02409nas a2200253   4500008004100000050003700041245008100078210006900159260000900228300001000237490000700247520167300254653003901927653001401966100001801980700001401998700001402012700001602026700001502042700001502057700001302072700001502085856005502100       2005                        eng d  aOSU Libraries: Guin SH370.A1 J6100aUpdate on research concerning the summertime mortality of the Pacific oyster0 aUpdate on research concerning the summertime mortality of the Pa  c2005  ap.3360 v243 aPacific oyster (Crassostrea gigas) summer mortalities are a recurring problem in the United States, Japan, France, and Mexico. During the 2002 to 2003 growing season, for example, farmers in Carlsbad, California; Netarts Bay, Oregon; and Willapa Bay and south Puget Sound, Washington, reported up to a 50% loss of market-ready oysters occurring over a brief 2-3 wk span. Research findings indicate genetic pedigree, ploidy, culture practice, and prior exposure to environmental stress have varying influences on the expression of the summer mortality disease in Pacific oysters. The ability of oysters to survive episodes of summer mortality is in part genetically determined and perhaps enhanced through selective breeding of families showing high survival traits. Pedigreed lines of oysters with different genetic histories, produced by the Oregon State University Molluscan Broodstock Program (MBP), displayed markedly differential survival, yields, and growth rates. An ongoing Western Regional Aquaculture Center (WRAC) project is exploring an alternative approach that utilizes crossbreeding, the crossing of inbred lines of oysters to produce "hybrids." Initial evaluations of hybrid lines grown out in Hood Canal, Washington, in 2001 to 2002 suggest exceptional performance. Triploid and diploid oysters appear to have different optimal environments. The definition of their respective requirements and responses is essential for maximizing their survival and productivity. Field experiments and grower observations have demonstrated sporadic high triploid mortalities and wide variation in survival compared with diploid oysters planted at the same locations.10aPacific oyster = Crassostrea gigas10ashellfish1 aSuhrbier, A D1 aCheney, D1 aElston, R1 aFriedman, C1 aGriffin, F1 aLangdon, C1 aDavis, J1 aChristy, A  uhttps://netarts.library.oregonstate.edu/node/13696