Editing Selective breeding (section)

===Shellfish response to selection===

====Oysters====

Selection for live weight of Pacific oysters showed improvements ranging from 0.4% to 25.6% compared to the wild stock.<ref>{{Cite journal | doi = 10.1016/s0044-8486(02)00621-x| title = Yields of cultured Pacific oysters Crassostrea gigas Thunberg improved after one generation of selection| journal = Aquaculture| volume = 220| issue = 1–4| pages = 227–244| year = 2003| last1 = Langdon | first1 = C. | last2 = Evans | first2 = F. | last3 = Jacobson | first3 = D. | last4 = Blouin | first4 = M. | bibcode = 2003Aquac.220..227L}}</ref> Sydney-rock oysters (''Saccostrea commercialis'') showed a 4% increase after one generation and a 15% increase after two generations.<ref>{{Cite journal | doi = 10.1016/0044-8486(96)01328-2| title = Progress in a Sydney rock oyster, Saccostrea commercialis (Iredale and Roughley), breeding program| journal = Aquaculture| volume = 144| issue = 4| pages = 295–302| year = 1996| last1 = Nell | first1 = J. A. | last2 = Sheridan | first2 = A. K. | last3 = Smith | first3 = I. R. | bibcode = 1996Aquac.144..295N}}</ref><ref>{{Cite journal | doi = 10.1016/s0044-8486(98)00408-6| title = Third generation evaluation of Sydney rock oyster Saccostrea commercialis (Iredale and Roughley) breeding lines| journal = Aquaculture| volume = 170| issue = 3–4| pages = 195–203| year = 1999| last1 = Nell | first1 = J. A. | last2 = Smith | first2 = I. R. | last3 = Sheridan | first3 = A. K. | bibcode = 1999Aquac.170..195N}}</ref> Chilean oysters (''Ostrea chilensis''), selected for improvement in live weight and shell length showed a 10–13% gain in one generation.
Bonamia ostrea is a protistan parasite that causes catastrophic losses (nearly 98%) in European flat oyster ''Ostrea edulis'' L. This protistan parasite is endemic to three oyster-regions in Europe. Selective breeding programs show that ''O. edulis'' susceptibility to the infection differs across oyster strains in Europe. A study carried out by Culloty et al. showed that 'Rossmore' oysters in Cork harbour, Ireland had better resistance compared to other Irish strains. A selective breeding program at Cork harbour uses broodstock from 3– to 4-year-old survivors and is further controlled until a viable percentage reaches market size.<ref>{{Cite journal | doi = 10.1016/s0044-8486(01)00569-5| title = An investigation into the relative resistance of Irish flat oysters ''Ostrea edulis'' L. to the parasite ''Bonamia ostreae''| journal = Aquaculture| volume = 199| issue = 3–4| pages = 229–244| year = 2001| last1 = Culloty | first1 = S. C. | last2 = Cronin | first2 = M. A. | last3 = Mulcahy | first3 = M. I. F. }}</ref><ref>{{Cite journal | doi = 10.1016/j.aquaculture.2004.04.007| title = Potential resistance of a number of populations of the oyster ''Ostrea edulis'' to the parasite ''Bonamia ostreae''| journal = Aquaculture| volume = 237| issue = 1–4| pages = 41–58| year = 2004| last1 = Culloty | first1 = S. C. | last2 = Cronin | first2 = M. A. | last3 = Mulcahy | first3 = M. F. | bibcode = 2004Aquac.237...41C}}</ref>

Over the years 'Rossmore' oysters have shown to develop lower prevalence of ''B. ostreae'' infection and percentage mortality. Ragone Calvo et al. (2003) selectively bred the eastern oyster, ''Crassostrea virginica'', for resistance against co-occurring parasites ''Haplosporidium nelson'' (MSX) and ''Perkinsus marinus'' (Dermo). They achieved dual resistance to the disease in four generations of selective breeding. The oysters showed higher growth and survival rates and low susceptibility to the infections. At the end of the experiment, artificially selected ''C. virginica'' showed a 34–48% higher survival rate.<ref>{{Cite journal | doi = 10.1016/s0044-8486(02)00399-x| title = Dual disease resistance in a selectively bred eastern oyster, ''Crassostrea virginica'', strain tested in Chesapeake Bay| journal = Aquaculture| volume = 220| issue = 1–4| pages = 69–87| year = 2003| last1 = Ragone Calvo | first1 = L. M. | last2 = Calvo | first2 = G. W. | last3 = Burreson | first3 = E. M. | bibcode = 2003Aquac.220...69R}}</ref>

====Penaeid shrimps====
Selection for growth in Penaeid shrimps yielded successful results. A selective breeding program for ''Litopenaeus stylirostris'' saw an 18% increase in growth after the fourth generation and 21% growth after the fifth generation.<ref>{{cite journal | last1 = Goyard | first1 = E. | last2 = Patrois | first2 = J. | last3 = Reignon | first3 = J.-M. | last4 = Vanaa | first4 = V. | last5 = Dufour | first5 = R | last6 = Be | year = 1999 | title = IFREMER's shrimp genetics program | journal = Global Aquaculture Advocate | volume = 2 | issue = 6| pages = 26–28 }}</ref> ''Marsupenaeus japonicas'' showed a 10.7% increase in growth after the first generation.<ref>{{Cite journal | doi = 10.1016/S0044-8486(99)00237-9| title = Response to selection and heritability for growth in the Kuruma prawn, ''Penaeus japonicus''| journal = Aquaculture| volume = 181| issue = 3–4| pages = 215–223| year = 2000| last1 = Hetzel | first1 = D. J. S. | last2 = Crocos | first2 = P. J. | last3 = Davis | first3 = G. P. | last4 = Moore | first4 = S. S. | last5 = Preston | first5 = N. C. | bibcode = 2000Aquac.181..215H}}</ref> Argue et al. (2002) conducted a selective breeding program on the Pacific White Shrimp,'' Litopenaeus vannamei'' at The Oceanic Institute, Waimanalo, USA from 1995 to 1998. They reported significant responses to selection compared to the unselected control shrimps. After one generation, a 21% increase was observed in growth and 18.4% increase in survival to TSV.<ref>{{Cite journal | doi = 10.1016/s0044-8486(01)00830-4| title = Selective breeding of Pacific white shrimp (''Litopenaeus vannamei'') for growth and resistance to Taura Syndrome Virus| journal = Aquaculture| volume = 204| issue = 3–4| pages = 447–460| year = 2002| last1 = Argue | first1 = B. J. | last2 = Arce | first2 = S. M. | last3 = Lotz | first3 = J. M. | last4 = Moss | first4 = S. M. | bibcode = 2002Aquac.204..447A}}</ref> The Taura Syndrome Virus (TSV) causes mortalities of 70% or more in shrimps. C.I. Oceanos S.A. in Colombia selected the survivors of the disease from infected ponds and used them as parents for the next generation. They achieved satisfying results in two or three generations wherein survival rates approached levels before the outbreak of the disease.<ref>{{Cite journal | doi = 10.1016/j.aquaculture.2008.09.011| title = Breeding for disease resistance of Penaeid shrimps| journal = Aquaculture| volume = 286| issue = 1–2| pages = 1–11| year = 2009| last1 = Cock | first1 = J. | last2 = Gitterle | first2 = T. | last3 = Salazar | first3 = M. | last4 = Rye | first4 = M. | bibcode = 2009Aquac.286....1C}}</ref> The resulting heavy losses (up to 90%) caused by Infectious hypodermal and haematopoietic necrosis virus (IHHNV) caused a number of shrimp farming industries started to selectively breed shrimps resistant to this disease. Successful outcomes led to development of Super Shrimp, a selected line of ''L. stylirostris'' that is resistant to IHHNV infection. Tang et al. (2000) confirmed this by showing no mortalities in IHHNV- challenged Super Shrimp post larvae and juveniles.<ref>{{Cite journal | doi = 10.1016/s0044-8486(00)00407-5 | title = Postlarvae and juveniles of a selected line of ''Penaeus stylirostris'' are resistant to infectious hypodermal and hematopoietic necrosis virus infection| journal = Aquaculture| volume = 190| issue = 3–4| pages = 203–210| year = 2000| last1 = Tang | first1 = K. F. J. | last2 = Durand | first2 = S. V. | last3 = White | first3 = B. L. | last4 = Redman | first4 = R. M. | last5 = Pantoja | first5 = C. R. | last6 = Lightner | first6 = D. V. | bibcode = 2000Aquac.190..203T}}</ref>