observed among larvae from the different treatments, indicating that, in surviving individuals, the digestive structures were properly developed and the larvae had acquired an adult mode of digestion. Based on the artificial diet used, our results suggested that pikeperch larvae can be weaned from day 15 p.h. without significant adverse effect on digestive capacities (except for alkaline phosphatase) or development of digestive tract, while earlier weaning impaired the onset of the maturation processes of the digestive system, both in terms of morphological structures and enzymatic activities.

Effect of stocking density on survival and growth performance of pikeperch, Sander lucioperca (L.), larvae under controlled conditions

The effect of stocking density on the survival and growth of pikeperch, Sander lucioperca (L.), larvae was examined in two consecutive experiments. In experiment I, 4-day-old larvae [body wet weight (BW): 0.5 mg; total body length (TL): 5.6 mm] were reared in 200-l cylindro-conical tanks in a closed, recirculating system (20 ± 0.5°C) at three stocking densities (25, 50 and 100 larvae l−1) and fed a mixed feed (Artemia nauplii and Lansy A2 artificial feed) for 14 consecutive days. At densities of 25 and 100 larvae l−1, growth rate and survival ranged from 2.7 to 1.9 mg day−1 and from 79.2 to 72.3%, and fish biomass gain ranged from 0.6 to 2.0 g l−1, respectively. There were two periods of increased larval mortality: the first was at beginning of exogenous feeding and the second during swim bladder inflation. In experiment II, 18-day-old larvae (BW: 35 mg; TL: 15.6 mm) obtained from experiment I were reared under culture conditions similar to those of experiment I, but at lower stocking densities (6, 10 and 15 larvae l−1). The fish were fed exclusively with artificial feed (trout starter) for 21 consecutive days. At densities of 6 and 15 larvae l−1, the growth rate and fish biomass gain ranged from 28.8 to 23.1 mg day−1 and from 2.0 to 3.3 g l−1, respectively. The highest survival (56.5%) was achieved at a density of 6 larvae l−1. Mortality at all densities was mainly caused by cannibalism II type behaviour (27–35% of total). In both experiments, growth and survival were negatively correlated and fish biomass gain positively correlated with stocking densities. The present study suggests that the initial stocking density of pikeperch larvae reared in a recirculating system can be 100 individuals l−1 for the 4- to 18-day period post-hatch and 15 individuals l−1 for the post-19-day period.

Effects of clay turbidity and density of pikeperch (Sander lucioperca) larvae on predation by perch (Perca fluviatilis)

Increased turbidity reduces visibility in the water column, which can negatively affect vision-oriented fish and their ability to detect prey. Young fish could consequently benefit from high turbidity levels that can provide a protective cover, reducing predation pressure. Perch (Perca fluviatilis) are commonly found in littoral zones of temperate lakes and coastal areas of the Baltic Sea. Pikeperch (Sander lucioperca) spawn in these areas, so perch is a potential predator for pikeperch larvae. We conducted laboratory experiments to test the predation of perch on pikeperch larvae at different turbidity levels (5-85 nephelometric turbidity units), densities of pikeperch larvae (2-21 individuals l(-1)) and volumes of water (10-45 l). The logistic regression showed that the probability of larvae eaten depended significantly on turbidity and volume of water in the bags, while density of larvae was not significant. However, because container size is known to affect predation, the data was divided into two groups based on water volume (10-20 and 25-45 l) to reduce the effects of container size. In either group, probability of predation did not significantly depend on volume, whereas turbidity was significant in both groups, while density was significant in larger water volumes. Thus, high turbidity impaired perch predation and protected pikeperch larvae from perch predation. Because density of larvae was also a significant factor affecting predation of perch, the dispersal of pikeperch larvae from spawning areas should also increase the survival of larvae.

The use of tannic acid to remove adhesiveness from pikeperch, Sander lucioperca, eggs

The studies conducted in 2003–2004 focused on the possibilities of applying a tannic solution to remove adhesiveness from pikeperch eggs. Spawners were caught in Lake Pątnowskie (central Poland) and then transported to the Goslawice Fish Farm. After initial selection, the fish were weighed, measured and stimulated with human chorionic gonadotropin. Gametes were obtained 5 days after the first injection. The weight and diameter of the eggs, and the commercial fecundity of individual females were determined. The eggs were fertilized with the dry method. After the addition of water, the eggs were mixed for 4 min, and then divided into 20 g portions. After determining the number of eggs in the various portions, the adhesiveness removal procedure was performed. Three concentrations of tannic acid solution (500, 1000, 1500 mg L−1) and three exposure times (0.5, 2, 5 min) were applied. The eggs were incubated in Weiss jars. The studies indicated that both the solution concentration and the exposure time significantly (P<0.05) impacted pikeperch egg hardening, the degree of adhesive removal and embryo survival. The tannic acid solution concentration of ≤500 mg L−1 applied for 0.5–2 min was not effective; the eggs clumped and it was impossible to separate them even with intensive mixing. Better results were obtained using higher tannic acid concentrations and/or by lengthening exposure time. The adhesiveness of pikeperch eggs disappeared completely after 5 min exposure to tannic acid solution concentrations of 500–1500 mg L−1 or after 2 min exposure to solution concentrations of 1000–1500 mg L−1. In these variants, the embryo survival rate to the eyed-egg stage was 78.0–84.0% (2003) and 82.3–84.7% (2004). However, high tannic acid concentration had a negative impact on the pikeperch larvae hatching. The greatest decrease in survival rate was observed in groups exposed to a tannic acid solution of 1500 mg L−1 for 2 and 5 min periods. Thus, the optimum method for removing pikeperch egg adhesiveness was to apply a solution of tannic acid at a concentration of 500 mg L−1 for 5 min or 1000 mg L−1 for 2–5 min.

Rearing of pike-perch larvae using formulated diets - first success with starter feeds

The present study evaluated the performance of two commercial diets: AgloNorse (AN) and BioKyowa (BK), and two experimental, formulated diets based on casein (C) or casein plus casein hydrolysates (CH) in rearing of pike-perch larvae (Sander lucioperca L.). All fish were 5 day old and control group was fed live Artemia nauplii. Fish were sampled periodically for histological comparison of morphological changes in the digestive tracts. Survival of fish fed Artemia nauplii, BK and AN was similar: 54.4%, 50.8% and 52.4%, respectively, while the fish fed formulated diets C and CH showed considerably lower survival: 28.4% and 21.6% respectively. After 5 weeks of rearing, the average body mass of fish ranged from 212±32 mg in Artemia fed group to 53.8±6.8 mg in C diet fed group. A considerable vacuolization of supranuclear zone in enterocytes of posterior intestine was observed in the larvae fed commercial diets. No anomalies in liver development were found. Hepatocytes of fish fed BK diet showed larger glycogen storage areas, compared with those occupied by lipids. The highest zymogen accumulation of pancreatic cytoplasm was observed in fish fed Artemia. In fish fed C and CH diets, anomalies in digestive system development were indicated by lower and less numerous intestinal folds, smaller hepatocytes, retarded development of gastric glands, and in CH group – also local fatty degeneration of liver.

Dynamics of Total Body Fatty Acids During Early Ontogeny of Pikeperch (Sander lucioperca) Larvae

The fatty acid composition of pikeperch (Sander lucioperca) was determined according to their physiological status, during starvation (10 days) and feeding (28 days). In starved larvae, polyunsaturated, monounsaturated and saturated fatty acids were utilized as metabolic substrates until day 9. At day 10, all fatty acid levels remained stable or, at least, increased in larval body. Among fatty acids, docosahexaenoic acid 22:6 n-3 was used preferentially (20.3% from total fatty acids utilized) followed by palmitoleic acid 16:1 n-7 (13.9%) and then by oleic 18:1 n-9 (12.3%), linoleic 18:2 n-6 (10.1%), linolenic 18:3 n-3 (9.7%) and eicosapentaenoic 20:5 n-3 (9.1%) acids. On the other hand, arachidonic acid 20:4 n-6 was utilized very lowly (0.3%). In fed larvae, no utilization of body fatty acids was observed during the experiment. It seems that energy requirements (and others) of fed larvae were satisfied by feed.

Induction of Out-of-Season Spawning of Pikeperch, Sander Lucioperca (L.)

Pikeperch were induced to spawn 3 months prior to the natural spawning period through photothermal and hormonal stimulation. Females (five specimens in each group) were stimulated with injection of human chorionic gonadotropin (hCG) once (200 IU kg−1), twice (200 IU kg−1, second dose after 48 h–400 IU kg−1) or three times (200 IU kg−1, after 24 h–200 IU kg−1 and after another 24 h–200 IU kg−1). The control group was injected once with 0.9% NaCl. The males were stimulated with a single hormone dose of 200 IU kg−1. Eggs were obtained from all the hormonally treated fish. None of the control group females, which were only stimulated photothermally, ovulated any eggs. The time of ovulation was 66–71 h following the first injection, and the eggs viability until the eyed stage (from 71.5 to 77.5%) did not depend on the number of hormone doses (P > 0.05). The out-of-season spawning method described in this paper could be used to provide pikeperch larvae for intensive culture systems (recirculating water systems) before natural spawning season and to produce larger-sized pikeperch fingerlings for stocking.

The diet and growth of larval and juvenile pikeperch (Stizostedion lucioperca (L.)): A comparative study of fishponds and a reservoir

Diet of larval and juvenile pikeperch (Stizostedion lucioperca) reared in ponds wasinvestigated and compared with the diet ofpikeperch from a reservoir. The standard lengthof first feeding pikeperch larvae in ponds was6.1 mm, on average, and although rotifers werepresent in the diet, their numericalcontribution can be considered asinsubstantial. Rotifers were soon replaced bynauplii of cyclopoid copepods, which werehighly positively selected and contributedlargely to the diet up to a larval length of 10 mm.Daphnia spp. were consumed from the onsetof exogenous feeding, but were not positivelyselected until 15 mm. Anothersmaller cladoceran Bosmina longirostriswas highly negatively selected and did notcontribute significantly to the diet. A clearpositive selection for larger relatively tosmaller prey and a preference for Daphniafrom a body length of 15 mm onwards could beobserved. In the reservoir, rotifers were notfound in the diet of pikeperch larvae even inthe smallest individuals. Dominant food itemswere nauplii and 1st copepodite instar ofEudiaptomus gracilis and Cyclopsspp. Cladocerans – Daphnia galeata andto a lesser extent Diaphanosomabrachyurum appeared in the pikeperch diet at alength of about 10 mm. A shift from copepods toDaphnia spp. and especiallyLeptodora kindtii could be recognised inpikeperch at a length of 20 mm. When comparing ourdata from nursing ponds with the data fromŘimov reservoir, similar trends in dietcomposition were observed.

Growth response of pikeperch larvae in relation to body size and zooplankton abundance

The most critical period at onset of feeding in pikeperch Stizostedion lucioperca is short (&lt;5 days at 20° C). The larvae are sensitive to prey density during the first week of exogenous feeding. First‐feeding larvae of 6.5 mm total length (LT) needed prey densities of &gt;585 prey l−1 to maintain mass (Cmaint), whereas 5 days older larvae of 7 mm LT Cmaint= 55 prey l−1 and for 11 mmLT larvae Cmaint&lt;10 prey 1−1. Changes in specific growth rates for larvae of 7 and 11 mm were similar to a type‐II functional response curve reaching a specific growth rate of 26 and 30% day−1, respectively, at 1000 prey l−1, whereas the 6·5 mm larvae showed a linear growth response reaching a specific growth rate of only 9% day −1 at 1000 prey l−1. The results suggest that prey density is a limiting factor, which might contribute to the high variation between year‐class Strengths.

Growth response of pikeperch larvae in relation to body size and zooplankton abundance

Growth response of pikeperch larvae in relation to body size and zooplankton abundance

Development of yolk complex, liver and anterior intestine in pike-perch larvae,Stizostedion lucioperca(Percidae), according to the first diet during rearing

Pike-perch Stizostedion lucioperca larvae fasted or given two diets (artificial feed, zooplankton) were studied by transmission electron microscopy and using specific cytological dyes. The objective of this work was to assess the changes in the yolk sac, liver and anterior intestine following the mouth opening stage (95 °C.d, day 5 - 5.8 mm) from endo- to exotrophy periods. The yolk sac included a syncytial envelope closely bound to the proteinaceous vitellus and the oil globule. Its development was similar to that observed in trout (Oncorhynchus mykiss and Salmo fario trutta )and sea-bream (Sparus aurata, ) but without vitellus fragmentation into platelets. Vitellus resorption was never achieved in dying larvae. From the end of the endotrophic phase onwards, the amount of hepatic glycogen decreased. Carbohydrate disappeared at the beginning of the exotrophic phase then increased after 220 °C.d (day 10 - 6.0 mm), mainly in zooplankton-fed larvae. Lipids from enterocytes, sinusoids and general blood Stream showed a similar development. They were abundant at 95 °C.d, progressively disappeared up to 260 °C.d (day 12 - 6.3 mm), and increased again from 350 °C.d (day 16 - 6.7 mm) onwards if larvae were fed zooplankton. Dietary lipids did not seem to immediately replace yolk lipids despite absorption in the gut. Various hypotheses are proposed to explain the physiological abnormalities of this critical larval stage. Although zooplankton appeared to have better nutritional qualities than the artificial feed, these two foods proved to be quite unsatisfactory as they induced liver cell changes typical of food deficiency, generally observed in starving larvae.

The effect of biomanipulation of the zooplankton on the growth, feeding and survival of pikeperch (Stizostedion lucioperca) in nursing ponds

The following treatments were evaluated for use in rearing pikeperch larvae (Stizostedion lucioperca L.) in nursing ponds: treatment with Dipterex (Bayer); concurrent stocking with common carp (Cyprinus carpio L.); short flooding periods and prefeeding fish larvae. Treatment with Dipterex (active ingredient trichloorfon, i.e. 00-dimethyl-2,2,2, trichlorohydroxyethyl phosphonate) gave zooplankton populations dominated by rotatoria and nauplii at the onset of exogenous feeding and dominated by copepods later on. Cladocerans dominated the plankton in untreated ponds but were never prominent in treated ones. Stomach analysis revealed a fast changing feeding preference in pikeperch from nauplii and copepodites towards cladocerans and chironomids. The excellent food conditions for first feeding pikeperch larvae in Dipterex treated ponds resulted in a significant higher number of harvested fingerlings. In spite of the more favourable food conditions in untreated ponds during the second half of the culture period, a significant growth difference was not found. Concurrent carp stocking did not affect significantly the survival and growth of the pikeperch, although it decreased the accessability of chironomids for pikeperch. Short flooding periods and prefeeding pikeperch larvae failed as useful management strategies for pikeperch nursing. Pikeperch fingerlings cultured in ponds are larger than those found in natural populations at the same time, giving them a high chance to become piscivorous and to increase the year class strength when stocked in natural waters.