Scallop Aquaculture Research Articles

Growth ofArgopecten purpuratus(Mollusca: Bivalvia) on a natural bank in Northern Chile: sclerochronological record and environmental controls

Daily striae on the shell of the scallop, Argopecten purpuratus, were used to investigate its growth in a protected population within La Rinconada Bay, near Antofagasta (2nd Region, Northern Chile), and to determine how environmental forcings control shell growth. This sclerochronological approach was useful to describe daily shell growth a posteriori. Mean shell growth rates were calculated daily between February and October 1999 from shells of six specimens harvested on 15 October 1999. A multiple regression analysis performed on shell growth and environ- mental data shows that a temperature increase stimulates shell growth whereas particulate organic carbon concentration might be stressful above 2.5 mg L −1 . The lunar cycle might also have an effect on growth, most potent around New Moons, by synchronizing an endogenous oscillator. The age at commercial size (90 mm) was only 10-11 months in La Rinconada Marine Reserve and the von Bertalanffy growth parameters were K = 2.24 y −1 and H∞ = 117 mm. Differences in shell growth performances between this study and previous ones dealing with A. purpuratus growth may be explained by the different methods used for shell growth modelling, higher growth rate on the seabed compared to suspended cultures, and particular environmental forcings (e.g. El Nino Southern Oscillation-ENSO events). Growth performance seems better during La Nina than during El Nino events, probably because of the large temperature in- crease (above the highest temperatures recorded in normal conditions) and the decline in coastal upwelling (which affects food availability) during El Nino. La Rinconada Marine Reserve appears as a very favourable site for A. purpu- ratus growth, probably because of the active upwelling zone off Antofagasta. These new insights on A. purpuratus shell growth confirm the importance of La Rinconada Marine Reserve as an area supporting repopulation of endangered wild stocks and scallop aquaculture in Chile.

Loss of allele diversity in introduced populations of the hermaphroditic bay scallop Argopecten irradians

The bay scallop Argopecten irradians is a hermaphroditic bivalve native to the Atlantic coast of the United States that was introduced to China for aquaculture production in 1982. It now supports a major aquaculture industry in China. Introduced species often start with limited genetic variability, which is problematic for the further selective breeding. Bay scallop aquaculture is exclusively hatchery based and as the initial introduction consisted of only 26 scallops, there have been concerns about inbreeding and inbreeding depression in cultured populations in China. In this study, eleven simple sequence repeat (SSR) markers were used to compare genetic variation in cultured populations from China with that in a natural population from the east coast of America. Although the difference in heterozygosity was small, the Chinese populations lost 9 of the 45 alleles (20%) found in the wild population. The reduced allele diversity suggests that the Chinese bay scallop populations experienced a bottleneck in genetic diversity that remains significant despite several recent introductions of new stocks aimed at expanding the gene pool. The loss of allele diversity may affect future efforts in selective breeding and domestication, and results of this study highlight the need for additional introductions, advanced breeding programs that minimize inbreeding and continued genetic monitoring.

Benthic foraminifera at a scallop aquaculture site in Minonosok Bay, the sea of Japan

The species composition and distribution of benthic foraminifera at a scallop aquaculture site in shallow Minonosok Bay (southern Primorye) were studied. Ninety-three species of benthic foraminifera were found in Minonosok Bay in 1998 and 83 species in 2000; representatives of the families Elphidiidae, Discorbidae, Trochamminidae, and Ataxophragmiidae dominated. In 1998, the calcareous species Cribroelphidium frigidum was most abundant; in 2000, calcareous Protelphidium asterotuberculatum and arenaceous species Trochammina inflata and Eggerella advena were dominant. The effect of scallop cultivation on the distribution of benthic foraminifera was local. The species composition and population density of foraminifera directly under scallop cages were decreased, compared to areas of the bay where there were no mariculture operations.

Study on Influences of the Scallop Aquaculture on the Material Cycle in Lake Saroma

Study on Influences of the Scallop Aquaculture on the Material Cycle in Lake Saroma

A BIOECONOMIC MODEL FOR CHAM SCALLOP (PATINOPECTEN YESSOENSIS) AQUACULTURE IN KOREA

A bioeconomic model of cham scallop aquaculture in Korea was used to determine an optimal farm grow-out strategy. The model used estimated cost functions for two culture methods and growth functions based on three environmental characteristics for each region (Kojin and Chumunjin). Stochastic growth was incorporated using probabilities of alternative environmental states (based on expected levels of water temperature, salinity, and dissolved oxygen) by region, culture method, and month. The model revealed a 26% potential increase in net present value from altering management of a single rotation. Optimal multiple rotations required up to four different rotations depending on the region and culture style. Farmers could increase economic returns by delaying harvest and subsequent plantings in order to market larger, more valuable scallops. Resource managers could increase resource rents by adjusting the licensing system to account for regional-style differences and by targeting the planned aquaculture investments.

Characterization of 35 microsatellite loci in the Pacific lion‐paw scallop (Nodipecten subnodosus) and their cross‐species amplification in four other scallops of the Pectinidae family

AbstractFour microsatellite‐enriched DNA libraries yielded 35 microsatellite loci from 100 primer pairs designed for Pacific lion‐paw scallop, Nodipecten subnodosus. The number of alleles ranged from four to 28. Three of the 35 loci were not in Hardy–Weinberg equilibrium and linkage disequilibrium was found for one pair of loci. These microsatellites will be used to analyse the population structure of the species in Mexico's Baja Peninsula to propose management strategies for scallop aquaculture development. Twenty‐six primer pairs cross‐amplified in Nodipecten nodosus, whereas none (Argopecten ventricosus) or few cross‐amplified in the Argopecten species.

Lion's paw scallop (Nodipecten subnodosus, Sowerby 1835) aquaculture in Bahia Magdalena, Mexico: effects of population density and season on juvenile growth and mortality

This study examined the effects of density and growing season on growth and survival of juvenile lion's paw scallops (Nodipecten subnodosus) in Estero San Buto, a mangrove channel in Bahía Magdalena, Mexico. Scallops were kept in plastic mesh bags in oyster trays at three population densities (500, 1000 and 2000 organisms per tray, or low medium and high density respectively) over a period of 2 months from October to December 2001 and from February to April 2002. Growth (shell height increment) was measured every 7–12 days and mortality was evaluated at the end of the experiment (dead shell count). Overall growth was fast (0.24–0.38 mm day−1) in comparison with other pectinids. Significant differences were found for both, density and season, with faster growth occurring at lower densities and during the fall season when the water temperature was higher. Mortality was low (0.5–3.0% 60 day−1) except for the high-density treatment in the fall (44% 60 day−1). Crowding together with high water temperatures and increased metabolic oxygen demand of the scallops and possibly competition for food were the probable reasons for this high mortality. Overall, mortality was lower in the spring, when temperatures were lower, O2 values were higher and food was more abundant.

Down under the southeastern Pacific: marine non-indigenous species in Chile

This article presents the first compilation of marine non-indigenous species (NIS) of algae and macro-invertebrates invading Chilean waters. A total of 32 cosmopolitan and non-cosmopolitan species are reported. Among them there are six species considered as extending their southern range of distribution in connection with El Nino events. The article highlights negative and positive impacts caused by marine NIS invasions. Among the first are Codium fragile var. tomentosoide, considered as a pest in Gracilaria chilensis aquaculture facilities in northern Chile, and Ciona intestinalis, a pest in scallop aquaculture installations. Among the second are bio-engineers species, such as the ascidian Pyura praeputialis and the sea grass Heterozostera tasmanica, which have caused an increase in local biodiversity and enhancement of nursery grounds via the creation of new habitats. Further more, invaders such as the algae Mastocarpus papillosus, Porphyra linearis and P. pseudolinearis represent new exploitable resources, extracted by coastal food gatherers along the coast (M. papillosus) or potential species to develop aquaculture. Additional information is presented on the anemone Anemonia alicemartinae, which appears to be a native species (?), having shown in the past 40–50 years, a geographical southward range extension of approximately 1900 km. The number of NIS reported for Chile is compared with those published for the southwestern Atlantic, South Africa, North America (Atlantic and Pacific coasts) and New Zealand. It is suggested that probably the low number of Chilean NIS is due to the fact that the Chilean coasts are environmentally less stressed than other coasts in the world, due to the scarcity of estuaries, gulfs, enclosed bays, lagoons and low human populations. These kinds of sheltered areas have been suggested as centers for bio-invasions, due to the high rate of human-mediated transfer and increase of pollutants. Furthermore, none of NIS reported from Chile show a fast geographical expansion rate (exception of A. alicemartinae), nor invading strategies such as those described for marine NIS in other latitudes, where notorious ecological unbalances following invasions have been observed. An alternative hypothesis is that the low number of marine NIS invading Chile is underestimated, since the modern list of species generated through specific taxonomically intensive port and harbor surveys is still lacking. Fifteen species (five invertebrate and 10 fish) have been deliberately imported to Chile for aquaculture. The invertebrates appear to be controlled within aquaculture facilities and have not established naturalized populations or caused direct ecological impacts on local communities. On the contrary, several millions of salmoniforms (and rainbow trout) have escaped from farming facilities in southern Chile and established naturalized populations. Studies on ecological impacts are lacking. These escapees are also playing a role in the enhancement of artisanal and sport fishery activities.

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(Salmosalar), 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 μg 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.

Drilling position of the ear affects growth and mortality of scallop ( Patinopecten yessoensis, Jay) in ear-hanging culture

We evaluated the effect of where the hole is drilled in the shell when using the ear-hanging or Nimai-ake method in scallop aquaculture. We examined its influence on growth and mortality during 8-month growth trials on the scallop Patinopecten yessoensis at Shikabe, Japan. Our observations showed: (1) no differences in growth and mortality between drilling the hole in the posterior compared to the anterior ear; (2) that drilling at positions next to the ligament causes increased mortality; (3) that the lowest increase in shell height and total weight is obtained when the hole is drilled next to the ligament on the anterior ear; and (4) that growth is greatest when the hole is drilled near the corners of the ears (either on the anterior or posterior ears).

Genetic considerations in transfers and introductions of scallops

As the potential of scallop aquaculture becomes increasinglyrealised, transfers (movement within a species' range) andintroductions (movement outside a species' range) of scallops arebecoming more common. To predict the genetic consequences oftransfers, information on genetic differences between source andrecipient populations is vital. Morphological, allozyme and DNAbased data on genetic differentiation of scallop populations andscallop sub-species are presented and discussed. Otherconsiderations are the numbers of individuals transferred andwhether they are wild stock or hatchery product. Loss of geneticdiversity is difficult to avoid in hatchery conditions althoughthere are ecological advantages to using disease-free hatcheryseed. Mitochondrial DNA data indicating significant geneticconsequences of the introduction of Argopecten irradians fromthe USA to China are discussed and compared with data onPatinopecten yessoensis introduced from Japan to Canada.Potential risks and consequences of hybridisation should beexperimentally assessed before introductions of scallops arecarried out. Hybridisation is unpredictable and can lead to lossof genetic diversity or breakdown of co-adapted gene complexes.The use of sterile triploid scallops for introductions to avoid hybridisation and reduce ecological impact has merit butreversion to diploidy may occur.

Optimization of a large-scale scallop hanging culture operation

Scallop aquaculture may be conducted by deploying the bivalves in a sequence of suspended containers in the ocean. The growth and mortality rates at each stage depend partly on the period in which they are deployed and the duration until they are harvested. For a large-scale hanging culture operation, a linear program was created to determine the optimal duration for each stage of the growout process which maximizes the net present value of the profits. Evaluations were made on the effects of limits on the handling of containers during each period, bounds on the sales of mature scallops to smooth the system output, and restricted overall capacity. At the general level, the model illustrates the nature of the start-up period, and the expected cycles of expenditures and revenues. From a detailed perspective, the fluctuations in activity levels between periods and seasons provides insights for streamlining production and the relative value of the resources for planning purposes. Some interesting phenomena appear in an analysis of a representative aquaculture farm. In maximizing profits, the scallop sales pattern is very spiky. Placing a smoothing restriction on final harvests does not affect profit much, and has an unexpected benefit of levelling manpower better than a constraint on labour. The effect of increasing the workforce or productivity is demonstrated by the use of shadow prices. The maximum scallop throughput for a given lease area and spacing can also be estimated.

A site management system for shellfish aquaculture

A production management and planning system has been developed for large‐scale hanging culture operations. The relational database was designed to provide a fast, reliable and versatile tool for managing large volumes of production data at a scallop aquaculture site. The application development process is described, starting with the set of management decisions to be supported by the software. Best practices used for data structure design included normalization and entity‐relationship diagramming. The process‐based design resulted in visually consistent and user‐friendly interfaces which minimize data entry errors. An integrated forecasting model, based on seasonal exponential smoothing, extrapolates stagewise mortalities and flows calculated from the database. Typical simulation results demonstrate how forecasts provide insight into the grow‐out dynamics for capacity planning, manpower planning, and dealing with seasonal fluctuations in the yields. The software generates daily production reports, weekly harvesting schedules and long‐range planning information.

The Most Suitable Balance between Workers and Facilities for the Thinning and Ear Hanging Work of Scallop Aquaculture.

The thinning and ear hanging work of scallop aquaculture can be regarded as a line production system.Previous studies evaluated the optimization of an assembly line using the sum of labor and facility cost per day. This paper introduces a new evaluation measure to improve work system based on two points as follows; (1) To convert the operation efficiency to production cost; and (2) To transform the fixed cost of the facility to a total depreciation per planned production quantity.The results of the calculation show that the new evaluation measure is the most suitable for the work, because the work system optimized by the new evaluation measure has a greatly higher efficiency and fewer facilities than that produced by the previous evaluation measure.

ホタテガイ養殖業の分散・耳吊り作業のラインバランシング法による効率評価

Improvement of production efficiency in the thinning and ear hanging work of scallop aquaculture has long been required, since the work involves processing a huge number of scallops in a certain season, and is the most, labor-intensive part of the scallop production.Through analytical investigations of the work, it was found that variations in process planning greatly affect the productivity of the work.This paper describes the results of analytical investigation of process planning using the concept of line-balancing and the efficiency of combining work elements or minimizing balance-delay. The estimation results for several process planning using the measured standard work time for each work element are also given. The results show that the optimum process planning with high productivity can be estimated, and that by selecting the number of workers at each work station, higher productivity could be achieved.

Seasonal studies of seston lipids in relation to microplankton species composition and scallop growth in South Broad Cove, Newfoundland

The concentration and nutritional awlity of suspended particulate matter at an experimental scallop aquaculture site on the east -1 of Newfoundland, Canada, was determined at 3 depths over an 8 mo sampling period. Lipid classes and fatty acids were measured chromatographically and the seston components were identified and quantified by microscopy. These measurements were correlated and then related to the growth of juvenille scallops Placopecten magellanicus introduced to the site. The low seston concentrations obsewad throughout the year were punctuated by 4 large inputs: the spring diatom bloom, a resuspension ment. a summer microzooplankton and nanoflagellate bloom, and a fall increase in zooplankton faecal :pellet and heterotrophic dinoflagellate concentrations. The largest inputs of lipids were associated with the resuspension event and the summer bloom. The resuspended particles included the benthic permate diatom Cyrosigrna spp. which contained large lipid globules. High concentrations of polvunwrmated triacylglycerols occurred at this time; more saturated triacylglycerols were prominent in the sunmer The acyl lipids contained unusually high proportions of the long-chain polyunsaturated fatty acid 20:406 which was correlated (p < 0.05) with the proportion of mlcrozooplankton in the seston. The C16 fatty acid ratio 16:1~7/16:0, used previously as a diatom biomarker, was strongly correlated (p < O.01) with the proportion of centric diatoms. Scallop growth appeared to be related less to the major-ts of total lipids to the water column and more to the proportion of the essential fatty acid 22:6 in the acyl lipids. This fatty acid was associated principally with cryptophytes (p < 0.02).

Three-dimensional reconstruction of a paramyosin filament

Scallop aquaculture owes its commercial success to a global appreciation of the gastronomic delights of scallop striated adductor muscle. Early physiologists were also impressed by the high muscle to body weight ratio, the apparent purity of the fibres and the clarity of function of the two main adductor muscles. More recently, biochemists have shown that these muscles possess a mode of regulation that is closely related to mechanisms found both in vertebrate smooth muscles and in non-muscle cells; furthermore, because scallop myosins have been shown to possess unique physical properties making them ideally suited for biochemical manipulation, they remain a key model for studies on the function and regulation of muscle contraction. This chapter summarises current knowledge regarding the intricate structure of the muscles and their biochemical and physiological processes and function.

Aquaculture of Sea Scallops and Abalone in Japan

ABSTRACTIn Japan, farming of sea scallops (Patinopecten yessoensis) and abalone (Haliotis discus) is expanding at a rapid rate. Approximately 16 prefectural laboratories are producing 2 to 3 million seed abalone annually. These are sold to the fishermen for planting on natural grounds. Studies are underway to utilize heated water from power plants to speed up the abalone's growth. Plans are also underway to develop artificial growing grounds for abalone culture.Extensive areas in Hokkaido and Mutsu Bay (Honshu) are being utilized in the long‐line culture of scallops. It has been estimated that 40,000 tons of scallops will be harvested in 1972 and 100,000 tons may be produced in 1973.Some of the methods now being utilized to farm scallops and abalone in Japan could possibly be applied in the United States.