Adult Scallops Research Articles

Molecular cloning and transcriptional regulation of an allograft inflammatory factor-1 (AIF-1) in Zhikong scallop Chlamys farreri

The allograft inflammatory factor-1 (AIF-1) is one of the key factors associated with inflammatory response. In the present study, the full-length cDNA of AIF-1 was identified from Zhikong scallop Chlamys farreri (named as CfAIF-1) by EST (expressed sequence tag) analysis and RACE (rapid-amplification of cDNA ends) approaches. The cDNA of CfAIF-1 consisted of a 5-terminal untranslated region (UTR) of 58bp, a 3-UTR of 607bp with a poly (A) tail, and an open reading frame (ORF) of 468bp encoding a polypeptide of 155 amino acids with the putative molecular mass of 17.8kDa. There was an EF hand Ca2+-binding motif in the deduced amino acid sequence of CfAIF-1 which was conserved in other AIF-1s. CfAIF-1 shared closer phylogenetic relationship with invertebrate counterparts than vertebrate. The mRNA transcripts of CfAIF-1 were dominantly expressed in hepatopancreas, hemocytes and adductor. During scallop ontogenesis, the CfAIF-1 mRNA was expressed at a low level at early developmental stages from eggs to blastula, and then increased significantly from gastruta to late veliger larvae (P<0.05). Moreover, the mRNA expression levels of CfAIF-1 in the hemocytes of adult scallop were significantly up-regulated during 12–48h after LPS, PGN and poly I:C stimulation (P<0.01), but there was no significant fluctuation detected after glucan stimulation. Furthermore, the challenge of bacteria Vibrio anguillarum remarkably induced the mRNA expression of CfAIF-1 in hemocytes at 6h (P<0.05) and 12h (P<0.01). All these results collectively indicated that CfAIF-1 might be involved in the immune response during the ontogenesis and contribute to the defense against microbe infection in scallops.

Environmental Hypoxia Reduces the Escape Response Capacity of Juvenile and Adult ScallopsArgopecten purpuratus

ABSTRACT Natural beds and cultures of the scallop Argopecten purpuratus are exposed to hypoxia periodically because they are located near upwelling zones. We evaluated the effects of environmental hypoxia on juvenile and adult scallops' escape responses and recovery capacities using 3 different hypoxic cycle (i.e., a gradual decrease and increase of dissolved oxygen) trials. Trials 1 and 2 consisted of single (1-day) hypoxic cycles; trial 3 included exposure to several consecutive daily hypoxic cycles over 7 days, which occurs in the natural environment. Trial 1 evaluated the combined effects of energy demands from escape responses and metabolism on escape responses. during environmental hypoxia. Trial 2 evaluated only the effect of environmental hypoxia on the escape responses. Before and after the hypoxic cycles, the scallops were exposed to their main predator, the sea star Meyenaster gelatinosus. We evaluated 6 indicators of the scallops' escape response: reaction time, the total number of claps, dura...

Comparative analysis of scallopChlamysfarreri infected by acute viral necrosis virus(AVNV)in two areas

Acute viral necrosis virus(AVNV),which caused mass mortality of scallops Chlamys farreri,is a DNA virus. In the present study,the detection of AVNV was conducted on culture scallops from different culture modes and seeds to search appropriate culture modes and seeds which could reduce mortality of culture scallops. Ten adult scallops were sampled regularly from scallop single-cultured system( Liuqing River,Qingdao) and scallop-kelp co-cultured system( Sanggou Bay,Rongcheng) per month,both contained scallops originating from wild-seed and artificial-seed(March 2010- April 2011,total 480 scallops were sampled). The scallops were taken to the lab at low tempreture. Mantle tissue DNA was extracted and used as the template for nest-PCR to evaluate infection of AVNV. The results show ed that the infection rates of AVNV for cultured scallops from wild-seed and artificial-seed were 21.1% and 18.9% in Liuqing River, while in Sanggou Bay the infection rates were 11.1% and 5.6%. In both sampling sites,high infection rates were detected in July and August. Highest infection rate in Liuqing River reached 80%,while in Sanggou Bay that was only 40%. The present study indicated that scallop-kelp co-cultured system and artificial-seed could effectively decrease the infection rate of AVNV,which could be useful methods to control occurrence of scallop disease.

Physiological Effects and Biotransformation of PSP Toxins in the New Zealand Scallop,Pecten novaezelandiae

Algal blooms produced by toxic dinoflagellates have increased worldwide, resulting in economic losses to aquaculture and fisheries. In New Zealand, the effects of paralytic shellfish poisoning (PSP) toxins on the physiology of the native scallop, Pecten novaezelandiae, are relatively unknown. Adult scallops (shell length, 94 mm) were exposed to low concentrations of the toxic PSP-producing dinoflagellate Alexandrium tamarense for 10 days followed by 8 days of depuration during which clearance rate, excretion rate, and the level of PSP toxins accumulated in the tissues were measured. For the first 6 days, scallops that had been exposed to toxic dinoflagellates had significantly lower clearance rates than the control group that was exposed to nontoxic dinoflagellates. By day 10, scallops had recovered their original clearance rate, and this rate continued throughout the depuration period. Excretion and oxygen uptake were unaffected by the PSP toxins. Differences in the toxin profile of the toxic dinoflagellates and the tissues of the scallops confirmed biotransformation of PSP algal toxins in the scallop digestive gland, where the majority of the PSP toxins were located. After 10 days of feeding on the toxic dinoflagellate, the PSP toxin level of the tissues reached 297 µg STX di-HCl equivalents/100 g. A depuration period of 8 days was insufficient to reduce the PSP toxin to safe levels (80 µg STX di-HCl equivalents/100 g) for consumption of the whole scallop.

A C1q Domain Containing Protein from Scallop Chlamys farreri Serving as Pattern Recognition Receptor with Heat-Aggregated IgG Binding Activity

BackgroundThe C1q domain containing (C1qDC) proteins refer to a family of all proteins that contain the globular C1q (gC1q) domain, and participate in a series of immune responses depending on their gC1q domains to bind a variety of self and non-self binding ligands.MethodologyIn the present study, the mRNA expression patterns, localization, and activities of a C1qDC protein from scallop Chlamys farreri (CfC1qDC) were investigated to understand its possible functions in innate immunity. The relative expression levels of CfC1qDC mRNA in hemocytes were all significantly up-regulated after four typical PAMPs (LPS, PGN, β-glucan and polyI:C) stimulation. During the embryonic development of scallop, the mRNA transcripts of CfC1qDC were detected in all the stages, and the expression level was up-regulated from D-hinged larva and reached the highest at eye-spot larva. The endogenous CfC1qDC was dominantly located in the hepatopancreas, gill, kidney and gonad of adult scallop through immunofluorescence. The recombinant protein of CfC1qDC (rCfC1qDC) could not only bind various PAMPs, such as LPS, PGN, β-glucan as well as polyI:C, but also enhance the phagocytic activity of scallop hemocytes towards Escherichia coli. Meanwhile, rCfC1qDC could interact with human heat-aggregated IgG, and this interaction could be inhibited by LPS.ConclusionsAll these results indicated that CfC1qDC in C. farreri not only served as a PRR involved in the PAMPs recognition, but also an opsonin participating in the clearance of invaders in innate immunity. Moreover, the ability of CfC1qDC to interact with immunoglobulins provided a clue to understand the evolution of classical pathway in complement system.

Habitat Affects Survival of Translocated Bay Scallops, Argopecten irradians concentricus (Say 1822), in Lower Chesapeake Bay

Bay scallop (Argopecten irradians) populations existed in Chesapeake Bay until 1933, when they declined dramatically due to a loss of seagrass habitat. Since then, there have been no documented populations within the Bay. However, some anecdotal observations of live bay scallops within the lower Bay suggest that restoration of the bay scallop is feasible. We therefore tested whether translocated adults of the southern bay scallop, Argopecten irradians concentricus, could survive during the reproductive season in vegetated and unvegetated habitats of the Lynnhaven River sub-estuary of lower Chesapeake Bay in the absence of predation. Manipulative field experiments evaluated survival of translocated, caged adult scallops in eelgrass Zostera marina, macroalgae Gracilaria spp., oyster shell, and rubble plots at three locations. After a 3-week experimental period, scallop survival was high in vegetated habitats, ranging from 98% in their preferred habitat, Z. marina, to 90% in Gracilaria spp. Survival in Z. marina was significantly higher than that in rubble (76%) and oyster shell (78%). These findings indicate that reproductive individuals can survive in vegetated habitats of lower Chesapeake Bay when protected from predators and that establishment of bay scallop populations within Chesapeake Bay may be viable.

Influence of environmental factors on the growth of the juvenile, maturing juvenile, and adult tropical scallop, Euvola ziczac (Pteroida: Pectinidae), in suspended culture conditions

We carried out growth trials on three size groups of the scallop, Euvola ziczac, during two short-term (34-36 days) periods at 8, 21, and 34 m depth in Cariaco Gulf, Venezuela, in order to evaluate the effect of environmental factors on growth. Growth was greater in juveniles (initial size: 20-22 mm shell length) than in maturing juveniles (30-40 mm) and adults (70-75 mm). Somatic tissue growth was more than two-fold greater in juveniles than in maturing individuals. Adult scallops showed losses of tissue mass. The first period (December-January) covered the transition from a stratified water column to upwelling conditions, with initial high temperatures and low phytoplankton biomass followed by lower temperatures and greater phytoplankton biomass. The second period (February-March) consisted of upwelling, characterized by low temperatures and high phytoplankton production. The greater growth of juvenile and maturing scallops during the second period, particularly at 8 m depth, was associated with the greater availability of phytoplankton, related to coastal upwelling. The first development of gonads in maturing scallops only occurred in the second period, associated with food availability, and the degree of development was correlated with the depth. Our growth trials, which were too short to permit the negative impact of the development of fouling, showed that the growth of E. ziczac was enhanced in the presence of abundant phytoplankton biomass.

An Assessment of Juvenile and Adult Sea Scallop,Placopecten magellanicus, Distribution in the Northwest Atlantic using High-Resolution Still Imagery

Recent surveys using high-resolution imagery have enabled improved detection of Atlantic sea scallops, Placopecten magellanicus, between 10 mm and 65 mm in shell height, allowing the observation of juvenile scallops in the wild, which was previously difficult. Using these high-resolution images from 2008 and 2009 surveys of Georges Bank and the Mid-Atlantic Bight, the distribution and crowding levels of juvenile and adult scallops were examined. Mean crowding values revealed differences in small-scale distribution of scallops that were undetectable with density estimates. Juveniles on Georges Bank were 2.6–3.9 times more crowded than adults, and 2.9–7.4 times more crowded than juveniles and adults in the Mid-Atlantic Bight. The increased crowding of juvenile scallops on Georges Bank may be the result of differences in substrate, sea star interactions, and abundance of filamentous flora and fauna. The incorporation of high-resolution imagery into optical surveys represents an important development in the advancement of survey techniques because it has the potential (1) to quantify year class strength of 1-y-old scallops more accurately; (2) to improve growth, mortality, and biomass estimates in stock assessments; and (3) to advance our understanding of scallop ecology, including recruitment processes and population dynamics.

Complex habitat boosts scallop recruitment in a fully protected marine reserve

This study investigated the effects of a fully protected marine reserve on commercially valuable scallops and benthic habitats in Lamlash Bay, Isle of Arran, United Kingdom. Dive surveys found the abundance of juvenile scallops to be greater within the marine reserve than outside. A novel multivariate approach, based upon neural networks and generalised linear models, revealed the greater abundance of juveniles to be related to the greater presence of macroalgae and maerl within the reserve boundaries. This complex habitat appeared to have positively encouraged spat settlement. In contrast, the density of adult scallops did not differ between the two treatments, possibly due to the short duration of protection. However, the age, size and biomass of adult scallops were significantly greater within the reserve. Overall, this study suggests that the newly created marine reserve is already providing benefits which are flowing back to species targeted by fisheries, emphasising the importance of marine reserves in ecosystem-based management of fisheries.

Effect of emerged shipment on the physiological condition of the adductor muscle in adult giant lion's paw scallop Nodipecten subnodosus (Sowerby 1835)

Currently, there is an increasing interest in shipping live adult scallops to markets and broodstock to hatcheries; nevertheless, information about the shipping effect on live scallops physiology is very scarce. In a previous study, a method in emersion was developed to ship scallop seed out of water, but it was not known whether this method is useful to transport adult organisms. As a consequence, the purpose of this study was to evaluate the effects of transportation by the emersion method on the physiological status of the adductor muscle of adult giant lion's paw scallop. Live specimens were packaged in a container and transported in emersion for 11 h. Six scallops were frozen in a farm and a similar number were frozen as soon as they arrived to the laboratory. Physiological indices were determined in each lot and the survival was estimated 24 h after re-immersion. As a result of the transportation, a significant loss (P<0.05) of total carbohydrates, glycogen, adenosine 5′-triphosphate and adenilated energetic charge, and a significant increase (P<0.05) in the free amino acids concentration were observed. Eighty-eight per cent survival was achieved; therefore, we conclude that this method is appropriate for shipping live adult scallops of Nodipecten subnodosus.

Protracted Recruitment in the Bay ScallopArgopecten irradiansin a West Florida Estuary

Many studies have indicated that annual spawning of bay scallops (Argopecten irradians) peaks during discrete and limited periods each year. Spawning in most Florida bay scallop subpopulations has been shown to occur in fall, whereas more northerly U.S. populations typically spawn in late spring or summer. In this article we describe our efforts to expand our understanding of the seasonality of bay scallop recruitment dynamics in Florida. Visual surveys were conducted by divers each spring from 1994 to 2009 to estimate adult scallop abundance. Adult abundance was low (6.1 scallops/600 m2) during the first 3 y of the study (1994 to 1996), prompting a 7-y restoration effort intended to enhance the number of spawning adults and thereby enhance the local production of larval scallops. Adult abundances increased to an average of 21.9 scallops/600 m2 in 1997 to 2006, and then rose dramatically to an average density of 154.8 scallops/600 m2 in the most recent years (2007 to 2009). Artificial recruit collectors (n = 12) were deployed monthly near the Anclote River estuary beginning in 1997 and were allowed to soak for 2 mo at a time. Each collector's deployment period overlapped with the preceding and following trap's deployment period by 1 mo. The project is ongoing, but only data collected through December 2009 is included here (bay scallops recruited to the collectors during 163 of the 185 deployment periods). For the entire study period, the average recruitment rate was 0.3 scallops/collector/day, the maximum average for a single deployment period was 5.5 scallops/collector/day during November 2001 to January 2002, and the highest rate for a single collector was 19.6 scallops/collector/day during November 2001 to January 2002. In most years, the collectors retrieved in late fall and early winter had the highest settlement rate; a secondary recruitment peak was observed in the spring. A period of protracted recruitment (December 2005 to December 2009) occurred, during which scallops recruited to at least 1 of the 12 deployed collectors deployed during 53 consecutive deployment periods. The average recruitment rate for this protracted period was 0.4 scallops/collector/day; the maximum recruitment rate for a single deployment period (3.5 scallops/collector/day) and individual collector (17.7 scallops/day) occurred during December 2008 to February 2009. Early in our study, scallops were detected in a majority of our recruit collectors, and a protracted period of recruitment (October 2001 to February 2004) coincided with the multiyear restoration effort. However, the recent high adult densities and protracted period of recruitment occurred in the absence of any active restoration in this subpopulation, suggesting that, at least within the Anclote River estuary, the population has stabilized for the short term.

Increase in Bay Scallop (Argopecten irradians) Populations Following Releases of Competent Larvae in Two West Florida Estuaries

We propose the release of ready-to-set pediveliger larvae as a restoration strategy for bivalve shellfish. In this study, bay scallop (Argopecten irradians) larvae were released within two West Florida estuaries (Pine Island Sound and Boca Cicga Bay) currently closed to scallop harvest and where local scallop populations arc severely depleted relative to historical abundances. Populations in both estuaries appear to have limited larval supply and show no tendency toward natural recovery after decades of decline. Larvae were either released into enclosures or free released on four separate dates in each estuary. On a given day we used 1, 2, 3, or 4 enclosures per site; multiple release sites; and multiple releases within a year. Assessments were made via several methods, including larval recruitment to collectors, juvenile quadrat surveys, adult timed surveys, and adult transect surveys. In Pine Island Sound, following the initial larval releases in 2003, an isolated recovery in adult scallops was observed at the release site in 2004 followed by a massive resurgence in the local population in 2005. This population declined dramatically in 2006, however, and had completely collapsed by 2007. In Boca Ciega Bay, the series of larval releases did not immediately produce any detectable scallop patches, but the combined releases did immediately precede a population resurgence to levels greater than had been observed in the past three decades. Scallop abundance increased 10-fold at 10 stations in Boca Ciega Bay from 2007 to 2008. In both Pine Island Sound and Boca Ciega Bay, the increases in scallop populations were probably the result of successful survival, growth, and reproduction of the released larvae, followed by successful recruitment and growth of the subsequent generation.

Molecular Characterization of Myostatin Gene from Zhikong scallop Chlamys farreri (Jones et Preston 1904)

The scallop is an economically important sea food prized for its large and delicious adductor muscle. Studying the molecular basis of scallop muscle growth is important for both scallop breeding and our understanding of muscle mass regulation in bivalve. Myostatin (MSTN) is a conserved negative regulator of muscle growth and development. Here we report the MSTN gene from Zhikong scallop (Chlamys farreri Jones et Preston 1904). The C. farreri MSTN consists of 11651 nucleotides encoding 457 amino acids. The gene has a 3-exon/2-intron structure that is conserved with vertebrate homologs. The exons are 586, 380 and 408 bp in length, respectively, and separated by introns of 5086 and 1518 bp. The protein sequence contains characteristic conserved residues including a cleavage motif of proteolysis (RXXR) and nine cysteines. Three transcription initiation sites were found at 62, 146, and 296 bp upstream of the translation start codon ATG. In silico analysis of the promoter region identified a TATA-box and several muscle-specific regulatory elements including COMP, MEF2s, MTBFs and E-boxes. Minisatellite DNA was found in intron 1. By fluorescence in situ hybridization (FISH), the gene was mapped to the long arm of a pair of middle subtelocentric chromosome. Quantitative analysis of MSTN transcripts in embryos/larvae indicated high expression level in gastrulae and limited expression at other stages. In adult scallops, MSTN is predominantly expressed in striated muscle, with different expression levels in other tissues. Our data provide valuable genomic and expression information which will aid the further study on scallop MSTN function and MSTN evolution.

Strengthening recruitment of exploited scallops Pecten maximus with ocean warming

There is evidence that ocean warming has effects on the ecology, including recruitment dynamics, of marine organisms. In association with rising mean spring temperatures in the Irish Sea, a time-series of juvenile scallop Pecten maximus density around the Isle of Man showed a significant increasing trend since 1991. Favorable conditions (warmer water and correspondingly greater food availability) during gonad development can increase scallop gamete production. We examined the possibility that ocean warming has directly increased recruitment of exploited P. maximus around the Isle of Man by enhancing gonad development. From 1991–2007, there was a significant positive correlation between scallop recruitment and mean spring (the main period of gonad development) temperature in the year of larval settlement. Detrended (i.e., accounting for a time effect) recruitment data showed a marginally non-significant correlation to temperature. Gonadal somatic index of adult scallops and temperature were positively correlated. These relationships support the hypothesis that greater gamete production associated with ocean warming may be primarily responsible for observed increases in recruitment success and CPUE in a commercially important shellfish stock.

Gene expression analyses of essential catch factors in the smooth and striated adductor muscles of larval, juvenile and adult great scallop (Pecten maximus)

The scallop adductor muscle consists of striated fibres responsible for the fast closure of the shells, and smooth fibres able to maintain tension in a prolonged state of contraction called catch. Formation of the force-bearing catch linkages has been demonstrated to be initiated by dephosphorylation of the key catch-regulating factor twitchin by a calcineurin-like phosphatase, while the involvement of other thick filament proteins is uncertain. Here we report on the development of catchability of the adductor smooth muscle in the great scallop (Pecten maximus) by analysing the spatio-temporal gene expression patterns of the myosin regulatory light chain (MLCr), twitchin, myorod and calcineurin using whole mount in situ hybridization and real-time quantitative PCR. The MLCr signal was identified in the retractor and adductor muscles of the pediveliger larvae, and the juvenile and adult scallop displayed abundant mRNA levels of MLCr in the smooth and striated adductor muscles. Twitchin was mainly expressed in the smooth adductor muscle during metamorphosis, whereas the adult striated adductor muscle contained seven-folds higher twitchin mRNA levels compared to the smooth portion. Calcineurin expression predominated in the gonads and in the smooth adductor, and five-folds higher mRNA levels were measured in the smooth than in the striated fibres at the adult stage. In contrast to the other genes examined, the expression of myorod was confined to the smooth adductor muscle suggesting that myorod plays a permissive role in the molluscan catch muscles, which are first required at the vulnerable settlement stage as a component of the predator defence system.

Enhancing the Potential for Population Recovery: Restoration Options for Bay Scallop Populations,Argopecten irradians concentricus, in North Carolina

Historically depressed bay scallop populations in North Carolina have retained some capacity to replenish themselves. However, continued abnormally high predation by cownose rays, and growing degradation of seagrass beds may limit bay scallop population recovery. We modified existing methods for protecting spawning adult scallops from cownose rays (stockades) and enhancing scallop set (spat collectors in the natural habitat and in managed shore-side ponds) to determine whether the population growth of bay scallops could be enhanced. We found, with one important exception, that spawner sanctuaries inside stockades could be used to concentrate and protect adult scallops during a time when they are susceptible to ray predation. Spat collector bags proved effective not only in gathering scallop spat but serving as nurseries for juvenile scallop grow-out. The results from our pond experiments were mixed: spat collector bags did not do well in the pond, but an alternative collector design holds promise for making shore-side ponds important sources for inexpensive scallop seed. The simple techniques examined in this study can be used to enhance the potential of bay scallop populations to recover from low abundances, and were applied successfully to enhance North Carolina bay scallops during the two years of this project.

How healthy are cultivated scallops (Argopecten purpuratus) from Chile?: A histopathological survey

Scallop (Argopecten purpuratus) cultivation is an important economic activity in the central-northern region of Chile, and diseases are a permanent concern for farmers and fishing authorities. A one year-long survey was undertaken to find out what parasites and putative pathogens are present in cultivated scallops from three locations: Caldera, Guanaqueros and Tongoy. Ninety adult scallops were sampled from each location, on each season of the year. The soft parts were fixed in Davidson´s fluid, and processed routinely for histology. The prevalence of infection for each parasite and pathologic condition were assessed. Larvae were sampled from three hatcheries and fixed for transmission electron microscopy. The same was done with digestive gland and gill tissues from the first 10 adults of each group sampled for histology. The same parasites and pathologic conditions were found in scallops from the three locations studied: inclusions of rickettsial-like organisms (RLOs) in epithelial digestive gland tubule cells of adults, and in the velar rim of one larva, haemocyte infiltration in gills and digestive gland, two types of granulomas of unknown aetiology in visceral and mantle connective tissues, mineral concretions in kidney, and the protozoan Trichodina sp., a ciliate ectoparasite, on the gills. However, the prevalences of all conditions varied greatly between the three sites and/or seasons. Based on the absence of significant mortalities among cultured scallops at the three sites during the reported survey year, it is concluded that the surveyed scallops were healthy, and that the pathological conditions reported here are generally benign.

Primary Settlement Substrate of Scallop, Zygochlamys patagonica (King and Broderip, 1832) (Mollusca: Pectinidae) in Fishing Grounds in the Argentine Sea

Abstract The Patagonian scallop (Zygochlamys patagonica) fishery started in the Argentine Sea after exploratory cruises developed during 1995. Knowledge concerning the habitat requirements involved in the settlement processes of the target species was lacking. The main objectives of this study are to find Z. patagonica spat and to assess the characteristics and distribution of its primary settlement substrate (PSS). We observed under binocular microscope different invertebrate species (potential PSS) collected during 2006 from 125 sampling sites between 37° to 44°S and 83–133 m depth. Spat were found on the hydroid Symplectoscyphus subdichotomus (n = 215) and on adult Patagonian scallops (n = 51, attached to the encrusting sponge Iophon proximum, amphipod, and polychaete tubes in nearly half of the cases). To analyze possible interactions between the benthic assemblage and scallop spat throughout the study area, we performed a faunal analysis including the species considered potential PSS (hydroids and sc...

Post-transport recovery of cultured scallop (Pecten maximus) 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 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.

Evidence for greater reproductive output per unit area in areas protected from fishing

Marine protected areas are advocated as an essential management tool to ensure the sustainable use of marine resources by providing insurance against over-exploitation and through the provision of refuge for a large biomass of sexually mature adults. Using a unique fishing gear-restriction, voluntary management system as a large-scale experiment, we found that adult scallops (Pecten maximus) within areas protected from towed bottom-fishing gear had heavier adductor muscle tissue and gonads that were 19%–24% heavier than those of scallops in fished areas, while other body and age characteristics were similar in both areas. The scallops within the protected area also occurred at a much higher abundance than adjacent, chronically fished (× 12.83) and wider commercially exploited (× 2.18) areas. These results provide evidence that the use of towed bottom-fishing gear can further exacerbate the effects of overfishing through the suppression of the reproductive potential of individuals of similar body size. These findings underline the utility of using closed areas as tools for fisheries conservation of sedentary species of commercial importance.