Larval and post‐larval growth,spat production and off‐bottom cultivation of the smooth venus clam Chionista fluctifraga

Harvesting practices of the clam Chionista fluctifraga show a decline in commercial size and densities, but no strategies have been developed to maintain clam beds. Aquaculture represents an alternative for preserving this resource. Adult clams from commercial grounds were used as broodstock. Conditioning, induction of spawning, cultivation of larvae, settlement of eyed larvae and nursing of postlarvae were performed in the hatchery for producing spat. Larvae and postlarvae were used to measure increase in shell height and data were fitted to exponential growth models. Spat were placed in floating trays and maintained in off‐bottom cultivation for 9 months. Samples of clams and tissues were collected monthly to measure absolute growth, shell height increase and a condition index. Larvae, postlarvae and juveniles showed exponential growth patterns. Mean shell height increased about 0.030 mm day^?1 during larval and post‐larval stages and 0.049 mm day^?1 during field cultivation. Pediveligers (height 215 ± 83 μm) entered metamorphosis at days 9–13 after fertilization, and postlarvae reached 3011.7 ± 325.5 μm (height) at day 60. After field cultivation, survival was about 95%; juvenile shell height was 20.6 ± 2.2 mm, and total weight was 5.3 ± 0.7 g. Growth rates were superior to natural conditions and the condition index was high throughout the study. Our results show that spat of C. fluctifraga can be produced in the hatchery, and that field production can be maintained in off‐bottom trays until reaching commercial size. Aquaculture activities for this species need to be established and evaluated.     

Growth and gonad development of the tropical black-lip pearl oyster, Pinctada margaritifera (L.), in the Gambier archipelago (French Polynesia)

The growth and reproductive cycle of cultured black-lipped pearl oysters, Pinctada margaritifera (L.), were studied in the Gambier Islands (134°52′ W, 23°07′ S) from September 2002 to August 2003. Temperatures were recorded throughout the year, revealing seasonal temperature variations between 22.3 and 27.8°C. The mean annual chlorophyll a value, as computed from satellite data, was 0.188 ± 0.075 μg L⁻¹. To study growth and reproduction, 720 two-year-old individuals were ear hung on long-lines suspended at a depth of 7 m. Samples were taken twice a month to obtain the following measurements: shell height; wet weight of flesh and total oyster; dry weight of adductor muscle, mantle and visceral mass; and glycogen content. Gonad development was also studied by histology on parallel samples. Growth was relatively fast during the first 6 months of the study: average shell height increased from 89.1 ± 9.1 to 119.7 ± 10.8 mm and total weight from 93.4 ± 24.5 to 155.1 ± 33.6 g, between September and the end of March. Subsequently, from April to August, no significant growth was observed for shell and flesh, while the muscle weight decreased significantly. Condition index (CI), defined as the ratio of wet weight of the visceral mass to shell weight, and histological changes in the gonad revealed 3 significant reproductive events of different intensities. The analysis of correlations revealed a specific effect of the chlorophyll a concentration on the growth of shell and soma, and one of the temperature on tissue glycogen content. This study also showed also that CI could be an efficient indicator of reproductive events in pearl oyster. It thus appears that the development of gonads goes on throughout the year in the Gambier Islands, without any detectable phase of sexual rest.     

中国仙女蛤人工育苗试验

2009年在福建平潭进行了2批次中华仙女蛤人工育苗试验。结果表明,亲贝性腺发育成熟程度与催产方法是影响中国仙女蛤亲贝催产成功率和排放率高低的主要因素;在2批亲贝的平均鲜出肉率分别为(31.6±2.0)%和(32.8±2.3)%的前提下,采用阴干、碘钨灯照射提高亲贝体温、流水刺激相结合的物理综合刺激方法可有效地催产中国仙女蛤并培育出健康苗种。但中国仙女蛤亲贝排精产卵的个数比例较小,即亲贝的排放率较低,2批次育苗的排放率分别仅为16.7%和26.7%。2批次共培育出平均壳长为2.87±0.14mm的中国仙女蛤苗种1 331×106cfu。     

深凹壳型香港牡蛎选育群体生长性状的遗传参数估计

为了培育壳型和生长性状优良的深凹壳型香港牡蛎新品系,以广东台山镇海湾野生香港牡蛎天然采苗的2龄养殖群体为基础群体,以壳型指数D为指标,按照10%留种率和1.755选择强度,利用截头法进行深凹壳型香港牡蛎的群体选育;分析了幼虫期、中间培养期、养成后期的选择反应、遗传获得和现实遗传力等遗传参数。结果发现,选择组的壳高和壳型指数D均大于对照组,遗传参数估算值随着个体的增大而增加。幼虫期,壳高的平均选择反应、平均遗传获得、平均现实遗传力分别为0.363±0.167、1.678%±0.416%、0.207±0.095,中间培养期分别0.639±0.115、7.618%±2.666%、0.364±0.065,养成后期分别为0.668±0.179、8.861%±3.072%、0.381±0.102。养成后期,壳型指数D的平均选择反应、平均遗传获得、平均现实遗传力分别为0.748±0.066、9.090%±0.565%、0.426±0.038。研究结果为培育深凹壳型、生长性能良好的香港牡蛎优良品种提供了实验依据和理论基础。     

Analysis of growth and first reproduction of hatchery‐reared juvenile Cortez oyster (Crassostrea corteziensis) in northwestern Mexico: proposal of a minimal fishing size

This study presents complimentary data of early growth and age/size of first reproduction of hatchery‐reared Crassostrea corteziensis juveniles cultivated in the field for 9 months. Samples of oysters and gonads were collected monthly to determine absolute growth and growth rates, as well as overall gonad development. At the end, adult oysters ranging 75.6 ± 0.62 mm shell height (SH) yielded a mean growth rate of 0.308 mm day⁻¹, which is among the highest reported for the species. Gametogenesis began in March–April and spawning occurred during August and September. Males outnumbered females at smaller sizes, but female were more abundant at larger sizes. From planting time in the field, the age/size of first maturity was 3.25 months for males (42 mm SH) and 4.5 months for females (54 mm SH), with a mean population age of 4.75 months for males (size range 55–59 mm) and 5.25 months for females (60–64 mm). Based on these results, and the time needed for hatchery care prior planting juveniles in the field (2.25 months), we propose limiting fishing of wild oysters to sizes >65 mm height to allow them to breed at least once and contribute to restoring wild populations.     

长牡蛎"海大3号"生长繁殖与营养成分的周年变化

为阐明长牡蛎"海大3号"新品种的生长与繁殖特性,自2016年11月份至2017年10月份对养殖于山东省荣成海区长牡蛎"海大3号"群体的生长、性腺发育及营养成分的周年变化及其与环境因子的关系进行研究。结果显示,在海区水温较低的冬季1—2月份,长牡蛎"海大3号"生长缓慢,性腺处于休止期;随水温升高,在春季3—4月份配子开始发育,雌雄个体发育基本同步,4—5月份壳高生长速率加快,湿重显著增加;在夏季,随配子发育壳高生长速率降低,7月份因配子排放湿重下降;在产卵后的秋季长牡蛎"海大3号"壳高和湿重均显著增长。营养分析结果表明,随性腺发育,外套膜、性腺-内脏团、鳃和闭壳肌中糖原含量呈下降趋势,为配子发育提供能量;脂质和蛋白质作为配子主要结构物质在性腺中不断累积,随配子排放而显著降低;在秋季,4个组织中较高的蛋白质含量为机体的快速生长提供物质基础。同时外套膜作为构成壳物质的分泌器官,在8—9月份其糖原含量和脂质含量显著增加,这暗示机体的快速生长需要一定能量储备。研究表明,长牡蛎"海大3号"的生长和繁殖活动受海区水温季节性变化的影响,并与各组织营养成分密切相关。春季和秋季为机体快速生长时期,夏季为配子集中排放期;糖原是生长繁殖活动的主要能量来源,脂质是配子主要结构物质,蛋白质是机体产后恢复和快速生长的物质基础。     

Spat Collection and Growth to Commercial Size of the Tehuelche Scallop Aequipecten tehuelchus (D'Orb.) in the San Matias Gulf, Patagonia, Argentina

Studies on larval settlement and growth of the commercial scallop Aequipecten tehuelchus were carried out over a 2-yr period in San Matias Gulf, Argentina. Gonadal index was used to indicate spawning and spat collectors were deployed when spawning began. Artificial spat collectors (mono-filament bags filled with thin shrub branches) were placed at a depth of 25 m in two areas of the Gulf during two seasons (1989–1990 and 1991–1992). Maximum settlement occurred by mid-February during the first season and by mid-January in the second season. Larger numbers of spat were found in collectors placed near the sea bottom. After settlement, spat were removed and placed in cages for growout. Scallops reached the average commercial size (60 mm shell height) 16 mo later. Mortality rate during the entire period was 10%.     

栉江珧研究现状及开发利用前景

对广泛分布于温、热带近海海域的大型深水贝类栉江珧的分类地位和地理分布作了介绍，并就栉江珧栖息状况，对水温、盐度、pH、溶解氧等各种环境因子适应性的生态习性作了详细描述。论述了水温对栉江珧的生长、性腺周期发育的影响。对栉江珧人工繁育过程中的亲贝暂养、催产及幼体培育的技术和养殖现状进行了总结。简要概述了江珧科物种同工酶的研究进展，并对栉江珧资源保护及可持续利用和今后研究方向作了探讨。     

大竹蛏生产性人工繁育试验

2007年对大竹蛏进行了生产性人工繁育试验。对亲本不同批次催产效果、不同规格亲本产卵差异、孵化密度进行了比较,研究了D形幼虫发育与温度的关系以及幼虫发育各阶段生长规律等,结果显示,大竹蛏属分批成熟、分批产卵的潜居性贝类,不同批次个体平均产卵量(36~118)×104cell,个体总产卵量294×104cell。壳长8~10 cm的亲贝产卵量大,催产效果好。受精卵适宜的孵化密度为5~10 cell/mL。在水温21~24.5℃条件下,D形幼虫经8~5 d生长,发育变态为附着稚贝。D形幼虫壳长日生长33.33±4.22μm,1 mm前的稚贝壳长日生长108.33±22.57μm,1~10 mm的稚贝平均旬生长量2.12 mm,10.4~30.6 mm的苗种平均旬生长量为2.02 mm。当水温下降到15℃后,大竹蛏苗种生长滞缓。2007年培育出壳长11.52±0.27 mm的稚贝2 165×104cfu,平均成活率12.1%。     

Effect of Different Live Prey on Spawning Quality of Short‐Snouted Seahorse,Hippocampus hippocampus (Linnaeus, 1758)

The importance of a suitable diet for reproduction has been recognized as one of the major factors in ornamental aquaculture. In seahorses, mysids have been described as preys in the wild. Also, Artemia has been usually employed for rearing fish, including syngnathids. Therefore, the aim of this work was to evaluate the effect of these live preys on the spawning quality of Hippocampus hippocampus. After 108 d, no differences were found in adults concerning all biological parameters evaluated, but broodstock fed on mysids showed better results than Artemia regarding number of spawning events (12 vs. 3), brood sizes (233.50 ± 59.04 vs. 68.00 ± 57.97 juveniles), and newborn seahorses standard length (10.61 ± 0.64 vs. 8.75 ± 1.32 mm). The better nutritional quality of mysids, overall in Docosahexanoic acid, could be one of the main responsible factors. However, mysids stock is conditioned by natural catches and rearing techniques are little known. Another alternative would be to combine them with Artemia in mixed diet. Further research must be done concerning mysids breeding techniques to delineate their employment as a sustainable prey for seahorse aquaculture. This trial showed for the first time the effect of mysids to enhance reproduction efficiency in H. hippocampus.     

Comparison of shell strength in wild and cultured scallops (Pecten maximus)

Shell strength development of the scallop Pecten maximus collected from wild stocks and from suspended cultures was described over the culture period when most of the growth takes place (20–110 mm shell height). Shell strength, shell height and shell thickness were determined in scallops of age groups 2–5 years. Wild and cultured scallops showed a strong divergence in shell strength development in scallops older than age group 3, which was not reflected in the concurrent development of shell height and thickness, indicating that factors other than shell height and shell thickness explain the differences in observed shell strength. In wild scallops, shell height, shell thickness and age accounted for about 65% of the variation in shell strength, while the same variables accounted for about 30% in cultured scallops. Wild scallops had stronger shells than the cultured scallops of the same size (53–68 mm shell height) grown at the same site, suggesting that factors related to suspended culture could explain the weak shells in cultured scallops. The results indicate that conditions related to suspended culture can have a negative impact on shell strength development in P. maximus. As the shell is the primary protection against decapod predation in scallops, a better understanding of what affects the shell strength is of importance for the development of release strategies in bottom culture of P. maximus.     

太平洋牡蛎2龄贝的生长

通过１９９８扑３月 １２月对太平洋牡蛎２龄贝生长进行测定得出：壳高在４～６月初生长最快;７月、１２月为出肉率最高时期;７月末８月初为２龄贝产卵期。     

Gonad development, larval settlement and growth of Mytilus edulis L. in a suspended population in Hvalfjördur, south-west Iceland

Annual cycles of gamete development in Mytilus edulis L. in south-west Iceland were investigated during 1986 to 1987. Histological preparations of the gonads showed that all individuals were fully mature in the beginning of June in both years and one spawning period was recorded each year at a sea temperature of 10-12^oC. The main spawning took place from the middle of July to the middle of August, and from the middle of June to the end of July in 1986 and 1987, respectively. Redevelopment of the gonads after spawning was observed in February when both food availability, measured as chlorophyll a concentration, and temperature were low. Rapid gonad maturation took place during the spring phytoplankton bloom in March-April. Larval settlement was heavy on the artificial collectors used. The length of the larval period was estimated as being 4-5 weeks and peak settlement occurred in the middle of September. The size of the early plantigrades settling on the collectors during the study period indicated direct settlement of mussel larvae from the plankton onto the collectors. One year after settlement the spat averaged 24.6 mm ± 6.0 (SD) shell length and two years after settlement a market size of 50.8 mm ± 5.7 (SD) was reached. Growth was correlated with food availability, measured as chlorophyll a concentration. The growth season lasted from March to October with the greatest shell growth in late summer. The results showed that the growth of M. edulis was markedly increased by suspending the animals in a more favourable environment than that found on the natural mussel beds.     

Growth and reproduction of the lion's paw scallop Nodipecten subnodosus in a suspended culture system at Guerrero Negro lagoon,Baja California Sur,Mexico

The lion's paw scallop, Nodipecten subnodosus (Sowerby) has considerable aquacultural potential due to its fast growth and large adductor muscle. Prior investigations throughout northwestern Mexico's littoral have reported highly variable growth rates; furthermore, no studies are available of the environment on growth and gametogenesis in this species under culture conditions. This investigation assesses the effect of food availability and temperature on the growth and gametogenesis of N. subnodosus in a suspended culture system at Guerrero Negro lagoon, Mexico. After 1 year of cultivation, N. subnodosus reached 69.13 mm in shell height (SH) (0.196 mm day^?1, 14 months old). Two significant growth spurts were observed: over the two first months of culture (August and September 2001, mean growth rate 0.4 mm day^?1) and in September 2002 (0.3 mm day^?1), both related to high temperatures and chlorophyll a concentrations. The onset of gametogenesis occurred in April 2002, with an increase in temperature (10‐month‐old scallops, 54.5 mm SH). The first spawning occurred in October and November (86.2 and 93 mm SH), with peak temperatures. These results, together with the analysis of previous reports, indicate that N. subnodosus has a higher preference for temperate areas; therefore, the Guerrero Negro lagoon appears to be a suitable site to culture this species.     

Growth and survival of the scallop Lyropecten (=Nodipecten) nodosus (L. 1758) in suspended culture in the Cariaco Gulf (Venezuela) during a non-upwelling period

Growth and survival of the scallop Lyropecten nodosus were studied in 1997 at two sites (inner and outer Turpialito Bay) during a non‐upwelling period normally occurring between August and November. Individuals had an initial shell height of 4.86 cm (SD=1.64 cm). Both experimental groups were held in suspended plastic baskets at the same depth (4 m). Measurements of shell height and dry weights of shell, gonad, digestive gland, remaining tissues and shell biofouling were taken at monthly intervals. Environmental parameters, including temperature, phytoplanktonic biomass, total particulate material (TPM) and associated organic (POM) and inorganic (PIM) fractions, were recorded simultaneously. At the end of the study, significant differences in growth and survival of scallops were observed between the two experimental sites. Scallops maintained inside the bay showed a 22% greater increase in shell height (7.41±0.27 cm) than those placed outside the bay (6.37±0.41 cm). Survival of scallops inside the bay was 31% higher compared with scallops outside. The greater availability of food of phytoplanktonic origin during the first two experimental months (July and August) together with greater POM throughout the whole experimental period except September, at the inner bay site, probably explained survival and growth differences observed between the two locations. Results suggest that, during the non‐upwelling period (characterized by low primary productivity and high water temperatures), POM of sedimentary origin may play an important role as an energy source required for metabolic and reproductive activities of L. nodosus.     

Growth and survival of the pearl oyster Pinctada imbricata (Röding 1758) in supended and bottom culture in the Golfo de Cariaco, Venezuela

We evaluated growth and survival rates of Pinctadaimbricata in relation to environmental changes during nine months insuspended and bottom culture in the Golfo de Cariaco, Venezuela. Juveniles,measuring 13 mm in length, were cultured using two methods, (1) inSpanish-type baskets suspended at 3–4 m in depth from a longline and (2) in baskets embedded on the seabed (7–8 m indepth). At monthly intervals, we quantified mortality and took a sample ofoysters to determine shell length (dorsal-ventral axis) and the dry mass of theshell, muscle and remaining tissues. We also quantified the dry mass of foulingon the shells (a potentially important environmental factor). Survival rateswere slightly higher in suspended culture (98–100%), although notsignificantly higher than on the bottom. The growth rate was higher in suspendedculture than on the bottom culture, and the difference between culture methodswas greater for tissue and shell biomass than for shell dimensions. At the endof the study, oysters measured 55 mm in shell length for oysters insuspension and 45 mm for those on the bottom. Although growth wasnot significantly correlated with any environmental factor, it tended toincrease with increases in chlorophyll a during periods ofupwelling, thus suggesting that phytoplankton abundance enhanced the growth ofPinctada imbricata. The pearl oyster Pinctadaimbricata should be an excellent species for aquaculture activities,given its high rates of growth and survival in suspended culture and itseconomic importance in the Caribbean region.     

Growth and mortality of the king scallop grown in suspended culture in Malaga, Southern Spain

Growth and mortality of the king scallop, Pecten maximus, werecompared when grown in cages and by ear hanging in suspended culturein Fuengirola, Malaga, in southern Spain. Seed (juveniles) used in theexperiment was collected in September 1997 that had settled on collectorsin April-June, of that year. Culture in suspended cages began in January1998 when the seed measured 42.7 (3.3) mm shell height and ended inFebruary 1999. Significantly faster growth was found at a minimum culturedensity (16 scallops/cage) than at two other densities (24 and 36scallops/cage). Depth (1, 5 and 10 m from the bottom) influenced growth,poorest growth occurred closest to the bottom. Under optimum growingconditions, 16 scallops/cage suspended 10 m from the bottom, scallops grewto 10 cm shell length (legal size) by February 1999.In ear hanging culture, ropes were moored in April (51.3 (4.5) mm),June (58.2 (4.5) mm) and November 1998 (64.3 (4.9) mm).Initially, rapid shell growth was observed in all three cultures.Subsequently, the shells became covered with barnacles, Balanus sp.,that possibly caused total mortality of the April culture and led to highmortalities in the two other cultures.     

3种螺对养殖鲍外壳附着牡蛎的防除作用

为研究养殖皱纹盘鲍(Haliotis discus hannai Ino)外壳附着牡蛎的防除方法,对比了疣荔枝螺(Thais clavigera Kuster)、润泽角口螺(Ceratostoma rorifluum)和甲虫螺(Cantharus cecillei)对鲍外壳表面牡蛎的防除效果。以桑沟湾筏式养殖鲍为研究对象,自7月中旬开始,每隔15 d左右分别投放3种螺到鲍养殖笼中,共投放6次,以始终未投放螺的养殖笼为对照组。结果显示,实验结束时甲虫螺组中鲍壳上平均存活牡蛎数目为(0.04±0.04)个/只,疣荔枝螺组和润泽角口螺组疣荔枝螺组分别为(2.49±0.91)个/只和(2.21±1.05)个/只,对照组为(3.33±0.46)个/只。投放3种螺组中鲍壳上存活牡蛎数均显著显著低于对照组(P<0.05),甲虫螺也显著低于其他2种螺(P<0.05)。投螺时间也会影响螺防除牡蛎污损的效果,投放时间过晚会导致螺捕食牡蛎后有明显的壳残留,牡蛎的壳高达到0.5 cm左右再投放螺即可保证防除效果。另外甲虫螺组鲍壳上死亡牡蛎残留壳长度为(0.73±0.27) cm,显著低于疣荔枝螺组...     

Evaluation of Five Microalgae Diets for Juvenile Pen Shells Atrina maura

–Juvenile pen shells Atrina maura were fed for 21 d with equal daily rations, equivalent to 6.5% of their live weight, of monoalgal cultures of Tetraselmis suecica, Isochrysis galbana, Chaetoceros muelleri, Chaetoceros calcitrans , and Thalassiosira pseudonana. Pen shell survival was 100% in all cases. All microalgae diets produced shell growth, and live and ash-free dry weight increases. However, the two Chaetoceros strains gave significantly better results, with shell height increases of 4.7 to 2.9 mm, live weight gains of 0.5 to 0.3 g, and final ash-free dry weights of 0.16 to 0.14 g after 3 wk. These results are not related to the algae gross biochemical composition, suggesting that other factors are involved in their nutritional value for this mollusc species.     

An artificial oyster‐shell reef for the culture and stock enhancement of sea cucumber,Apostichopus japonicus,in shallow seawater

Because of its high nutritional value and health benefits, aquaculture production of Apostichopus japonicus in China is the largest of any single species. Therefore, the development of new farming methods is of considerable significance. In this study, discarded oyster shells have been used to create an artificial reef for the culture of this species. The results have shown that from 6th March 2009 to 26th November 2009, the wet weight of sea cucumber increased from 49.57 ± 1.16 to 79.87 ± 1.46 g ind^?1. Between 16th July and 18th October, the specific growth rate and daily weight gain of A. japonicus differed significantly from other periods. Population density was higher within the reef compared with outside the reef area, and the difference was significant (P < 0.01). The maximum distance between A. japonicus individuals within the reef area on 3rd March and 16th July was 65.0 ± 3.3 and 62.9 ± 4.4 cm, respectively, but the difference was not significant (P > 0.05). The diatom species attached to the oyster shells were similar to those found in the stomach content of A. japonicus. In conclusion, the oyster‐shell reef provides a suitable habitat and shelter for the culture of the sea cucumber, A. japonicus.