lces 90 C.M.1990/ F:31 MARlCUI..TURE COMMlTEE

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1 lces 90 C.M.1990/ F:31 MARlCUI..TURE COMMlTEE COMPARATIVE STUDY OF LARVAE SURVIVAL AHn GROWTH IN SEA BREAM (Pagellus bogaraveo B) USING MICROENCAPSULATED OR LIVING-FOOD by Martinez-Tapia, C.; Fernandez-Pato, C. and Chereguini, O. Instituto Espanol de Oceanografia C. Oceanogräfico de Santander Apdo Santander. Spain. SUHHARY Trial in order to improve in growthing and survlvlng black-spot sea bream (f. bogaraveo) larvae using two different had been repported in this paper. on diets Comparison between two different diets showed that artificial food is an alternative to be used in aquaculture but in mixed diet, through live food. Differences between both groups were found less growth and high mortality occured in group feeding on artificial diet (t-student test p<.os and Breslow, Mantel-Cox p=.oooo test) respectively. RESUME Nous l'objetive dorade CE.. referons dans cette communication une experience est verifier la croissance et la survivance du la bogaraveo) avec l'usage de des differents regimes. dont larve La comparaison entre deux dietes differentes a montre la diete artificielle comme une alternative a utilisser en aquaculture, mais comme part d'une diete mixte avec aliment vivant. Nous avons trouve des differences entre les deux groups ayant une croissance plus petite (p<.05; t-student test) ce lui qui avait re9u une diete artificielle, et qui a en aussi une plus grande mortalite (p=.oooo;test Breslow;Mantel-Cox)

2 ~ --~ INTRODUCTION Following with research on black-spot sea bream larvae rearing see lces 90 CM/F 30, and being based on some studies about larval dietary with artificial food (Metailler R. et al, 1978; Gatesoupe, F. et al, 1984), this trial was carried out to obtain data on growth and survival of black-spot sea bream larvae when feeding with two different diets. The possibility of rearing larvae exclusively with artificial diet offer several advantages such as selection of size food according with those of fish, chemical composition of these artificial diets (proteins, vitamins, HUFFA'S, etc.) could supply dietary requirements of fish adequately in each stage of live, as well should be an easier way to provide it. Another advantage should be the possibility of doing without any food culture (phytoplancton, rotifers and Artemia) with the consequently economic profit. However, several disadvantages in the opossite to living food, makes that profitability of the using of microencapsulated food had been created or in the contrary usual way of living food in culture, until period rear require of transfer to artificial food. On the other hand, evaluate successfull of living food against microencapsulated diet could be contrasted in this trial. MATERIAL AND METHODS Eggs proceeding from spontaneous spawning of broodstock were removed from the tank through a water flow in surface. Eggs were counted and evaluated their hatching rate. They were later incubated in little cilinderconic tanks 80 1 volume. Larvae were transfered into fibre-glass tanks with volume of water, above which a fluorescent-tube provide 150 lux on water surface during 24 h a day. Temperature, oxygen saturation rate and salinity were recorded with an electrode oximeter Oxi 196 WTW for the two first parameters and a handle refractometer for the third. Aireation maintained an oxygen saturation from 75 to 95%. Only when oxygen rate decreased, supplementary pure oxygen were added. Water turnover were 2.5 times a day with a filtered water through 1~ filter. For feeding experience two random homogeneous groups were established: group A had a dietary on live-food whilst group B fad on artificial diet. Mortality was evaluated counting dead fish removed from the tank by daily siphoning.

3 .3 Periodically live larvae were sampled for checking growth in length as weil as their morphology. Later, survival and growth were tested by survival tables made with CUtler-Ederer method and compared by statistic tests of Breslow and Mantel-Cox. Possible diferences between length mean values were analyzed by t-student test. Feeding experience Both group A and B had the same development, on 4 day of culture larvae presented vestigial yolk absorbed and trials were as follow: Group A: Rotifers maintained in backer's yeast were introduced in larval tanks, previously enriched in Algal* in number of 40 ml- 1 until 28 th day of rear. At 12 th day of culture, artemia During the period in which both coincided density of food never was decreasing rotifers until 28 day never higher than 25 ml- 1 }. was also introduced. rotifers and Artemia higher than 40 ind.ml- 1 and Artemia {but this Artemia also were enriched (Gatesoupe,F. et ale op.cit.) in microencapsulated (Transit*) in order to increase feed requirements and satisfy their needs in HUFFA (Figure 1). Group B: Since 4 day-old larvae were fed on microencapsulated with small amounts of this and several times a day in order to maintain environmental quality. Microencapsulated from 10 to 80 ~ size were introduced in diet from 4 th to 18 th day of rear; when larvae were 8 days-old microparticulated food (Micron*) from 100 to 175 ~ size was added in diet. Since 12 to 28 new sizes of food were incorporated (200 to 425 ~); finally at 20 th day of culture until 28 th particles of ~ were included in diet (Figure 2). RESULTS Water temperature mean value on rearing period was 15.5 C, being 16.9 C the highest and 14.2 C the lowest. Salinity ranged between ppt (Table 1). * supplied by Trofic, see appendix

4 .4 Oxygen saturation rate were 75 to 95%; occasionally, oxygen was supplemented, to maintain these levels (Table 2). Both groups A and B presented some differences in length since 10 day old larvae (Figure 3), however statistic test (t-student) showed no differences until 26 day age larvae (p=.001), when group B mean length were mm ± SD whereas group A mean length was mm ± SD. Breslow test (p=.0000) and Mantel-Cox (p=.0000) indicate signifieative differences between both survival groups, as shows (Figure 4). In this figure we can see that both groups are similar until 12 th day of rear. Since this day probability of living deereases from 52% to 10% with treatement B, being null survival around the 20 th day (0.8%) whilst at the same day group A maintained a survival of 35-38%. In 28 th day, when group B larvae had desappeared, group A has a surviving of 20-25% CONCLUSIONS AND DISCUSSION According with result obtained from the experience reported, we could say that microencapsulated food (size 10 to 80 ~) combine several qualities sueh as size of particles, enough moisturizing to keep mobility in water surface, their capacity to float, as well as their colours which probably it should be atractive for larvae. Also this kind of food seems satisfy dietary requirements in those days that it is used. In fact, the same microencapsulated used trough live-food had shown these qualities in the other group of experience. However, the transfer to micropartieles that float, and are not atractive for larvae cause mortality. Only those largest individual'survive, before they are smaller surviving than those of the end of trial. are no be able to an increase the but as we showed other group at the could be considered as a new Nevertheless, storage range in size of partieles, with the species in culture. and handling make that microencapsulated way of research in order to obtain a wider with a eomposition in nutrients according However, mieroencapsulated seems be abble through the living food used as enrichement. REFERENCES Gatesoupe, I.J.; Robin, J.H.; Le Millinaire, C. and E. Lebegue. Amelioration de la valeur nutritive des filtreurs-proies par leur alimentation composee. Dans L'aquaculture du Bar et des Sparides. G.Barnabe et R.Billard R.D. ED. INRA. Publ., Paris, (1984),pp Metailler, R. and E. Alliot, (1978). Alimentation poissons marins a l'aide des proies inertes. Fasc.5, pp larvaire Oceanis, des V.4,

5 DAYS AFTER HATCHING o t I 40 ROTIFER ( ~)..._-----_..:...-_ ARTEMIJ\ NAUPLII (500~) po ARTEMIA METANAUPLII (1.000 ~) riwzli~ I\lrTEMIA I,in I FI CI AL I)I ET 10-80~ Microencapsu1ate ~ Microparticulate ~ Microparticulate!JOO JOO ~ Microparticuldte FIG.1-2: Feeding-time and kind os fo0itin black-spot sea bream larv~-

6 COMPARATIVE GROWTH LARVAE OF BLACK-SPOT SEA BREAM 1'<'\ ~ LJ..l 5 0::: :::l 4 -l.!:) 3 u DAYS - Mean length group A - Mean lenght group B Group A=living food diet Group B=microencapsulated food diet

7 CUMULATIVE PROPORTION SURVIVING TRAT. A TRAT o DAYS Cumu1ative proportion survival between groups fed in different diets. FIGURE 4

8 DIAS TEMPERATURA SALINIDAD DIAS TEMPERATURA SALINIDAD (OC) (%) (OC) (%) TABLE 1 DIAS NH 4 + O 2 SATURACION pr DIAS NH 4 + O 2 SATURACION pr mg/i mg/i DE O 2 (%) mg/i,. mg/i DE O 2 (%) : TABLE 2

9 .5 APPENDIX ALGAL Protein Lipids Carbohydrate Fatty acids (n-3 and n-6) 40 % 30 % 9.5 % 7 % TRANSIT (microencapsulated) Protein Lipids AGE Ash % % % % ENRIQUECEDOR ARTEMIA FATTY ACIDS (Linoleic and Linolenic series) 22:6 w-3 22:5 w-3 20:5 w-3 18:3 \'1-3 20:5 w-6 20:4 w-6 18:3 w-6 Supplernented with vitamins and carotens. HICRON (microparticulated) Protein 45 % Lipids,25 % Fibre <l % Ash <8 % TRANSITION DIET Protein Lipids Moisture Ash 55 % 6.5 % 24 % 6 %