![]() ![]() ![]() In Louisiana, diploid progeny of broodstock collected from a low-salinity site had higher survival when exposed to low salinity conditions (5.1 ± 3.0) than the progeny of broodstock from higher salinity regimes ( Leonhardt et al., 2017). There is however increasing evidence of divergence in salinity tolerance among GoM oyster populations even across a narrow geographic range ( Leonhardt et al., 2017 Marshall et al., 2021a Swam et al., 2022). However, triploids suffer greater mortalities in low salinity conditions (28 ☌) ( La Peyre et al., 2013 Munroe et al., 2013 Rybovich et al., 2016). Triploids can grow faster and have better meat quality, especially in the summer months, than do diploids because of reduced gametogenesis of triploids ( Allen Jr. Triploid oysters (3 N), bred to have three sets of chromosomes instead of the normal two sets (2 N), have been adopted in off-bottom aquaculture partially to offset the higher initial investment ( Petrolia et al., 2022). Crassostrea virginica has traditionally been grown sub-tidally on-bottom in GoM estuaries but production is being increasingly supplemented by off-bottom aquaculture ( Walton et al., 2013 Walton and Swann, 2021). Today, oyster farming is one of the highest valued sectors of aquaculture in the United States, with the Gulf region producing the most oysters (by volume) in 2017 ( National Marine Fisheries Service, 2020). Gulf of Mexico (GoM) and Atlantic estuaries for centuries. Ploidy level had the largest effect on triploid survival and growth followed by the hatchery site where the oysters were produced.Įastern oysters ( Crassostrea virginica) have been harvested from U.S. Broodstock parentage affected diploid mortality and growth, although results did not match with predictions made based on historical salinity at broodstock collection sites. Sex ratio, gametogenic stage, gonad-to-body ratio, condition index, and Perkinsus marinus infection were also measured periodically at both field sites Although high triploid mortality at the low-salinity site prevented complete analysis, results indicated that diploid parentage had little effect on triploid survival at low salinity. All progeny were deployed at low and moderate-salinity (averages of 9.3 and 19.4) field sites to monitor monthly growth and mortality. Diploid crosses were also produced using the wild broodstocks to verify expected differences in low-salinity tolerance among diploid progeny and between ploidy levels. As such, the effect of broodstock parentage was investigated on the low-salinity tolerance of triploid progeny produced by mating diploid females (collected from three Louisiana estuaries differing in salinity regimes) with male tetraploids at two hatcheries. Triploid Eastern oysters have been reported to suffer greater mortalities than diploids when exposed to low-salinity (<5) conditions in the U.S. ![]()
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