8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας 1059 THE KEGO breeding programs FOR sea bream (Sparus aurata) and sea bass (Dicentrachus labrax) in Greece Ingunn Thorland 1, Nikos Papaioannou 2, Lefteris Kottaras 2, Terje Refstie 1, Sotiris Papasolomontos 2 and Morten Rye 1 1 Akvaforsk Genetics Center AS, N-6600 Sunndalsψra, Norway 2 KEGO S.A., 1 st km Artaki Psahna Rd., 346 00 N. Artaki, Greece Summary The implementation of systematic genetic improvement programs is essential for the development of cost effective and sustainable aquaculture productions. Against this background KEGO S.A., a leading provider of genetically improved livestock in Greece joined Akvaforsk Genetic Center AS of Norway and initiated large scale, family based selection programs for sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) in 2002 and 2004, respectively. The programs were designed for production and performance testing of approximately 50 full- and halfsib families of each species annually, produced by artificial stripping of selected male and female breeders. The programs were initially focused primarily on improving growth rate, but the family based design allowed for inclusion of any trait of economic importance as the programs developed. New traits under consideration for inclusion are improved disease resistance and carcass quality. Key words: breeding program, genetic improvement, family selection, sea bass, sea bream ΤΟ ΠΡΟΓΡΑΜΜΑ ΦΥΣΙΚΗΣ ΕΠΙΛΟΓΗΣ ΣΤΗΝ ΤΣΙΠΟΥΡΑ(Sparus aurata) ΚΑΙ ΤΟ ΛΑΒΡΑΚΙ (Dicentrachus labrax) της KEGO ΣΤΗΝ ΕΛΛΑΔΑ Ingunn Thorland 1, Nίκος Παπαϊωάννου 2, Λευτέρης Κοτταράς 2, Terje Refstie 1, Σωτήρης Παπασολομώντος 2 and Morten Rye 1 1 Akvaforsk Genetics Center AS N-6600 Sunndalsψra, Norway 2 KEGO S.A. 1 ο χλμ Ν. Αρτάκης Ψαχνών 346 00 Ν. Αρτάκη, Ελλάδα Περίληψη Η εφαρμογή προγραμμάτων φυσικής γενετικής βελτίωσης κρίνεται απαραίτητη για την μείωση του κόστους παραγωγής και την εξασφάλιση της βιωσιμότητας του κλάδου των υδατοκαλλιεργειών. Σε αυτή τη βάση η KEGO Α.Ε. ένας από τους σημαντικότερους παραγωγούς και εισαγωγείς προηγμένου γενετικού υλικού χοιροτροφίας και πτηνοτροφίας στην Ελλάδα, δημιούργησε δύο μεγάλης κλίμακας προγράμματα φυσικής επιλογής για την τσιπούρα (Sparus aurata) το 2002 και για το λαβράκι (Dicentrarchus labrax) το 2004 αντίστοιχα. Τα προγράμματα είναι σχεδιασμένα για την παραγωγή 50 αμφιθαλών και ετεροθαλών οικογενειών ανά είδος κάθε χρόνο. Η λήψη τόσο του σπέρματος, όσο και των αυγών γίνεται με τεχνητό τρόπο (stripping) σε απόλυτα ελεγχόμενες συνθήκες από επιλεγμένους γεννήτορες. Τα προγράμματα εστιάζονται αρχικά στη βελτίωση του ρυθμού ανάπτυξης, αλλά ο βασισμένος σε οικογένειες σχεδιασμός, επιτρέπει στην πορεία την εισαγωγή νέων χαρακτηριστικών. Έτσι, χαρακτηριστικά όπως αντοχή σε ασθένειες, ποιότητα σάρκας κ.α. μελετώνται για την εισαγωγή τους στο πρόγραμμα. Λέξεις κλειδιά: φυσική επιλογή, γενετική βελτίωση, οικογενειακή επιλογή, τσιπούρα, λαβράκι
1060 8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας Introduction The implementation of systematic genetic improvement programs is essential for the development of cost effective and sustainable aquaculture productions. In the 1970 s and 80 s pioneering programs for species such as Atlantic salmon and tilapia have demonstrated the effectiveness of the application of quantitative methods to fish, and large-scale selective breeding programs are now in operation or underway for most major aquaculture species worldwide. (Gjedrem T., 1997). As an indication in 1975, 40 months growing period was necessary for Atlantic salmon in order to reach 4 kgs. Today, 20 months are enough for the same biomass. (GjΨen and Bentsen, 1997). Somewhat surprisingly, the bass and bream industry in the Mediterranean region of Europe has until recently been slow to take up this technology and thus failed to obtain highly significant improvements in production efficiency as seen for other key aquaculture species. Materials and Methods A combined family and within family-selection breeding program has been established for Sea bream during 2001. This design allowed the inclusion of traits, which enabled the continuous evolution of the breeding programme. In the initial phase the work was focused on improving growth rate and feed efficiency (through correlated response). Next traits targeted were those related to shape (eye appeal), skeletal deformities and disease resistance (vibrio, pastereulla, nodavirus). The breeding nucleus is situated at Enalios hatchery, Evia, Greece. Ensuring broad genetic variation was one of the initial priorities when the program started. Therefore, fish were collected broadly from indigenous Mediterranean sources including some from wild populations and others from western as well as eastern Mediterranean sources, thus securing large genetic variation. Each batch of fish was sampled for virology tests where PCR and cell culture analyses were used for Nodavirous (Institute of Aquaculture, University of Stirling, Stirling, UK) while in quarantine and before entering the hatchery facilities. The genetic variability of the base population recorded is shown in Figure 1. Starting in 2002 and for each year thereafter 50 full- and half-sib families were produced. Families were incubated and hatched in separate 150lt tanks. Rearing conditions (live feed, dry feed, light, water quality) were kept the same for all tanks in order to minimise the between tank family environmental effect. Twenty grams of fertilised eggs arising from individually selected BV in % of phenotypic mean 30 20 10 0-10 -20-30 -40 family Figure 1. Genetic variability of sea bream for weight at a mean of 251.2gr
8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας 1061 Figure 2: Estimated heritabilities of sea bream for growth, color and deformities. traits h 2 c 2 BW at market size 0.50 0.03 BW at tagging 0.25 0.05 color 0.15 0 (Flathead) 0.08 0.07 and marked parents were stocked in each tank to create each family. Ninety days later, fish were tested for successful swim bladder formation. At the same time the population of each family was scaled to 500 individuals by completely random selection (1 st standardisation). At days 120-130, where average body weight was in excess of 1gr., the population of each family was scaled down to 150 individuals again by random selection (2 nd standardisation). At day 200, where the body weight was 8-10gr, 60-70 randomly selected fish from each family were PIT tagged (Biomark Inc., Idaho, USA) using a suitably designed hypodermic needle. The fish from each family were then randomly divided in two groups and were shipped to two different sea cage sites also situated in Evia, Greece for the growing period. The cage sizes were 4x4 metres. Each month 10% of the fish in each cage were weighted and the feeding program adjusted. The feed use was standard extruded feed manufactured by KEGO S.A. The fish were grown under these conditions until they reach 350gr. At this stage, PIT tag ID, body weight, shape, external colour and deformities were recorded individually on the live fish. Based on these data preliminary breeding values (BV s) were estimated using Best Linear Unbiased Predictor (BLUP) analysis for families and individual fish (GjΨen and Gjerde, 1998). This became the base of the pre-selection of possible breeding candidates. Of the highest ranking candidates, approximately 100 males and 50 females were selected for the production of the next batch of families. Results-Discussion The calculated heritability of growth for sea bream was particularly high which indicated a high expectancy for significant improvements of this trait in subsequently selected generations (Gjerde and Schaeffer, 1989). The heritabilities for external color and deformities were estimated as medium to low (Figure 2). Based on these results and the relative economic value of the recorded traits an overall BV was calculated for each family and individual fish. The relative weighting of the traits in the BV Figure 3: Traits included in the index, relative weighting of traits in the index and correlation between values and index (ri,bv)/ sea bream BW at harvesging BW at tag- color Flathead R e l a t i v e 75% 5% 10% 10% weight r1, BV 0,95* 0,64 * 0,24* -0.05* *p,0.01
1062 8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας Figure 4: Individual Breeding Values (BV s) for sea bream index as well as the correlation between the individual trait values and the overall index are shown in Figure 3 The individual BV s for each fish were thus calculated and recorded in the selection procedure by rank (see Figure 4) It can be seen from figure 4 that the highest ranked individuals had a BV in excess of 80gr. against the average of the population which was 350gr. At the same time the lowest ranked fish had a BV of 80gr lower than average of the population. The recorded individual BV s and the fact that all individuals were separately tagged Figure 5: The predicted response of F1 generation trait Phenotypic Mean BV % Predicted response mean selected BW at market 327.8 + 51.2 +15.6% size BW at tagging 9.6 + 1.0 +10.1% color 1.7 + 0.03 +1.6% Deformities (Flathead) 11.7-0.4 +3.8%
8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας 1063 with their pedigrees known provide a power base to future selection for fast growth and other favorable traits while avoiding the inbreeding depression (Gjerde et al., 1983). The predicted response for the first commercial generation (F1) was finally calculated at +15.6% for growth at harvest weight of 350gr. (405gr). Experience from other species confirms that improvements of this magnitude are common and additive on a generation by generation basis (Rye and Eknath, 1999). This is particularly shown where inbreeding is carefully controlled through carefully designed selective breeding programs. The predicted response of the F1 generation for all traits is shown at Figure 5 Conclusion Natural Selective Breeding Programs which have successfully been used to improve key biological and commercial characteristics such as growth rate in salmon and tilapia have been transferred successfully to sea bream and sea bass. Results presented for sea bream confirm that growth rate improvements in excess of 15% per generation, can be secured against the base population commonly in current use for these species in east Mediterranean. Avoidance of inbreeding can secure a similar range of improvements in subsequent selected generations. Other traits of commercial significance, such as consumer appeal, eating quality and disease resistance can be incorporated into such family based selection programs once established. References Gjedrem, T. 1997. Selective breeding to improve aquaculture production. World Aquaculture, 28(1): 33-45 Gjedrem, T., Refstie,. and Gjerde, B., 1987. A review of quantitative genetic research in salmonids at AKVAFORSK. Second Int. conference on Quantitative Genetics: 527-535. Gjerde, B., Gunnes, K. and Gjedrem., 1983. Effect on inbreeding on survival and growth rate. Aquaculture, 34: 327-332 Gjerde, B. and Schaeffer, L.R. 1989. Body traits in rainbow trout. II. Estimates of heritabilities and phenotypic and genetic correlations. Aquaculture, 80: 25-44 GjØen, H.M. and Bentsen H.B. 1997. Past present and future of genetic improvement in salmon aquaculture. ICES J. Marine Sci., 54: 1009-1014 GjØen, H.M. and Gjerde, B.,1998. Comparing breeding schemes using individual phenotypic values and BLUP breeding values as selection criteria. Proc. 6 th World congress on Genetics applied to Livestock Production 111-114. Refstie, T. 1990. Application of breeding schemes. Aquaculture, 85: 163-169 Rye, M. and Eknath, A.E. 1999. Genetic improvement of tilapia through selective breeding-experience from Asia. European Aquaculture Society, Special Publication. No 27; June 1999: 207-208 Rye, M. and Refstie, T. 1995. Phenotypic and genetic parameters of body size traits in Atlantic salmon, Salmo salar L. Aquaculture research, 26: 875-885