Fisheries that target sedentary shellfish present several challenges for deriving management reference points. Stock-recruit relationships often function at a relatively large spatial scale, with planktonic dispersal of eggs and larvae connecting discrete settlement areas, but postsettlement demographics are heterogeneous among local settlement areas. Another challenge is that information on age composition is not available for many invertebrates. Case studies of sedentary shellfish fisheries demonstrate a series of methods for estimating reference points. Biomass dynamics models may be an option for some data-limited fisheries, but inferences of metapopulation productivity can be confounded by serial depletion, so fishery and survey data should be explored for spatial patterns. Yield-per-recruit and eggs-per-recruit models can be size-based and spatially stratified. Demographic models of the full life cycle can integrate regional recruitment processes and postrecruitment processes at smaller spatial scales. Although metapopulation dynamics and spatial heterogeneity in postsettlement demographics can be accounted for in reference points, achieving the optimum yield of sedentary shellfish is largely conditional on managing spatial fishing patterns.

Understanding population history and genetic connectivity is important for assessing the long-term viability of populations. The Atlantic surfclam (Spisula solidissima) has historically been subdivided into two subspecies: lesser-known S.s. similis in the South Atlantic Bight and Gulf of Mexico, and commercially important S.s. solidissima mostly north of Cape Hatteras. Novel populations of the “southern” S.s. similis subspecies were previously identified far north of their historical range limit. Here, to test a hypothesis of recency and isolation in the North, population samples from Southern New England S.s. similis were compared for the first time to a population sample from Georgia, as well as to S.s. solidissima. Population structure and demographic history were inferred using genetic variation at a combination of microsatellite, mtDNA, and nuclear intron loci. The Southern New England populations of S.s. similis had slightly lower nuclear DNA diversity than in Georgia. Genetic differentiation between Massachusetts and Georgia S.s. similis was weak and only significant for microsatellite markers. Consistent with weak differentiation, coalescent modeling of nuclear sequence variation indicated high levels of gene flow. All S.s. similis populations had extremely low mtDNA diversity, with only two mitochondrial cytochrome oxidase I haplotypes found in contrast to 15 haplotypes in S.s. solidissima. Collectively, the population genetic patterns are more parsimoniously explained by the northern S.s. similis populations originating from a postglacial expansion rather than recent colonization.

Severe declines in commercial and recreational fisheries of the bay scallop, Argopecten irradians, and the success of the Chinese industry have led to increased interest in aquaculture in the United States. In recent years, the Chinese industry has sought to improve production through marker-assisted selection and has identified several candidates that may be predictive of performance. We explored the utility of a subset of these markers [size-related quantitative trait loci (QTL) marked by ten microsatellites and four single nucleotide polymorphisms (SNP) in the myostatin gene] to improve the growth performance of bay scallops in North Carolina (NC) using quantitative genetics and marker-assisted selection. Mature scallops were collected from three wild populations in the fall of 2019 in Topsail Sound, Core Sound, and Bogue Sound. The wild scallops were brought back to the University of North Carolina Wilmington (UNCW) Shellfish Research Hatchery (SRH), and each group was spawned separately. The wild scallops were genotyped at the 14 markers to confirm their presence in NC populations. The 2019 offspring lines were genotyped, and growth monitored to evaluate the association of the microsatellite and myostatin SNP genetic markers with growth performance. Except for a single marker in a single line, no association of the markers with growth metrics was observed. Consequently, in the fall of 2020, performance-based selection was implemented by sorting 2019 lines into “Big” and “Little” groups based on shell height and spawned separately. Evaluation of microsatellite and SNP genetic markers in broodstock scallops revealed significant genetic differences among the size groups; however, no consistent significant association between the genetic markers and performance was observed in broodstock scallops. Offspring of the size-sorted groups were deployed to three NC aquaculture farms in April 2021 and monitored for 7 mo. Overall survival ranged from 3% on Farm B (terminated in August 2021) to 37% on Farm A and was 16% at UNCW (terminated in November 2021). Offspring of the “Little” broodstock survived better at UNCW (19% versus 14%) but there was no difference at the other two sites. Growth also differed among sites. At UNCW there were no significant differences in any of the growth metrics assessed between the offspring of the “Big” and “Little” broodstock; however, there were significant differences between the offspring on Farm A. The “Little” line was significantly smaller than the “Big” which was similar in size to the scallops at UNCW except for shell width and adductor muscle weight. The results of this study suggest the genetic markers identified for selective breeding in Chinese bay scallops are not applicable for predicting superior performance in NC bay scallops.

Blood cockle sampling and water quality monitoring were conducted monthly between September 2011 and June 2013 at four blood cockle aquaculture farms situated along the Selangor coast, of Malaysia. Histological observations of the gonads were performed to identify male and female blood cockles. The maturation of gonadal tissue was evaluated, and the relationship between the maturation status of blood cockles and water quality factors, such as salinity and chlorophyll a concentration, was examined at each station. Mature and spawning male cockles were present year-round at all stations except at Station C, where males were more susceptible to the influence of the estuary. Females exhibited a distinct seasonal change in gonadal tissue compared with males, with a higher proportion of spent-stage individuals during the dry season. In addition, the number of immature individuals, for which it was difficult to distinguish between males and females, increased during that period. These results showed that spawning activity on the Selangor coast is more prominent during the rainy season and less pronounced during the dry season. The relationship between salinity, chlorophyll a concentration, and the gonadal tissue maturation stage of the cockle was identified. These findings reveal that sexual maturation progressed in brackish water with a salinity of approximately 28 in both males and females. As salinity decreased to less than 25, the proportion of immature and spent-stage individuals that released sperm or eggs increased. Additionally, immature individuals' percentage increased when chlorophyll a concentration was low (<10 µg.L^–1), whereas mature individuals' percentage increased when concentrations were between 10 and 20 µg.L^–1. These findings suggest that the increase in chlorophyll a concentration and decrease in salinity in brackish water environments are environmental factors that influence the sexual maturation and spawning of blood cockles.

Since October 2016, the endangered fan mussel, Pinna nobilis, has suffered mass mortality episodes throughout the Mediterranean Sea caused by a haplosporidian parasite, Haplosporidium pinnae, which could eventually lead to the extinction of the species. In response to this crisis, rescue projects have emerged in several Mediterranean countries and tend to focus on reintroducing individuals to their natural environment. To ensure that the reintroduction of healthy P. nobilis is successful, it is imperative that the parasite is no longer present in the natural habitat and that there is no risk of a new infection. Instances in which molluscs have been infected by haplosporidian parasites, in habitats where the host species was absent for a couple of years, have been reported, suggesting that haplosporidian parasites can persist in the ecosystem for at least 2 y. We hypothesized that H. pinnae could survive without P. nobilis, using another host and without causing similar mortality. This study aimed to test if other bivalve species living in the same environment as P. nobilis could act as potential reservoirs for the parasite. The presence of the parasite was investigated using haplosporidian PCR barcoding with specific primers in 15 species of marine bivalves collected at eight sites spread along the Southern French Mediterranean coast. Out of 116 specimens, successful PCR amplifications were obtained in seven individuals of Cerastoderma glaucum but the amplified sequences were not attributed to H. pinnae, and the species remains to be identified. This study did not succeed in detecting a species of mollusc that could potentially maintain the parasite responsible for fan mussel mortality in the environment, but does provide initial results that significantly enhance our understanding of the ongoing pandemic that is currently devastating P. nobilis populations.

Pinto abalone populations in the Salish Sea, WA have declined precipitously in the last several decades and have not recovered despite fishery closure in 1994. The Puget Sound Restoration Fund, in collaboration with state and federal agencies, has been outplanting juvenile pinto abalone at sites in the San Juan Archipelago, and some sites are much more successful than others despite similar physical characteristics. The sites, however, likely differ in oceanic parameters, such as temperature, salinity, and pH, which are in turn changing as the climate of the Earth is changing. The purpose of this study was to investigate the effects of temperature fluctuation and pCO₂ levels on the survival, growth, and oxygen consumption of juvenile pinto abalone. In a fully crossed experiment, juvenile pinto abalone were held at either currently ambient (400 ppm) or elevated (1,200 ppm) pCO₂ and at constant (10°C) or fluctuating (10 → 14 → 10°C) temperature. Survival was monitored weekly and growth was measured after 4 wk. In a second experiment, abalone were held in the same crossed pCO₂ and temperature treatments, and oxygen consumption was measured. High pCO₂ and fluctuating temperature both significantly decreased abalone survival. Abalone growth was not affected by pCO₂ level (temperature could not be analyzed due to very poor survival in the fluctuating temperature treatments). In addition, there was an interaction between fluctuating temperature and pCO₂ level on abalone oxygen consumption. Abalone in the constant temperature treatment had higher oxygen consumption when exposed to elevated pCO₂; however, this pattern was not observed in the fluctuating temperature treatment. The results of this experiment indicate that outplant sites with minimal temperature fluctuation and lower pCO₂ levels could lead to improvements in outplanting success of juvenile pinto abalone.

White abalone (Haliotis sorenseni) are an endangered species found along the southern California and Baja, Mexico coast. To recover the species population, conservation aquaculture is currently used to culture the species for out planting to wild habitat. Withering syndrome, caused by the bacterium Candidatus xenohaliotis californiensis attacking the digestive tract is known to impact the survivorship of the species in captivity. An experiment to test the effectiveness of probiotic Bacillus licheniformis in reducing the impact of the disease on white abalone exposed to infected red abalone was conducted. During this study, unexpected shell loss was observed in both the red and white abalone. Shell loss had been observed in other facilities, but the rate of shell loss in this experiment was on a larger scale than previously observed (43% in white abalone and 52% in red abalone). There was no significant difference detected in shell loss rate between experimental disease treatments indicating that the probiotic was not responsible for the shell loss. The initial study was abandoned, and two subsequent studies were conducted to better understand the cause of the shell loss. Shell loss syndrome was investigated to determine if the shell loss was infectious, but the shell loss could not be replicated via exposure to symptomatic animals. This observational study discusses other possible causes of shell loss syndrome including water quality, shell irritants, and other stressors. Although no specific cause of shell loss could be determined it is possible that a combination of stressors on the abalone in this experiment could have caused shell loss. This investigation details the rate and progression of shell loss, the impacts of shell loss on abalone health, and the survival rates of abalone with shell loss syndrome.

Türkiye (Turkey) includes distinct environmental conditions, including several types of temperate zones and abundant natural resources, and is a significant hub for the production, export, and regulatory issues of land and sea snails. Studies on species identification have shown that there are over 700 species of snails representing 36 families in Türkiye. The family Helicidae includes Eobania vermiculata, Cornu aspersum, Cantareus apertus, Theba pisana, Helix asemnis, Helix cincta, and Helix lucorum. In Türkiye, C. aspersum, H. cincta, and H. lucorum are the three most economically significant land snail species. The sea snail, Rapana venosa is also harvested. Snails are exported in various forms, such as live, cooked, frozen, canned, and empty shells. Despite snail meat being consumed in prehistoric times, it is only occasionally consumed in Türkiye. Thus, snails are processed in food processing facilities that meet the required standards for export. Consumption of snails is common in many nations throughout the world and, as Türkiye owns approximately 40% of the global snail market, it contributes significantly to the national exports to countries including those in the European Union, South America, the United States, Japan, and China, especially France, Italy, Germany, and Romania. Particularly in the land snail market, suppliers competing with Türkiye include Bulgaria, Romania, Hungary, Albania, Lithuania, Latvia, and Estonia. An increasing trend has been noted in heliciculture in recent years. The sole species of sea snail exported from Türkiye is the Rapa whelk R. venosa, and it is typically sold processed (frozen, shelled, or unshelled). Since 2000, there have been variations in its production levels, but an upward trend has been noted. Between 2012 and 2021, R. venosa, the primary market for which is southeast Asian nations, was primarily exported from Türkiye to France (855.5 tons), South Korea (722.3 tons), the United States (630.9 tons), and Japan (462.9 tons). With an annual average production of 3,650.5 thousand tons of processed sea snails and an income of 26,562,520 (USD) from this production, Türkiye has the biggest market share among the other Black Sea nations. Finally, owing to their superior quality and flavor, edible snail species found in Türkiye are favored. Türkiye is thus one of the major exporting nations. Construction of processing facilities for snails is required, as is ensuring that the microbiological quality meets international regulations for human consumption, to boost production and market share. Improved legal standing is also necessary, e.g., there should be a general restriction on the scope and timing of collecting snails from nature. Scientific advice from subject-matter authorities should be sought to determine harvest regulations.

Although populations of the eastern oyster Crassostrea virginica have been the focus of numerous studies for more than a century, less is known about the coastal lagoon populations such as those of Delaware's Inland Bays. Increasingly, oyster restoration projects in coastal regions are incorporating oyster stocking programs to restore areas with reduced oyster populations to capture both economic benefits and ecosystem services provided by healthy reefs. In Delaware, the Center for the Inland Bays conducted a volunteer oyster gardening program lasting 20 y employing disease-resistant hatchery spat. Using a suite of microsatellite loci, we examined the genetic profiles of locally recruited inland bay oysters, nearby wild Delaware Bay oysters, and the disease-resistant hatchery strain to evaluate the potential impact of the gardening program. The Inland Bay samples showed genetic profiles similar to the wild Delaware Bay population, suggesting an extant resident population providing a consistent larval supply, potentially clouding the contribution of the hatchery-spawned gardened oysters.

Disseminated neoplasia (DN) is a form of cancer in bivalve molluscs that can be transmissible between individuals and in some cases across species. Neoplastic cells are highly proliferative, and infection is usually lethal. Commercially valuable bivalve species (mussels, cockles, softshell clams, and oysters) are affected by outbreaks of DN, making disease diagnosis and mitigation an important issue in ecological restoration efforts and aquaculture. Basket cockles (Clinocardium nuttallii) are native to the North American Pacific coast from California to Alaska. Recent concern from some Coast Salish Tribes regarding an observed long-term decline in basket cockle populations in Puget Sound, WA has increased interest in monitoring efforts and subsequent collection for aquarium-reared broodstock. Disseminated neoplasia was detected in Puget Sound basket cockle populations, delaying aquaculture efforts so that potential broodstock could be assessed for the presence of DN. This study details a minimally invasive, inexpensive, nonlethal method for high-throughput screening for DN in adult basket cockles. The hemolymph smear screening method to diagnose DN in C. nuttallii can be applied at field sites at low financial cost. Results of the hemolymph smear technique were validated against whole tissue histology, the standard method for DN diagnosis. Due to the similar cellular morphologies of DN in different bivalve species, it is proposed that hemolymph histology can likely be applied for diagnosing DN in other bivalves.

Pearl culture in Fiji relies on a supply of pearl oysters obtained through the strategic deployment of spat collectors. Although the design and deployment of spat collectors aim to maximize the recruitment of pearl oysters (Pinctada and Pteria spp.), this activity incidentally captures many other bivalves as bycatch. This study explored whether tropical rock oysters (specifically Magallana bilineata and Saccostrea spp.) were present and sufficiently abundant as bycatch from pearl oyster spat collectors, to support additional commercial opportunities. The results showed that the absolute (0.7 ± 2.1 spat collector^–1) and proportional (2.9% of all bivalves) abundance of these taxa was very low, which would limit oyster harvest in meaningful quantities. Although the prospect of creating additional revenue streams from bycatch could be seen as an incentive to on-grow and sell tropical rock oysters despite their low abundance, it is argued that greater benefit would come from prioritizing activities related to pearl oysters and associated downstream products such as mabé pearl, shellcraft, and pearl-meat production. Ultimately, existing spat collection activities within the cultured pearl sector did not have the anticipated potential to support supplemental aquaculture of tropical rock oysters.

Antilipopolysaccharide factors (ALF) are antimicrobial peptides in the humoral defense mechanism in shrimps, with broad activity against bacteria, viruses, and fungi. Several ALF and their isoforms have been reported in decapod crustaceans, showing structural and functional differences. This work describes the Litopenaeus vannamei antilipopolysaccharide factor 5, initially found in a hepatopancreatic transcriptomic database. The LvALF5 gDNA sequence is 1,619 bp, with a complete mRNA sequence of 934 bp. The ORF encodes a 124 amino acids sequence, including a 26 amino acids signal peptide and 98 amino acids mature peptide, highly similar to the Litopenaeus stylirostris ALF peptide sequence (96%). This peptide shows main differences in the LPS-binding domain, having only 2 positive amino acids conserved. The evolutionary analysis shows that LvALF5 is in cluster 2, which indicates that structurally it has characteristics of the other white shrimp isoforms. LvALF5 is highly expressed in healthy shrimp hemocytes, 20-fold more than in other tissues. It is up-regulated during bacterial and viral challenges. Inhibition experiments using a recombinant LvALF5 show a more efficient antibacterial activity against Vibrio parahaemolyticus than Staphylococcus aureus bacteria strains.

Ever since the Taiwanese government introduced the giant freshwater shrimp (GFS) (Macrobrachium rosenbergii) to Saint Lucia in the 1980s, its production has increased significantly. This production although has contributed significantly to the well-being of local farmers and the gross domestic product of Saint Lucia, its productivity is however threatened by challenges such as scarcity and high cost of live feed (nauplii from Artemia sp.), poor funding, insufficient and substandard hatcheries, poor infrastructures, high mortality rate of postlarvae due to adverse climate, diseases, and knowledge gap between researchers and local farmers (inadequate extension services). Among these challenges, the total reliance on scarce and expensive live feeds (nauplii from Artemia sp.) is the most crucial . Therefore increasing production costs is of the utmost importance and requires urgent attention. Although it would not be possible to completely substitute nauplii, combining it with other inexpensive, readily accessible, and locally sourced feed components is paramount. As evident in postlarvae-producing countries, alternative diets have been compounded and fed in place of nauplii to lower production costs without any negative impact on the general performance of GFS postlarvae being recorded. This could be adopted and replicated in the production of GFS postlarvae in Saint Lucia because most of the ingredients such as powdered fishmeal, duckweed, moringa leaf, freshwater daphnia and rotifers, and microalgae are readily available and accessible within the country.

Incirrate octopodes are the only cephalopods that exhibit transient epidermal structures called Kölliker's organs (KO) in the early development stages. This work describes for the first time the histological formation process of these organs during embryonic development and of the paralarva of Octopus hubbsorum Berry, 1953, as well as their morphological characteristics. Egg masses were collected in the Gulf of California and the species was identified by molecular analysis. The histological formation of KO starts when the funnel is fully developed and ends when the embryo is ready for hatching. Differences were observed compared with the only complete histological description of KO currently available. In O. hubbsorum, the basal membrane wraps the basal and lateral cells until the KO erupts, and the cell conformation of KO (binding with muscle cells) is completed when the mantle covers the ventral margin of the funnel and chromatophores are visible. The KO of O. hubbsorum are of intermediate size and show a higher density compared with other species, especially in the arms. The cellular degradation of KO is reported here for the first time; KO disappears within 48 h posthatching, contrary to observations reported for other species in which these organs last more than 30 days, even before settlement. It is concluded that in this species, KO probably facilitate hatching or are an evolutionary reminiscence, and it is ruled out that they facilitate buoyancy before settlement.

Subsistence and small-scale aquaculture are important economic and livelihood activities in developing countries including the Philippines. Community-based aquaculture of the sea cucumber (sandfish, Holothuria scabra) has been promoted as a sustainable supplemental livelihood activity among rural coastal communities, however, uptake remains poor and the economic viability of communal sea cucumber ranching has yet to be demonstrated. This study assessed the potential of sandfish farming as a supplemental economic activity for established small-scale grouper (Epinephelus coioides) farmers in Bolinao, northwestern Philippines, on the assumption that the adoption of sandfish culture may be more successful when attempted by established aquaculture farmers. The average growth rate of sea cucumbers reared in the pens without groupers was highest at 2.0 ± 0.4 g day^–1 during the first 50 days of rearing. By 141 days, sandfish reared without grouper attained an average weight of 234.7 ± 2.2 g. The highest growth rate of sandfish reared with groupers was recorded at 4.2 ± 1.8 g day^–1 after 19 days of rearing in the coculture pens whereas the lowest growth rate (-0.73 ± 0.1 g day^–1) was recorded by day 128. Additionally, the growth performance and survival of groupers reared with sandfish were high. From an initial average weight of 141.3 ± 35.2 g, groupers attained an average weight of 340 ± 27.8 g and 393.8 ± 17.8 g after 102 and 163 days of rearing, respectively in the grow-out pens. Farmers generated an estimated income of PHP 7,200 and PHP 29,015 from the sale of dried sea cucumbers and live groupers, respectively. Results indicate that the adoption rate, economic viability, and sustainability of sandfish mariculture may increase when technology is transferred to farmers already engaged in aquaculture. More broadly, the integration of sandfish culture with that of fish and other culture species, such as molluscs, utilizes the ability of sea cucumbers to remediate nutrient-rich sediments, improving sustainability.