The above noted paper is being officially retracted as a publication in the Journal of Shellfish Research. The paper was originally published in Marine Sciences, Volume 36 (8) in 2012 in Chinese with an English Abstract. This constitutes duplicate publication. The authors have agreed to this retraction. The paper is no longer citeable.

The Australasian sea cucumber, Australostichopus mollis, has an extensive distribution; it is found along the coast of southern Australia and throughout New Zealand's coastal waters. This species is very similar in appearance to the highly prized Japanese sea cucumber, Apostichopus japonicus, and as a consequence has attracted increasing interest for commercial fishing and aquaculture. The sea cucumber A. mollis currently supports a small commercial fishery in New Zealand of 10–20 t/y. A review of the research on this sea cucumber indicates that the development of aquaculture for this species has been impeded by a general lack of background biological knowledge. Future research needs to be targeted toward resolving the constraints the aquaculture industry is facing for this species, including reliable methods for broodstock conditioning, mass larval rearing, juvenile nutrition and husbandry, as well as development of effective grow-out technology and identification of suitable farming sites.

In an attempt to decelerate the rate of coastal erosion and wetland loss, and protect human communities, the state of Louisiana developed its Comprehensive Master Plan for a Sustainable Coast. The master plan proposes a combination of restoration efforts including shoreline protection, marsh creation, sediment diversions, and ridge, barrier island, and hydrological restoration. Coastal restoration projects, particularly the large-scale diversions of fresh water from the Mississippi River, needed to supply sediment to an eroding coast potentially impact oyster populations and oyster habitat. An oyster habitat suitability index model is presented that evaluates the effects of a proposed sediment and freshwater diversion into Lower Breton Sound. Voluminous freshwater, needed to suspend and broadly distribute river sediment, will push optimal salinities for oysters seaward and beyond many of the existing reefs. Implementation and operation of the Lower Breton Sound diversion structure as proposed would render about 6,173 ha of hard bottom immediately east of the Mississippi River unsuitable for the sustained cultivation of oysters. If historical harvests are to be maintained in this region, a massive and unprecedented effort to relocate private leases and restore oyster bottoms would be required. Habitat suitability index model results indicate that the appropriate location for such efforts are to the east and north of the Mississippi River Gulf Outlet.

A series of fall surveys and spring resurveys from 2005 to 2010 were examined to determine whether overwinter mortality was a common occurrence in oyster populations from Delaware Bay. Box counts tended to be lower in the spring more often than expected by chance. Occasionally, counts of live oysters also declined. A proportionately larger reduction in dredge efficiency during the winter for boxes compared with live oysters was judged the most likely reason, rather than disarticulation of boxes. Little evidence for overwinter mortality was found; however, reefs in the center of the salinity range exhibited a larger decrease in live oysters than boxes in the spring resurvey. This happenstance provided the only evidence for overwinter mortality that could be distinguished above the countervailing trend provided by the decline in catchability of boxes that frequently occurred. Before ascribing variations in population descriptors during the winter to biological processes, the alternative of an overwinter change in the efficiency of the sampling gear must be excluded.

This study represents the first evaluation of “naturally mated” triploid oysters in South Carolina (SC) waters in an attempt to create new business opportunities for the SC shellfish industry. Triploid eastern oysters, Crassostrea virginica, were grown alongside both a locally derived SC diploid line and an SC-Virginia (VA) diploid line at 6 commercial grow-out sites along the coast of South Carolina from August 2011 through March 2012. The triploid oyster line was created by fertilizing SC eggs with tetraploid VA sperm. The 2n SC-VA line was created by fertilizing SC eggs with VA diploid oyster sperm, and the 2n SC-SC line was created using both eggs and sperm from SC broodstock. The growth performance (shell height, biomass, and percent market size) of oysters was evaluated on commercial culture grounds, working in close cooperation with commercial fishermen. Oysters were deployed in various gear types, but conditions for growth among lines were standardized within sites. All grow-out sites had similar high salinity (>23 psu) and were established in shallow water (range, 0–6 ft, depending on tidal stage). Oysters were sampled frequently throughout the nursery period, 1mo after field deployment, and quarterly thereafter (data not presented) until an individual grower determined that at least 1 of the 3 oyster lines was ready to be harvested, at which time all 3 lines were sampled for the last time. At the final sampling, the mean shell height of the triploid oysters was significantly greater (P < 0.001) than at least 1 of the 2 diploid lines at all sites. Triploid ash-free dry tissue weights were found to be significantly greater (P < 0.001) than at least 1 of the diploid lines at all sites. The percent of market size oysters (shell height, >76 mm) was greater for the triploid oyster line than for either of the diploid lines at all sites except the Romain River site, where the use of a shellfish tumbler was applied during husbandry to address “overset.” One of the primary impediments to producing high-quality single oysters destined for the half-shell market is the unwanted fouling of the grow-out product, often by wild oyster spat resulting from naturally high levels of oyster recruitment, a phenomenon referred to as overset. The results of this study are important for the commercial shellfish industry in South Carolina through its demonstration that current triploid technology has the ability to create a quality oyster product, within a timeframe that avoids the intense period of oyster recruitment in the spring, following that of seed production, in the form of locally produced oysters for the lucrative, single, half-shell oyster market.

Ostreid herpesvirus 1 (OsHV-1) and variants (OsHV-1 var, OsHV-1 µvar, Irish genotype) have had a significant impact on the Pacific oyster, Crassostrea gigas, industry worldwide and on the survival of larvae and juveniles of several other bivalve species in Europe. Diagnostic techniques used to screen for this pathogen include histology, polymerase chain reaction (PCR), and quantitative polymerase chain reaction (qPCR), which allows for quantification of the virus. Techniques used to confirm infection include PCR, in situ hybridization, and transmission electron microscopy, which have variable sensitivity and specificity. In this study, several new primers were designed to amplify the C region in the ORF4 gene of the virus. This region is variable and diagnostic among OsHV-1 and variants. To date, the routinely used C2/C6 primers, which are used to screen for OsHV-1 and variants, amplify a product of 709 bp whereas the new primers described in this study amplify products of 296 bp, 385 bp, and 400 bp. Several C. gigas samples, which had been exposed to herpes virus and variants were screened, and a sample of wild mussels (Mytilus spp.) was used as a negative control. The performance of the new PCR and primers was compared with the performance of the C2/C6 primers and qPCR. The effect of tissue storage and DNA extraction on PCR performance was also examined. The results of this study indicate that the new PCR and primers are more rapid, sensitive, and cost-effective compared with the C2/C6 PCR, and are as sensitive as qPCR. The results also highlight the impact that sample storage, tissue selection, DNA extraction method used, and subsequent storage of DNA have on PCR success or failure.

The tropical rock oyster Striostrea prismatica is a commercially valuable bivalve mollusc found along the Pacific tropical coast. A laboratory study was conducted to investigate broodstock acclimation at two temperatures (28.3 ± 0.9°C and 22.2 ± 0.9°C) fed a combined microalgae diet (Chaetoceros gracilis and Isochrysis galbana at 150 cells/µL/day and 100 cells/µL/ day, respectively) for 7 wk, and to investigate seven treatments to stimulate spawning of individuals acclimated at both temperatures. Treatments to induce spawning consisted of a 10°C temperature decrease for 60 min (HS1), a temperature increase to 30°C for 30 min (HS2), a 5°C temperature increase for 60 min followed by 30 min of desiccation (HSD), a decrease in salinity to 15 psu for 30 min (SS1), an increase in salinity to 96 psu for 30 min (SS2), overfeeding with C. gracilis microalgae (OF), and the addition of oyster sperm (SPM). All treatments were treated with oyster sperm after 1 h of the last stimulus. Spawning success was evaluated by measuring egg production, fertilization percentage, and response time of spawning. Only broodstock held at 28°C spawned (51.8%). All organisms in the HSD treatment spawned after 1.40 ± 1.01 h. Oocytes released per individual and fertilization rate averaged 34.88 ± 23.81×10⁶ and 89.82 ± 5.90%, respectively. Addition of sperm enhanced spawning success in the HS1, HS2, and SS1 treatments.

The aim of this study was to identify effective techniques for the culture of the winged oyster (Pteria penguin) by comparing the growth and mortality of juveniles cultured on a self-designed wire collector and in traditional circle nets. The juveniles were hatchery reared, nearly 5 mo old, and were cultured in Li'an Lagoon, Hainan Island, China. The mean shell height (SH) and total weight (TW) of the juveniles was 26.06 ± 3.43 mm and 5.85.88 ± 2.258 g, respectively. They were held for 7 mo in suspended culture either on self-designed wire collectors or in circle nets. The collector was made of galvanized seizing wire, consisting of a top circle, a bottom circle, and 3 pillars between the 2 circles. Every collector was settled with approximately 150 spat and hung naturally in the sea. The oysters cultured in circle nets had three stocking densities: 10 juveniles (D10), 20 juveniles (D20), and 30 juveniles (D30) per net. Juveniles held on wire collectors and in D10 circle nets showed the greatest growth during the experiment, and had significantly greater shell height (SH), maximum diagonal length, hinge length, and TW than oysters in other densities. Oysters in D30 showed the lowest mean SH and maximum diagonal length, hinge length, and TW. Mortality ranged from 3.33% in D10to approximately 17% for oysters in D30 and on wire collectors. When other factors such as cost of equipment, labor, and ease of construction were considered along with growth and survival, the method of natural hanging on a wire collector is highly advisable in Li'an Lagoon because this method takes advantage of the strong byssi of winged oysters, substantially reduces cost, is easy to construct, and promotes increased growth. Although the loss of oysters was relatively high, it was balanced positively by growth rate and cost reduction, because the spat are hatchery produced and easily available.

To understand the influences of environmental conditions on the performance of pearl oyster spat, we conducted four experiments to evaluate separately the effects of salinity (21, 24, 27, and 30), diet (Isochrysis zhanjiangensis, Platymonas subcordiformis, Chlorella; 50% I. zhanjiangensis/50% P. subcordiformis, 50% I. zhanjiangensis/50% Chlorella, and 50% P. subcordiformis/50% Chlorella), diet availability (high, medium and low), and rearing site (hatchery and sea) on the growth and survival of pearl oyster Pinctada maxima spat. Results showed that environmental conditions exerted significant effects on the growth of P. maxima spat. Salinity and rearing site also had significant effects on survival, but no significant differences were observed in terms of survival between the diet and diet availability treatments. Growth declined with decrease in salinity. Spat reared at high salinities (30 and 27) showed larger shell length growth and greater survival than those at low salinities (24 and 21). Spat fed on a single diet (Chlorella) had poorer shell length growth than those fed on diets composed of more than one species. Spat reared on a medium ration (4.0 × 10⁴ cells/mL/day) had greater shell length growth than those reared at high (8.0 × 10⁴ cells/mL/day) and low (2.0 × 10⁴ cells/mL/day) rations. Spat held in the sea had greater shell length growth than those held in the hatchery. However, survival rate of spat was greater in the hatchery than in the sea. These results suggest that seed production of P. maxima spat could be optimized by extending the nurture period in the hatchery. Moreover, various diets should be provided to ensure balanced food intake.

The Sydney rock oyster, Saccostrea glomerata, mass selection breeding program was established in 1990 in the Georges River, New South Wales, and has successfully developed lines of oysters resistant to QX disease (Marteilia sydneyi) and winter mortality disease (WM; Bonamia roughleyi). Each new generation is assessed in the Georges River, but the performance of these oysters in other estuaries affected by these diseases is unknown. To investigate the potential for genotype and environment interactions, and to assure farmers, survival and growth of progeny of the fourth-generation breeding lines developed in Georges River were assessed in two other key farming areas; the Hawkesbury River and Merimbula Lake, NSW, Australia. Hawkesbury River is affected by QX and was used to assess the QX-resistant oysters (QXr). Merimbula Lake is affected by WM, and this estuary was used to assess the WM-resistant oysters (WMr) and the dual WM and QX resistant line (WM QXr). Oysters that are QXr in the Hawkesbury River, and the WMr oysters in Merimbula Lake, had significantly lower mortality and faster growth compared with controls at the final measurement. Oysters that are QXr in the Hawkesbury River at the Marra Marra Creek and Kimmerikong Bay sites attained the 50-g "plate grade" benchmark after 24 mo of culture and had lost only 29.4% and 16.9% of oysters originally stocked, respectively. Meanwhile, QX caused losses of 93.7% and 95.7% in controls at these 2 sites, respectively. In Merimbula Lake, at the conclusion of the experiment WMr oysters were significantly heavier, were larger, and had significantly lower mortality than WM QXr and control oysters. Growth and survival of WMr, WM QXr, and QXr oysters were comparable with that measured in the Georges River.

The impact of the dinoflagellate Alexandrium catenella on the early development of the Pacific oyster Crassostrea gigas was investigated by exposing embryos or larvae to different concentrations of A. catenella. Embryonic and newly hatched larval developments were inhibited after exposure to A. catenella at a concentration of 100 cells/mL. In particular, the trochophore larvae showed a retarded metamorphosis to the D-shaped larval stage, and could not finish the hatching process at concentrations exceeding 1,000 cells/mL. Adverse effects of A. catenella on the development of feeding larvae and settlement rate were shown at concentrations of more than 300 cells/mL. The survival rate of embryos and trochophore larvae were sensitive to A. catenella and it decreased significantly at a concentration of 300 cells/mL. The survival rate of D-shaped larvae was reduced significantly at a concentration of 600 cells/mL, whereas the umbo larvae and eye-spot larvae were affected significantly at a high concentration of 2,000 cells/mL only. The results obtained in this study demonstrate that A. catenella severely affects the early stage of development of C. gigas, but the effects of harmful algae on early development of oysters are varied during different stages.

Eastern oysters, Crassostrea virginica (Gmelin 1791), were sampled from seven Florida estuaries from January 2005 through December 2007 as part of the prerestoration monitoring and assessment component of the Comprehensive Everglades Restoration Plan. Study locations included Tampa Bay, Mosquito Lagoon, Sebastian River, St. Lucie estuary (3 study sites), Loxahatchee River (2 study sites), Lake Worth Lagoon, and Biscayne Bay. Settled oyster density was monitored twice per year at stations within each study site. Oyster recruitment, water temperature, and salinity were monitored on a monthly basis. Salinity varied greatly among the estuaries, and each study site fell into 1 of 2 primary salinity regimes: one relatively stable and with higher salinities (mean range, 24–35), and the other more variable and with lower salinities (mean range, 12–17). All 7 estuaries were impacted, to varying degrees, by the relatively active 2005 tropical storm season as well as local water management practices during the study. Two of the estuaries, St. Lucie and the Sebastian River, were severely impacted by controlled introductions of freshwater, which decreased salinities below the range that oysters can tolerate. As a result, live oysters were virtually absent from the study sites in both estuaries in 2005, when the freshwater introductions were most pronounced. At the opposite extreme, long-term reduction of freshwater flow into Biscayne Bay has exacerbated already increasing salinities and has resulted in the absence of reef-building oysters at that study site. Oysters were present at all other study sites, but densities were lower in 2005 than in subsequent years because of substantial salinity decreases after tropical storms in 2004 and 2005. The greatest and most stable oyster densities were found in Tampa Bay, where mean oyster density reached 400/m² by fall 2007. Recruitment was observed at each site on recruitment arrays retrieved from April through December, although the timing, duration, and intensity of the recruitment season varied annually and among study sites. The Tampa Bay, Mosquito Lagoon, Loxahatchee River, and Lake Worth Lagoon sites exhibited a bimodal recruitment pattern with peaks in the spring and fall. At the remaining sites, which were the most strongly affected by water management practices, recruitment patterns were sporadic and inconsistent throughout the study. The lowest recruitment rates occurred in 2005, when the density of settled oysters was also low, presumably because of reduced salinities resulting from a combination of active tropical storm seasons and controlled freshwater introductions.

Studies were carried out to determine the effect of four factors that may be important to optimize larval settlement of the scallop Nodipecten nodosus in a land-based nursery system: (1) ambient light (tanks were exposed to direct sunlight, kept in partial darkness, and kept in total darkness), (2) necessity for cleaning tanks (whether they should be cleaned daily or left untouched), (3) microalgal diet (ISO, Isochrysis galbana diatoms; PAV, Pavlova lutheri diatoms; and a mix, J. galbana P. lutheri diatoms fed once or twice a day), and (4) whether broodstock conditioned with an astaxanthin-enriched diet increased settlement. Effects of ambient light did not affect settlement statistically; however, an increase in settlement of 25% was recorded between settlement in tanks kept in total darkness and those exposed to sunlight. Cleaning tanks affected shell height of spat, with larger spat occurring in tanks cleaned every day compared with tanks not cleaned (mean, 1,387.95 (µm). Spat fed with a mix achieved the largest size (mean, 765.9 |µm), followed by PAV (mean, 717.12 µm), then ISO (mean, 515.4 (µm). A significantly greater shell height was found by feeding a mix twice a day. Larval settlement was accelerated when broodstock was fed the astaxanthin-enriched diet. We concluded that to optimize growth and settlement of N. nodosus larvae, broodstock should receive a supplement of astaxanthin during conditioning, settlement tanks should be exposed to sunlight and cleaned daily, and the spat should be fed with a mixed diet twice daily.

The use of an autonomous underwater vehicle (AUV) survey method for population density estimates of Iceland scallops Chlamys islándica (O.F. Müller) was evaluated. The main focus was on statistical evaluations and survey design. The underlying objective was to illustrate how a repeated AUV survey approach can be used to generate variance estimates of population parameters to verify statistical precision of population density estimates. As a case study, 5 small-scale surveys were conducted at a site off West Iceland. The scallops were enumerated visually from a random selection of photos of the seafloor and the count data were used to estimate mean scallop population abundance with confidence limits. A nested random effects model yielded no significant difference among the 5 surveys, showing that such small-scale surveys are repeatable. The application was small scale, but the methodologies established can be applied to larger areas of a similar nature.

Gametogenic activity of the cockle Cerastoderma glaucum was studied monthly in a littoral population collected from the Gulf of Gabès area. The analysis of oocyte diameter and histological examination of gonads indicates that C. glaucum showed a defined pattern of seasonal gametogenic development. An intense reproductive activity was observed throughout the year, mainly during the autumn and winter seasons. Spawning occurred most of the year, without prolonged periods of reproductive inactivity. Histological observations showed strong interindividual variations of gonad maturity stages over the same sampling period. The study also revealed spawning asynchrony in this species and the presence of various stages of maturity within the same individual. This strategy allows for a semicontinuous production of larvae in a way that some of the larvae will encounter favorable environmental condition over time, which favors their subsequent development. The current study also reveals an occasional manifestation of hermaphroditism.

Estimating age and maturity of the commercially harvested queen conch (Strombus gigas) offers fishery managers a unique challenge: How can these variables be determined if only the soft, edible parts of the marine gastropod are landed in port whereas the shells used for aging purposes are discarded at sea? Throughout the greater Caribbean region, including The Bahamas, the age and maturity of S. gigas are estimated by measuring the thickness of the flared lip of the shell. Given the traditional fishery practices for queen conch, including at-sea processing, developing proxy measures for S. gigas age and maturity would greatly benefit fishery managers. To this end, we used traditional morphometric analysis to find a significant inverse relationship between the ratio of operculum length to operculum width and shell lip thickness. A logistic regression model using the same operculum metric and a breakpoint of 15mmfor shell lip thickness as an indication of S. gigas maturity predicted correctly the maturity level for 86% of queen conch sampled in The Bahamas. This study provides the proof of principle for relationships between operculum measures and queen conch age and maturity that can be applied by fishery managers throughout the geographical range of the species.

Malathion is an organophosphate pesticide that is sprayed agriculturally and for public health threats such as malaria and West Nile virus. It can contaminate surface waters, where it can interact with aquatic organisms. In addition to combating exposure to pesticides, aquatic organisms must defend against biotic stressors, which could intensify effects imparted by chemicals. We investigated effects that exposure to an environmentally relevant malathion concentration (0.001 µg/L) and predation cues imparted on immune system function and reproductive output in individuals in the pond snail species Lymnaea stagnalis (Linnaeus, 1758) (Gastropoda: Pulmonata). Snails were grown in four exposure treatment groups: nonmalathion— nonpredation, nonmalathion—predation, malathion—nonpredation, and malathion—predation. Malathion exposure caused a decrease in hemocyte numbers, which was unaffected by predation cue exposure, and a decrease in egg numbers, which was amplified by predation cue exposure. These results demonstrate that pesticides can affect fitness-related traits in a manner that can be accentuated by natural stressors.

An invasive population of the Asian shore crab Hemigrapsus sanguineus was discovered in 1988 near the mouth of Delaware Bay, and populations now occur from North Carolina to Maine. The shore crab H. sanguineus competes with indigenous species and has displaced resident crabs throughout its invasive range. However, there have been few studies that document changes in populations of H. sanguineus after the species has become established.We compare sympatric populations of the Asian shore crab and a native mud crab (Panopeus herbstii) that were monitored initially in 2001 and again in 2011 and 2012. The historical study was conducted in a rocky habitat near Cape Henlopen at the southern terminus of Delaware Bay (38.793° N, 75.158° W). Results showed large differences in the relative abundance of the two species throughout the duration of the study. The Asian shore crab H. sanguineus accounted for 75% of total crab abundance in 2001, but abundance had decreased to less than 25% in both 2011 and 2012. Similar results were obtained when we compared the two species in terms of biomass. Additional sampling in 2012 showed comparable low values for H. sanguineus when compared with P. herbstii at two stations about 25 km and 50 km farther south along the coast. In contrast, H. sanguineus was strongly dominant at a station 50 km north of the historical sampling site. Percentage rock cover and size of rocks varied little among sampling locations, and all sites were proximal to the coastal ocean. However, basal sediment at the northern station was coarser than sediments at the other sites, which may have restricted the occurrence of mud crabs. Overall results of the study indicate a resurgence of native mud crabs at sites where sedimentary characteristics provide adequate habitat.

Feeding trials were carried out to determine the effects of Cu supplementation in Artemia on growth, antioxidant enzyme activity, and osmotic stress tolerance of the Chinese mitten crab (Eriocheir sinensis) larvae. The crab at zoea stage 3 were fed with 4 types of Artemia nauplii enriched with 0 mg Cu/mL (control), 0.1 mg Cu/mL (treatment 1), 0.2 mg Cu/mL (treatment 2), and 0.4 mg Cu/mL (treatment 3), respectively. Although Cu enrichment did not enhance the survival rate significantly, crab megalopa fed Artemia in treatments 1 and 2 showed greater body weight and larval stage index than those in the control group. The levels of Cu in Artemia affected significantly the crude lipid content and major fatty acid composition in megalopa. The superoxide dismutase and catalase activity of the megalopa in treatment 3 were greater than those in the meglopa fed Artemia enriched with other levels of Cu. The ability to tolerate salinity stress in megalopa in treatments 1 and 2 was also improved in comparison with the control and treatment 3 groups. This study demonstrates that the level of Cu at 33–52 µg/g dry matter in A. nauplii is required to improve the growth, salinity tolerance, and antioxidant ability of E. sinensis larvae.

This review has the available information about the digestive physiology and morphology of three decapod species from Argentina: Pleoticus muelleri, Artemesia longinaris, and Neohelice granulata. The anatomy of the foregut may be modified in closely related species with similar feeding habits; however, the main features of the decapod crustacean digestive tract are similar to other species. Crustaceans express a set of highly active digestive enzymes that hydrolyze the major food items and include proteinases, lipases, esterases, and glucanases. The close relationship between diet and the range of digestive enzymes produced is well documented; however, digestive responses to specific nutrients differ widely among the species. Variations in digestive enzyme expression during early development reflect changes in digestive capabilities and can be used to identify early developmental feeding transitions. This information provides a deeper insight into nutrition, dietary preferences, and strategies of resource utilization, making possible the development of new aquacultural practices and providing data about the ecological niche that species occupy in aquatic systems. There is no doubt that the occurrence and activity of digestive enzymes are influenced by many internal and external factors, such as diet, molting, and development. The research of three Argentine decapod species is discussed in this review and provides a better understanding of basic digestive physiology. This information important to investigations of nutrition and feeding ecology of crustaceans.

In Newfoundland, the American lobster (Homarus americanus) fishery has considerable socioeconomic value. Concern about the sustainability of this fishery continues to be a concern as a result of high exploitation rates. Conservation initiatives (marine protected areas, a slot fishery, and v-notching) have been established in several lobster fishing areas (LFAs) in western Newfoundland to increase the number of large lobsters and fecundity (egg production) of populations. However, there has been concern by harvesters in western Newfoundland, where slot fisheries are in effect, that the large lobsters being caught are rarely ovigerous.We used extensive field data from 5 LFAs in western Newfoundland (LFA12, LFA13A, LFA13B, LFA14A, and LFA14B) to test whether the spawning odds depend on size in a slot fishery, where large females were present in sufficient numbers to allow reliable estimates. Three analyses of size-dependent spawning odds were conducted via logistic regression: 2 analyses by year for LFA14A and LFA14B from 2006 to 2011 and 1 spatial analysis for 5 LFAs (LFA12, 13A, 13B, 14A, and 14B) during the same year (2010). In 4 of 6 y, for both LFA14A and LFA14B, spawning odds increased with size, and for 3 of the 5 LFAs for the same year, spawning odds increased with size. We found no evidence of a decrease in spawning odds with size and, equivalently, no decrease in percent ovigerous with increasing size. Our results support the use of spawning odds to calculate the effects of sustainability measures in lobsters.

An investigation was conducted of the combined effect of salinity and temperature on growth, survival, and biomass productivity of postlarval and early juvenile pink shrimp Farfantepenaeus duorarum (Burkenroad 1939) produced from a single spawning event. The study used a factorial block design consisting of three salinity treatments (15, 35, and 55), each replicated, within three temperature treatment (22°C, 27°C, and 32°C) water baths. The study was divided into two phases: postlarval (first 28 days) and early juvenile (second 28 days). Growth was assessed every 7 days throughout the experiment by measuring carapace length (CL) and wet weight (WWT) of 15 randomly selected shrimp from each temperature/salinity replicate tank. After the first study phase, survival was assessed and experimental aquaria were reset with 30 randomly selected shrimp from the same temperature—salinity replicates. Survival was assessed again at the end of the early juvenile phase. The effect of treatments was evaluated by average growth (average finalWWT), survival, and average final biomass production. Exponential growth rates (CL andWWT) and temperature physiological coefficients (Q₁₀) were also computed. Effects of temperature and salinity on growth and survival were variable, and no significant interaction among the treatment factors was observed. Biomass production increased consistently with temperature (postlarval, P > 0.0001; early juvenile, P < 0.0001) and decreased at the highest salinity (55; postlarval, P = 0.0140; early juvenile, P < 0.0001). Significant reductions in all performance outcomes except postlarval growth (P > 0.05) were observed at the high salinity of 55. The response of growth to salinity was not significant until the early juvenile treatment phase, whereas the effect of temperature on growth was significant during both phases. Hypersalinity (salinity, 55) had a detrimental effect on performance outcomes; however, performance outcomes at salinities of 15 and 35 were comparable. These results have implications for the natural productivity of pink shrimp in Florida Bay, where conditions are often hypersaline.

The purpose of this study was to evaluate the effect of stocking density and the occurrence of compensatory growth in the white shrimp Litopenaeus vannamei in the nursery phase reared in a biofloc culture system. Two experiments were performed in a recirculating water system with 12 experimental tanks (microcosm), each with a bottom area of 0.5 m². The tanks were supplied by a matrix 70-m² biofloc technology water tank (macrocosm), where a shrimp biofloc technology systems culture was maintained concurrently. The water was returned to the system by gravity, providing a daily renewal rate of approximately 4,800%. During the first experiment, L. vannamei postlarvae with an initial weight of 0.003 g were cultured for 30 days at densities of 1,500, 3,000, 4,500, and 6,000 shrimp/m². The cultures reached significantly different final weights (P < 0.05) of 0.45 g, 0.33 g, 0.30 g, and 0.23 g, respectively. Mean survival rates were greater than 87.6% in all treatments. To evaluate the occurrence of compensatory growth in L. vannamei after a period of enclosure stress, the second experiment was organized in 2 phases. During the first, shrimp postlarvae were reared at densities of 1,500, 3,000, 4,500, and 6,000 shrimp/m² for 35 days. The shrimp were then restocked at a density of 300 shrimp/m² and were maintained until compensatory growth was observed. In 20 days, the shrimp showed full compensatory growth. The mean final weight and survival rate did not differ significantly (P > 0.05) between the treatments. The results confirm that the strategy of enclosure rearing can be applied to the culture of L. vannamei.

There is the potential to exploit new markets if fishermen are able to land live shrimp (Pandalus borealis, Krøyer 1838). For this trade to be economically viable, a high survival rate during capture and storage is essential. This study investigates possible factors such as trawl duration, sorting, storage temperature, storage time, and storage density that can affect the mortality of shrimp in captivity. Oxygen consumption and ammonia production at different storage temperatures are also investigated. Oxygen consumption and ammonia excretion increased with temperature. Storage of live shrimp in flow-through water for 48 h shows a survival rate greater than 95% at 2°C and 5°C. The survival rate was approximately 70% and 50% after 48 h and at 10°C and 15°C, respectively. Storage density did not impact survival, whereas increasing trawl tow time led to an increase in mortality. The sorting process of shrimp led to a minor increase in mortality, probably as a result of increased air exposure and mechanical stress. Trials using cooled water in August had a greater survival rate than uncooled surface water. However, survival was less than for shrimp caught during winter. This might be a result of the shrimp undergoing molting or warmer air temperatures. It was concluded that capture and transport to local markets is most likely to succeed during winter and early spring, when water and air temperatures are cooler and the shrimp are not molting.

Catch-at-size data were analyzed for Farfantepenaeus californiensis from fishing seasons 1978/1979 to 1994/1995. The catch-at-size model could be fitted to the catch-at-size data for the different fishing seasons. It was observed that the recruitment to the fishery changed suddenly during the study period, and the recruitment to the fishery may occur over a range of length classes. The recruits were defined as size classes less than 93.5mmin abdominal length. Recruitment varied from 200–3,800 million recruits. In contrast, the size classes were larger than 93.5 mm in terms of abdominal length, and the number of adults varied from 3,500,000–50,000,000. In the study zone, it was not common to find remnant biomass of adults. Consequently, the most abundant size intervals of abdominal length were 62.4 mm, 67 mm, and 72.2 mm. The results of the harvest rate-at-size showed that the size interval from 65–80mmin abdominal length was less than 0.05. The highest levels of harvest rate-at-size were estimated to be 85–125mm in abdominal length, with an estimated variation of 0.6–0.9. It was observed that individuals less than 93.5 mm in abdominal length are in the range of length classes in which recruitment to the fishery occurs. These recruits support the fishing pressure and the yield of the fishery; in contrast, the presence of adults is scarce. Therefore, this fishery in the region is strongly recruitment dependent.

Survival, behavior, hemolymph pH, osmolality, and chloride ion concentration as well the total metabolic rate (heat dissipation rate) of the isopod Saduria entomon from the brackish Baltic Sea were investigated after exposure to carbon dioxide-induced water acidification (pH, 7.5, 7.0, and 6.5; control pH, 8.2) keeping other parameters constant (temperature, 10°C; salinity, 7). The short-term (12 h per each pH treatment) exposure to carbon dioxide-induced water acidification did not cause significant changes (P < 0.05) in the resting metabolic rate or the scope of activity in S. entomon; however, high interindividual variability was observed. The 2-wk exposure to lowered pH values did not affect either the activity of the isopods or their survival rate significantly (P > 0.05), which was greater than 90% in all pH treatments. The hemolymph pH increased significantly (P < 0.05) with a decrease of water pH from a control pH of 8.2 down to a pH of 7.0. Hemolymph osmolality increased significantly (P < 0.05) at pH 7.5, but exposure to pH 7.0 did not cause further increase in this parameter. Reduction of water pH did not affect the hemolymph chloride ion concentration. Obtained results indicated that S. entomon is adapted to large fluctuations of carbon dioxide levels in the water primarily to compensate for acid—base disturbances without additional energetic costs.

Based on seasonal sampling in the Beibu Gulf (Tonkin Gulf), South China Sea, from August 2010 to May 2011, biological characteristics such as growth, reproduction, and ingestion of 2,179 mitre squid, Uroteuthis chinensis, were investigated. The results showed that the maximum and minimum mantle lengths of U. chinensis were 438 mm and 49 mm, respectively, whereas the corresponding body weights were 723 g and 7.3 g, respectively. Both mantle length and body weight peaked in spring. The relationship between mantle length (L, in millimeters) and body weight (W, in grams) was W = 1.43 × 10^-3 × L^2.19 (R² = 0.92), and between mantle length and gutted weight (W, in grams) was W = 1.04 × 10^-3 × L^2.24 (R² = 0.97). The number of females was equal to that ofmales, with a sex ratio of 1:1.01. Furthermore, no obvious seasonal change was observed. There was no stage VI of gonad maturation, and stage I was dominant year-round. The feeding intensity was low and the empty stomach rate was high throughout the year. The mean trophic levels from spring to winter were 3.6, 2.7, 3.0, and 3.3, respectively. The results indicated considerable differences in the sampling areas. In addition, seasonal changes in catch and distribution were observable whereas biomass varied greatly.

Catchability (q) is a key parameter for the assessment and management of stocks because it is widely used to estimate other parameters such as fishing mortality and resource abundance. However, the common assumption in fisheries assessment that q remains constant through time, individual size, and space can mask the effect of fishing gear, or fleet, when applicable, and the behavior of the organisms, especially when different behavior can be portrayed by different components of the population structure. In the current study, the parameter q was evaluated for the octopus fishery (Octopus maya and Octopus vulgaris) in Yucatan, Mexico, using two deterministic techniques. In the first, q is assumed to be constant by size, age, and type of fleet, whereas the second technique assumes different sources of variation in q associated with the size of individuals, fleet characteristics, and fishing zone. Results suggest that q estimated using the second technique provides information that allows understanding the effect of fishing gear, fleets, and fishing sites at different levels of the population structure. Differences were observed in the patterns of q among fishing zones, with a high vulnerability of small organisms in the central and western zones of the study area throughout the fishing season, whereas the opposite was found in the eastern zone. Differences were also observed in the catchability of octopuses by fleet and species. The results suggest the presence of multiple intra-annual cohorts, which are not considered if q is assumed constant, as currently applies for the official assessment of the resources, with the corresponding fisheries management implications. The results are explained within this framework, and the potential effects of sequential externalities are discussed.

Species of Vibrio can persist in blue mussels, especially when they are present in high numbers as a result of a large uptake from the aquatic environment. This study investigated the uptake, localization, and persistence of three Vibrio species relevant to human health in blue mussels (Mytilus edulis) after artificial contamination. Mussels M. edulis were kept in tanks of artificial seawater spiked with Vibrio spp. to monitor bioaccumulation of these bacteria in corresponding bivalves. Bacteria accumulated rapidly in the bivalves, reaching high concentrations after 1.5 h. The highest Vibrio sp. counts were detected in the digestive glands, with 6.9 × 10⁸ cfu/g for Vibrio parahaemolyticus, 1.5 × 10⁷ cfu/g for Vibrio cholerae, and 2.2 × 10⁷ cfu/g for Vibrio vulnificus. Among bivalve compartments, the digestive glands showed the fastest enrichment of Vibrio and maintained the highest Vibrio numbers throughout the examination period. After transfer to a tank containing filtered, sterile seawater, the Vibrio load in bivalves showed a continuous reduction. However, even after 7 days of depuration, an average concentration of approximately 10³ cfu/g remained in the digestive glands of M. edulis. In clearance assays, a general clearance rate of 0.02 log cfu/g/h was calculated for all three strains. For the first time, in vivo accumulation counts and clearance kinetics of Vibrio within mussel compartments are shown, highlighting a strong concentration of Vibrio in the digestive glands whereas other tissues continued to accumulate significantly less Vibrio.

Research on eosinophilic and basophilic granulocytes in bivalve species has focused primarily on their morphologies and dye affinities. Few studies have investigated the immune functions of these granulocytes because of limitations in experimental methods. These methods must meet two criteria: (1) the studied granulocytes must survive and (2) eosinophilic granulocytes must be distinguishable from basophilic granulocytes. Unfortunately, few current methods have met both criteria. In this study, neutral red, a low-toxicity dye, was used to stain the hemocytes in three bivalve species (the clam Paphia undulata, the scallop Chlamys farreri, and the oyster Ostrea plicatula). The results show that the granulocytes in these three bivalve species are classified into 2 categories: eosinophilic granulocytes with a colorless or light-yellow cytoplasm and basophilic granulocytes with a deep-red cytoplasm. In addition to the difference in tinctorial property, the population of eosinophilic granulocytes was also significantly less than that of basophilic granulocytes (P < 0.05). The observed percentages of total hemocytes were 16.2 ± 2.28% versus 50.5 ± 5.34% in P. undulata, 7.8 ± 2.15% versus 51.5 ± 4.24% in C. farreri, and 22.3 ± 1.92% versus 40.2 ± 3.84% in O. plicatula. With respect to dimension parameters such as cell diameter, nucleus diameter, and nucleus diameter/cell diameter between eosinophilic and basophilic granulocytes, no significant differences were observed in either P. undulata or O. plicatula. These results suggest that neutral red staining can be used to distinguish eosinophilic from basophilic granulocytes. In addition, because of its nontoxic properties, neutral red staining is a promising method for the study of the immune function of these two types of granulocytes.

The Humboldt Current that bathes the west coast of South America is affected by different influences at daily to decadal periodicities. Environmental influences such as upwelling or coastal trapped waves as well as climate influences such as El Niño southern oscillation and Pacific decadal oscillation events interact and modify the thermonutricline depth of this Humboldt Current System. The position of this thermonutricline plays a key role in Humboldt Current System functioning by driving sea surface temperature (SST) and primary production variations. As filter feeders, bivalves are particularly affected by SST and primary production, and their shells can provide information about these two environmental factors. Using sclerochronology, we studied three bivalve species from different ecological niches living along the Peruvian—Chilean coast. Depending on the species, thick or thin sections, etched or not, were studied using an optical microscope. Increment thicknesses were measured at the surface of the shell and/or in cross-section. Moreover, the mineralogical composition of the different layers of the studied shells was determined on thin sections by Fourier transform infrared spectroscopic analyses. Growth results were then interpreted tentatively in terms of environmental variations. For the free-living, short-lived Pectinidae Argopecten purpuratus, the daily growth rhythm is linked to the solar period whereas growth amplitude seems to be related to the occurrence of spawning events, probably triggered by specific water temperature patterns. tidal regime and SST seem to be the major environmental parameters that govern shell growth rhythms and/or increment thickness for two nearshore species—the Mytilidae Choromytilus chorus and the Veneridae Eurhomalea rufa—which grow more slowly and have a life span longer than A. purpuratus, and have a strong potential for paleo-environmental and paleo- El Niño southern oscillation reconstruction. These results need to be confirmed studying multiple shells to quantify individual growth variations and to enhance the significance of the findings on the different environmental parameters recorded in the growth patterns of the South American bivalve species studied.

Filter feeding was compared in the blue mussel Mytilus edulis, Mediterranean mussel Mytilus galloprovincialis, Pacific oyster Crassostrea gigas, Chinese pleated oyster Crassostrea plicatula, Chinese scallop Chlamys farreri,Manila clam Tapes phillipinarum, razor clam Sinonvacula constricta, and blood cockle Tegillarca granosa over 95 dietary conditions across nine locations in Europe and China. Conditions included natural seawater enhanced, on occasion, with variable additions of microalgal monoculture and/or natural silt collected from the surface of nearby mudflats, thereby ensuring that diets ranged from oligotrophic to hypereutrophic (>325 µg chlorophyll a/L) and highly turbid (>1,250 mg total particulate matter/L). Building on past insights into differential particle processing, we resolved the availability, filtration, and ingestion of organic matter rich in chlorophyll a, and which matter is known to be ingested selectively, from all remaining organics, such as detritus, bacteria, protozoans, and/or colloids. The forms of fitted relations that best described feeding responses were different for chlorophyll-rich versus remaining organics, that difference being consistent in all eight bivalve species, including when measured in the same species across different locations. Throughout, positive linear relations between net ingestion of chlorophyll-rich organic matter and the availability of that chlorophyll-rich organic matter indicated that each species ingested constant proportions of the organics associated with chlorophyll a, with no limitation evident to such ingestion over our experimental range. Alternatively, ingestion of the remaining organics by each species increased as saturating functions of the availability of those remaining organics alone. Differences were evident between species both in the proportions of available chlorophyll-rich organic matter that were ingested and in saturated ingestion rates for the remaining organics. Comparison of those differences suggests an evolutionary trade-off among species between their relative abilities to process chlorophyll-rich versus remaining organics. Differences also suggest congeneric adaptation to natural habitat, impressing a need for careful appraisal of each and every bivalve species. Significant costs of particle sorting, digestion, and absorption, evidenced as metabolically derived material egested and assayed within feces, were greatest in species with higher saturated capacities for the ingestion of remaining organics. Last, we describe how, compared with predictions based on chlorophyll a or total particulate organic matter alone, our approach resolving coincident differential availabilities and processing of chlorophyll-rich versus remaining organic matter has improved the accuracy of growth simulations when applying single calibrations of the generic shellfish model ShellSIM across coastal habitats that contrast in seston composition.

In quota-managed fisheries in which harvestable mass of individuals varies seasonally, harvesting can be tailored either to reduce exploitation rates without lowering quota or to increase catch limits without raising the fisheries' risk profile. Using data from the South Australian greenlip abalone (Haliotis laevigata) fishery, we demonstrate that changing harvesting from summer to autumn would allow either (1) a 13% reduction in the number of abalone harvested for the same quota, thereby reducing fishing mortality; or (2) a 13% increase in the landed weight of catch (16.5% increase in revenue) while leaving the number and mean length of individuals harvested unchanged. These benefits accrue because (1) the landed weight-to-length ratio is greater in autumn and (2) heavier abalone are more valuable. Consequently, changing the seasonal timing of harvest can serve to increase landed revenue, reduce exploitation rate, or achieve a combination of these 2 management objectives.

The exploitation of bivalves is an ancient activity in Portugal, with social, economic and cultural importance. The exploitation of shellfish is largely dependent on the capture and production of molluscs. Bivalves have a relevant impact on both the harvesting and production sectors. In the production sector, bivalves are suitably represented, but the higher incomes are obtained mostly from captures. Clams and cockles are the main harvested bivalves, whereas clams and oysters were the most produced. Produced or captured bivalves (live, fresh, frozen, or canned) are targeted mainly to the national market whereas Japanese oysters are entirely exported and mussels are channeled for both markets. Exploitation of bivalves has shown important progress; however, there is still considerable potential for expansion of this sector in Portugal. New strategies to overcome constraints in this activity are urgently needed—namely, (1) improving communication among stakeholders, (2) encouraging the organization of the sector, and (3) adding value to the product by creating new market opportunities.