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Aquaculture is the fastest growing food production sector in the world and is quickly diversifying. In the Northwest Atlantic, interest in sea scallop (Placopecten magellanicus) (hereafter scallop) aquaculture has grown substantially. However, technical and economic challenges have hindered industry growth. We conducted bioeconomic simulations for various sized farms that targeted either live “whole” scallops or the shucked adductor muscle “meat.” The majority of farms selling whole scallops were profitable. However, all farms selling meats generated negative returns. Labor made up the greatest portion of costs in model simulations and increased linearly with farm size, representing a significant bottleneck. Whole scallop farm value was most sensitive to changes in (1) market price and (2) time to market. Our analysis suggests four strategies to increase farmed scallop production in the Northwest Atlantic: (1) mechanize low density net culture, (2) optimize net stocking densities, (3) build site selection tools, and (4) invest in consumer education, end-markets, and biotoxin testing for whole scallops. The sector will require a combination of regulatory, industry, and research cooperation to overcome these pressing challenges, but holds the potential to profitably diversify the bivalve aquaculture industry.

Large marine ecosystems (LMEs) are highly productive regions of the world ocean under anthropogenic pressures; we analyzed trends in sea surface temperature (SST), cloud fraction (CF), and chlorophyll concentration (CHL) over the period 1998–2019. Trends in these parameters within LMEs diverged from the world ocean. SST and CF inside LMEs increased at greater rates inside LMEs, whereas CHL decreased at a greater rates. CHL declined in 86% of all LMEs and of those trends, 70% were statistically significant. Complementary analyses suggest phytoplankton functional types within LMEs have also diverged from those characteristic of the world ocean, most notably, the contribution of diatoms and dinoflagellates, which have declined within LMEs. LMEs appear to be warming rapidly and receiving less solar radiation than the world ocean, which may be contributing to changes at the base of the food chain. Despite increased fishing effort, fishery yields in LMEs have not increased, pointing to limitations related to productivity. These changes raise concerns over the stability of these ecosystems and their continued ability to support services to human populations.

Small-scale fisheries, which are often distributed over large spatial scales and occur in rural settings, tend to lack financial resources and capacity to conduct research on local issues. One approach to overcome this challenge is to use relatively inexpensive environmental monitoring methods with stakeholder engaged science and participatory modeling. Here, we present a case study focused on water pollution impacts and tidal circulation in a mid-coast Maine (USA) estuary to develop a simulation model and a partnership approach that can support soft-shell clamming communities to effectively address water quality, namely bacteriological closures of mudflats. We deployed multiple low-cost drifter buckets, Lagrangian flotation devices that measured surface current speeds and provided validation data for a hydrodynamic model based on finite volume community ocean model (FVCOM). The drifter buckets resolved the influence of wind, tidal currents, and bathymetry on surface water circulation patterns between the main channel and adjacent mudflats, highlighting the impact of cross-estuary winds during slack tides on potential bacterial transport. We calculated residence time using the validated FVCOM model: in the prohibited area (~ 2.5 days), and the conditional area (~ 0.5 days). This information has already influenced local management decisions and helped shape new conservation projects. In addition to contributing new understanding about tidal patterns in this coastal region, our novel methodology of combining field techniques, FVCOM modeling, and stakeholder engagement helps show how engaged research approaches can improve regulatory outcomes for small-scale fisheries while also protecting public health.

The Magnuson–Stevens Fishery Conservation and Management Act mandates US fisheries minimize adverse effects of fishing on essential fish habitat (EFH). The Gulf of Maine (GoM) American lobster (Homarus americanus) fishery is the most valuable US fishery and can deploy more than three million traps annually. To date, the impact of this fishery on benthic EFH has not been addressed quantitatively. To evaluate the impact of the GoM lobster fishery on EFH, we incorporated lobster fishing effort into a model linking habitat susceptibility and recovery to area impacted by fishing gear: the Swept Area Seabed Impact model. Impact to EFH was localized along the coast and highest along midcoast Maine. Upwards of 13% of the benthos is in the process of recovery, but between 99.92% and 99.96% of initially affected habitat fully recovers. These estimates suggest that lobster fishing negligibly contributes to accumulation of EFH damage in the GoM due to the expansive area fished and the small footprint of each trap. Identifying areas of persistent impact is crucial in developing effective fisheries management for critical marine habitats.

In-water remediation strategies, implemented in conjunction with traditional watershed management, could help minimize the impact of excess nitrogen (N) on marine ecosystems. Seaweed farming and harvesting may have potential as in-water N remediation tools in the Western Gulf of Maine (WGoM), but more understanding of the associated spatial and temporal variability is needed. In this study, Saccharina latissima was grown and collected from four WGoM sites in 2016–2019 and analyzed for tissue N content and stable isotopes. The source of N taken by the kelp was not obvious from monthly nor interannual mean δ15N measured in the kelp tissue, and the interannual means were significantly different between sites in the same bay. Mean kelp biomass across all sites and years was 9.84 (± 2.53)–14.84 kg (wet weight) per meter of longline at time of harvest (late May–early June). Nitrogen content of the S. latissima tissue was 1.04–3.82% (± 0.22) (dry weight) throughout the growing season and generally decreased through the spring. Using these results, we estimated that harvesting a hypothetical hectare of S. latissima after 6–7 months of cultivation in the WGoM would have the potential to remove 19.2 (± 4.8)–176.0 (± 7.7) kg N ha−1, depending on the density of longlines. The wide ranges of both biomass at time of harvest, and δ15N and percent N content in the kelp tissue, highlight the need for site-specific pilot studies, even within a specific bay, prior to implementing kelp aquaculture as an in-water tool for N bioextraction.

Coastal and estuarine food webs receive large inputs of both autochthonous and allochthonous detritus, which serves as an important dietary input for a variety of detritivorous and omnivorous organisms. Surfactants, which aid digestion by solubilizing hydrophobic lipids, are found in the gut-fluids of many fish and invertebrate consumers. To develop a biomimetic assay to explore how source of primary production and age may affect the bioavailability of nutritional lipids from detrital food sources, we assessed the capacity of a model surfactant, sodium taurocholate (STC), to solubilize fatty acids from three primary producers, a haptophyte (Isochrysis galbana), a rock-weed (Ascophyllum nodosum), and a marsh grass (Spartina alterniflora). Comparing lipids solubilized by a constant concentration of STC to traditional Folch-extracted yields, we assessed relative bioavailability of nutritional lipids from fresh and decayed material of each primary producer. We focused on the solubilization of storage triacylglycerols (TAG) and the fatty acid constituents of all lipids (FA). With a temperature of 5 °C, 28.7 mM STC solubilized 44 ± 12% of total FA from S. alterniflora and about half that fraction for I. galbana and A. nodosum after 15 h in the dark unstirred. In the form of TAG, STC solubilized 53 ± 19% of pure triolein as a reference and similar proportions from S. alterniflora (56 ± 19%) and I. galbana (48 ± 2%) but only 9 ± 3% from A. nodosum. Both approaches (TAG and FA) thus show significant differences in bioavailability among these three sources. Two months of decay had inconsistent effects on overall lipid yields but substantial effects on composition. Degradation led to decreased total phospholipids and long-chain polyunsaturated FA and increased break-down products (free FA and diacylglycerols), saturated and monounsaturated FA, and bacterial FA. Lower FA bioavailability and reduced degradation rates in A. nodosum may be due to its higher polyphenol and alginate concentrations. Although we mimicked only one component of the digestion process of lipids, this study represents a first step in developing a biomimetic assay to assess the relative bioavailability of nutritional lipids.

Many studies have examined the vulnerability of calcifying organisms, such as the eastern oyster (Crassostrea virginica), to externally forced ocean acidification, but the opposite interaction whereby oysters alter their local carbonate conditions has received far less attention. We present an exploratory model for isolating the impact that net calcification and respiration of aquacultured eastern oysters can have on calcite and aragonite saturation states, in the context of varying temperature, ocean-estuary mixing, and air-sea gas exchange. We apply the model to the Damariscotta River Estuary in Maine which has experienced rapid expansion of oyster aquaculture in the last decade. Our model uses oyster shell growth over the summer season and a previously derived relationship between net calcification and respiration to quantify impacts of net oyster calcification and gross metabolism on carbonate saturation states in open tidal waters. Under 2018 industry size and climate conditions, we estimate that oysters can lower carbonate saturation states by up to 5% (i.e., 0.17 and 0.11 units on calcite and aragonite saturation states, respectively) per day in late summer, with an average of 3% over the growing season. Perturbations from temperature and air-sea exchange are similar in magnitude. Under 2050 climate conditions and 2018 industry size, calcite saturation state will decrease by up to an additional 0.54 units. If the industry expands 3-fold by 2050, the calcite and aragonite saturation states may decrease by 0.73 and 0.47 units, respectively, on average for the latter half of the growing season when compared to 2018 climate conditions and industry size. Collectively, our results indicate that dense aggregations of oysters can have a significant role on estuarine carbonate chemistry.

In fisheries acoustics, the target strength (TS; dB re m2) is used to compute biological metrics such as fish biomass and density. The TS is challenging to characterize because of its stochastic relationship with fish physiology, orientation, depth, species assemblage, and size distributions. These challenges were addressed by using acoustic and physical samples of fish from trawls in the Penobscot River Estuary, Maine. The pelagic species assemblage was dominated by clupeids and osmerids. The TS was measured from individual fish using single target detection and echo tracking algorithms. An expectation–maximization algorithm was applied to identify the components of the TS and total length (TL; cm) distributions for the mixed species assemblages. Regressions were used to estimate the parameters of TS = α log10(TL) + β. The parameters, α = 31.2 [standard error (SE) 0.87] and β = –79.6 (SE 0.93), were similar to published studies from these species, but our slope and intercept were higher than those in studies from freshwater and lower than those from marine systems. These results suggest that acoustic surveys in estuaries with mixed species assemblages should carefully consider alternatives to “standard” TS-fish length equations. These results will provide necessary parameters to allow for interpretation of acoustic survey data from systems with a similar composition of pelagic species.

Quantifying change after large habitat restoration efforts is critical to assessing the effort's success. After river restoration activities, fish abundance is expected to increase and also fluctuates naturally by season and with environmental conditions. A side‐looking hydroacoustic system was used to estimate fish abundance in the Penobscot River, ME, from 2010 to 2016 during predam (2010–2013) and postdam (2014–2016) removal years during nonice periods. Automated data processing enabled continuous abundance estimates from fish tracks. A threefold increase in mean fish abundance was recorded after dam removal. A fourfold increase in median fish abundance occurred in the fall relative to spring and summer of the same year, regardless of dam presence. Interannual fish abundance in every season monitored increased at least twofold after dam removal. We related variability in fish abundance to tide, discharge, temperature, diurnal cycle, daylength, moon phase, and restoration activities (focusing on dam presence). Daylength corresponding to the fall and summer was the most important indicator for higher fish abundance. Fish abundance was generally greatest in the fall during outgoing tides at night, with lesser peaks occurring during the month of June at night. Before dam removal, fish abundance peaked when water temperature was less than 9.25°C, at night, during outgoing tides. After dam removal, fish abundance peaked when daylength was less than 11.3 hr, at night, during outgoing tides, when water temperature was above 4.56°C and no full moon was present. Peak fish abundance occurred during only 0.02–2.3% of the total time sampled. The threefold increase in fish abundance recorded after dam removal was observed despite yearly stocking efforts of adult alewife increasing 24% in postdam removal years. Finally, parallel studies of fish presence in the Penobscot River were used to compare the utility of this method as an indicator of fish abundance in response to dam removal.

The expansion of oyster aquaculture relies on identifying and utilizing estuarine conditions that enable the economical production of a filter-feeding species. Detrital complexes may provide nutrition to oysters between beneficial phytoplankton blooms. The upper Damariscotta estuary is the most successful aquaculture site in Maine for eastern oysters Crassostrea virginica. To examine the impact of labile detrital protein detected in this estuary on oyster growth, we monitored enzymatically hydrolysable amino acids (EHAA, labile protein), chlorophyll a (chl a) and particulate organic matter (POM) biweekly, along with continuous monitoring of temperature, turbidity, and chl a by a Land/Ocean Biogeochemical Observatory (LOBO) buoy. Oyster feeding and growth were measured biweekly in the field and in a controlled laboratory experiment to assess responses to detrital proteins. Phytoplankton alone provided insufficient nutrition for field oysters based on measured POM absorption rate, suggesting a role for additional organics such as detritus in oyster nutrition. Oysters readily absorbed phytodetritus under laboratory conditions and cleared phytodetritus with high efficiency under field conditions. Bioavailable EHAA in the field was nearly completely absorbed by oysters, unlike POM, and seasonal EHAA concentrations correlate well with field growth rates. These indications of protein limitation on oyster growth are not explained by phytoplankton, which cannot account for all EHAA, and are consistent with seasonally abundant, labile detrital protein and observed phytodetritus. Detrital protein influence on this species implies that EHAA measurements can improve aquaculture site selection, help determine nutritional carrying capacity of estuaries, and help explain clarification of water columns by these filter feeders.

Ocean warming can drive poleward shifts of commercially important species with potentially significant economic impacts. Nowhere are those impacts greater than in the Gulf of Maine where North America's most valuable marine species, the American lobster (Homarus americanus Milne Edwards), has thrived for decades. However, there are growing concerns that regional maritime economies will suffer as monitored shallow water young‐of‐year lobsters decline and landings shift to the northeast. We examine how the interplay of ocean warming, tidal mixing, and larval behavior results in a brighter side of climate change. Since the 1980s lobster stocks have increased fivefold. We suggest that this increase resulted from a complex interplay between lobster larvae settlement behavior, climate change, and local oceanographic conditions. Specifically, postlarval sounding behavior is confined to a thermal envelope above 12°C and below 20°C. Summer thermally stratified surface waters in southwestern regions have historically been well within the settlement thermal envelope. Although surface layers are warming fastest in this region, the steep depth‐wise temperature gradient caused thermally suitable areas for larval settlement to expand only modestly. This contrasts with the northeast where strong tidal mixing prevents thermal stratification and recent ocean warming has made an expansive area of seabed more favorable for larval settlement. Recent declines in lobster settlement densities observed at shallow monitoring sites correlate with the expanded area of thermally suitable habitat associated with warmer summers. This leads us to hypothesize that the expanded area of suitable habitat may help explain strong lobster population increases in this region over the last decade and offset potential future declines. It also suggests that the fate of fisheries in a changing climate requires understanding local interaction between life stage‐specific biological thresholds and finer scale oceanographic processes., Ocean warming has rapidly expanded the amount of thermally suitable bottom habitat for settling American lobster postlarvae in the Gulf of Maine. Local oceanography, coupled with nonlinear responses to warming, may have led to a demographic expansion disproportionate to the relatively small change in bottom temperature. Habitat expansion offshore may explain population increases northeastward and decreases in inshore settlement densities.

Characterizing relative temporal and spatial variations in both the living and detrital components of bivalve food is required to predict bivalve growth across environments with contrasting seston compositions. The present article describes how remote sensing can be applied for such characterization, both over large spatial scales and fine spatial resolutions (i.e., farm scale; 10's of meters), thereby providing key information for bivalve aquaculture operations and site selection, including the restoration of native species. Using natural seawater samples collected from contrasting culture sites in North America and Europe, a simple model was developed to predict the total particulate organic matter (POM) available as food to bivalves from high-resolution remote-sensing images of coastal embayments which estimate chlorophyll (CHL) and turbidity, in which CHL acts as a proxy for living organics and turbidity as a measure of total suspended particulate matter (SPM). The resulting POM derived from satellite images, along with temperature and CHL, are then used as inputs to the bivalve bioenergetic model, ShellSIM, to predict the growth of Mytilus edulis, Crassostrea virginica, and Ostrea edulis along the coast of Maine, one of the most convoluted coasts in the United States, for aquaculture site selection.

States in the Northeast United States have the ambitious goal of producing more than 22 GW of offshore wind energy in the coming decades. The infrastructure associated with offshore wind energy development is expected to modify marine habitats and potentially alter the ecosystem services. Species distribution models were constructed for a group of fish and macroinvertebrate taxa resident in the Northeast US Continental Shelf marine ecosystem. These models were analyzed to provide baseline context for impact assessment of lease areas in the Middle Atlantic Bight designated for renewable wind energy installations. Using random forest machine learning, models based on occurrence and biomass were constructed for 93 species providing seasonal depictions of their habitat distributions. We developed a scoring index to characterize lease area habitat use for each species. Subsequently, groups of species were identified that reflect varying levels of lease area habitat use ranging across high, moderate, low, and no reliance on the lease area habitats. Among the species with high to moderate reliance were black sea bass (Centropristis striata), summer flounder (Paralichthys dentatus), and Atlantic menhaden (Brevoortia tyrannus), which are important fisheries species in the region. Potential for impact was characterized by the number of species with habitat dependencies associated with lease areas and these varied with a number of continuous gradients. Habitats that support high biomass were distributed more to the northeast, while high occupancy habitats appeared to be further from the coast. There was no obvious effect of the size of the lease area on the importance of associated habitats. Model results indicated that physical drivers and lower trophic level indicators might strongly control the habitat distribution of ecologically and commercially important species in the wind lease areas. Therefore, physical and biological oceanography on the continental shelf proximate to wind energy infrastructure development should be monitored for changes in water column structure and the productivity of phytoplankton and zooplankton and the effects of these changes on the trophic system.

Ocean acidification (OA) is increasing predictably in the global ocean as rising levels of atmospheric carbon dioxide lead to higher oceanic concentrations of inorganic carbon. The Gulf of Maine (GOM) is a seasonally varying region of confluence for many processes that further affect the carbonate system including freshwater influences and high productivity, particularly near the coast where local processes impart a strong influence. Two main regions within the GOM currently experience carbonate conditions that are suboptimal for many organisms—the nearshore and subsurface deep shelf. OA trends over the past 15 years have been masked in the GOM by recent warming and changes to the regional circulation that locally supply more Gulf Stream waters. The region is home to many commercially important shellfish that are vulnerable to OA conditions, as well as to the human populations whose dependence on shellfish species in the fishery has continued to increase over the past decade. Through a review of the sensitivity of the regional marine ecosystem inhabitants, we identified a critical threshold of 1.5 for the aragonite saturation state (Ωa). A combination of regional high-resolution simulations that include coastal processes were used to project OA conditions for the GOM into 2050. By 2050, the Ωa declines everywhere in the GOM with most pronounced impacts near the coast, in subsurface waters, and associated with freshening. Under the RCP 8.5 projected climate scenario, the entire GOM will experience conditions below the critical Ωa threshold of 1.5 for most of the year by 2050. Despite these declines, the projected warming in the GOM imparts a partial compensatory effect to Ωa by elevating saturation states considerably above what would result from acidification alone and preserving some important fisheries locations, including much of Georges Bank, above the critical threshold.

The Gulf of Maine has recently experienced its warmest 5-year period (2015–2020) in the instrumental record. This warming was associated with a decline in the signature subarctic zooplankton species, Calanus finmarchicus. The temperature changes have also led to impacts on commercial species such as Atlantic cod (Gadus morhua) and American lobster (Homarus americanus) and protected species including Atlantic puffins (Fratercula arctica) and northern right whales (Eubalaena glacialis). The recent period also saw a decline in Atlantic herring (Clupea harengus) recruitment and an increase in novel harmful algal species, although these have not been attributed to the recent warming. Here, we use an ensemble of numerical ocean models to characterize expected ocean conditions in the middle of this century. Under the high CO2 emissions scenario (RCP8.5), the average temperature in the Gulf of Maine is expected to increase 1.1°C to 2.4°C relative to the 1976–2005 average. Surface salinity is expected to decrease, leading to enhanced water column stratification. These physical changes are likely to lead to additional declines in subarctic species including C. finmarchicus, American lobster, and Atlantic cod and an increase in temperate species. The ecosystem changes have already impacted human communities through altered delivery of ecosystem services derived from the marine environment. Continued warming is expected to lead to a loss of heritage, changes in culture, and the necessity for adaptation.

Detritus is a frequent, poorly defined, component of bivalve growth and carrying capacity models. The purpose of this study was to determine the proportional contributions of detrital material derived from primary producers (phytoplankton, macroalgae, Spartina alterniflora, and terrestrial leaf litter) to particulate organic matter (POM) and blue mussel’s (Mytilus edulis) diet within a temperate bay (Saco Bay, ME, United States). We assessed which detrital sources, if any, warranted incorporation into modeling efforts. Stable isotopes (δ13C and δ15N) and fatty acid biomarkers (FA) of mussels, size fractionated (Saccharina latissima, Ascophyllum nodosum, Chondrus crispus, Spartina alterniflora and leaf litter) collected between 2016 and 2017 were used to estimate endmember contributions to POM and mussel diets. Based on FAs dinoflagellates were the most abundant phytoplankton in Saco Bay, even during the fall diatom bloom. Diatoms within the bay were primarily centric, but pennate diatoms were at times present in the water column (e.g., in September). Following abundances of dinoflagellates, and centric and pennate diatoms, 22:6ω3 (DHA) was the most abundant essential FA (8.6 ± 0.1% total FAs), followed by 20:5ω3 (EPA: 7.0 ± 0.1%) and 20:4ω6 (ARA: 0.3 ± 0.1%). On average, phytoplankton derived organic matter contributed 22.1 ± 0.3% of the total POM in the bay. The concentration of non-fresh phytoplankton organic matter, or remaining organic matter (REMORG), was positively correlated with all endmember biomarkers. However, the proportion (%) of vascular plant, macroalgal, and detrital FAs was negatively correlated with the concentration of REMORG. This finding suggests in periods of low productivity, vascular plant and macroalgal detritus are proportionally more important contributors to POM. Mussels were broad spectrum omnivores, consuming phytoplankton, zooplankton, and detrital material. Detrital contributions to mussel diets were important (minimum of 16% of diet). Although small, macroalgae’s dietary contribution (8%) to M. edulis may be important. Macroalgal detritus contained essential FAs (20:5ω3 and 20:4ω6) that could supplement mussel diets, as M. edulis in Saco Bay were likely limited by 20:5ω3. Consideration of how macroalgal detritus affects the availability of essential FAs in POM may be useful to incorporate into aquaculture site selection.

Sea surface temperature (SST), salinity, and chlorophyll concentration (CHL) have changed in the US Northeast Shelf ecosystem over recent decades. The changes in these parameters were distinctly marked by change points around the year 2012 resulting in a 0.83°C increase in SST, a 0.3 PSU increase in salinity, and decrease in CHL in excess of 0.4 mg m-3. Where temperature and salinity shifted in mean level around their respective change points, CHL declined in a more monotonic fashion. Modelled data suggest that the shift in CHL resulted in a greater contribution of pico- and nanophytoplankton and a decreased contribution of microphytoplankton to overall CHL. Complementary estimates of the contribution of different phytoplankton functional types suggest a diminished contribution of diatoms to the phytoplankton community. Hence, not only is there evidence of a decline in the overall primary production capacity of the ecosystem, but also evidence of a fundamental change in the size and quality of phytoplankton supporting food webs. Two ecosystem responses to the observed changes in SST, salinity, and CHL were analyzed. Both length and weight at age have declined for a number of species, and both measures of growth appear to be negatively associated with temperature and positively associated with CHL. Biomass of fish and macroinvertebrates has declined in recent years, with a decrease in pelagic species associated with a decrease in CHL, while the decline in demersal species was more associated with an increase in temperature. Collectively, these ecosystem changes appear to be the result of the complex interactions of both thermal effects and changes at the base of the food web.

Scallops are one of the most heavily traded and widely consumed seafood in the world and the vast majority of production comes from aquaculture. In 2018, the global value of scallop aquaculture was over $5.8 billion USD with farms producing nearly three times the biomass as the entirety of the wild harvest. North American (specifically U.S. and Canadian) scallop aquaculture lags far behind the rest of the world. The U.S. is home to a valuable Atlantic sea scallop (Placopecten magellanicus) fishery. Yet demand for scallops far outstrips supply and the U.S. imports an almost equal amount, by value, of farmed scallop products. To capitalize on this trade imbalance, U.S. and Canadian aquaculturists have been developing a farmed sea scallop (hereafter scallop) industry, employing the Japanese practices of suspended net culture and the sale of whole and “roe-on” products. We examined the combined effects of culture method and environment on scallop shell growth and mortality. We compiled all published net cultured scallop shell growth and mortality rates recorded in the last 45 years in the Northwest Atlantic. Using generalized additive models (GAMs), we identified significant nonlinear interactions between growth, mortality, environmental conditions, and culture methods applicable from Maine, USA to Newfoundland, Canada. Optimum shell growth occurs within a temperature window of 10–15 °C. Growth is higher in pearl nets than in lantern nets, and is also highly sensitive to stocking density, which has large implications for farm sizes and thinning practices. Maximum mortality occurs at the highest temperatures in our dataset (~17 °C), while stocking density is only a significant predictor of product loss at high densities. Scallops are also more susceptible to mortality at shell heights under 25 mm. Both mortality rates and shell height growth rates were lower in the late spring and early summer after accounting for temperature effects. Careful temperature based site selection and proactive low density stocking can mitigate the effects of intraspecific competition and reduce handling related mortality. Identifying lease sites that provide both optimal environmental conditions and adequate space for low density net culture will be an important step in expanding scallop aquaculture in the Northwest Atlantic.

Aim: This study examined phytoplankton blooms on a global scale, with the intention of describing patterns of bloom timing and size, the effect of bloom timing on the size of blooms, and time series trends in bloom characteristics. Location: Global. Methods: We used a change‐point statistics algorithm to detect phytoplankton blooms in time series (1998–2015) of chlorophyll concentration data over a global grid. At each study location, the bloom statistics for the dominant bloom, based on the search time period that resulted in the most blooms detected, were used to describe the spatial distribution of bloom characteristics over the globe. Time series of bloom characteristics were also subjected to trend analysis to describe regional and global changes in bloom timing and size. Results: The characteristics of the dominant bloom were found to vary with latitude and in localized patterns associated with specific oceanographic features. Bloom timing had the most profound effect on bloom duration, with early blooms tending to last longer than later‐starting blooms. Time series of bloom timing and duration were trended, suggesting that blooms have been starting earlier and lasting longer, respectively, on a global scale. Blooms have also increased in size at high latitudes and decreased in equatorial areas based on multiple size metrics. Main conclusions: Phytoplankton blooms have changed on both regional and global scales, which has ramifications for the function of food webs providing ecosystem services. A tendency for blooms to start earlier and last longer will have an impact on energy flow pathways in ecosystems, differentially favouring the productivity of different species groups. These changes may also affect the sequestration of carbon in ocean ecosystems. A shift to earlier bloom timing is consistent with the expected effect of warming ocean climate conditions observed in recent decades. Supporting Information

The Finite-Volume Community Ocean Model (FVCOM) is an advanced coastal circulation model widely utilized for its ability to simulate spatially and temporally evolving three-dimensional geophysical conditions of complex and dynamic coastal regions. While a body of literature evaluates model skill in surface fields, independent studies validating model skill in bottom fields over large spatial and temporal scales are scarce because these fields cannot be remotely sensed. In this study, an evaluation of FVCOM skill in modeling bottom water temperature was conducted by comparison to hourly in situ observed bottom temperatures recorded by the Environmental Monitors on Lobster Traps (eMOLT), a program that attached thermistors to commercial lobster traps from 2001 to 2013. Over 2 × 10 6 pairs of FVCOM-eMOLT records were evaluated by a series of statistical measures to quantify accuracy and precision of the modeled data across the Northwest Atlantic Shelf region. The overall comparison between modeled and observed data indicates reliable skill of FVCOM (r 2 = 0.72; root mean squared error = 2.28 °C). Seasonally, the average absolute errors show higher model skill in spring, fall and winter than summer. We speculate that this is due to the increased difficulty of modeling high frequency variability in the exact position of the thermocline and frontal zones. The spatial patterns of the residuals suggest that there is improved similarity between modeled and observed data at higher latitudes. We speculate that this is due to increased tidal mixing at higher latitudes in our study area that reduces stratification in winter, allowing improved model accuracy. Modeled bottom water temperatures around Cape Cod, the continental shelf edges, and at one location at the entrance to Penobscot Bay were characterized by relatively high errors. Constraints for future uses of FVCOM bottom water temperature are provided based on the uncertainties in temporal-spatial patterns. This study is novel as it is the first skill assessment of a regional ocean circulation model in bottom fields at high spatial and temporal scales in the Northwest Atlantic Shelf region.

• The model 13.9W 0.61 can accurately estimate BSA of juvenile Atlantic salmon (21.83-1115.84 g).

Adding to the challenge of predicting fishery recruitment in a changing environment is downscaling predictions to capture locally divergent trends over a species’ range. In recent decades, the American lobster (Homarus americanus) fishery has shifted poleward along the northwest Atlantic coast, one of the most rapidly warming regions of the world's oceans. Building on evidence that early post‐settlement life stages predict future fishery recruitment, we describe enhancements to a forecasting model that predict landings using an annual larval settlement index from 62 fixed sites among 10 study areas from Rhode Island, USA to New Brunswick, Canada. The model is novel because it incorporates local bottom temperature and disease prevalence to scale spatial and temporal changes in growth and mortality. For nine of these areas, adding environmental predictors significantly improved model performance, capturing a landings surge in the eastern Gulf of Maine, and collapse in southern New England. On the strength of these analyses, we project landings within the next decade to decline to near historical levels in the Gulf of Maine and no recovery in the south. This approach is timely as downscaled ocean temperature projections enable decision makers to assess their options under future climate scenarios at finer spatial scales.

Despite the profitability of the wild Atlantic Sea Scallop, Placopecten magellanicus, fishery, the U.S. still imports more than 26,000 tonnes of various scallop products annually. Atlantic Sea Scallop (hereafter referred to as scallop) aquaculture is one method of mitigating this imbalance. We examined scallop growth at three sites across the mouth of Penobscot Bay, Maine to determine the coupled effects of lantern net stocking density and temperature on growth and mortality. Scallops were held in high and low (20 and 10 individuals tier−1, respectively) density treatments, and shell height measurements were recorded monthly for one year. We divided the growth rate analysis into three periods: winter - spring, summer, and fall. During summer across all sites, growth rates were 75 % higher in low-density nets than in high-density nets. We observed significant nonlinear relationships between shell height growth rate, temperature, and stocking density. Optimal growth occurred within a window of 10–15 °C. Above this threshold, there was a distinct negative relationship between temperature and growth. Our results highlight the importance of maintaining low densities within nets, particularly during periods of high temperature and growth. However, handling in summer and early fall may lead to mortality. Therefore, we recommend that growers stock nets at low densities in the spring, ensuring that they will not require thinning during peak temperatures. Similarly, finding sites that maximize time within a thermal envelope of 10–15 °C will be critical, which in the case of the Gulf of Maine will most likely warrant leasing sites at the mouths of estuaries and bays. These locations offer a combination of sufficient depth and space for sparsely stocked nets, adequate food levels, and optimal salinity and temperature.

Facing challenges to the civic purpose of higher education, some scholars and administrators turn to the rhetoric of engagement. Simultaneously, the political philosophy of cosmopolitanism has gained intellectual favor, advocating openness to the lived experiences of distant others. We articulate linkages between these two discourses in an extended case study, finding that a cosmopolitan ethos of engagement in a rural context can improve (1) understanding among people ordinarily separated by spatialized social-ecological differences, (2) prospects for longer term environmental sustainability, and (3) the visionary potential of collaborative inquiry. Despite globalization of food systems and neoliberal shifts in fishery management, an annual fisheries forum facilitates coalitions that overcome dichotomies between technocratic and local knowledge, extending benefits to fishing communities, academia, and public policy. Iterative and loosely structured capacity building expands informally through affective processes of recognition and care, as decentralized leadership supports collective mobilization toward alternate futures.