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1.
This study provides for the first time an evaluation of the natural availability of scallop seeds along the coastal area of Taranto (Mediterranean Sea, Southern Italy). To select the best artificial collectors to harvest scallop seeds in this area, cylindrical collectors (Cyl) were compared to traditional ‘Japanese‐style onion bags’ (Bag) across three sites. Scallops represented 26.6% of total bivalve recruitment among all collectors (782 ± 331 ind. m?2). The most recruited scallops were Flexopecten glaber and Mimachlamys varia. The white (F. glaber) and black scallops (M. varia) were abundant at all three sites, while the queen scallop, Aequipecten opercularis, was only found at one site. Beyond the recruitment of scallops, numerous other potential commercial bivalve species were collected, including Limaria tuberculata, which was the most abundant bivalve species (33.3% of total recruitment). At all sites, Bag collectors had higher recruitment than Cyl collectors. Scallops recruited in artificial collectors exhibited a multicohort size distribution at most sites, suggesting potentially continuous reproductive activity in the scallop populations. F. glaber, M. varia and L. tuberculata could be good candidates to diversify the aquaculture production because of the availability of seed and their growth rate. Moreover, the farming of these bivalves integrates well with other forms of aquaculture (e.g. mussels), thus potentially offering farmers an additional source of income.  相似文献   

2.
The great scallop, Pecten maximus is a potentialaquaculture species in Norway, but production to date has been low. Greatscallop landings in 2000 were 571 tonnes, exclusively from harvesting wildstocks, landed by divers. Approximately two million juveniles of 15mm shell height have been produced annually in a hatchery since1998, and distributed to farmers. Research projects on larvae and juvenilesinclude studies of various antibacterial treatments, improved culture systemdesigns and application of probiotics. Results from hanging cultures underdifferent environmental conditions indicate a strong correlation between lowtemperature and poor survival, and point out the importance of careful selectionof cultivation sites. Good growth potential of scallops in Norwegian waters hasbeen shown, and it is possible to reach market size of 10 mm shellheight in three to four years. Experiments with fences and other strategiesprotecting cultured scallops on the seabed from predation by crabs are inprogress.  相似文献   

3.
杨彩霞  李赟  王崇明  曲朋  黄倢 《水产学报》2013,37(10):1579-1584
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。  相似文献   

4.
Epibiont and predator effects on the growth and mortality of the northern scallop Argopecten purpuratus were evaluated in cultures in southern Chile.The most common epibionts were bryozoans, hydrozoans and algae in both study sites, Metri Bay (41°36; 72°43W) and Chidhuapi Channel (41°49S; 73°05W).After 12 months of culture in pearl nets and lantern nets, the scallops size did not show statistically significant differences in cultures with and without epibionts in both study sites nor were there differences in the growth either with or without the presence of predators (decapod crustaceans). The growth rate was higher in Chidhuapi Channel than in Metri Bay.Mortality was concentrated in the initial phase of culture in pearl nets. During the culture phase in lantern nets, the mortality rate was lower than 3%. The mortality rate in scallops with epibionts was higher than when these were removed in the culture phase in pearl nets. In Metri Bay the mortality rate with predators was higher than without predators. Epibionts and predators did not affect mortality in the culture phase in lantern nets.Epibionts and predation are important factors in the early mortality of scallops and therefore in the success of culture. Epibiosis, however, is not important in scallop growth in southern Chile. This is related to the composition of the epibionts and to the low temperatures which probably limit the growth of algae and invertebrates.  相似文献   

5.
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.  相似文献   

6.
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.  相似文献   

7.
Efforts to restore bay scallop populations in the United States throughtransplantation of wild stock and reseeding of hatchery-reared individuals haveincreased due to declines in natural populations, yet little is known of thecomparative spawning patterns and relative reproductive investment of thesedifferent groups. In this study, spawning patterns of wild scallops from asource population in Northwest Harbor, New York and of scallops transplanted toa distant site in the same embayment (Flanders Bay) were similar.Hatchery-reared scallops held in pearl nets in Hallock Bay, New York showed thesame temporal spawning pattern and level of reproductive investment as scallopsfrom adjacent wild populations and wild scallops held in pearl nets. We suggestthat hatchery-reared scallops may be equally valuable as potential broodstockfor reseeding operations as wild scallops of the same size, provided thatappropriate conditioning and rearing practices are maintained. Both wild andhatchery-reared scallops may be transplanted a short period (i.e. 2–4weeks) prior to expected spawning to provide a source of potential broodstockinareas where natural population densities are low.  相似文献   

8.
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.  相似文献   

9.
Hatchery-reared sea scallop (Placopecten magellanicus) spat weremonitored for growth and recovery in three experiments to determine themost suitable system for nursery culture. In Experiment I, four size classesof nursery-sized spat held at two depths from October to July exhibiteddeclining growth rates over the winter period and increased growth ratesin the spring. Overall, season, depth and initial size had a significantinfluence on the absolute and specific growth rates of scallops. Recovery,defined as number of scallops remaining after mortality and loss of spatthrough gear mesh, was influenced by season and initial size, but notdepth. Scallops in the 3.0 mm+ size class had higher growth rates andrecovery than those in the 1.4–1.6 mm, 1.7–1.9 mm and 2.0–2.9 mm sizeclasses. In Experiment II, two gear types containing similar size spat werecompared. Growth rates were significantly higher in 3.0 mm pearl nets thanin 3.0 mm collector bags, although recovery was similar between the twoequipment types. Experiment III, two stocking densities of nursery-sizedspat were compared in collector bags. Neither growth rate nor recoverywere significantly different for the two densities (2600 and 5200spat/collector bag) tested. Overall, these studies indicated that importantparameters for optimizing the growth and recovery of scallops in a farm-based nursery system include season, initial spat size, deployment depthand gear type.  相似文献   

10.
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.  相似文献   

11.
This study focused on the comparison of growth and mortality of Lion's Paw scallops Nodipecten subnodosus from Gulf of California and Pacific populations and their reciprocal transplants, cultured in suspended module and bottom culture in Baja California Sur, Mexico. Environmental parameters were monitored to determine site‐specific differences and were correlated with scallops' population‐specific responses. Significant differences in growth were found between sites, populations and grow‐out methods. Growth performance of scallops originating from the Pacific population was lower and uniform between Pacific and Gulf culture sites, whereas Gulf scallops cultured at the Pacific site grew better. Growth and survival was higher in suspended than bottom culture, mainly due to depth‐associated differences in food and oxygen supply. Increasing temperatures and decreasing food and oxygen during summer months resulted in depressed growth and elevated mortality. At the Pacific site, this was partially compensated by considerably higher food availability. Gulf scallops resisted high diurnal temperature changes at San Buto significantly better than Pacific scallops. They also survived generally better than the Pacific population, independent of site and grow‐out method, indicating physiological adaptations to high temperatures and low food availability in their habitat. Consequently, the Gulf population appears to be more feasible for aquaculture operations in coastal lagoons with stressful conditions.  相似文献   

12.
In 1995, landings of Great scallops, Pecten maximus(L.) increased dramatically in Jersey from around one tonne in the previousyear, to 66 tonnes and this continues to rise. This was caused by theintroduction of scallop diving permits and diversification of the fishingfleet.Due to this increase in effort it was decided that the feasibility of ranchingone-year-old juvenile scallops should be investigated. 100,000 scallops werepurchased from Ireland and seeded in specifically selected coastal sites. Thescallops grew from 22.8 mm shell length and 1.17 grams to 57.6mm and 23.2 grams in the first six months after seeding, and to93.3 mm and 88.9 grams during the subsequent 12 months. Growthrateslowed considerably during winter months. Given these growth rates the scallopswill reach market size in three years from settlement, less than the 4, 5 and 6years taken in Guernsey, the Eastern Channel and the offshore Irish Searespectively. Although growth rates are not unique and are comparable withotherinshore sites in the UK, they are significant for scallop farming in Jerseywaters. Mortality following re-seeding and predation rates by crab and starfishappears to be lower than reported by other workers. However this has not yetbeenquantified.  相似文献   

13.
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.  相似文献   

14.
In Atlantic Canada, both Mytilus edulis and M. trossulus occur naturally in sympatric populations and readily hybridize forming genotypically complex assemblages that vary widely in relative species composition throughout the region. We monitored growth in single year‐class cohorts of rope‐cultured Mytilus spp. during a 14‐month period from sleeving of seed to harvest at three commercial mussel farms in Notre Dame Bay, Newfoundland, Canada. Electrophoretic variation at the mannose phosphate isomerase (Mpi) enzyme locus was used to categorize the two species (M. edulis and M. trossulus) and their hybrids. Seed populations varied significantly among sites in relative proportions of each species and hybrids. Growth in shell length, wet weight and shell weight varied significantly with Mpi genotype at all three farm sites. Growth in flesh weight varied significantly with Mpi genotype at two of the three sites. Growth rates for all weight variables were consistently significantly greater in M. edulis than in sympatric M. trossulus. Growth in shell length was significantly different between sympatric M. edulis and M. trossulus at only one farm site. Growth rates of hybrids were typically intermediate between sympatric M. edulis and M. trossulus, but were often statistically similar to one or other of M. edulis or M. trossulus. We conclude that the production of rope‐cultured blue mussels in Atlantic Canada is significantly influenced by genotype‐dependent growth variation in naturally occurring mixed‐species stocks. Our results also suggest that farm site production may be increased and intrasite variability reduced at farm sites currently using indigenous mixed‐species stocks by substitution and growout of transplanted seed from unispecific M. edulis stocks.  相似文献   

15.
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.  相似文献   

16.
There is a great interest in establishing mussel farming in Dakhla bay. Selection of suitable sites is more meaningful only if a reliable culture method at proposed site is included. We compared two different culture methods, longline and pole, over 1 year (June 2016 to June 2017). Growth indicators for Perna perna (size and weight growth rates, frequency distributions and estimating growth curves) were analysed from seeding to harvest. The results highlighted the influence of culture method on growth rates of mussels (p < 0.05). At harvest, individuals reared on longline presented higher growth rates and consequently reached greater weight and length values than those reared on pole. Mussels reared at the longline grew 73.2 mm and gained 53.5 g WL (live weight) and 3.3 g Wt (tissue dry weight) after 12 months of cultivation. However, mussels cultured at the pole gained only 52.3 mm, 26.7 g WL and 1.6 g Wt. Aerial exposure of mussels at low tides could explain this reduced performance on pole compared with longline. Size frequency distributions at harvest fitted bimodal distribution in both cultures due to an asymmetric competition among individuals. Effect of density started in both treatments after 7 months of culture when mussels reached 60–70 mm, implying an increment of their food and space requirements. To prevent overcrowding, the initial density should have been reduced through “thinning‐out.” The longline method exhibited high‐performance growth and hence is highly recommended for cultivation of P. perna in Dakhla bay.  相似文献   

17.
We investigated handling time, persistence time and shell‐breaking techniques by crab, Cancer pagurus (L.) (13–15 cm carapace width), offered cultured scallops, Pecten maximus(L.), within the recommended release size for bottom culture. Three shell height groups were used: 50–55, 60–65 and 70–75 mm. The results showed that the crabs managed to open scallops from all the three size groups. The median handling time in the 50–55 mm group (788 s) was significantly different from the median handling time of the 60–65 mm (2482 s) and 70–75 mm (2980 s) groups. The median persistence time increased significantly with each scallop size, from 89 s in the 50–55 mm group to 97 s in the 60–65 mm and 125 s in the 70–75 mm group. We observed a change in the shell‐breaking techniques from a dominance of smashed scallops in the 50–55 mm group to more punched and chipped scallops in the 60–65 and 70–75 mm groups. The shift in predation behaviour when crabs were offered 50–55 mm scallops compared with the larger groups is discussed in relation to strategies in the release of scallops to seabed cultures.  相似文献   

18.
Nodipecten (Lyropecten) subnodosus (Sowerby 1835), the largest pectinid in tropical waters, has been continuously exploited. In support of sustainable development for this species, we started basic growth studies to establish aquacultural practices. N. subnodosus was cultured using triangular plastic cages in La Paz Bay (1995–1996) to describe growth and survival; we determined relationships between quantity of available food and growth and behaviour of body component indices. This culture system allows an isometric shell growth of scallops over 13 months; 56.8±2.1 mm height, 54.5±2.1 mm length and 23.0±1.1 mm width. Allometric growth was found between weight and height, length and width (survival was 44.3%). Body component indices and growth increased progressively until the summer of 1996 when all indices decreased negatively, influenced by high water temperatures. Gonad tissue developed during the first year. Gametogenic activity was evident, presenting the first spawn in summer. Particulate organic and inorganic matter and chlorophyll concentrations were relatively constant during the study, and there was no evidence relating these values to growth and body component indices. Culture of N. subnodosus is feasible in La Paz Bay. However, high water temperatures in summer reduced growth and survival rates.  相似文献   

19.
The hard clam Mercenaria mercenaria was unintentionally introduced into Tokyo Bay during the 1990s. We analysed 528 bp of partial mitochondrial DNA of the cytochrome c oxidase subunit 1 (COI) gene extracted from 135 specimens collected from populations at five sites in Tokyo Bay to determine the genetic structure of this species. Mercenaria mercenaria populations in Tokyo Bay were dominated by haplotype 1, as in the native area. Haplotype 3, which is absent in the populations north of Cape Hatteras (North Carolina, USA) was detected at all five sites. The haplotype diversity in Tokyo Bay was as high as that in the native area, except at two canal sites, while the nucleotide diversity was lower. Thirty-five new haplotypes were found that displayed only a few nucleotide differences. Pairwise F ST values were not significantly different between any sites in the Tokyo Bay and the east coast of America, with values for all sites in Tokyo Bay clustering near the Florida populations. The analysis of molecular variance (AMOVA) results also support this result. This study revealed that M. mercenaria populations in Tokyo Bay have a high haplotype diversity and that populations around Florida may be the source region.  相似文献   

20.
Scallop spat produced for continued culture normally requiretransportation between sites, and the associated stresses may causemortalities. In the present experiment, scallops of 40–55 mm shell heightwere emersed in air for time intervals up to 24 h and their behaviourexamined once re-immersed. Scallops were placed upside-down and thenumber of movements and the cumulative numbers righting in 5 min timeblocks were recorded. The greatest frequency for all behaviouralresponses was found at 15–17 °C in August. Responses were reducedin November and June (9–11 °C) and least at 5 °C in January.All effects of treatment, temperatures and season, and increases in airexposure were significantly different. Following the treatments, mortalitiesafter 10 days in culture was about 10–30% for scallops emersed for 18 and24 h in August and June. Scallops did not show significantly differentbehaviour whether they were emersed upright or inverted. However,scallops emersed at 15 °C had fewer responses than scallops held at <10 °C, so chilling during transport may prolong scallop vitality. Theresults suggest that air exposure >12 h should be avoided. At temperatures>9 °C, behavioural responses may be a simple and effective method toassess vitality which can assist in the management of scallop culture.  相似文献   

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