Effect of ploidy on the mortality of Crassostrea gigas spat caused by OsHV‐1 in France using unselected and selected OsHV‐1 resistant oysters

The effect of ploidy on the mortality of Crassostrea gigas spat caused by the ostreid herpesvirus (OsHV‐1) genotype μVar was investigated at five sites along the Atlantic coast in France in 2011. Sibling diploids and triploids were produced using either unselected or selected OsHV‐1‐resistant oysters. No significant interactions were found between the factors of environment, genotype and ploidy at the endpoint dates. The mean mortality rates at the sites were 62% and 59% for diploids and triploids, respectively, and the two rates were not significantly different. The mean mortality rates were 33% and 32% for sibling diploids and triploids, respectively, when OsHV‐1‐resistant parents were used and 91% and 85%, respectively, when unselected parents were used. The results were confirmed through other broodstocks tested in 2013. Our study is the first to clearly show that mortality related to OsHV‐1 is similar between diploids and triploids in C. gigas when the same germplasm is used for both ploidy. Furthermore, OsHV‐1 resistance was not substantially altered by triploidization, indicating that the achieved selective breeding of diploid oysters for OsHV‐1 resistance can be translated into improved survival in triploids.     

长牡蛎第三代选育群体生长性状的选择效应

为了培育长牡蛎的高产抗逆新品种,实验采用群体选育方法构建了中国、日本和韩国3个种群的快速生长选育系,2007年至今已连续进行了6代选育。本实验对长 牡蛎选育F₃代壳高和活体体质量的增长、选择反应和遗传获得等遗传参数进行了分析。结果表明,从第120日龄开始,中国、日本和韩国3个选育群体的壳高和 活体体质量均显著高于对照组,在420日龄时,平均壳高较对照组分别高13.4%、10.1%和10.5%,平均活体体质量较对照组分别重18.5%、13.4%和11.6%;壳高的平均现实遗传力分别为0.447±0.226、0.471±0.297和0.367±0.167,表明适于对壳高的生长速度进行进一步的选育。长牡蛎中国、日本和韩国选育F3代活体 体质量的遗传获得平均值分别为16.01%±3.82%、15.03%±5.21%和11.57%±5.15%,表明对长牡蛎壳高的生长速度进行选育时,活体体质量的生长速度也得到了明显提高。本研究结果可以为长牡蛎快速生长品系的连续选育提供依据。     

Different responses between orange variant and cultured population of the Pacific oyster Crassostrea gigas at early life stage to temperature‐salinity combinations

Although breeding of rare shell colour variants has drawn widespread attention from shellfish breeders, the potential disadvantages of their adaptive capacity have been ignored in practice. To explore the difference in adaptive capacity between orange shell variant (OSO) and commercially cultured population (CPO) of the Pacific oyster Crassostrea gigas at early life stage, the development to D‐larvae and larval survival and growth (just 23 and 30°C for larval experiment) of them were compared under different temperature (16, 23 and 30°C) and salinity (17, 25 and 33 psu) combinations. In this study, at 23°C and 25 psu, for both OSO and CPO there was no difference in fertilization rates and survival (p > .05) (mean percentages of D‐larvae after fertilized 40 hr ≥ 95.00%; mean larval survival rates on day 10 > 80.00%). However, the percentage of D‐larvae of CPO at 40 hr was significantly (p < .05) higher than OSO at temperatures of 16 and 30°C and 25–33 psu and 17 psu at 23°C. Similarly, CPO has a better larval survival on day 10 and growth than OSO at salinities of 17 and 33 psu at 23°C. Overall, our results indicate that OSO can have an equally good performance like CPO at early life stage under optimal condition (23°C; 25 psu), but the potential disadvantages in adaptive capacity will be shown at suboptimal conditions. These findings can guide future hatchery breeding of OSO, and suggest the potential disadvantages in adaptive capacity in rare colour variants need more attention in further breeding.     

Bivalve hatchery technology: The current situation for the Pacific oyster Crassostrea gigas and the scallop Pecten maximus in France

The French oyster farming industry relies almost exclusively on juveniles collected from the natural environment; the supply of spat produced by hatcheries is low, about 10 % of the industry's requirements. Development through selective breeding of oyster stocks which are better suited for aquaculture purposes, is likely to reverse this tendency since only hatcheries will be able to supply such animals. Scallop farming, which at present is poorly developed in France, relies exclusively on hatchery produced spat. Although hatchery technology is constantly being improved, significant production problems remain which must be solved before hatcheries become a major supplier of juveniles for the industry. This paper describes the present state of hatchery technology in France based on experimental results obtained with the great scallop Pecten maximus and the Pacific oyster Crassostrea gigas, over the past ten years. Compared to the great scallop, the Pacific oyster has higher D larva yields (60 % for C. gigas vs. 30 % for P. maximus) and a faster larval growth rate (10 μm·d⁻¹ for C. gigas vs. 5 μm·d⁻¹ for P. maximus). However, Pacific oysters have a greater heterogeneity during larval development and higher mortality rates (40 % for C. gigas vs. 25 % for P. maximus) which produce lower overall yields of pediveliger larvae ready-to-set for Pacific oysters (15 %) compared to the great scallop (30 %). Development of continuous larval and post-larval culture methods along with development of continuous phytoplankton technology offers one of the most promising methods to improve molluscan hatchery techniques.     

Shell shape and meat condition in selectively bred Sydney rock oysters,Saccostrea glomerata (Gould, 1850): The influence of grow‐out methods

The Australian edible oyster industry has been severely impacted by disease and declining yields since the 1970s. Selective breeding of Saccostrea glomerata is one measure addressing these problems by producing fast‐growing, disease‐resistant oysters. Farmers report that selected oysters have different growth characteristics than their wild counterparts using conventional grow‐out methods. This study investigated how different grow‐out methods influence commercially valuable oyster characteristics including shell length, shape, surface growth deformities and meat condition. In June 2015, selectively bred S. glomerata spat were deployed in two estuaries (Hawkesbury River and Georges River) in NSW, Australia, using three grow‐out methods (fixed trays, Stanway cylinders and floating baskets). In November 2015, oysters were transferred among grow‐out methods to test for the effects of changing grow‐out methods on oyster growth patterns. Oysters transferred from baskets to cylinders and from trays to cylinders had, on average, deeper and wider shells, a higher meat condition and fewer shell surface deformities than oysters in other grow‐out method combinations. However, these oysters were smaller than oysters not grown in cylinders. While there were some differences in growth patterns between the estuaries, overall it was the grow‐out methods that most influenced oyster characteristics. This was attributed to differences in the amount and magnitude of movement oysters experienced in the grow‐out methods, as recorded by motion sensors. This study demonstrates how grow‐out methods can be managed to achieve desired growth trajectories and therefore improve marketability among selective bred S. glomerata.     

壳金长牡蛎家系的建立及生长和存活性状的比较

于2014年6月,以经过2代家系选育和2代群体选育共连续4代选育的壳金长牡蛎为亲本,采用巢式设计,成功构建25个全同胞家系,同时以未经选育的壳色即普通灰白色的个体子代为对照组,评估各家系和对照组在幼虫、稚贝期的生长和存活差异。结果显示,不同时期,壳金长牡蛎选育家系各生长性状平均值均高于对照组平均值,其中在幼虫期不同日龄,壳金长牡蛎所有家系壳高和存活率平均值均高于对照组,分别提高2.27%~16.67%和1.72%~9.40%;在稚贝期各阶段,壳金长牡蛎所有家系壳高、壳长、总重量及存活率的平均值均高于对照组,分别提高10.04%~19.79%、6.56%~17.78%、10.44%~32.92%和0.20%~4.26%;不同壳金家系间的生长及存活性状具有显著差异,排序也存在不一致性,其中G19和G28家系表现出较高的生长及存活性能,在11月龄,G19和G28家系的壳高、壳长、总重的累积生长量比所有家系平均值分别提高4.78%、8.22%、12.38%和7.61%、4.02%、9.04%,与对照组相比,分别提高15.31%、15.31%、24.11%和18.42%、10.85%、20.42%;存活率比所有家系平均值和对照组分别提高11.70%、12.71%和11.92%、12.94%。研究表明,壳金长牡蛎选育群体的生长性状具有一定的优势,但存活性状有待进一步的改良;家系G19和G28可作为优良品种培育的育种材料。本研究为培育快速生长和存活率高的壳金长牡蛎新品种提供了基础资料。     

Phenotypic indicators for cultured pearl size improvement in the black‐lipped pearl oyster (Pinctada margaritifera): towards selection for the recipient growth performance

The black‐lipped pearl oyster, Pinctada margaritifera, is the most important farmed species in French Polynesia and the basis of the most valuable export industry. Mass production of black pearls relies on a surgical operation requiring tissue from a donor pearl oyster to be grafted, together with a nucleus made of shell, into the gonad of a recipient oyster. Improving pearl size through family selection remains one of the main challenges for future aquaculture development. This study analyses the relative contribution of donor and recipient oysters to pearl size. To this end, hatchery‐produced donor oysters of two batches, large and small (based on shell height), were used to supply grafts for recipients, which were then monitored individually for their growth performance by recording shell height, width, and thickness, and total live weight (flesh + shells) every 6 months (four biometric measurement times) over 20 months of culture. Pearls issued from the two batches of donors showed no significant differences in nacre weight or thickness. In contrast, recipient oyster shell height and total weight were increasingly positively correlated with these pearl size parameters over the culture period, becoming significant at 8 months post‐grafting. Potential therefore exists to use shell height and oyster weight as phenotypic indicators for selective breeding of recipient oysters with high growth performance to increase pearl size in P. margaritifera.     

Insights on the association between somatic aneuploidy and ostreid herpesvirus 1 detection in the oysters Crassostrea gigas,C. angulata and their F1 hybrids

Cytogenetic abnormalities associated with viral infections, including from viruses of the Herpesvirales order, have been reported in vertebrate species. Ostreid herpesvirus 1 (OsHV‐1) has been detected worldwide during mortality outbreaks of the Pacific oyster Crassostrea gigas. On the other hand, a high proportion of aneuploid cells in somatic tissues have been observed in C. gigas. In this study, we analysed the putative association between aneuploidy levels and the detection of OsHV‐1 in gills of C. gigas, the Portuguese oyster C. angulata and their F1 hybrids cultured in Ria Formosa (Portugal). OsHV‐1 was detected by PCR in 5.4% of the total of oysters analysed (n = 111) namely in 11.1%, 8.0% and 1.7% of C. gigas, C. angulata and F1 hybrid respectively. Sequencing analysis of a viral fragment amplified with the C2/C6 primer pair revealed a high similarity with the OsHV‐1 reference type. Moreover, in situ hybridization confirmed the presence of OsHV‐1 in gill tissue. Oysters where OsHV‐1 was detected had a significantly higher mean percentage of aneuploid cells (25%) than the ones where the virus was not detected (18%). However, the overall low percentage of positive samples contrasted with the high mean percentage of aneuploidy observed, with 50% of the oysters analysed showing a percentage of aneuploid cells between 20% and 30%. We hypothesize that somatic aneuploidy may adversely affect oysters making them more prone to OsHV‐1 infection, but the virus is unlikely to be the cause of somatic aneuploidy.     

Enhancing lipid nutritional quality of oysters by hybridization between Crassostrea gigas and C. angulata

In the present study, hybrid and inbred oysters were produced by factorial hybridization between two closely related species, the Pacific oyster Crassostrea gigas and the Portuguese oyster C. angulata. Tissues samples were used for the analysis of total lipid content (TLC) and fatty acid composition (FAC). In general, FAC but not TLC in hybrid oysters was significantly different from inbred oysters. Hybrid oysters have significantly lower ∑SFA composition but higher ∑PUFA composition than inbred oysters, with heterosis for ∑SFA, ∑MUFA and ∑PUFA of ?6.03%, ?6.53% and 14.31% respectively. Moreover, hybrid oysters have significantly higher EPA + DHA content and n3/n6 PUFA ratio than inbred oysters, indicating higher lipid nutritional quality than inbred oysters. Among them, the hybrid ♀ C. gigas × ♂ C. angulata appears to be the most nutritious. These results indicated that the lipid nutritional quality of oysters can be improved by hybridization.     

Increased harvest of anadromous hatchery steelhead,Oncorhynchus mykiss (Walbaum), through return timing manipulation

Harvest hatchery programmes serve to augment fisheries but should also minimise impacts to wild populations. In an experiment to increase harvest in an anadromous hatchery steelhead, Oncorhynchus mykiss (Walbaum), terminal river fishery, a new hatchery strain, was created using selective breeding of early arriving adults to the river. First‐generation progeny of the new early arriving strain were reared and released over 4 years concurrent with releases of the standard hatchery strain. This study compares adult return timing, terminal harvest and straying behaviour of progeny of the early arriving and standard hatchery strains. The new strain migrated towards the terminal river fishery earlier, they were harvested earlier in the eight‐month fishing season and their overall harvest was 17% greater, but 7.7% of the new strain strayed to other rivers compared to 5.0% of the standard strain. Selective breeding to match adult return timing with fishing effort may help bolster harvest, but a paired release evaluation, such as was conducted in this study, would be prudent before switching all hatchery production to a selectively bred strain.     

Genetic relatedness and differentiation of hatchery populations of Asian seabass (Lates calcarifer) (Bloch, 1790) broodstock in Thailand inferred from microsatellite genetic markers

After more than 20 years of hatchery production of Asian seabass in Thailand, genetic information is still lacking for effective genetic management and a selective breeding programme. This study aimed to evaluate genetic status of existing hatchery populations and genetic consequences of a selective breeding attempt. We examined genetic relatedness in seven hatchery samples, including a selectively bred population (RACF‐F1), compared with three wild samples using 11 microsatellite loci. Genetic diversity and relatedness values within most hatchery samples, except for RACF‐F1, did not differ from those of wild populations (P > 0.05). RACF‐F1 had the lowest allelic diversity and effective population size (A_r = 6.99; N_e = 7.8) and highest relatedness values (mean r_xy = 0.075–0.204). Pairwise Φ_ST values, principal component analysis and model‐based cluster analyses revealed three genetically distinct hatchery groups: Eastern Thailand (CHN, RACF, NSCF and SKCF), Southern Thailand (NICA) and the Andaman Sea (STCF). Results suggest that exiting domestic populations capture reasonable amount of genetic variation and can be useful for a base population for genetic improvement programmes. In addition, given the rapid increase in relatedness that we observed in one selectively bred population, we recommend using selection methods and hatchery practices that reduce variability in family contribution in the subsequent generations.     

长牡蛎壳金选育群体生长性状的选择效应

长牡蛎是一种世界性的养殖贝类,同时是我国最重要的经济贝类之一,壳色美观和快速生长是目前长牡蛎遗传育种的2个重要目标。2010年通过长牡蛎壳色性状的家系选育,获得了壳白、壳黑、壳金和壳紫4种壳色品系。实验以第二代壳金品系为基础群体,对长牡蛎壳金群体的生长性状进行定向选育,分析了长牡蛎壳金选育群体壳高性状的选择反应、遗传获得和现实遗传力。结果显示,养成阶段选择组的壳高均大于对照组,350日龄后表现出显著的生长优势;幼虫期,壳高性状的平均选择反应、遗传获得和现实遗传力分别为0.549±0.277、3.717%±2.611%和0.339±0.171,养成期分别为0.436±0.138、8.253%±1.014%和0.270±0.086。选择组的贝壳金黄色和外套膜金黄色比例分别提高了22%和10%。研究结果为长牡蛎壳金优良品系培育提供了重要基础资料。     

Sex-specific growth and condition of the Pacific oyster (Crassostrea gigas Thunberg)

In order to study the possibility of gaining commercial benefit from culturing an excess of one sex of the Pacific oyster (Crassostrea gigas), comparative data on the growth rate and condition of male and female oysters are reported. Historically, measurement of sex‐specific growth rate in oysters has been overlooked or confounded by protandric sex. The recent conclusion that the sex ratio of Pacific oysters is predominantly under genetic rather than environmental control introduces the possibility of manipulating sex ratio for commercial gain if they exhibit asynchronous sex‐specific growth rates. Pacific oysters were cultured intertidally in Smoky Bay, south Australia. The observations, made over the 7‐month gametogenic cycle from August to February to ensure no sex reversal, were of growth rates of male and female oysters and ambient chlorophyll a concentrations. Mean shell growth of female oysters was significantly faster than that of males (4.5 ± 3.3 compared with 3.8 ± 3.2 μm day^?1 mm^?1 total length). Sex‐specific asymmetries in length and weight were generally significant and increased in magnitude during the 7‐month study period, suggesting potential commercial benefits from increasing the proportion of cultured female oysters. The fastest increase in the sex‐specific disparity in growth and condition came after the October chlorophyll a peak, suggesting that females utilize blooms more efficiently than males. Our results compare favourably with methods currently used to increase oyster growth (e.g. triploidy can provide growth gains of 13–51%).     

Effects of controlled air exposure on the survival,growth, condition,pathogen loads and refrigerated shelf life of eastern oysters

The benefits of exposing eastern oysters to air during commercial culture have not been well‐characterized. An adjustable longline system (ALS) designed in Australia and recently adopted by the nascent aquaculture industry in the northern Gulf of Mexico, allows growing oysters at any position in the water column and is perfectly suited to study the benefits of air exposure. Four‐month old diploid oysters were deployed in an ALS and divided into three groups: 1) oysters exposed to air daily for 8–12 hr during low tide, 2) oysters exposed to air weekly (~24 hr once a week), and 3) oysters kept subtidally. Oyster mortality and growth rates, Perkinsus marinus load and condition index were then determined every 3 months over 2 years, while refrigerated shelf life and Vibrio vulnificus load were determined in summer and early fall of the second year. Summer mortalities were delayed, P. marinus infection intensities tended to be lower and condition index was significantly higher in oysters exposed to air daily compared with oysters exposed to air weekly or held subtidally. Shell heights of oysters exposed to air daily were lower for most of the study due to a lower growth rate during the initial sampling interval following deployment. No consistent differences were found in V. vulnificus loads or refrigerated shelf lives between the groups. It is recommended that ALS be set so that oysters are kept subtidally fall through spring to promote growth, and exposed to air daily during summer to delay P. marinus proliferation.     

Pacific oysters crassostrea gigas (Thunberg) of possible French origin in natural spat in the British Isles

• 1 Hatchery-reared Pacific oysters (Crassostrea gigas) grown in the British Isles and Guernsey originate from an introduction through quarantine of small numbers of oysters from British Columbia, Canada.
• 2 Previous electrophoretic analysis of samples of these oysters have shown the glucose phosphate isomerase locus to be monomorphic.
• 3 Recent analysis of oysters from a commercial hatchery in Guernsey revealed a second allele at low frequencies which was unexpected and was thought to indicate the presence of oysters from another stock.
• 4 Samples of hatchery-reared oysters from France showed that they were highly polymorphic and carried the unexpected allele and four others.
• 5 A natural spatfall of oysters from the River Teign (Devon) was sampled and these carried three alleles which were also found in the French C. gigas. This suggests that there has been movement of C. gigas possibly of French origin into this river.
• 6 This finding and its implications in terms of conservation and management are discussed.

     

Genetic parameters of growth and survival in the Pacific oyster Crassostrea gigas

The Pacific oyster Crassostrea gigas is a representative bivalve mollusc that is widely cultured in the world and is the largest molluscan group cultured in China. In order to assess the feasibility of improving survival of C. gigas through genetic selection, the heritability and genetic correlations for growth and survival traits between different life stages were examined. Genetic parameters were estimated based on intraclass correlations of 49 full‐sib families (29 half‐sib families) in larvae (4 and 20 days after fertilization) and spat (140 days after fertilization) stages. The heritability for growth traits in larvae and spat was 0.30–0.86 and 0.53–0.59, respectively, and varied with ages. The heritability of survival was low in larvae (0.13 ± 0.05 and 0.17 ± 0.04, respectively for 4 and 20 days after fertilization) but medium (0.39 ± 0.07) in spat, suggesting that selection for increasing spat survival was feasible. The genetic correlation between growth traits within age was medium to high and positive (ranging from 0.47 to 0.96, respectively, between shell length (SL) and shell height (SH) at 20 days and between SL and SH at 140 days after fertilization), suggesting that selection to improve single growth trait will cause positive response in another growth traits in C. gigas. The genetic correlations between survival and growth traits at 140 days were low but positive (ranging from 0.23 to 0.27, respectively, between survival and SH and between survival and SL at 140 days after fertilization), suggesting that selection for survival may not have a negative response in growth. Overall, this study suggests that survival traits should be taken as improving target of next selection breeding programme in C. gigas.     

Suspended culture evaluation of Pacific oyster Crassostrea gigas in a tropical estuary

The growth and survival of Crassostrea gigas were evaluated in hanging culture in the Chone River estuary (Bahía de Caráquez), Manabí province, Ecuador. Oyster seeds (~10 mm) were confined in lantern nets at a density equal to the occupation of half the surface of the basket base, until reaching commercial size (80 mm). A sample for oyster biometric, parasitic and bacterial analysis was obtained monthly. Temperature, salinity, oxygen concentration, seston and phytoplankton biomass were determined. At the end of the study, the oysters were analysed for heavy metal concentration. The commercial oyster production was extrapolated to estimate the possible economic performance of a family production module (a 7 × 7 m bamboo raft). The results show a great biological feasibility of culture of C. gigas with harvests of commercial size oysters in only 5 months and acceptable survivals (accumulated >70%, after 3 weeks of crop seed selection). The heavy metal concentrations and the parasitological and bacteriological analyses did not indicate levels of contamination. The economic projections suggest that, even with a profitability of 57%, the initially invested capital could be recovered within the first harvest.     

Family by environment interactions in shell size of 43-day old silver-lip pearl oyster (Pinctada maxima), five families reared under different nursery conditions

To understand the influence the environment and associated genotype by environment interactions will exert on future silver-lip pearl oyster (Pinctada maxima) selective breeding programs, this study assessed the relative performance in four shell growth traits of spat from five full-sib families, when spat were communally reared at different salinities (29, 34 and 40 ppt), food availability (high, medium and low), food quality (high, medium and low), and in a hatchery vs. ocean environment for 43 days.Rearing environment was found to influence growth expression, with significant differences evident when oysters were grown at different salinities in the ocean instead of hatchery, or when fed algae of differing nutritional quality. As indicated by MANOVA, family comparative growth performances were also altered when the environment changed, with significant environment by family interactions apparent in the food quality, food availability and hatchery vs. ocean rearing treatments. Changes in salinity, however, did not affect relevant family performances.These results indicate that growth and relative family performance in P. maxima may change dependent on local environmental conditions and that genotype by environment effects may need to be considered in breeding programs for this species.     

Stress Gene Expression in Crassostrea gigas (Thunberg, 1793) in response to experimental exposure to the toxic dinoflagellate Prorocentrum lima (Ehrenberg) Dodge, 1975

Harmful algal blooms (HABs) are natural phenomena with different effects on the aquatic environment that affect both human economy and health. Several genomic studies have been done to characterize the effects of contaminants on Crassostrea gigas. However, oysters’ molecular response to HABs exposure needs to be studied more. In this study, we challenged C. gigas with Prorocentrum lima, a diarrhoetic toxin producer, under controlled experimental conditions considering dinoflagellate density and exposure time (acute and sub‐chronic) as variables. The expression profile of six stress response genes was analysed by semiquantitative RT‐PCR: Glutamine synthetase (GS), Glutathione S‐transferase (GST), heat shock protein 70 (HSP₇₀), and heat shock protein 90 (HSP₉₀), CuZn superoxide dismutase (SOD) and melanogenic peroxidase (POX). The results revealed that these gene expressions depend on exposure time and cell concentration. In general, an increased expression was observed in all tested cell densities as immediate response to exposure (0–3 h); whereas lower expression levels than control were observed after 6 h. Treatment with 3,000 cells mL^‐1 promoted higher expression than control on most genes after 336 h of exposure. This is the first report providing information at molecular level on C. gigas response to dinoflagellate blooms.     

长牡蛎生长性状遗传力、遗传相关和表型相关分析

为了查清乳山(RS)和崆峒岛(KTD)海域长牡蛎生长性状各指标的遗传力、遗传相关和表型相关,本实验通过部分因子交配设计和人工授精的方法建立家系,并在乳山和崆峒岛海域进行养殖。用混合线性模型分别计算RS和KTD海域188日龄、338日龄和474日龄长牡蛎生长性状各指标的遗传参数。结果发现:不同日龄长牡蛎生长性状各指标,在乳山海域的遗传力是0.28~0.55,为中高遗传力,在崆峒岛海域的遗传力是0.34~0.63,为高遗传力;与乳山海域相比,崆峒岛海域各指标的遗传力偏高。运用亲本模型,将日龄和地点作为固定效应,计算得到壳高、壳长、壳宽和湿重的遗传力分别为0.25±0.08、0.29±0.09、0.14±0.05和0.26±0.09。不同海域、不同日龄的遗传相关和表型相关结果各不相同,但各指标间均呈现正相关;总体来讲,性状间的遗传相关大于表型相关。实验结果有助于掌握山东半岛南北两侧长牡蛎生长性状的数量遗传学参数,为制定长牡蛎在该海域的选育技术路线提供数据支持。