Two groups of turbot, Scophthalmus maximus L., of 0.5 and 1.2 kg initial
mean weight were fed a semimoist diet containing fish, fish meal and
vitamin-mineral complex. The trial was carried out in tanks of 16 cubic
meters, for aperiod of a year. Resul ts on feed conversion index and
growth in weight are give

Forés, R. (Rafael)

Iglesias-Estévez, J. (José)

Olmedo-Herrero, M. (Mercedes)

Peleteiro-Alonso, J.B. (José Benito)

Sánchez-Conde, F.J. (Francisco Javier)

English

Repositorio Institucional Digital del IEO

International Councilfor the Exploration of the SeaC.M. 1988/F:9Mariculture Committee•EXPERIMENTAL FEEDING AND GROWTH OF TURBOT (SOPHTHALMUSMAXIMUS L.) FROM 0.5 TO 2.7 KG IN GALICIA (SPAIN)byJ. Sanchez, J.B. Peleteiro, R. Fores, M. Olmedo and J. IglesiasInstituto Espanol de OceanografiaCentro Costero de Vigo - Cabo EstayApartado 1552 - 36280 VrGO (Spain)ABSTRACTTwo groups of turbot, Scophthalmus maximus L., of 0.5 and 1.2 kg initialmean weight were fed a semimoist diet containing fish, fish meal andvitamin-mineral complex. The trial was carried out in tanks of 16 cubicmeters, for aperiod of a year. Resul ts on feed conversion index andgrowth in weight are given.RESUMEDeux groupes de turbot, Scophthalmus maximus L., d'un poids moyen ini-tial de 0.5 et 1. 2 kg ont ete al imentes avec une regimen semi-humideque contient du poisson, farine de poisson et un complexe de vitamineset mineraux. L'experience a ete mene dans des bassins de 16 metres cubi-ques pendant une periode d' une annee. On donne les resultats du tauxde conversion et croissance en poids.•INTRODUCTIONIn recent years, the excellent qualities of turbot (Scophthalmus maximusL.) as a species for fish cul tivation have been demonstrated (JONES etal., 1981). Its high growth rate, easy handling, the possibility of work-ing with high stock densities due to its 10'.11 level of oxygen consumption(BROWN et al. , 1984) plus the 10'.11 mortali ty rate and Hs high marketprice are all factors contributing to its cultivation value.The marine environmental conditions on the coasts of Galicia (NW of Spain)are very sui table for the cul tivation of turbot: sea water temperatureranges between 12°C and 20°C and salinity values are very constant (32- 35}'..). This leads to very good results in the growth of this species,which reaches a commercial market size in less time than in northern,colder European waters.There is much data available concerning the rate of growth of turbotfrom the weaning stage to 0.5-1 kg final weight (PURDOM et al. , 1972,SMITH 1976, POXTON et al., 1982). Some authors have reported growth ratesin larger sizes (PERSON et a1., 1980). Studies carried out by Ig1esiaset al., 1987, analyze the growth of two groups of turbot reaching finalweights of 1.2 and 1.9 kg.This paper reports the resul ts obtained in aperiod of a year, workingwi th two groups of turbot belonging to two different size classes wi thinitial mean weights of 1.2 and 0.5 kg, the objective being to determinewhat the rate of increase in weight cf adult turbot is, under pilot-scalefarming conditions .MATERIAL AND METHODSThe trials were carried out in the Fish Farming Research facili ti es ofthe Spanish Institute of Oceanography in Vigo.Two groups of turbot having 1.2 kg (group A) and 0.5 Kg (group B) meanwet weights at the beginning of the ongrowing experiment, were measuredto the nearest cm (the next 10west) and weighed to the gram, every twomonths. Group A consisted of 109 individuals and group B of 123. Theturbot were kept in two polystyrene tanks holding 14 cubic meters ofsea water each, in open circuit. The tanks were square with rounded cor-ners, having a central outlet and airlifts in the corners to maintaina centripetal current for se1f"-cleaning purposes. The water f10w was0.01 cubic meter per kg of" fish, per hour.•The turbot were fed once a day, in the morning. The were kept under lownatural light intensity during most of the day. Artificial light wasswi tched on only before and during the food intake. The ration of foodsuppl ied was calculated as a percentage of their mean weights, and i twas constant between measurements (every two months). Uneaten food wasrecorded daily.The diet consisted of a moist paste, cylinder shaped, of 22 and 28 mmdiameter. The same ingredients were used from the beginning to the endof the trial. These were: chopped blue whi ting (Micromesistius poutassouRisso), fish meal wi th a high protein content, and a vitamin-mineralcomplex. Percentages and chemical composition are given in Table I. Thefood was made every 3-4 days and kept in a refrigerator at 3°C. The fishwere given a prophylactic bath in formaline and green-malachite treatedwater every two months.Ingredients % Analysis %Chopped blue whiting 46.5 Moisture 43.0Fish meal 46.5 Protein 38.5Lipids 4.7Vitamin-mineral 7.0 Ash 10.1Table I: Turbot diet: composition in percentagesRESULTS AND DISCUSSIONMean weights are given in Table 11. The increase in weight in the two groupsstudied remains very constant throughout the whole period. Group A gaineda total ammount of biomass of 1454.7 gr reaching a final weight of 2722.3 gr,while in group B the values were 1404.2 gr and 1915.7 gr. Figure 1 showsthe rate of increase in mean weight wi th time. The rate of increment isvery constant and can be considered lineal, the most noteworthy being thatolder fish (group A) achieve the same weight increment as younger ones -(group B). Eight months is the period needed to gain 1 kg in both groups.This high growth rate can be considered a very good record if compared withdata reported from other authors in northern European countries (PERSONet al. , 1980).Apparently, no relationship between temperature and rate of growth has beenobserved in these trials; the fish accepted the food fairly weH in anyseason. This fact could be due to the narrow range of extreme values oftemperature recorded throughout the year (see Table II).TABLE Ir(1 ) ( 2) Stocking(3) (4)No. of fish Mean '.weight Conversion index Temp.Month densityA B A B A B A B (0 C)Jun. 109 123 1267.6 511. 5 9.9 4.5 17.6Aug. 108 123 1620.2 797.1 2.87 1.92 12.5 7.0 18.2Oct • 106 121 1822.3 988.1 4.49 2.49 13.8 8.5 17.5• Dec. 106 118 2107.7 1223.1 3.34 2.24 16.0 10.3 14.0Feb. 106 116 2336.4 1556.2 3.41 2.12 17.7 12.9 13.0*Apr. 64 116 2499.1 1763.4 3.04 3.13 11.4 14.6 14.1Jun. 64 116 2722.3 1915.7 3.35 3.62 12.4 15.9 17.31. Expressed in grams2. Food consumed/weight gained3. Biomass (kg/vo1ume of sea water (cubic meters»4. Mean monthly values(*) 42 fish were se1ected for broodstock and transferred to another tank•Values of food eonversion indexes (food ingested/weight gained) are gi yenin Table 11. They are very eonstant for the whole period in group A, rangingfrom 2.87 to 3.41 (the abnormal value of 4.49 in Oetober was due to ineorreet administration of food). In group B they are slightly better, tendingto inerease wi th age: 1.92 at the beginning of the trial, whieh was thebest value reeorded for both groups, and 3.62 at the end.Stoeking densities are shown in Table 11. They were rather low in both tankswith A ranging from 9.9 to 12.4 kg m-3 with a maximum of 17.7 in Fe-groupbruary, and B values being 4.5 kg -3 at the beginning of the experi-group mment, and 15.9 at the end. The reason for maintaining these low stoekingdensities was that the fish were being kept not only for ongrowing but forbroodstoek renewal purposes as well. When taking into aeeount similar growthrate results working with densities from 4 to 75 kg m-3 (IGLESIAS et al.,1981), it ean be eoneluded that the rate of growth achieved with the stoekmgdensities reported in this paper ean also be obtained with higher ones (suchas the 30 kg m-3 which is usual in turbot farms in Galicia).(1) Expressed in cm..•In contrast to what was observed in the weight increase, which is linealin both groups during the period considered, a slight tendency towards sta-bilization in growth can ben noted from about the size of 42 cm onwards.However, this observation has only a relative significance given the factthat the number of fish studied was low and that no separation was madebetween males and females which, as has been shown (JONES, 1974), have adifferent growth rate at these ages.The mortality rate is low in both cases: 2.7% in group A and 5.7% in groupB. No severe diseases were observed in the period studied.CONCLUSIONThe resul ts presented in this paper indicate that the increase in weightin large size turbot () lkg) remains very constant until reaching almost3 kg, which corresponds to three years in captivity in Galician waters.Low mortali ties , reasonably good food conversion indexes, higher marketprices in large size turbot together wi th the possibili ty of using themas future broodstock indicate that prolonging the period of ongrowing canbe profitable under industrial farming conditions .t30002500~tl{)-IJ 2000.ctl{).....llJ;;tc: 1500l1lllJ~1000~.y././/500JUN AUG OCT DEC FEB APR•JUNFig. 1: Growth in mean weight in aperiod of a yearin two groups of turbot with initial mean -weights of 1267.6 gr (group A) and 511.5 gr(group B).••-------------------REFERENCESBROWN, J.A.G., A. JONES and A.J. MATTY (1984). "Oxygen metabolism of farmedturbot (Scophthalmus maxi~~s). I. The influence of fish size --and water temperature on ~etabolic rate. Aquaculture, Amsterda~36, 273-281.IGLESIAS J., M. OLMEDO, J.J. OTERO, J.B. PELETEIRO and M.R. SOLORZANO (1984"Growth, under laboratory conditions, of turbot, Scophthalmusmaximus, from the Rla de Vigo (north-west Spain). Marine Bio-10gy 96, 11-17.JONES, A. (1974). "Sexual madurity, fecundity and growth of the turbotScophthal~us maximus L. J. mare biol. Ass. U.K. 54, 109-125.JONES A., J.A.G. BROWN, M.T. DOUGLAS, S.J. THOMPSON and R.J. WHITFIELD."Progress towards deve10ping methods for the intensive farmingof turbot (Scophthalmus maximus L.) in cooling water from a n~clear power station. In: Proceedings of Wor1d Symposium on NewDevelopments in the Utilization of Heated Effluents and of Re-circulation Systems for Intensive Aquaculture, Stavanger, Nor-way, 28-30 May 1980, Vol 11, 00 481-496. Ed. by A.G. Coche. R~me: F.A.O. 1981 a. (Teeh. Pap. ?A.O. European Inland FisheriesCommission No. 39).PERSON-LE RUYET J., J. BARRET, D. L'ELC:-:AT et G. NEDELEC (1980). "Donnes Strla croissance du turbot d'elevage, Scophthalmus maximus, entre3 mois et 3 ans. Int. Counc. Explor. Sea Comm. Meet. (Maricu1t.Comm. F:29) 1-19.POXTON, M.G., K.R. MURRAY and B.T. LINF::':)T (1982). "The growth of turbot(Scoptha1mus maximus) in recirculation sistems". Aquacultura1Engineering 1, 23-34.PURDOM, C.E., A. JONES and R.F. LINCOLN (1972). "Cu1tivation trials with -turbot (Scophtha1mus maximus L.). Aquacu1ture. Amsterdam 1, -213-230.SMITH, P.L. (1976). "The development of a nursery technique for rearing turbot (Scophthalmus maximus), from metamorphosis to ongrowing s!ze. Progress since 1970 by the British White Fish Authority.F.A.O. Technical Conference on Aquacu1ture, Kyoto, Japan, 26 -May-2 June. FIR: AQ/Conf./76/E:30. 13 pp.

Experimental Feeding and Growth of Turbot (Scophthalmus maximus L.) from 0.5 To 2.7 Kg in Galicia (NW Spain)

Sánchez-Conde, Francisco Javier

Peleteiro-Alonso, José Benito

Forés, Rafael

Olmedo-Herrero, Mercedes

Iglesias-Estévez, José

Digital.CSIC

http://www.repositorio.ieo.es/e-ieo/bitstream/10508/5416/1/CM%201988%20F%209.pdf

Experimental Feeding and Growth of Turbot (Scophthalmus maximus L.) from 0.5 To 2.7 Kg in Galicia (NW Spain)

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