The impact of breeding on productivity of Atlantic Salmon and Rainbow Trout farming

1. The impact of breeding on productivity of Atlantic Salmon and Rainbow Trout farming Presentation prepared by: Ladeiro, Susana nº 22987 Marques, Miguel nº 23137

2. Aquaculture Main objective:To produce as much fish as possible Increase growth Diet composition Environmental conditions Protect from disease Immunization Antibiotics Protect from predators Cages Tanks Selective breeding and biotechnological techniques may be used to improve the fish characteristics in order to maximize productivity

3. Selective breeding Nowadays selection programmes are an integrated part of animal and plant production, playing an important role in domestication, increasing yields and survival rates and also in improving product quality. • Obstacles: • Lack of complete control of artificial reproduction; • Lack of controlled mating; • Difficulties of hatching and feeding larvae and fry. In aquaculture • Advantages: • High fertility • External fertilization • Low expenses for broodstock maintenance • More efficient breeding programmes design

4. Definition of the traits to be improved • Economic importance • Scoring the trait • Heritability above zero • Evaluation of the overall genetic capacity (breeding value) of potential breeding animals • Selecting the highest ranking individuals as parents for the next generation

5. Examples of phenotypic traits of economic importance Very important but difficult to measure and control Food conversion efficiency Very important and correlated with food conversion Growth rate The later the better Age at sexual maturity Complex and of low heritability. Survival/disease resistance Body size; meat colour; fat content; etc. Body quality Number of eggs is high, however, egg quality is very important Fecundity

6. Breeding strategies Inbreeding depression (reduced performance) Important to keep a low inbreeding rate Inbreeding Crossbreeding Exploits non-additive genetic variance Breeding method for additive genetic improvement within a population Best for continuous genetic improvement over a long period of time Avoids mating between close relatives Selects individuals with most positive genes Purebreeding

7. Inbreeding • reduces the frequency of heterozygous genotypes and increases the frequency of homozygous genotypes • frequency of heterozygous offspring is smaller than it is with random mating • much of the harmful effect of inbreeding is due to rare recessive alleles that would not otherwise became homozygous • decreases of 30 % or greater in growth production, survival and reproduction in salmonid fishes “It is as important to prevent production losses due to inbreeding, as it is to increase production from genetic enhancement.” (Dunham et al., 2001)

8. Pure breeding has to be chosen as the breeding method If we avoid the mating of close relatives, then it may be possible to keep the inbreeding stable and at low levels In order to eliminate possible inbreeding and to secure a broad genetic base Produce synthetic populations by crossing the avaiable strains

9. Sex manipulation Sex reversal Breeding Progeny testing Gynogenesis Androgenesis Predominantly, or completely, male or female populations, or a “super-male” genotype (YY) The primary aim is to take advantage of sexually dimorphic characteristics (including flesh quality), control reproduction or prevent establishment of exotic species All female populations have been successfully developed for salmonids, carps and tilapias

10. Mainproblems • Environmental - biodiversity, genetic conservation, and environmental risk of genetically altered aquatic organisms; • Research - funding and training of scientists; • Economic and consumer issues - proprietary rights, dissemination, food safety and consumer perceptions; • Political issues - government regulation and global cooperation; • Ethics - manipulating and owning life at the chemical and biological level.

11. Life cycles Oncorynchus mykiss Salmo salar • generation interval of 4 years • raised in sea cages until 3-5 Kg of weight • generation interval of 3 years • raised in sea cages until 2-4 Kg of weight

12. In wild Salmo salar populations stratification by age classes and sexes on the spawning grounds avoids inbreeding increases genetic variability high levels of genetic variability even in small populations Complex mating strategy of Atlantic salmon Although the presence of a great number of farmed salmon mixed with wild ones may represent a problem!

13. Beginning of salmon farming in the 1960’s Norway The number of farms has increased greatly over the last decades. Supplies about 75 percent of the Norwegian industry with improved eyed eggs 1975 – National Breeding Programme for Atlantic salmon and rainbow trout

14. Extensive breeding experiments with Atlantic salmon and rainbow trout started in 1971. Different goals were achieved, as more and more generations of farmed fish became avaiable : • Incresase growth rate • Delay age at sexual maturation • Increase disease resistance • Improve meat quality 65% of all the salmon and rainbow trout produced in Norway is genetically improved fish

15. Dividing a population in wild-breeding captive-breeding reduces the genetically effective population size (Ne) because increases the variance in reproductive success whichincreases inbreeding (mating between close relatives) loss of genetic variation

16. Hatchery programs for conservation and/or harvest adults are usually caught during the breeding season stripped for their gametes Removal of sperm in male adults Stripping of eggs in female adults

17. Mixed-milt fertilizations • maximize fertilization success • minimizing work load for hatchery managers eggs from several females are combined with milt of several males in a single container But leads to sexual selection by sperm competition… SUCESS depends not only of sperm velocity and longevity, but also, of sperm cell density and milt volume!

18. Multi-male fertilization hatchery equalizing milt volume not equalizing milt volume reduces the loss of genetic variation lose relatively more genetic variation favors younger males who may have fast sperm to compensate for their subdominance at the spawning place gives fast-growing males a reproductive advantage

19. Hatchery-induced sperm competition produces induces variance in male reproductive success artificial selection for certain life-history traits which increases the inbreeding coefficient causing loss of genetic diversity in hatchery-produced offspring

20. Problems in river management – Impact in wild populations High number of fishes that escape and mate with the native stock Dilutes the native genes decreasing de variability of the hybrid descendents originating reproductive and ecologicalinterferences in the native stock • overlay with wild larvae and juveniles • competition for spawning sites • competition for food and territory

21. Genetic profile of wild populations molded by natural selection creating Adapted genes for long term survival and maximum productivity introduction of new genes Decreases populations productivity Populations productivity will continue to decrease until natural selection restores a genetic constitution that is more favorable to the population, which may take many generations to happen.

22. The migrating spawning season differs between wild and aquaculture salmons Wild salmon migrates earlier! Tummel River’s Case Little overlay and the two types of salmon have progressed in different times. As a result, farmed fishes have altered the age composition of the adult stock population, influencing the salmon availability for the fisheries that operate in a specific period of time. Impact in Fisheries

23. In Norway, there is a gene bank to preserve the genetic characteristics and the intrinsic variability of the threatened wild stocks, making sure of maintaining a stability for long periods of time. fighting • threat of farmed fishes that escapes fish farms • losses due to parasitic infections and water acidification

24. Final concerns • New informations of breeding consequences will be provided as generations of Salmo salar and Oncorynchus mykiss appear; • Efforts to avoid the escape of farmed fish must be made • New alternatives must arrise, since many exploration sites still use milt-mixed fertilizations.

25. References • Dunham, R. (1996). Results of early pond-based studies of risk assessment regarding aquatic GMOs. 126th Annual Meeting of the American Fisheries Society, Dearborn, MI, August 26-29 1996. Abstract No. 381; • Dunham, R.A., Majumdar, K., Hallerman, E., Bartley, D., Mair, G., Hulata, G., Liu, Z., Pongthana, N., Bakos, J., Penman, D., Gupta, M., Rothlisberg, P. & Hoerstgen-Schwark, G. (2001). Review of the status of aquaculture genetics. In R.P. Subasinghe, P. Bueno, M.J. Phillips, C. Hough, S.E. McGladdery & J.R. Arthur, eds. Aquaculture in the Third Millennium. Technical Proceedings of the Conference on Aquaculture in the Third Millennium, Bangkok, Thailand, 20-25 February 2000. pp. 137-166. NACA, Bangkok and FAO, Rome; • Gjedren, T. (2000). Genetic improvement of cold-water fish species. Aquaculture Research 31: 25-33; • Gjerde, B. (1993). Breeding and Selection. In Salmon Aquaculture, edited by Heen, K., Monahan, R.L. and Utter, F. 1-9. England: Fishing News Books. • Juanes, F., Perez, J. & Garcia-Vazquez, E. (2007). Reproductive strategies in small populations: using Atlantic salmon as a case study. Ecology of Freshwater Fish, 16 No 4, pp. 468-475; • Monahan, R. L. (1993). An Overview Of Salmon Aquaculture. In Salmon Aquaculture, edited by K. Heen, R. L. Monahan and F. Utter, 1-9. England: Fishing News Books. • Myhr, A.I. & Dalmo, R.A. (2004). Introduction of genetic engineering in aquaculture: ecological and ethical implications for science and governance. Aquaculture250: 542-554; • Rudolfsen, G., Figenschou, L., Folstad, I., Tveiten, H., Figenschou, M., (2006). Rapid adjustments of sperm characteristics in relation to social status. Proceedings of the Royal Society B273: 325–332; • Shearer, W.M. (1992). The Atlantic Salmon: Natural History, Exploitation and Future Management. Fishing News Book; • Snook, R.R., (2005). Sperm in competition: not playing by the numbers. Trends in Ecology and Evolution20: 46–53; • Wedekind, C., Rudolfsen, G., Jacob, A., Urbach, D. & Muller, R. (2007). The genetic consequences of hatchery-induced sperm competition in a salmonid. Biological conservation 137: 180-188;