Post-transport recovery of cultured scallop (<Emphasis Type="Italic">Pecten maximus</Emphasis>) spat,juveniles and adults

High mortality associated with transport operations in scallop culture has been a major problem faced by European farmers. Simulated transport with Pecten maximus L. spat <2 mm, spat 15–30 mm, juveniles 30–50 mm and adults >100 mm were carried out in Spain, Ireland and Norway. Different time and temperature combinations were studied in order to maximise post-transport survival and establish best practices. Out-of-water transport could result in 100% survival if conditions were right, but the response to emersion stress depended on size, season and location. Post-transport recovery decreased with emersion time and was strongly influenced by temperature. Air exposure was tolerated for a longer time by adult scallops than spat and juveniles, but the results differed among trials in the different countries. The maximum emersion time that gave post-transport survival ≥80% was 12 h for the smallest spat, 18 h for larger spat and 24 h for juvenile and adult scallops. Adults were less affected by transport temperatures that deviated from ambient seawater temperature than spat and juveniles. In general post-transport recovery was high when sea temperature was <10°C, but during warm-water seasons special care should be taken to avoid stressful and lethal transport conditions. A transport temperature <12°C was recommended, though not more than 10°C below ambient culture temperature. A maximum transport time of 9 h was suggested for spat and juveniles to attain post-transport survival close to 100%, but 12–24 h was feasible during the cold-water season or at favourable transport temperatures.     

Differential responses to low salinity on gene expression,physiological and biochemical indexes between the golden and brown noble scallops Chlamys nobilis

Low salinity is one of important environmental factors which often led to mass mortality of the noble scallop Chlamys nobilis cultivated in the South coast of China. It is well known that enzymic system and non‐enzymic system both play crucial roles in all living organisms against severe environments. To investigate how change about enzymic system and non‐enzymic system in the stenohaline marine bivalve under low salinity stress, an acute challenge lasting 48 hr was conducted using golden and brown noble scallops in the present study. The serine proteinase inhibitor from the noble scallop (CnSPI) was first cloned and expressed in different tissues. After low salinity stress, the gene expression levels were determined in haemocytes and compared between golden and brown scallops. Meanwhile, total carotenoids content (TCC) in adductor, superoxide dismutase (SOD) enzymatic activity and methylenedioxyamphetamine (MDA) content in gill and haemocytes were also determined and compared between the two colours scallops. Results showed that the CnSPI gene expression levels were significantly decreased after low salinity stress, and the golden scallops had higher gene expression levels than brown scallops (p < .05) at most times. Moreover, after low salinity stress, TCC, SOD enzymatic activity and MDA content also fluctuated, and the golden scallops contained higher TCC and SOD, but lower MDA than the brown ones. The present results indicated that enzymic system and non‐enzymic system were both changed under low salinity stress in the noble scallop and significantly different responses to the stress existed between golden and brown individuals. The SPI gene and carotenoids (CAR) both play a resistant role to low salinity stress in the noble scallop.     

上海市售扇贝冻品品质评价模型构建及关键影响因素分析.

为分析上海销售端扇贝冻品的品质状况及存在的问题,探究市售扇贝冻品的品质评价方法以及冻藏过程中导致其品质劣变的关键因素,本研究依据冰柜温度、冻藏时间、产品形式、包装方式和摆放位置共5种常见影响因素,对上海市售的11种扇贝冻品商品进行采样,测定白度、解冻损失、蒸煮损失、持水力、回复性、内聚性、弹性、咀嚼性、硬度和感官评分共10项品质指标,利用因子分析构建扇贝冻品品质评价模型,并结合多元线性回归分析确定影响扇贝冻品品质劣变的关键因素。结果显示,扇贝冻品10项品质指标之间存在一定相关性,通过因子分析提取了3个因子成分,累计方差贡献率为73.33%,可以代替原有指标来综合评价扇贝冻品的品质,建立了市售扇贝冻品的品质评价模型：f=0.467f1+0.302f2+0.231f3,其中,f1公因子包括弹性、回复性、内聚性、蒸煮损失和持水力,f2公因子包括硬度、白度和咀嚼度,f3公因子包括解冻损失和感官评分;进一步由多元线性回归分析得出,冻藏时间、冰柜温度和产品形式是影响扇贝冻品品质的关键因素,其他2种因素无显著影响。研究表明,基于因子分析和多元线性回归的方法能够较好地进行扇贝冻品的品质评价并分析导致其品质劣变的影响因素。     

提高海湾扇贝虾池保苗成活率技术研究

利用６５亩虾池进行提高海湾扇贝保苗成活率技术研究，入池稚贝２．１亿粒，经４３天暂养，出池商品苗９７２０万粒，成活率达４６．３％，纯益３５．８４万元。而海上保苗成活率仅为１０％左右。１９９４年２月，专家鉴定认为，本研究居国内先进水平。     

Stress and mortality in the supply chain of live scallops Pecten maximus L., from scuba diver to market

Here, we report results from a project where the aim was to study stress and mortality in the supply chain from harvest to market for live scallops Pecten maximus L., hand‐picked by scuba divers. With experiments conducted both during the warm (September) and cold (April) seasons, emphasis was put on how mechanical influence, stacking height, post‐harvest water storage and dry transport affected scallop fitness. When scallops were exposed to mild‐ or hard mechanical shocks (dropped three times from 50 or 150 cm), it was found that hard mechanical shock caused up to 90% mortality during subsequent water storage. Results from the experiments where scallops were stored at different stacking heights (15, 30 and 50 cm) in water showed that both the duration of storage and the stacking height had a significant effect on mortality. Higher stacking heights also affected survival in subsequent transport. For long‐term storage (>7 days), it is recommended to limit the stacking height of scallops stored in tanks to reduce risk of mortality. Respiration experiments showed an average oxygen consumption of 0.10 and 0.24 mg O₂ min^?1 kg^?1 f.w. in the cold and warm season respectively. Water supply during storage of scallops should be adjusted to water temperature and biomass. Registration of mortality and analysis of the Adenylic Energy Charge of scallops followed through the production cycle from harvest to market indicate that it is the sum of stressors that are determinable for final survival.     

Seasonal variations in growth and clearance rate of the Zhikong scallop <Emphasis Type="Italic">Chlamys farreri</Emphasis> suspended in the deep water of Haizhou Bay,China

The growth and survival of the Zhikong scallop Chlamys farreri suspended in deep water of Haizhou Bay were studied from July 2007 to June 2008, and the biodeposition method was used to estimate the clearance rate of C. farreri under field conditions. Results showed that the scallop grew fast during all the culture time, with the exception of summer. The condition index of the scallop increased with time and reached the highest value in spring of the second year. The survival of scallops was 60.8 ± 3.9% at the end of this study, mortality occurring mainly during the summer and autumn of the first year. The clearance rate fluctuated obviously with season,with the highest value in September 2007, and the lowest value in March 2008. Factors accounting for variations in growth and clearance rate of scallops are also discussed.     

虾夷扇贝易逝期干露处置与活品复水性

为探索捕后初期处置对虾夷扇贝活品品质的延迟效应,将捕后虾夷扇贝分易逝期及后易逝期两个阶段进行研究,分别模拟海上及陆基两个处置环节。易逝期处置条件为冷却干露,分别设置12、24及48 h 3个处理组,即E12、E24及E48;后易逝期处置是将经易逝期的活体扇贝重新置于海水中复水24 h,分别为E12’及E24’。以失重率、存活率、闭壳肌pH、糖原、ATP关联化合物、AEC值及超氧化物歧化酶(SOD)活性等为指标,对活品品质进行跟踪分析。结果显示:①易逝期干露处置的扇贝品质有不同程度下降,E48全部死亡;E12和E24具有100%的存活率,糖原含量在易逝期初期快速下降,由初始点的18.95降至12 h时的14.66 mg/g。②易逝期处置对后易逝期的扇贝活体有延迟效应,复水12 h内,体质量和糖原显著恢复,同时SOD活性显著下降,表明了应激状态的缓解;随着复水时间的延长,各项生化指标反映出活体再次进入应激状态时,E12’的活品货架期明显优于E24’。研究表明,扇贝从采捕至陆基暂养净化存在一个品质易逝期,易逝期处置对后易逝期的活品品质有延迟效应。经易逝期处置的扇贝可恢复,短时间12 h的易逝期处置更有助于扇贝恢复。有效控制易逝期条件参数,复水后活品可表现出很好的恢复性;易逝期胁迫程度越大,即便在易逝期结束时仍具有良好指标,但在后易逝期会呈现持续衰竭趋势,其活力、品质及活品货架期亦将会受影响。     

Predation risk management of sea stars (Asterias amurensis and Distolasterias nipon) by adjusting the density and size of seeded scallops (Mizuhopecten yessoensis): an improvement to local mariculture

Optimizing the release density and size of juvenile commercial species for local ecosystems is a critical issue that should be considered when countering predation impacts. To ascertain whether mariculture production of the Japanese scallop (Mizuhopecten yessoensis) could be enhanced by modifying releasing practices, we experimentally investigated the effects of density and size of scallop seeds on their survival in the presence of two sea star species, Asterias amurensis and Distolasterias nipon, with different predation capacities. Under current mariculture practices, the juveniles are briefly exposed to air just before release; therefore, we also examined how air exposure stress increased the predation risk. Scallop survival in the presence of both sea stars increased by?>?20% by increasing scallop size from 30 to 50 mm. Increasing scallop density (range: 5 to 30 scallops m^?2) increased each individual’s survival in the presence of A. amurensis but had no significant effect on predation by D. nipon. Therefore, the release of smaller quantities of large-sized scallops rather than larger quantities of small scallops is recommended to reduce D. nipon predation. In the presence of sea stars, especially by D. nipon, the predation impact on small scallops increased after just a few hours of air exposure, indicating that air exposure of juvenile scallops should be minimized. Our results will mitigate the economic cost of mariculture by facilitating the determination of optimal release conditions for juvenile scallops.

     

Temperature and size range for the transport of juvenile donkey's ear abalone Haliotis asinina Linne

Live transport of hatchery‐produced juvenile donkey's ear abalone Haliotis asinina Linne was examined to evaluate the effect of transportation on the survival of juvenile abalone. Simulated transport experiments were conducted to determine the appropriate temperature using 5, 10 and 20 g L^?1 of ice to air volume for 8 h and the appropriate size using two size groups (Size A, 15–20 mm, 0.5–1.3 g, and Size B, 30–35 mm, 5.3–8.5 g) up to 24‐h out‐of‐water live transport. Survival was significantly higher (P<0.001) when 10 g L^?1 of ice was used to decrease the temperature to the range of 17–23 °C. At this temperature, both size groups subjected to simulated transport for 8 and 10 h had 100% survival after 48 h, while mortality occurred in abalones subjected to 16 and 24 h of simulated transport. The Size B abalone subjected to 24 h of transport had significantly higher survival (64.4 ± 2.9%) (P<0.001) than the Size A abalone (5.5 ± 1.6%) after 48 h. Live juvenile abalone were successfully transported to the field applying the protocols developed in the lab experiment. This study serves as a guide for handling and shipping live juvenile abalone.     

Effects of copper- and tin-based anti-fouling compounds on the growth of scallops (Pecten maximus) and oysters (Crassostrea gigas)

Fouling is an important problem in shellfish cultivation. This paper gives the results of growth trials of adult and juvenile scallops, and adult Pacific oysters in enclosures treated with various anti-fouling compounds: copper(I) oxide-based paint, bis-(tri-n-butyltin) oxide (TBT)-based paint, and copper-nickel alloy mesh trays.With the copper oxide treatment there was some increase in the growth of scallop spat, but no effect was observed on the growth of adult scallops or Pacific oysters. The copper-nickel trays, however, caused high mortalities and inhibited growth in adult scallops, but had no effect on oysters. The TBT paint was detrimental to the growth and survival of juvenile scallops, and caused high mortalities, poor growth and thickened shells in oysters. It had no effect on adult scallops.     

The influence of temperature and presence of predators on growth,survival and energy allocation for reproduction in the Catarina scallop Argopecten ventricosus

Environmental factors are known to modify the life history of marine ectotherms. In a 16‐month laboratory experiment, we investigated the influence of temperature and presence of predators on life‐history parameters including shell growth, survival and the energy investment in reproduction and body mass of the short‐lived (2–3 years) scallop Argopecten ventricosus. In parallel, A. ventricosus was maintained in the field at the Pacific coast of Baja California, México, to compare growth, survival and reproductive effort under natural conditions. For the laboratory treatments, scallops were reared at simulated field temperatures (SFT), 5 °C above SFT and in the presence of predators. Elevated water temperatures caused higher growth and gonad production, although at the cost of increased mortality. Presence of predators induced energy allocation to muscle rather than gonad growth, deferred spawning and extended survival. Field scallops exhibited higher growth, higher reproductive investment and were able to reproduce twice, whereas all laboratory scallops died after the first spawning. The natural variability of environmental parameters such as food and temperature may thus support optimal growth in the field, and when animals are protected from predators, reproduction in the second year of life.     

Utility of high-density plantings in bay scallop, Argopecten irradians irradians, restoration

Two different methods of establishing high-density spawner sanctuaries for bay scallop (Argopecten irradians irradians) restoration were evaluated over 2 years at a site in Northwest Harbor, East Hampton, New York, USA. Hatchery-reared scallops, which had been overwintered at nearby sites, were free-planted directly to the bottom in late March/early April at an initial target density of 94?C128 scallops/m². In addition, scallops were stocked in off-bottom culture units consisting of three vertically stacked 15-mm mesh ADPI^® bags at densities of 50, 100, or 200 scallops/bag (=117, 234, or 468 scallops/m²), respectively. Survival of scallops differed significantly by year, planting method, and scallop source. Survival of free-planted scallops was generally lower than caged scallops. Better survival of free-planted scallops in 2005 versus 2006 likely reflected the presence of luxuriant eelgrass beds in 2005, which were absent in 2006. Survival of scallops in ADPI bags was not appreciably related to stocking density. Shell growth was highest for free-planted scallops; in cages, growth was somewhat better at 50 versus 200 scallops/bag. Wet weights of epibionts were significantly higher in caged versus free-planted scallops. Reproductive condition of scallops stocked at 50/bag was usually higher than at 200/bag. Both free-planting and off-bottom systems yielded high densities of adult bay scallops at the time of spawning, which ensures a higher probability of successful fertilization of spawned eggs and thus a greater potential for success of restoration efforts.     

不同温度下充氧包装的活品海湾扇贝品质变化

为延长海湾扇贝贮运过程中的存活期并保证其品质,将海湾扇贝平铺放入HDPE材质的包装袋(32 cm×25 cm),并充入体积分数为99.9%的氧气,密封后将充氧包装的海湾扇贝分别置于0、5、10、15℃4个不同温度下,探讨不同温度对其品质的影响。试验结果显示,密封充氧包装的海湾扇贝较低温条件下的存活率、感官评价分值和糖原明显高于同一时间的较高温条件,同时较高温条件下质量损失率、色度差、细菌总数上升速度均高于较低温条件。其中,0℃条件下无水保活效果最好,11 d出现死亡,15 d全部死亡。首次出现死亡时间比5、10、15℃组分别延长5、7、9 d;全部死亡时间比5、10、15℃组分别延长4、5、9 d。0℃条件下,其感官评价分值在0～4 d内接近满分,颜色变化最小,其色度差为3.98。综合各项指标变化,0℃条件下有利于延长充氧包装内海湾扇贝的保活时间,有效保持海湾扇贝活品品质。研究结果为活品海湾扇贝密封充氧保活保鲜技术提供数据参考。     

Potential predation rates by the sea stars Asterias rubens and Marthasterias glacialis, on juvenile scallops, Pecten maximus, ready for sea ranching

The potential for predation by the sea stars Asterias rubens and Marthasterias glacialis on seed-size (41 ± 3 mm shell height) juvenile scallops (Pecten maximus), ready for seeding in sea ranching areas, was investigated in a 30-day laboratory predation experiment. There was no significant difference (P > 0.05) in predation rate of large A. rubens (95–115 mm radium) and large M. glacialis (120–164 mm radius), which averaged 0.88 and 0.71 scallops individual⁻¹ day⁻¹, respectively. Maximum rates of predation were 2.44 scallops individual⁻¹ day⁻¹ for large A. rubens and 3.00 scallops individual⁻¹ day⁻¹ for large M. glacialis. Small M. glacialis (76–87 mm radius) had a significantly lower predation rate than large individuals of either species (average 0.13 scallops individual⁻¹ day⁻¹, P < 0.05). Small A. rubens (50–80 mm radius) only began to prey on scallops when average scallop size was reduced to 35 mm. Based on estimated density of sea stars at a Norwegian sea ranching site and average predation rates, a population of scallops seeded at 10 m⁻² would be reduced by between 0.5 and 11% in 1 month. Furthermore, using the highest observed predation rate, the degree of loss of scallops indicated that scallop culture via sea ranching would not be economically viable and thus methods for reducing scallop predation by sea stars are necessary.     

Efficacy of Netminder® silicone release coating for biofouling reduction in bay scallop grow‐out and comparative effects on scallop survival,growth and reproduction

Netminder^®, a water‐based silicone barrier release coating, was highly effective in reducing biofouling of lantern nets during grow‐out/overwintering of bay scallops, Argopecten irradians irradians, in a large‐scale restoration programme in New York, USA. Compared with untreated nets, scallops held in Netminder^®‐coated nets experienced reduced survival after 8 months, probably due to higher loads of epibionts on their shells. However, this was countered by higher reproductive and overall condition of scallops in treated vs. untreated nets; there were no consistent differences in shell growth in different net treatments. Although further testing is recommended under a wider range of conditions, we conclude that for the purposes of our scallop restoration work, coating nets with Netminder^® would eliminate the need for a gear change in spring, thus reducing labour costs; the coating process should be refined so that Velcro closures of nets do not become sealed shut.     

On the relationship between low winter temperatures and mortality of juvenile scallops, Pecten maximus L., cultured in western Norway

The mortality of juvenile scallops (Pecten maximus L.) cultured at two densities at 8‐ and 15‐m depth was investigated at 17 trial locations along the western Norwegian coast between latitudes 58 and 65°N. During the winter of 1995/1996, scallops suffered high mortality at many sites. The results show a clear relationship between minimum temperature recorded on the sites and scallop mortality. All the scallops died at sites where minimum temperatures were lower than 2°C, while a mortality rate below 30% was only obtained at locations where the minimum temperature was 4–5°C. At temperatures between 2 and 4°C, mortality was intermediate, ranging from 52% to 100%. There were no mortality differences between culture densities, while a significantly higher mortality at 8‐ than at 15‐m depth was shown for two of the four sites with a total mean mortality lower than 30%. The results are discussed in relation to low‐temperature conditions along the Norwegian coast to suggest risk assessments for site selection in scallop culture.     

Polyculture of sea scallops (Placopecten magellanicus) suspended from salmon cages

Commercial and developmental operations for the culture of the seascallop, Placopecten magellanicus, are present in AtlanticCanada and New England. In an experiment designed to examine the commercialfeasibility of polyculture of scallops with Atlantic salmon(Salmo salar), we measured growth andsurvival of sea scallops grown in suspension at two salmon aquaculture sites innortheastern Maine (Johnson Cove (JC) and Treats Island (TI)). Sea scallop spatwere grown in pearl nets and deployed on drop lines containing ten nets inAugust 1994. One drop line of ten nets was sampled about every four months andscallops were counted, measured and weighed. Scallop tissues were also analysedfor paralytic shellfish toxins (PSP). The maximum level of PSP recorded duringthe study was 1174 g STX equiv.·100 gtissue^–1 (excluding adductor muscle weight). After one year,shell heights were 53.6 and 56.4 mm, growth rates were 0.11 and0.12 mm per day and wet adductor muscle weights were 3.3 and 4.1g (TI and JC, respectively). These growth rates were comparable tosea scallops grown in suspension culture to a nearby scallop aquaculture siteand other areas in Atlantic Canada. Reduced rates of survival were found duringthe latter part of the experiment and were attributable, in part, to heavyfouling, predators and high stocking density. The potential for supplementalincome, diversification of the salmon aquaculture industry, and feasibility ofculturing scallops at adjacent sites to salmon operations does exist.     

两个海区栉孔扇贝感染AVNV的比较分析

急性病毒性坏死病毒(acute viral necrosis virus,AVNV)是一种能导致栉孔扇贝大规模死亡的DNA病毒,研究通过检测不同养殖模式和不同苗种来源的栉孔扇贝样本携带AVNV的情况,以寻找合理的养殖模式和苗种,降低疾病的发生。以扇贝单一养殖的青岛流清河海区和贝藻间养的荣成桑沟湾海区为采样点,每月(2010年3月—2011年4月)定期采集2个海区野生苗养殖和人工苗养殖的栉孔扇贝样品各10只,共得到扇贝样本480只。取扇贝外套膜组织,提取DNA,采用巢式PCR检测扇贝感染AVNV的情况,并对2个海区2类栉孔扇贝AVNV感染率进行比较。结果显示,在2个海区的2类栉孔扇贝体内均检测到AVNV,流清河海区野生苗和人工苗养殖栉孔扇贝AVNV感染率分别为21.1%和18.9%,桑沟湾海区2类扇贝AVNV感染率分别为11.1%和5.6%;2个海区AVNV感染扇贝均集中在7、8月份,其中,流清河海区最高可达80%,桑沟湾海区最高仅40%。研究表明,贝藻间养和选用人工苗能有效减少AVNV对养殖扇贝的感染,是控制养殖扇贝发病死亡的有效措施。     

Growth,survival and immune activity of scallops,Chlamys farreri Jones et Preston,compared between suspended and bottom culture in Haizhou Bay,China

We examined the growth, survival and immune response of the scallop, Chlamys farreri, during a 1‐year period in deep water of Haizhou Bay. Scallops were cultured using two methods: (1) in lantern nets at a 5 m depth and (2) in a bottom culture system (sleeves) on the seabed at about a 25 m depth. Shell heights, meat dry weight and immune activities in the haemolymph (superoxide dismutase and myeloperoxidase) were measured bimonthly or quarterly from July 2007 to June 2008. Survival was measured at the end of the study and environmental parameters in the experimental layers were monitored during the experiment. The growth and immune activities of scallops were lower when the water temperature was high, which was consistent with the main mortality occurring in summer. The growth and immunity of scallops were higher in the suspended culture than in the bottom culture during the experiment, with the exception of shell growth during the last study period. Survival of scallops in the suspended culture (54.6±12.3%) was significantly lower than that in the bottom culture (86.8±3.5%) at the end of this study. We conclude from our results that the high mortality of C. farreri can be prevented by culturing them in a bottom culture system before November of the first year, and then transferring them to a suspended culture to improve scallop production.     

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.