The bay scallop is a culturally important species that once supported significant fisheries along the U.S. east coast. Mass population declines in the 1900s led to a nearly total loss of the fishery in most states, including Rhode Island. In certain areas, intensive, long-term restoration efforts have effectively restored scallop populations and fisheries on a small scale, but indicate that such plans must be scoped specific to systems. In an effort to support the development of an upcoming Rhode Island Shellfish Restoration Plan, relevant knowledge on bay scallops was collated and summarized, and this information was used to create a habitat suitability index that can act as a guide to identify suitable restoration sites for renewed bay scallop restoration efforts in one of the largest coastal salt ponds in Rhode Island, Point Judith Pond. Point Judith Pond was once the epicenter of the bay scallop fishery in the state of Rhode Island, and the ranked index suggests multiple sites throughout the pond are likely to once again provide adequate habitat for bay scallops. Restoration strategies such as caged spawner sanctuaries and the release of competent larvae in areas identified as suitable by the index are recommended for future restoration planning of this species.

Generalized linear models (GLM) and generalized additive mixed models (GAMM) were developed to examine for differences in fishing power, also referred to as a vessel effect, for three commercial fishing vessels chartered by the Virginia Institute of Marine Science (VIMS). The vessels conducted a fishery-independent sea scallop dredge survey of the MidAtlantic sea scallop resource in 2015. Surveys have continued since 2015 using a multivessel approach, and understanding the implications of a potential vessel effect on scallop catch is important for management and assessment of the resource. Surveys are conducted yearly to support annual fishery specifications and contribute biological and catch data for stock assessments. Generalized linear models tested for an effect of vessel on the total number of scallops captured and indicated survey strata and rotational area were significant predictors. Generalized additive mixed models tested for a vessel effect on scallop catch-at-length with length, vessel, strata, rotational area, and an interaction of vessel and length as fixed effects and survey station as a random effect. Two preferred GAMM were identified for the catch-at-length analysis. One model indicated that strata and rotational area had significant effects on scallop catch-at-length, whereas the interaction term was not significant. The second model did not include the interaction term or vessel as a predictor. Results presented here are consistent with previous calibration studies conducted for scallop dredge surveys suggesting that scallop catch is robust to the effect of vessel and support the use of a suite of industry vessels in the VIMS sea scallop surveys.

Outbreaks of oyster diseases caused by the World Organization for Animal Health (OIE)-listed protozoan pathogens have been a global concern for several decades. With the wide application of species-specific and sensitive polymerase chain reaction (PCR) techniques, it is now well known that even the Pacific oyster, insusceptible to Perkinsus marinus, Bonamia ostreae, Bonamia exitiosa could act as a carrier host. Furthermore, one of the transmission pathways of oyster pathogens includes anthropogenic activities, such as the discharge of ballast water or hull attachment during international maritime shipping. In this survey, OIE-listed pathogens, including B. ostreae, B. exitiosa, and Marteilia refringens were screened in the Pacific oysters growing in small bays off the south coast of Korea using PCR with OIE-recommended species- or genus-specific (Bonamia) primers. The survey sampled 1980 oysters from 35 sites in small bays in the south, where more than 95% of the national productions are yielded. The PCR screening indicated that none of the oysters screened in this study were positive for B. ostreae, B. exitiosa, P. marinus, and M. refringens. This study first investigated the OIE-listed protozoan pathogens in the Pacific oysters culturing in Korea, and the results indicated that the Pacific oysters raised on the south coast of Korea are free from those OIE-listed pathogens. For secure and sustainable oyster farming on the south coast, however, regular monitoring of such invasive oyster pathogens is recommended, as the international maritime trade activities are increasing in Korea.

Oysters are farmed worldwide and one of the main problems is infestation by polydorin polychaetes. The native Crassostrea gasar and the exotic Pacific Crassostrea gigas oysters support aquaculture production along the subtropical southern Brazilian coast. Worm infestation rates in the two oyster species were evaluated, hypothesizing that infestation is related to stocking densities and hydrodynamic intensity. The main oyster production areas in Brazil were sampled: Parana state, Medeiros (25° 22′ S, 48° 27′ W), Ponta Oeste da Ilha do Mel (25° 29′ S, 48° 22′ W), and Cabaraquara (25° 49′ S, 48° 34′ W) and the Santa Catarina state, Riberão da Ilha (27° 43′ S, 48° 33′ W). Generalized linear models were performed to analyze the effects of sites characterized by different stocking density, hydrodynamic intensity and mean sea surface temperature (SST), the condition index, and the oyster species (native or exotic). Polydorin infestation was higher (mean of 6.02 polydorins/oyster) under higher oyster stocking densities and intermediate hydrodynamic intensity sites (Riberão da Ilha, in the Santa Catarina state). In Parana State, the two sites with similar stocking densities, Ponto Oeste (7,638 oysters/m²) and Cabaraquara (7,550 oyster/m²) presented a higher polydorin infestation in the site with low hydrodynamic intensity and higher mean SST (5.34 vs. 2.64 polydorins/oyster, respectively). The condition index was not impacted by the polydorin infestation. Native C. gasar showed a higher polydorin infestation than the exotic C. gigas (6.02 vs. 1.36, respectively), indicating a higher vulnerability to worm infestation. These results may lead to a better understanding of the infestation patterns of locally grown oysters and to the implementation of better farming management.

New marine mollusc fishery resources are constantly being incorporated to the international market. The marine gastropod Buccinanops cochlidium (Dillwyn, 1817) is a potential fisheries resource with excellent nutritional qualities. Recently, the first legislation that regulates marine gastropod fisheries based on size limits and reproductive seasonality was established in Argentina, although some biological parameters that are useful to its implementation are still needed. Fisheries managed with size limits require accurate estimates of age and growth that can be estimated through stable isotope sclerochronology. The age and growth of B. cochlidium at Playa Villarino, in north Patagonian gulf San José, Argentina was studied between 2005 and 2006. The δ¹⁸O profiles of B. cochlidium shells analyzed in this study showed a maximum age of 5 y. Opercular rings and shell growth breaks, which record age in some other gastropods, gave higher counts than the number of years shown in isotope profiles. Thus, morphological proxies are unable to correctly asses age and growth in B. cochlidium. These results are useful to support and complement the first fisheries regulation of marine gastropods recently implemented in Argentina, aimed to conserve this vulnerable and valuable resource.

The genetic resources of oysters in Louisiana and the Gulf of Mexico are threatened due to high unexplained oyster mortality. Germplasm repositories are collections of cryopreserved genetic material stored alongside associated information that are used to protect genetics resources and facilitate breeding programs in agricultural industries. Therefore, there is great need for oyster repositories. Development of repositories has been slow despite research on high-throughput cryopreservation protocols because of logistical complexities. The goal of this study was to begin to address the gap between cryopreservation research and repository development in oyster aquaculture by modeling a cryopreservation protocol to understand and improve the process. The steps of a high-throughput cryopreservation protocol were defined and mapped in a process flow diagram. A simulation model was created using time study data, and key bottlenecks in the process were identified. Finally, model variations using alternate types of devices (tools or equipment) were created to address the identified bottlenecks. The model was found to accurately simulate the cryopreservation process. Parameters such as number of straws frozen per oyster, batch size, and number of operators significantly affected how the model performed and device choices produced substantial improvements. Simulation modeling has the potential to inform how cryopreservation pathways and repository systems in aquatic species should be structured and operated. There is ample opportunity for future work such as analyzing the impacts of production scale on cryopreservation processes.

Selective breeding of mussels based on nacre color forms the basis for cultivating freshwater pearls with specific colors, as the color of cultured pearls is mainly determined by the nacre color of the donor mussel. In this study, the nacre colors of four selected Hyriopsis cumingii strains (blue, red, golden, and white) were measured and analyzed. The results showed that the three nacre color parameters L*, a*, and b* significantly differed (P < 0.01) between the four H. cumingii strains. Two principal components (PC1 and PC2) were extracted based on a principal component analysis, and their cumulative contribution rate ranged from 92.81% to 93.44%. The color parameters a* and b* had the greatest influences on PC1 and PC2, respectively, indicating that these two color parameters were the main factors contributing to the nacre color differences of the four strains. The nacre color parameters of the four H. cumingii strains were also investigated extensively using discriminant analysis, and the discrimination accuracies of the four strains were 76.7%, 80.0%, 72.5%, and 100.0%. Reflectance spectrum analysis showed that the nacre reflectance spectra of the four H. cumingii strains differed considerably and the spectral reflectance curves of the different nacre colors were clearly separated, indicating that spectral analysis represents an effective method for identifying different H. cumingii strains.

Yellow shell morphotypes of the pearl oyster Pinctada fucata martensii are rare and intriguing, whereas polyene pigments in mineralized shells from yellow pearl oysters have not been identified. An in situ micro-Raman spectroscopy and scanning electron microscopy investigation were performed on yellow and brown shell pearl oysters. Carotenoids or polyene pigments were found in both prismatic and nacreous layer from yellow pearl oysters. The peaks of pigments in the yellow prismatic surface were at wavenumbers of 1,280.8, 1,318.7, 1,146.1, and 1,577.2 cm^–1, whereas those in the nacreous layer were at 1,135.3 and 1,530.6 cm^–1. In brown pearl oysters, carotenoids related vibration peaks were not found in the prismatic layer, whereas slight spectra in the nacreous layer at wavenumbers of 1,136.3 and 1,531.4 cm^–1 were attributed to polyene pigments. Pigments in the prismatic and nacreous layers of the yellow shell were not the same, and the former showed shorter polyene backbones and more complex molecular structures. This research provided characteristic Raman spectra for brown and yellow shell phenotypes of pearl oysters and can contribute to explore the connection between polyene pigments and biomineralization.

Vitellogenin (Vg) is the precursor of yolk protein, which plays an important role in the reproduction and development of oviparous animals. In this study, vitellogenin1 (Vg1) from Sepiella japonica was cloned and characterized, and its potential function in ovarian development was investigated. The full-length cDNAs of Vg1 was 5853 base pair (bp) that encoded 748 amino acids. Sequence analysis revealed that the overall protein sequence of Vg1 shared 66% identity with that of Uroteuthis edulis. Analyses with quantitative reverse transcription polymerase chain reaction (RT-qPCR) showed that the highest expression of Vg1 occurred in the ovary. As ovary developed, the expression of Vg1 increased in both ovary and liver from oogonia phase (I) to interstitial growth phase (III), and reached to the peak value at stage III. In addition, we examined the effects of Gonadotropin-releasing hormone (GnRH) on Vg1 expression in the ovary and liver were examined. The data showed that GnRH increased mRNA expression of Vg1, indicating that exogenous GnRH initially affected Vg1 expression and then influenced ovarian maturation. This study suggests that Vg1 might be involved in ovarian development in cephalopods.

The cuttlefish Sepia pharaonis Ehrenberg, 1831, is a widely distributed tropical cephalopod species in the Indo-West Pacific region. This cuttlefish is vulnerable to the influence of coastal trawlers, especially during early stages when they spawn and juveniles prey in coastal waters. The pharaoh cuttlefish is very popular worldwide because of its nutritional, medicinal, and industrial values, but the protection of wild cuttlefish populations is becoming a serious concern because of the overexploitation of wild resources and increasing demand for live cuttlefish. The development of culture techniques for pharaoh cuttlefish will help protect natural populations and biodiversity. To understand its commercial prospects, the distribution, taxonomic, biological resources, and nutritional values are summarized and reviewed. The promising culture of pharaoh cuttlefish flourished recently due to strong market demand and promising profit, and it has been facilitated by technical progress in the production of juvenile cuttlefish and commercial products. Recent advances in artificial breeding, biological resources, and biological characteristics, achievements in culture methods and regulations, the application of biotechnology in its culture and problems, and challenges to further culture are discussed in detail to capture the newest developments in pharaoh cuttlefish aquaculture.

Continuous environmental disturbances and the crayfish plague have restricted freshwater crayfish populations in Greece. Therefore, the need for the establishment of a repopulation policy in Greece and the increasing commercial interest for the species, dictated in the Thessaly County, have imposed the investigation of the optimum husbandry and dietary requirements of Astacus astacus in culture conditions. Hundred and five adult crayfish were placed in cement tanks for 60 days and fed a semipurified diet, whereas 90 adult crayfish were placed in similar cement tanks for the same time period and fed a control diet consisting of fresh fish and carrots. The semipurified diet had a Protein: Energy ratio of 21.29 mg Prot. kJ^–1, a protein level of 37.95%, and a lipid level of 9.6% (on a Dry Matter basis). By the end of the experiment, crayfish fed the semipurified diet gained almost 5 g of weight with acceptable survival rates. Despite the total substitution of corn oil by soy oil and the partial substitution of fish oil (by 3%) and fishmeal (by 7%) with other plant-derived materials, in comparison with their levels in the semipurified diet of a previous experiment, dietary linoleic, and linolenic acids have been substantially high whereas dietary arachidonic acid and EPA, DHA have been somehow lower compared with the respective ones of the semipurified diet of a previous experiment. Although EPA tail muscle tissue has been progressively augmented throughout the experiment, DHA respective levels seemed to stay unaffected and at similar levels throughout the experiment. These results dispute the ability of noble crayfish for bioconversion of EPA to DHA and call for further investigation.

The genus Corbicula is well known as one of the most invasive bivalves globally, and is morphologically variable and taxonomically complicated. Continuous effort has been made to establish the correspondence between morphological forms and genetic lineages of Corbicula, mostly across invasive populations, but far less for the native populations, especially for exploited ones that support important Corbicula fishery. This research studied a Corbicula population that supported the largest artisanal and commercial Corbicula fishery in China, in terms of the morphotypes composition, ploidy, mt COI sequence, phylogenetic relationship, and habitat preferences. Two morphotypes with 9.5% mt COI genetic divergence, that is, the “distantly-placed-ridges morphotype”-morph D, and the “closely-situated-ridges morphotype”-morph C were identified. Morph D individuals contained diploids and triploids, and were closely related to the invasive lineage. They were found in higher proportions in lotic habitats with lower transparency and chlorophyll α. Morph C were all diploids and sister to C. fluminalis and C. japonica. They had higher proportions in lentic habitats. Thus, fishery management of Corbicula should consider multiple compositions of the Corbicula resource. Further research that confirms the population parameters difference of the two morphotypes and surveys in other water systems should be conducted. Moreover, the two morphotypes were sympatric representatives of the invasive and noninvasive Corbicula lineages, comparisons between them and with their congener invasion populations suggested that preference of flowing water and polyploidy might contribute to the invasive success of some Corbicula lineages in addition to androgenesis.

Environmental ecotoxicology studies use sea urchin skeletal components to examine potential changes in concentrations of trace element pollutants. To date, such studies have not considered how body size may alter the innate concentrations of trace elements in a given skeletal component. The present study examines this issue using the common nearshore sea urchin Lytechinus variegatus as a model species. Concentrations of barium, boron, manganese, and strontium was measured using ICP-OES in three major skeletal subcomponents (Aristotle's lantern, spines, and test) of individuals' representative of five size cohorts spanning the late juvenile to adult. Concentrations of three of the four elements, barium, boron, and manganese, varied significantly with body size, largely declining as test diameter increased. As concentrations of trace elements was normalized to skeletal mass originated from collections of individuals in pristine bay waters and from the same population at the same time, differences in trace element concentrations are innately ontogenetic. Accordingly, future ecotoxicological studies employing skeletal subcomponents of sea urchins should consider the relationship between trace element concentration and body size when designing sampling regimes.

Marine heatwave (MHW) events are emerging as dominant and disruptive extreme disturbance events on the Pacific coast. These events are expected to have significant impacts on shellfish species and aquaculture operations. In general, thermal stress induced by MHW events has been documented to have impacts on the productivity and biodiversity of coastal marine ecosystems in California. Yet, there is limited understanding on how thermal stress will affect economically important shellfish species, especially at vulnerable early life stages. This study assessed the effect of high temperature stress that resembled recent local MHW conditions on the larval stages of the Kellet's whelk, Kelletia kelletii, an emerging seafood species from California temperate reefs. Adult whelks were collected at temperate reef sites in the Santa Barbara Channel, and larvae were sourced from egg capsules laid by adult whelks in the laboratory. Thermotolerance trials were determined for two stages of K. kelletii larvae: encapsulated veligers and veligers that had emerged from the capsules as hatchlings. During the trials, larvae were scored for two metrics: (1) mortality and (2) developmental abnormality. After exposure of larvae to a range of temperatures (15°C–37°C) in acute thermotolerance trials (1 h), the mortality of veligers and hatchlings occurred at similar temperatures. In contrast, temperatures that induced developmental abnormalities for both encapsulated veligers and hatchlings were lower than temperatures that caused mortality. And further, temperatures that induced abnormal development were different for the two stages. These results provide some of the first insights on effects of environmentally relevant MHW temperatures on larval forms of the Kellet's whelk, and suggest the potential decline of populations in situ in response to continued stress from local MHW events.

The upper Gulf of California, Mexico is a marine protected area (MPA), considered important for the conservation and protection of species. The present study assessed the resource–consumer interactions of two ray species (Rhinoptera steindachneri and Hypanus dipterurus), to know the importance of shellfish in the food-web dynamics of two predators present in this MPA. A total of 33 prey species for R. steindachneri and 48 prey species for H. dipterurus were recorded. The bivalve Tellina subtrigona (%IRI = 99.5) was the most important species in the diet of R. steindachneri; whereas the gastropod Mitrella dorma (%IRI = 32.7) was the primary prey of H. dipterurus. The ray R. steindachneri had a lower Shannon's index of diversity (H' = 0.49) than H. dipterurus (H' = 1.41). Based on Amundsen's graphical method, R. steindachneri have a specialist feeding strategy; whereas H. dipterurus presented a mixed strategy that includes both specialist and generalist organisms. However, the trophic specialization evidenced by these rays may reflect the grouping behavior of their prey, which tend to form large aggregations. Both ray species are secondary consumers (TL_{R. steindachneri} = 3.10 and TL_{H. dipterurus} = 3.12) of shellfish. Nevertheless, there is a low similarity in the prey species composition between them (ANOSIM: R = 0.47), indicating that these two ray species have different diets, and therefore, each ray species has specific resource–consumer interactions. This information allows to understand the importance of shellfish in the food-web dynamics in the ecosystem and MPA effectiveness in the upper Gulf of California for species at risk, like ray species.