INVESTIGATIONS ON TECHNOLOGICAL PARAMETERS IN INTENSIVE REARING OF PIKE-PERCH (STIZOSTEDION LUCIOPERCA)

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INVESTIGATIONS ON TECHNOLOGICAL PARAMETERS IN INTENSIVE REARING OF PIKE-PERCH (STIZOSTEDION LUCIOPERCA)

T. Molnár (1)_{, Cs. Hancz} (2), M. Molnár (3)_{, Gabriella Stettner} (4)

Original scientific paper

ABSTRACT

Market demands and competition force the production of high quality freshwater fish in European aquaculture. In Hungary pike-perch is the most „noble” and perhaps the most sensitive fish species. One of the constraints of the increasing its production in natural waters, reservoirs and ponds is the shortage in adequate sized alevins. The possible solution of this problem can be the elaboration of intensive rearing technics of pond pre-reared fry. The aims of the present work were to test the growing capacity, feed conversion and survival of pike-perch in intensive circumstances. Fish were kept in 130 l aquaria working in recirculation system at an average water temperature of 220.5 C. Two stocking densities were applied (18 and 36 fish/aquarium). Minced fish (test) and live prey (control) were offered twice a day till satiation in two replications. The experiment lasted 4 weeks. According to our results minced fish is suitable feed in the intensive rearing of pike-perch alevins. Daily food intake was only influenced significantly by different feeds (2.01g vs.4.53 g, test and control, respectively). Feeding and stocking density had significant effect (P=0.001 and 0.017) on the average weight gain (0.52 g and 1.40 g for minced fish and live feed, respectively, 1.02 g in lower and 0.90 g in higher density). Owning to the high variances treatment effect on feed conversion proved to be not significant. Average survival of the minced fish fed group was 62.2 % vs. 78.8 % of the live fish fed alevins. This difference was significant (P<0.01) in the first two weeks when almost all of the losses happened due to cannibalism and other unknown reasons. Based on our results a period of 10–14 days is needed for pre-reared pike-perch to change gradually their feeding from zooplankton to minced fish diet.

Keywords: pike-perch, feeding, stocking density, intensive rearing

INTRODUCTION

The pike-perch is one of the most noble and perhaps the most sensitive fish in Hungary. Market demands and competition force the production of high quality freshwater fish in European aquaculture. One of the constraints of the increasing pike-perch production in natural waters, reservoirs and ponds is the shortage in adequate sized alevins. The possible solution of this problem can be the elaboration of intensive rearing technics of pond pre-reared fry. It seems to be justified since the intensive rearing of its North American relative (Stizostedion vitreum) is more or less resolved. There are recommendations for the adequate stocking density (Kuipers and Summerfelt, 1994; Chesire and Steele, 1972) and encouraging preliminary results are published for the transformation to dry and semi-moist foods (Colesante et al., 1986; Kuipers and Summerfelt, 1994). Intensive rearing of the pike perch larvae on artificial diet is not viable because the previous experiments showed poor growth and high mortality (Klein Bretteler, 1989; Schlumberger and Proteau, 1991) and the pre-rearing in ponds is easy to resolve. The great growing capacity of the pre-reared pike perch can be well exploited with high value artificial foods and from 2 grams to more than 300 grams growth can be achieved on 22-26 o_{C temperature in a year (Hilge, 1990).}

Our final aim was to study growing capacity, food conversation and survival of the pike-perch under intensive conditions.

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(1) Tamás Molnár, Ph.D student, (2) Csaba Hancz, DSc, (3) Marcell Molnár, Ph.D student, (4) Gabriella Stettner,

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The study was carried out in the Fish Laboratory of the University of Kaposvár , from 14th _{of June to 16}th _{of July 1999.} After a two weeks period of conditioning the experiment continued for 4 weeks. Against Ichtyophtirius infection malachit green was applied in the first two weeks.

In this period the fingerlings were kept in 150 l troughs and live bream fry was fed ad libitum. After this period fish were introduced into 10 aerated, 150 l aquaria under 18 and 36 individual/ aquarium. Starting weight was 1,86 1,01 gram and the average initial length was 54,48 9,54 millimetre. Control group in 5 aquaria was fed by live prey ad libitum and in the other 5 aquaria the treatment group received only minced fish from the beginning. The different stocking densities were divided in the same ratio between the treatment and control groups. Feed was offered two times a day, weight and length measurements were made weekly on all individuals. The average temperature was 22  0,5 C in the aquaria working in recalculation system.

Statistical analysis was carried out with SPSS for Windows 8.0, the effects of the different rearing conditions were estimated with ANOVA and chi-square test. The means were compared by S-N-K test.

RESULTS AND DISCUSSION

Growth data of the different treatment combinations are shown in Tables 1 and 2.

Table 1. Growth data of pre-reared pike-perch in the combinations of the living prey- minced fish feeding and 18-36 stocking density

Minced fish –18 Minced fish -36 Living prey-18 Living prey-36

Initial weight 1.49  0.59 1.72  0.90 2.34  1.39 2.02 1.14

Initial length 51.88  7.96 53.90  9.98 57.36 11.76 55.62 9.87

Final weight 3.84 1.85 5.12  3.08 10.38  3.32 7.62 2.48

Final length 66.81 9.94 70.65 14.48 95.46 12.24 86.75 9.85

SGR (%/day)a _{3.38 3.90 5.32 4.74}

a _{The Specific growth rate was counted by the next way}

where: weight1 = initial weight, and weight 2 = final weight

Table 2. Parameters of the growth equations belonging to the different treatment combinations

Treatment combination Coefficient of

determination Significance level (p<)

Coefficient of regression 1_(k)

Constant (lnA)

Minced fish

18-density 0.522 0.008 0.035 0.234

36-density 0.406 0.047 0.043 0.305

Living prey

18-density 0.615 0.007 0.058 0.733

36-density 0.636 0.001 0.050 0.603

1 _{lnW = lnA + kt}

100 days

weight1 ln

weight2

ln  _

 SGR

3,92 3,96 4,67

2,32 5,58

2,70 3,00

4,00 5,00 6,00

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ta

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Changes in the daily food intake according to feeding

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Figure 2. Changes in the average weight gain according to feeding

Figure 3. Changes in the average weight gain according to the stocking density

Daily food intake (2.01g vs.4.53 g, test and control, respectively) was only influenced significantly by different feeds (Figure1), stocking density had no significant effect.

Feeding (Figure 2) and stocking density (Figure 3) had significant effect (P = 0.001 and 0.017) on the average weight gain and in the second case the differences appeared on the first and third experimental week.

Owning to the high variance treatment effects on feed conversion proved to be not significant mainly in the first two experimental weeks. (First week: 6.524.12 and 4.191.38 g/g , second week 3.260.46 and 6.695.95 g/g for the 36

1,05 0,24 1,31 0,38 1,48 0,74 1,77 0,71 0,00 0,20 0,40 0,60 0,80 1,00 1,20 1,40 1,60 1,80 A v e ra g e w e ig h t g a in (g /i n d iv id u a l/ w e e k )

1 2 3 4

Experimental weeks

Changes in the average weight gain according to feeding

live prey minced fish

0,50

0,79 0,86 0,83 1,01

1,22 1,24 1,24

0,00 0,20 0,40 0,60 0,80 1,00 1,20 1,40 A v e ra g e w e ig h t g a in (g /in d iv id u a l/w e e k )

1.hét 2.hét 3.hét 4.hét

Experimental weeks Changes in the average weight gain

according to the stocking density

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Average survival of the minced fish fed group was 62.2 % vs. 78.8 % of the live fish fed alevins. This difference was significant (P<0.01) in the first two weeks when almost all of the losses happened due to cannibalism appearing as a consequence of the starvation after the food change and other unknown reasons. The treatment effect on cannibalism was not significant. Based on our results a 10 – 14 day period is needed for pre-reared pike-perch to change gradually

their feeding from zooplankton to minced fish diet. It is supported by Nickum’s results (1978), who found that in pond

pre-rearing of walleye (Stizostedion vitreum) losses due to starvation appear in the first two weeks.

CONCLUSION

Based on our results the intensive rearing of pond pre-reared of pikeperch on not living food (minced fish) is viable. In the experimental period the stocking density had significant effect only on the average weight gain and not statistically significant but well perceptible effect on the food conversion in the first two experimental weeks. Since the stocking density had no effect on the survival and cannibalism further experiences are needed to determine the optimal density.

Average survival of the minced fish fed group was 62.2 % vs. 78.8 % of the live fish fed alevins. This difference was significant (P<0.01) in the first two weeks. Based on these data a 10–14 day period is needed for pre-reared pike-perch to change gradually their feeding from zooplankton to minced fish diet.

As a consequence of the change of feeding daily food intake and the average weight gain of minced fish fed groups were lower than the levels measured in the groups fed on live prey. In food conversion there is no significant treatment effect. Further investigations are needed with feeding of high value artificial foods.

REFERENCES

1. Chesire, W.F., Steele, K.L. (1972): Hatcheriy rearing of walleye using artificial food. Progressive Fish-Culturist 34:96-99

2. Colesante, R.T., Youmans, N.B., Ziolkoski, B. (1986): Intensive culture of walleye fry with live food and formulated diets. Progressive Fish-Culturist 48:33-37

3. Hilge,V. (1990): Beobachtungen zur aufzuht von Zandern (Stizostedion lucioperca L.) im Labor. Arch. Fish Wiss. 40 (1/2):167-173

4. Klein Breteler, J.P.G. (1989): Intensive culture of pike-perch fry with live food. pp.203-207. In: Aquaculture- a biotechnology in progress. Vol. 1. N. De Pauw et al. (Eds) European Aquaculture Society, Bredene, 1220p. 5. Kuipers, K.L., Summerfelt, R.C. (1994): Converting pond-reared Walleye fingerlings to formulated feeds: Effects of

diet, temperature and stocking density. Journal of Apllied Aquaculture, Vol 4(2):31-57

6. Nickum, J.G. (1978): Intensive culture of walleyes : state of the art. pp. 187-194. in R.L. Kendall,editor. Selected Coolwater Fishes of North America. American Fisheries Society Special Publication No.11, Washington, D.C. 7. Schlumberger, O., Proteau, J.P. (1991): Production de juveniles de sandre (Stizostedion lucioperca.). Aqua Revue