The continental shelf of the United States was once the preserve of commercial fishermen. This is no longer the case. The exclusive economic zone is increasingly becoming the focus of other economically powerful, sometimes incompatible uses, including green energy, shipping, communications, mining, military exclusion zones, and conservation regions. These other uses generally have fixed boundaries. The distribution of fished species moves in relation to warming of shelf waters, presenting challenges to both federal regional fishery management councils and industry alike. There is need for continued engagement between user groups with respectful use of guiding science and legal structure to ensure reasoned access for all, and stability for economies that are reliant on ocean shelf resources, including the fishing industry.

Shell planting to enhance oyster recruitment and habitat in Delaware Bay, NJ was reinitiated in 2005 with 3 y of federal funding. Since then, annual plantings of locally available surf clam and ocean quahog shell have been funded by the oyster fishery. The cured shell is deployed directly onto sites already containing commercially viable numbers of market-sized oysters in areas that are routinely fished sustainably. The locations targeted to receive shell plants vary and are selected to provide the greatest benefit throughout the fished reef tract. Annual sampling that included shell plants from 2005 through 2017 permitted evaluation of their performance. New oysters set and survive preferentially on newly planted shell during the first season and later at the same level as native shell for at least 10 y so that the benefit of once-added shell is retained for over a decade. Recruitment to shell plants enhances “good” sets and makes a critical difference during years of “poor” set. Plant substrate, now with oysters of its own, significantly outperforms native substrate in recruitment and survival of oysters in the second and third years post-planting, with enhancement declining exponentially over the first 4 y. An estimated half-life for this decline is just under 1 y. Beyond 3 y, the plant-based substrate continues to perform at least as well as native substrate. Size–frequency analysis shows that first-year oysters on planted substrate are larger than those on native substrate and that this difference carries through the fourth year of a plant. The volume contributed by live and dead oysters on planted substrate increases over the first 5 y until the contribution to the reef from planted substrate volume matches that of native substrate, thus carrying the enhancement forward through time. Annual survey data from the first 4 y of shell plants show that on seven of eight beds, live plus dead oyster density (number m^–2) was up to 2.8× greater on planted sites than on non-planted sites. Change in density averaged positive over time on both planted and non-planted sites but was greater on planted sites. Shell plants on beds in the Delaware Bay fishery provide 3–4 y of enhanced oyster productivity and continue to double the local native substrate productivity as they age, maintaining an active and productive fishery.

The geographic boundaries of many important habitat-building shallow estuarine oyster (Family Ostreidae) species are poorly understood, especially in subtropical and tropical waters. These keystone species often have extensive historical and extant ranges, in part because of their ability to adapt to diverse environmental conditions and the transfer and introduction of a few species worldwide for aquaculture production. In addition, oysters exhibit morphological plasticity additionally confounding species identification and taxonomy. Molecular techniques have led to significant improvements in oyster systematics and taxonomy but have not been applied to oysters from many tropical regions, including the coastal areas of the Indian Ocean such as Bangladesh. Because species' identification based on morphological traits alone, in this case primarily shell characteristics, were inadequate, phylogenetic analyses of mitochondrial cytochrome oxidase subunit I gene fragments was also done to confirm the identity of oyster specimens collected from Bangladesh coastal waters. Phylogenetic analyses of collected oyster samples confirmed the two monophyletic subclades of the Ostreidae family Crassostrea and Saccostrea, and five oyster lineages from the region of Bangladesh were identified: Crassostrea gryphoides, Crassostrea belcheri, Saccostrea cuccullata lineage B, S. cuccullata lineage F, and Saccostrea mordax. A new addition to the list of Crassostrea species, C. belcheri was found in Bangladesh, but C. belcheri, C. gryphoides, and S. cuccullata are considered “common” species in the neighboring states of India and Myanmar indicating a widespread distribution of these species along the entire coast of the Bay of Bengal. However, S. mordax, is a new record for the Bay of Bengal region including the coastal waters of Andaman and Nicobar Islands, and thus extends the geographical distribution of this species.

Suspension-feeding bivalve molluscs have evolved a highly effective mechanism for particle discrimination, which allows them to process efficiently the material to which they are exposed. The mechanisms controlling this preingestive sorting process have been described as either passive or active. Evidence of a passive selection mechanism has been demonstrated in several species of suspension-feeding bivalves. In contrast, to date there has been no evidence that active selection mechanisms underlay particle selection in bivalves, although the possibility of such mechanisms has been hypothesized numerous times. The present study was designed to examine active selection on the gill of the eastern oyster Crassostrea virginica. The gill was chosen for study because in oysters this organ is involved in particle selection. Two in vivo assays were designed in which the gill was exposed to dissolved cell exudate or extracts from the microalga Tetraselmis chuii, and the transport of polystyrene microspheres (25 µm) by the frontal cilia of the ordinary filament quantified by means of video endoscopy. Results demonstrated that the addition of exudates or extracts of T. chuii cells had no significant effect on the percentage of particles being transported dorsally (likely ingested) or ventrally (more likely rejected), and no differences in the number of particles in the ventral groove between control and experimental treatments. Results of follow-up experiments using covalently bound neoglycoproteins commonly found on cell surfaces of microalgal species demonstrated differences in transport of captured microspheres (10 µm, carboxylated) depending on the sugar type. Although chemoreception cannot be completely ruled out, these findings further indicate that physicochemical properties of particles, and not an active behavioral or physiological response (i.e., chemoreception of dissolved metabolites) by the animal, mediate particle selection in oysters.

Oysters are one of the most important groups in terms of production by fisheries and aquaculture in developed countries of temperate areas. In subtropical and tropical regions, oyster species are economic important resources but many are exploited in an artisanal way and without a legal framework, what can result in overexploitation. One alternative is aquaculture but biological information and development of techniques for local species are required. Therefore, this review organizes information on subtropical and tropical oysters from the American Pacific addressing on their fisheries, cultivation, management, and conservation. The study focuses on two native species Striostrea prismatica and Crassostrea corteziensis and two introduced species Crassostrea gigas and Crassostrea sikamea having more information and technological development. Fisheries and their problems are analyzed and some alternatives are proposed to improve their organization and preservation. The most important aquaculture technological aspects are described including the processes for the production of spat in hatcheries and the techniques used for field cultivation. Biological, physiological, and ecological studies as well as the implementation of legal measures are required to administrate, restore, and recover fisheries. The aquaculture of C. corteziensis and S. prismatica presents great advances but the other native species require the development of technologies to progress in many aspects. The production of C. sikamea is concentrated in one region without expecting further expansion, and the cultivation of C. gigas can be recreated on various sites and expanded to estuaries in tropical areas.

Ocean quahogs (Arctica islandica) are the longest lived bivalve on Earth. Individuals on the deep continental shelf off Georges Bank can survive for centuries, and in the colder, boreal waters of Iceland, ages over 500 y can be reached. Ocean quahog landings in the United States represent a $24 million industry, yet assessment models operate with no age data because of the substantial sample size required to develop adequate population age distributions for such a long-lived species, the unknown error associated with age estimates, and the extensive time and financial investment required to create production-scale age datasets. Inclusion of age data for this species requires precision metrics to evaluate aging uncertainty such as percent agreement, percent error, coefficient of variation, and tests of bias. To move forward using error-validated age-composition data, a 3-fold error protocol was developed using a large dual-reader dataset (n = 610) from Georges Bank. First, a proxy age-validation study was performed to corroborate an aging method, followed by error evaluation in the context of age-reader bias, precision, and error frequency. Error thresholds were established for each of the three error methods. Georges Bank samples ranged from 33 to 261 y of age and met the predetermined error thresholds for bias (conditionally because of significant and nonsignificant results), precision (average coefficient of variation less than 7%), and error frequency (less than 10%). Consequently, age estimates were deemed acceptable to support age frequency analyses. Precision and bias error were greatest for the youngest animals and, in the context of age-reader bias, error rates were higher for young male ocean quahogs than for young females. Improved age validation of young, sex-differentiated A. islandica will constrain aging error and guide refinement of both aging and age-error protocols.

During the past 2–3 decades, the spatiotemporal distribution of Mytilus spp. in coastal waters of the North Atlantic has changed considerably. In general, reduced abundances of Mytilus are observed, but there is a great degree of local variation, and some areas are also experiencing recovery after declining events. In this review, hypotheses regarding the causes behind the changes are presented with focus on a Swedish perspective. Excessive exploitation of mussel banks combined with direct and indirect effects of climate change are most probably the main drivers of Mytilus spp. decline in large parts of the North Atlantic. On the Swedish west coast, the wild stocks have disappeared despite no overfishing. Paradoxically, they thrive in mussel farms and on other non-demersal substrates. Changes in predation from, for example, increased wintering populations of eiders (Somateria molissima; 10-fold) and green crabs (Carcinus maenas; 3-fold), alteration of natural substrates elicited by eutrophication, and exacerbated by climate change (increased sea surface temperature, precipitation and extreme weather events) are most likely the key factors for the decline. Most anthropogenic stressors may not be decisive by themselves, but combined effects can potentially be fatal to Mytilus spp. adults and larvae.

The Queensland saucer scallop Ylistrum balloti fishery is a significant component of the Queensland East Coast Otter Trawl Fishery. In 1996, the saucer scallop stock collapsed, and by 2006, had partially recovered. In 2016, the stock again collapsed, when it was declared, and remains, overfished. In response to the collapses, fishery managers implemented an annual fishery-independent trawl survey of scallop abundance, although funding for the survey has been inconsistent. This study examined 8 y of discontinuous fishery-independent scallop trawl survey data (1997 to 2000, 2017 to 2020). A two-stage approach was introduced to firstly calibrate catch rates for differences between survey vessels for each year, and then derive adjusted mean densities (number ha^–1) for the 0+ and 1+ scallop age classes and total scallops, for each year and strata. Quasi-Poisson generalized linear models were used for both stages. Results showed that adjusted mean total scallop densities declined by approximately half from the early survey years (1997 to 2000) to the later survey years (2017 to 2020). Adjusted mean total scallop density and adjusted mean densities of the 0+ and 1+ age classes were lowest in 2020. The 1+ age class numerically dominated survey catch rates.

Northern abalone are an important component of the intertidal and subtidal ecosystems of the Pacific Coast. This research was carried out to test the feasibility of utilizing underwater stereo-camera technology to conduct surveys to estimate the abundance and size structure of northern abalone populations. Consistent with other studies, depth and substrate both impacted the density and length of northern abalone, and provided a basis for implementing stratification strategies for density estimation. The average deployment took about 18 min and resulted in 47 useable image quadrats. The estimated time to analyze each frame was about 3 min, translating into ∼2.5 h of processing time per deployment. The precision of the resulting density estimates was high (relative error ∼0.22–0.37 depending on the method used for stratification) and could be improved by increasing the number of study sites to 35 or greater. The pooled density of northern abalone was estimated as 1.07 individuals/ m^–2 (SE = 0.21) and the mean length of northern abalone across the study sites was 67.7 mm (SE = 0.08). Future stereo-camera surveys could be used as a cost-effective supplement to self-contained underwater breathing apparatus diver surveys to increase the precision of abundance and size estimates of northern abalone populations.

Ontogenetic allometric analyses can provide novel insights into aspects of evolution, ecology, and conservation. The present study exploits a model sea urchin to evaluate the ontogenetic allometry of skeletal defense and feeding efficiency. Individuals of Lytechinus variegatus were sampled from St. Joseph Bay, FL, and a range of different-sized late juvenile to adult individuals were weighed, measured, and dissected into skeletal components. Skeletal defense was evaluated by examining whole-body wet mass versus primary spine density (number/cm²), length (mm), breakage strength (N), and magnesium calcite levels (%). Feeding efficiency was indirectly inferred from the relationship between whole-body wet mass versus whole lantern dry weight and magnesium calcite content. It was found that between the late juvenile to adult growth phase, L. variegatus displays nonlinear and isometric scaling between body size and various metrics of skeletal spine defense. Intriguingly, most metrics of spine defense against predators displayed a nonsignificant, body-size-independent relationship, indicating L. variegatus invests heavily in spine defenses at an early age. In contrast, hyperallometric scaling best described the relationship between body size and lantern size (feeding efficiency) reflecting the potential importance of elevating food intake with increasing age.

Knowledge of juvenile recruitment (defined here as the quantitative addition of early benthic life stages to a local population) is important for conserving heavily harvested species and their critical habitats. Stone crabs (genus Menippe) are commercially and ecologically important throughout the Gulf of Mexico nearshore waters off Florida, but very little is known about their recruitment. Using standard commercial stone crab traps, megalopal and postsettlement juvenile (collectively, young-of-the-year, “YOY”) stone crabs were sampled at multiple spatial scales and for multiple stone crab generations to characterize geographical, seasonal, and interannual variation in their distribution and relative abundance (numbers collected on traps) in the Gulf of Mexico off peninsular Florida and north of the Florida Keys (the “Florida Gulf”). The influences of potentially relevant oceanographic and biological variables [temperature, salinity, benthic community on the traps (trap fouling community), depth, distance from shore] on YOY stone crabs were investigated at locations distributed throughout the study area. Trap fouling communities had never been analyzed in detail prior to this study; an importance index was developed to quantify the seasonality, commonality, and density of the fouling communities and organisms composing the communities. Continuous, long-term data from the Tampa Bay location allowed investigation of the effects of biological relationships [relative abundance of female Menippe carrying eggs (ovigerous), occurrences of red tide (Karenia brevis, a toxic dinoflagellate) blooms] and meteorological events [tropical cyclones, El Niño Southern Oscillation (ENSO) occurrences] on temporal patterns of variation in recruitment. High relative abundances of YOY stone crabs were collected off peninsular Florida from dense, complex benthic biota that grew on crab traps located off large, pristine estuaries in relatively turbid water less than 5 m deep, where salinity ranged 24–36 and water temperature averaged 29°C–32°C. Two major recruitment locations, stable through decades, consistently accounted for approximately 50% of the YOY stone crabs collected; two secondary recruitment locations similarly accounted for another 25%. Relative abundance of YOY stone crabs was highest nearshore at the major recruitment locations, particularly during years of high relative abundance. Approximately 65%–75% of the recruits were collected August to October; however, the timing of both peak relative abundance and lowest relative abundance shifted to later in the year as latitude decreased. Patterns of change among months in relative abundance differed among locations within years and among years within locations. Water temperature, salinity, and trap fouling community were the important determinants of temporal and spatial variation in YOY stone crab relative abundance; depth and distance from shore were also important in areas where they varied notably among stations within locations and across broader expanses of the study area. At Tampa Bay, a sharp increase in relative abundance of ovigerous females in spring was followed by a similarly sharp increase in YOY stone crab relative abundance (principally stage 3–5 crabs) 3 mo later; whereas a sharp decrease in ovigerous female relative abundance in autumn was followed by a similarly sharp decrease in YOY stone crab relative abundance 1 mo later. Coincidence of the normal autumnal decrease in YOY stone crab relative abundance with red tides and tropical cyclones prevented assigning clear relationships between seasonal change in relative abundance and these potential external influences. Annual decreases in relative abundance were significantly related to the occurrence of tropical cyclones that came near Tampa Bay during the previous year. Twice, confluences of multiple hurricanes, timely red tides, and ENSO events were followed by nearly complete, 1- to 2-y recruitment collapses. In contrast, a single meteorologically and oceanographically highly anomalous year coincided with exceptionally high abundances of both YOY and ovigerous female stone crabs. A relationship between YOY stone crabs and subsequent fishery harvest was not evident, possibly due to a variety of fishery practices. Because stone crabs are subjected to intense fishing pressure throughout the Florida Gulf, the YOY stone crab recruitment grounds and their associated estuaries should be protected from the effects of development, agriculture, aquaculture, and commercial and recreational crabbing.

An introduced population of European green crabs Carcinus maenas (Linneaus, 1758) was established in San Francisco Bay prior to 1991. Their subsequent northern range expansion is linked to larval transport in the Davidson Current to northern California (1993), southern Oregon (approximately 1996), the Oregon and Washington coastal estuaries and the west coast of Vancouver Island, British Columbia (1998). Range expansions through larval transport to the central British Columbia coast occurred before 2010, to Haida Gwaii in 2020, and into the inland Salish Sea in 2015 and 2016. Both the range expansions of C. maenas and local abundance are strongly linked to oceanic factors during their larval development. These include (1) strong northward flow of coastal waters during winter; (2) warm surface water temperatures (>10°C for larval development); and (3) coastal circulation patterns that keep larvae close to shore, where they can be carried by wind and tidal currents into estuaries and embayments to settle. The strongest year classes and largest range expansions occurred during the last two major El Niño events. The 1997 to 1998 El Niño resulted in the colonization of embayments in Oregon, coastal Washington, and on the west coast of Vancouver Island, while the El Niño of 2015 to 2016 and the Pacific Warm Blob are linked to the range expansion into the Salish Sea. More local range expansions along the west coast of Vancouver Island, to the central British Columbia Coast, to Haida Gwaii, and inside the Salish Sea occurred during non-El Niño years.

The ability to reliably produce small blue crabs through aquaculture allows for expanded development of the soft crab industry in the United States with little or no impact to the wild fishery. Research on soft crab aquaculture in Mississippi is based on a three-phase approach: hatchery production of megalopae, salinity acclimation and grow-out of early juveniles in raceways, and final growth to shedding crabs in shallow ponds. Limited access to quality salt water or to hard water aquifers in Mississippi, coupled with the high cost associated with salting ponds led to the development of techniques to produce peeler crabs in reduced salinities. Hatchery success has been variable (average 14%) with significantly lower production following the Deepwater Horizon Oil disaster in 2011. Protocols for hatching and rearing of larvae and methods developed for intermediate grow-out and salinity acclimation of juveniles are reviewed as well as the adaptation of a folk-fishing technique to harvest peelers from the ponds. Economic studies defined production parameters necessary to reduce costs and attain profitability in low salinity (1) pond culture. Increased survivorship of larvae and juveniles during the hatchery, intermediate grow-out and pond phases and stocking density in ponds were key determinants of profitability. Simulation results at various stocking densities indicated that production of shedding crabs could be economically feasible. Although individual culture runs in the current research approached survival rates that would ensure profitability, routine survivorship is currently below the projected estimates necessary to achieve that goal.

The color of aquatic animals plays an important role in consumer acceptability and perceived quality. In a previous study, a red claw crayfish Cherax quadricarinatus strain with steady and hereditary shell color of blue was selected. To evaluate the potential value of this strain in crayfish culture, the growth performance, carotenoid content, and temperature tolerance of two crayfish strains (shell color; blue and blue-green) were conducted. After the 56-day rearing period, blue crayfish showed higher feed intake and growth rate, but lower survival than blue-green crayfish. Astaxanthin was the main pigment observed in the carapace of both strains, and the content of astaxanthin in blue crayfish was 18.62 mg/kg of wet weight, which was significantly lower than that of astaxanthin in blue-green crayfish (83.23 mg/kg of wet weight). The 7-day survival of two crayfish strains less than 34°C was 100%, and blue-green crayfish showed stronger tolerance to high water temperature exposure (35°C–38°C) than blue crayfish. Furthermore, after high temperature stress, lower activities of superoxide dismutase and catalase, and higher malondialdehyde in the hepatopancreases of blue crayfish were observed than those in blue-green crayfish. This study provides important information for future breeding programs for the red claw crayfish.