Salmon Farming Research Articles

Effects of aquaculture effluents on the slender sea pen Virgularia mirabilis

This study aims to assess in situ the impact of effluents originating from an Atlantic salmon (Salmo salar) farm on a nearby slender sea pen (Virgularia mirabilis) field. We evidenced (1) the presence and persistence of emamectin residues (i.e. a common chemotherapeutants used for treating ectoparasites in salmons) in V. mirabilis tissue 56 days after treatment and (2) lethal and sublethal responses of V. mirabilis to effluents discharged by the salmon farm. Particularly, sea pens near the fish farm exhibited significant overproduction of mucus, contraction of polyps’ tentacles, and disappearance of associated fauna. Furthermore, sea pens located directly underneath the farm showed substantial tissue necrosis and, in the most severe case, complete tissue loss and mortality. Our results suggest that lethal damages on sea pens occur directly below the farm, and that sublethal effects are visible up to 500 m from the farm. However, the presence of V. mirabilis below the studied farm, which has been active for more than twenty years, suggests that V. mirabilis population possesses the capacity to recover from the impacts of the farm, thereby preventing the complete disappearance from the area. In this context, it would be particularly interesting to run a temporal survey following the health state of V. mirabilis during an entire production cycle to have a more precise overview of fish farm impacts on this species, including during and after the post-production fallowing period.

Assessing the environmental impacts of conventional and organic scenarios of rainbow trout farming in France

In France, rainbow trout farming in conventional flow-through systems raises environmental concerns. To address this, there is a growing interest in organic aquaculture. In this study, we employed an attributional life cycle assessment (LCA) to analyze the environmental impacts of rainbow trout production, comparing conventional and organic practices in a model fish farm. Our life cycle impact assessment revealed that organic farming significantly reduced environmental impacts per tonne of trout in seven of the nine selected impact categories. Notably, freshwater ecotoxicity exhibited the most significant difference, with organic systems showing a 35% decrease. The only exceptions were freshwater eutrophication and water dependence, where organic production led to higher impacts per tonne of trout. In conventional farming, emissions amounted to 14 kg of P eq./tonne, whereas in organic farming, the emissions were slightly higher (15 kg of P eq./tonne). For water dependence, one tonne of trout production in the conventional system mobilized 128 103 m3 vs. 185 103 m3 in the organic system. The environmental benefits of organic production were even more marked when using a surface-based functional unit (m2y). We demonstrated the benefits of organic trout production from an environmental perspective. However, our findings highlight the caution needed when interpreting LCA comparisons of such production systems that can be highly influenced by methodological choices such as the functional unit used.

Catch my drift? Between-farm dispersal of biofouling waste from salmon pen net cleaning: Potential risks for fish health

Biofouling is a serious challenge for global salmon aquaculture and farmers have to regularly clean pen nets to avoid impacts on stock health and farms' structural integrity. The removed material is released into the surrounding environment. This includes cnidarian species such as hydroids, whose nematocyst-bearing fragments can impact gill health and fish welfare. There is also increasing evidence of the association of parasites and pathogens with biofouling organisms and cleaning fragments. It is unknown whether and how far local current regimes disperse biofouling material and whether this material reaches and interacts with adjacent pens or even neighbouring farms downstream, or wild fish populations in surrounding environments.We focussed on the cnidarian hydroid Ectopleura larynx, one of the most abundant biofouling species on Norwegian aquaculture installations. Using a 3D hydrodynamic model parameterised with physical and biological properties of hydroid particles (derived via field and laboratory studies), we simulated the dispersal of net cleaning waste from two Norwegian salmon farms.Our results demonstrate that net cleaning waste is extensively dispersed throughout neighbouring pens, and even to adjacent aquaculture facilities. Salmon were exposed to concentrations of biofouling particles up to 41-fold elevated compared to background concentrations, and for up to 30.5 h. Maximum dispersal distance of hydroid particles was 5.5 km from the point of release, achieved largely within 48 h. Least-cost distance calculations show that this distance exceeds the nearest-neighbour distance of 70 % of Norway's salmon farms (654 farms).Our study provides some evidence that actions taken to manage biofouling at salmon farms may affect neighbouring farms and surrounding natural environments. The results highlight the potential risks associated with net cleaning: the dispersal of harmful cnidarian particles, associated pathogens, and non-indigenous species, thus underlining the need for novel farming or net cleaning technologies that prevent the release of potentially harmful cleaning waste.

The Species Composition and Prevalence of Thorny-Headed Worms (Acanthocephala: Echinorhynchidae, Neoechinorhynchidae and Pomphorhynchidae) in Trouts, Complex Measures to Control Them in Fish Farms in the Territory of Azerbaijan Republic

During period 2015-2020 spreading of acanthocephaliasis in the rainbow and brown trout in the fish breeding farms of Azerbaijan Republic was studied. Totally, from 668 fish examined specimens 430 (64.37%) were infected. Correlation of data on the extensiveness and intensity of invasion by thorny-headed worms (Acanthocephala) in trout farms is ventured to make an assumption about unfavorable epidemiological situation in trout breeding farms of the Republic of Azerbaijan. For the purpose of control acanthocephaliasis in trout, a number of drugs were used. The most effective drug was Tetramizole-20%, which was adopted in the trout farms.

Evaluation of novel PCR-based method to assess gill injuries in fish caused by the cnidarian Ectopleura larynx

Gill disease is a major threat to aquaculture of Atlantic salmon, with an unknown and likely underestimated contribution from cnidarians such as jellyfish and biofouling hydroids. To better understand the risk and thus enable mitigation, technology for the certain identification of cnidarian-related gill damage is needed. We used the hydroid Ectopleura larynx in a case study to determine whether the exposure of salmon to nematocyst-bearing hydrozoans can be deducted via non-destructive PCR-based methods. In a field experiment, we evaluated (i) whether swabbing the inside of the gill operculum in farmed Salmo salar and subsequent PCR analysis can provide quantifiable information about the presence of E. larynx material in the gill chamber and, if so, (ii) whether the screening results correlate with histological assessments of gill damage. The developed PCR methods were able to detect the presence of biofouling hydroids in ambient water. However, despite exposure to suspended hydroid particle concentrations that did result in gill damage in some salmon, quantitative PCR results did not correlate with histological gill assessments. For opercular swabs to serve as a diagnostic tool for detecting biofouling-mediated gill damage in live salmon, increased specificity of genetic markers and improved sampling methods are needed.Animal trial permit no. 24252 (granted 06.07.2020, Norwegian Food Safety Authority).

Seasonal Mortality of Wild Atlantic Menhaden (Brevoortia tyrannus) Is Caused by a Virulent Clone of Vibrio (Listonella) anguillarum; Implications for Biosecurity along the Atlantic Coastal United States

Atlantic menhaden are a highly migratory marine species in the Eastern United States that suffer from seasonal chronic mortality. Affected fish show neurologic signs referred to as spinning disease, including circling at the surface and erratic corkscrew swimming before death. We investigated three similar menhaden mortality events consistent with spinning disease in coastal New Jersey and New York between 2020 and 2021 to understand the cause. A unique strain of Vibrio (Listonella) anguillarum (serogroup O3) was detected regularly in high loads, particularly in the brains of moribund fish, by both metagenomics and bacterial isolation. The most common histopathological changes in moribund fish were hemorrhagic meningitis, encephalitis, pyknosis, and karyorrhexis of hematopoietic tissues in the kidney and spleen. Whole genome sequencing of isolates from moribund fish representing a wide spatial and temporal range showed that they were nearly identical clones, suggesting it to be a pathogenic strain circulating in the population. Though V. anguillarum is believed to be the main pathogen associated with spinning disease and mortality, Yersinia ruckeri (serotype O1) was isolated from smaller numbers of fish. Considering the highly migratory nature of Atlantic menhaden throughout the eastern United States and their use as bait for other fisheries, these findings identify potential biosecurity challenges that should be considered in Atlantic salmon aquaculture, fisheries, and emerging marine aquaculture in the region.

What affects the level of local social acceptance of salmon farming in Norway?

The concept of a social licence to operate (SLO) that first emerged related to mining has been developed into several strands of theoretical models and used to study the social acceptance of industries in different contexts. There is an emerging literature on SLO for salmon-farming, but very few quantitative analyses are done to identify and assess factors that affect the level of social acceptance. Models that explain social acceptance levels from people's trust in an industry or company, their confidence in governance, and views on procedural and distributional fairness (trust models) are designed for quantitative analysis, and they have been successful in explaining social acceptance levels for mining. In this paper, we use survey data to test whether the factors in trust models can also explain the level of local social acceptance for salmon farming in Norway. From the structural equation modelling analysis, we conclude that these models at best have limited explanatory power in our case. We then develop an alternative model to analyse social acceptance, where factors of perception and attitudes and respondents' individual characteristics are tested as direct regression paths to influence level of acceptance. This model explains the variation in the data well. The factors that most strongly affect the level of acceptance, and which industry or authorities also can influence, are the perception of to what degree aquaculture is environmentally sustainable, whether the industry acts according to society's expectations, and if the industry is trustworthy. Practical implications for the industry and governance are discussed.

Spatio-temporal variations in the mesozooplankton assemblages off Clarence Island, Magellan Strait, Chile

The seasonality in the light regime from subpolar regions impinges on limitations in the zooplankton dynamics. However, knowledge about seasonal variations in the mesozooplankton assemblages is limited in the southern tip of South America and around the Magellan Strait. Here, we studied the seasonal variation (summer vs. winter) and the spatial distribution (dozens of kilometers) of the mesozooplankton on the occidental shore of Clarence Island, Magellan Strait, Chilean Patagonia. A total of 69 taxonomic groups were identified in the samples, varying from 65 in summer (early March 2020) to 50 in winter (June 2020). Copepods numerically dominated the plankton, particularly Drepanopus forcipatus and Clausocalanus brevipes, although chaetognaths were also abundant in winter. The similarity in the composition was higher for samples collected in summer, whereas in winter there was larger variability in the zooplankton structure. At spatial scale, a large sound at the eastern coast of the island, Dyneley sound showed different composition of copepods compared to other channels both in summer and winter. Seasonal variation was five times larger than the spatial variation in the similarity of the mesozooplankton composition. Finally, higher richness and lower evenness were detected in austral summer, while the opposite was noticed in winter, with differences in alpha-diversity indices between seasons but not among locations. Understanding the drivers of seasonal variability in the zooplankton composition of this extreme ecosystem is essential for predictions of the impacts of salmon farming and climate change in southern Patagonia.

Sludge from sea-based Atlantic salmon (Salmo salar L.) production: quantification, composition, and potential application in integrated multi-trophic aquaculture

Future growth of Atlantic salmon (Salmo salar L.) in Norway is tied to finding solutions for major ecological challenges connected to salmon lice, escapees, and nutrient emissions from sea cages. At the same time, nutrient-rich sludge from salmon production comprises a valuable resource for the cultivation of lower trophic species using an integrated multi-trophic aquaculture (IMTA) approach. This study aimed to quantify the sedimentation of aquaculture sludge under sea cages of an Atlantic salmon aquaculture site and to qualify the composition of this sludge. Additionally, the study evaluated the hypothetical use of sludge from sea-based aquaculture as a feed source for polychaetes Hediste diversicolor. Using sediment traps, sludge samples were collected under two different Atlantic salmon sea cages, at two different depths, and three different sampling dates. Subsequently, they were quantified, and their composition was assessed with regards to carbon (C), nitrogen (N), phosphorus (P), lipid, fatty acid (FA), protein, amino acid (AA), and ash content as well as elemental ratios and composition of FAs and AAs. The quantity of collected sludge was significantly different between sea cages, with a strong positive correlation between feed input and collected sludge (R2 = 0.98, p < 0.05). Sampling depth did not affect the quantity of collected sludge in the sediment traps (2215 ± 480 mg DW day−1), and no significant difference in sedimented sludge as a proportion of theoretically produced sludge (12.94 ± 2.16%) was found when comparing the different cages and sampling depths. Furthermore, the composition of collected sludge was similar at all sampling points. The overall nutritional value was lower compared to sludge from land-based aquaculture; regardless, sludge from sea-based salmon production can in theory be considered a potential feed resource to be used for the production of polychaetes H. diversicolor.

Sustainable business model innovation, dynamic capabilities, and organizational design: Insights from Norwegian aquaculture

AbstractFirms must increasingly grapple with complex sustainability challenges. Business model innovation is needed to achieve radical sustainability improvements. Recent research highlights the interrelatedness between business model innovation, dynamic capabilities, and organizational design, calling for empirical work to better illuminate these relationships. These connections are relevant in sustainability contexts, where organizational barriers and drivers have been shown to either facilitate or hinder the development of dynamic capabilities for sustainable business model innovation (SBMI). This paper presents a case study of an emergent low‐carbon offshore aquaculture value chain in Norway to illuminate the importance and roles of these organizational factors. Based on our analysis, we identify those barriers and drivers present in the Norwegian salmon aquaculture industry; add to the body of theory around organizational design, dynamic capabilities, and SBMI; and offer insights for practitioners in the aquaculture sector aiming to develop dynamic capabilities for SBMI.

Salmon farming alters the structure and functioning of Norwegian maerl bed communities

Abstract Effluents resulting from fish farming activities can alter the structure and functioning of benthic ecosystems. In Norway, recent technological advances within the salmon industry have facilitated the expansion of aquaculture into shallower locations, leading to additional pressures upon coastal habitats. Maerl/rhodolith beds are important bioengineers in coastal waters—supporting highly diverse associated macrofaunal communities—and are likely to be particularly at risk. This study aims to investigate the environmental changes induced by fish farms in their vicinity and their impact on the structure and functioning of maerl bed macrofaunal communities. High dissolved nutrients and organic enrichment levels were observed close to the cages, associated with lower live maerl cover. Overall, the most substantial impact of salmon farms on macrofaunal communities was observed within 100 m from the cages. Nevertheless, changes in the structure and functioning of assemblages were evidenced up to 300 m. In the vicinity of the cages, communities were characterized by the dominance of endobenthic subsurface deposit feeders and opportunistic species, notably the polychaetes Chaetozone sp., Capitella sp. and Scoloplos armiger. Conversely, sites situated farther away from the cages exhibited higher abundances of epibenthic taxa, including crawlers, grazers and species sensitive to organic enrichment. Sites unaffected by the presence of fish farms were described by high abundances of the ophiuroid Ophiura robusta, the polychaete Proclea graffi and ostracods, reflecting more favourable environmental conditions. Such changes in macrofaunal communities highlight the vulnerability of maerl beds to the impacts of aquaculture, thus emphasizing the importance of rigorous site selection when establishing new fish farming facilities.

Effects of regional coordination of salmon louse control in reducing negative impacts of salmonid aquaculture on wild salmonids

Parasitic salmon lice (Lepeophtheirus salmonis) are a constraint to the sustainable growth of salmonids in open net pens, and this issue has caused production to level off in recent years in the most aquaculture-intensive areas of Norway. The maximum allowed biomass at a regional level is regulated by using the so-called “traffic light” system, where salmon louse-induced mortality of migrating wild salmon post-smolts is evaluated against set targets. As a case study, we have investigated how a specific aquaculture-intensive area can reduce its louse levels sufficiently to achieve a low impact on wild salmon. Analyses of the output from a virtual post-smolt model that uses data on the reported number of salmon lice in fish farms as key input data and estimates the salmon louse-induced mortality of wild out-migrating Atlantic salmon post-smolts, suggested that female louse abundance on the local farms must be halved in spring to reach the goal implied by the traffic light system. The outcome of a modelling scenario simulating a proposed new plan for coordinated production and fallowing proved beneficial, with an overall reduction in louse infestations and treatment efforts. The interannual variability in louse abundance in spring, however, increased for this scenario, implying unacceptably high louse abundance when many farms were in their second production year. We then combined the scenario with coordinated production with other louse control measures. Only measures that reduced the density of farmed salmonids in open cages in the study area resulted in reductions in salmon louse infestations to acceptable levels. This could be achieved either by stocking with larger fish to reduce exposure time or by reducing fish numbers, e.g. by producing in closed units.

Most of the escaped farmed salmon entering a river during a 5-year period were infected with one or more viruses.

Disease interactions between farmed and wild populations have been poorly documented for most aquaculture species, in part due to the complexities to study this. Here, we tested 567 farmed Atlantic salmon escapees, captured in a Norwegian river during 2014-2018, for five viral infections that are prevalent in global salmonid aquaculture. Over 90% of the escapees were infected with one or more viruses. Overall prevalences were: 75.7% for piscine orthoreovirus (PRV-1), 43.6% for salmonid alphavirus (SAV), 31.2% for piscine myocarditis virus (PMCV), 1.2% for infectious pancreatic necrosis virus (IPNV) and 0.4% for salmon anaemia virus (ISAV). A significantly higher prevalence of PMCV infection was observed in immature compared to mature individuals. The prevalence of both SAV and PMCV infections was higher in fish determined by fatty acid profiling to be 'recent' as opposed to 'early' escapees that had been in the wild for a longer period of time. This is the first study to establish a time-series of viral infection status of escapees entering a river with a native salmon population. Our results demonstrate that farmed escapees represent a continuous source of infectious agents which could potentially be transmitted to wild fish populations.

How Do Lumpfish Protect Themselves Against Viruses?

For many people, a delicious salmon dish satisfies their taste buds. Salmon farming is a big industry, providing food for millions of people every day. However, the journey of this delicious meal from the ocean to your plate depends on lumpfish, a cool-looking fish that protects farmed salmon by eating sea lice. Sea lice are small parasites known to attack salmon and can cause disease if not removed. Since lumpfish are vulnerable to diseases, it is crucial to understand more about this organism’s complex immune system, as this will help keep them healthy so they can then do their important “job” of eating sea lice. In this article, we will explain how we study the way the fascinating lumpfish defends itself against diseases.

Evolving blue development discourses and policies: Salmon farming industry and regional making in Chile

As the second biggest producer of salmon after Norway, Chile is one of the leading forces of aquaculture with a long history of being strongly focused on international markets. Based on contributions from critical geography, political ecology and the sociology of globalization, the article analyses the dominant narratives and policies deployed by the Chilean government and the salmon farming industry in successive contexts of boom and crisis of production activity in the archipelago of Chiloé (Los Lagos Region). In a context of a word-wide growing interest in the capabilities of the blue economy, a discourse analysis of governmental, industrial, and public-private institutional documents, together with semi-structured interviews to a broad number of stakeholders contributes to advance the understanding of and learn from the evolution and challenges faced by one the longest world’s salmon aquaculture leaders. The research identifies five discursive and policies phases over more than four decades of development. From an initial narrative that defines the region as “empty” and uses the discourse on salmon farming to justify territorial integration policies (1973–1982); to a second period in which the fostering of the salmon farming in the southern region served as a catalyst of national economic growth interests (1983–1994). It follows a boom phase characterized by the capitalization on the blue revolution discourse (1995–2006), which lasted until the territorial crisis resulting from the ISA virus, and the expansion of the industry towards southern regions (2007–2015). The analysis reveals a fifth phase starting in 2016 and ongoing by 2023, which characterized by the emergency and implementation of a new administrative right over coastal-marine areas to safeguard the traditional uses of indigenous communities, starts to challenge the long-standing hegemony of the salmon farming industry in Chile.

Influence of salinity on rainbow trout (Oncorhynchus mykiss) smolt development and postsmolt performance

Rainbow trout aquaculture has large potential for growth, but requires better understanding of aspects like smoltification and its effect on trout performance after seawater transfer. The present study examined the effect of three different salinities (fresh water, 3–5 ‰ and 15–16 ‰) on smoltification and growth of rainbow trout (70 ± 10 g) reared under constant light between March–June 2018; it also documented hypoosmoregulatory performance and growth of trout from all salinity treatments transferred to full seawater at three different times (Transfer 1: 26 April; Transfer 2: 24 May; Transfer 3: 21 June). Smolt development was assessed with markers commonly used for Atlantic salmon like gill Na+, K+-ATPase activity, gill mRNA transcription of key genes (nkaα1a, nkaα1b and nkcc1a) and plasma concentration of Cl− and Na+. Results evidenced that trout in brackish water experienced an earlier onset of smoltification, displayed by rapid changes in mRNA transcription of the ATPase α-isoforms nkaα1a (freshwater isoform) and nkaα1b (seawater isoform), which, in turn, induced an earlier peak of the Na+, K+-ATPase (NKA) activity. However, smoltification also commenced and progressed in fresh water most likely as a result of reaching a certain size. The salinity treatment did not influence growth during the smoltification period. After seawater transfer, all treatments in Transfer 1 (26 April) displayed the best capacity to acclimatize to full seawater (with clear upregulations of nkaα1b and nkcc1a after seawater entry) and the highest growth, compared to all treatments in Transfers 2 and 3. In contrast, few differences in growth and smoltification markers occurred between salinity treatments within each of the seawater transfers. This suggests that trout in the first transfer had the best smolt condition (were at the peak of smolt window), which allowed them to adapt and grow better in seawater. Overall, such results indicate that timing of seawater transfer can be more important for trout performance in the grow-out phase in the sea than the water salinity during the early rearing period. As such, although brackish water can be used to induce rainbow trout smoltification, transferring the fish at the peak of the smolt window can increase chances for best seawater performance.

Aquaculture related humpback whale entanglements in coastal waters of British Columbia from 2008-2021.

Over the past two decades, increasing numbers of humpback whales have been returning to feed in the inshore waters of British Columbia (BC) where marine aquaculture farms are situated. This has led to growing concerns that the presence of aquaculture farms may pose an entanglement threat to humpback whales. However, it is not known whether aquaculture facilities attract humpback whales, or whether there are factors that increase the likelihood of humpback whale, becoming entangled and dying. We examined eight reports of humpback whales interacting with Atlantic salmon farms in BC from 2008 to 2021 to evaluate the conditions that may have contributed to their entanglements. Of the eight entangled humpbacks, three individuals died and five were successfully disentangled and released. All were young animals (1 calf, 7 subadults). Multiple factors were associated with two or more of the reported incidents. These included facility design, environmental features, seasonality, humpback whale age, and feeding behaviour. We found that humpback whales were most commonly entrapped in the predator nets of the aquaculture facilities (6/8 incidents), and were less often entangled in anchor support lines (2/8). The presence of salmon smolts did not appear to be an attractant for humpback whales given that half of the reported entanglements (4/8) occurred at fallowed salmon farms. Almost all of the entanglements (7/8) occurred in late winter (prior to the seasonal return of humpbacks) and during late fall (after most humpbacks have migrated south). Overall, the number of humpback whales impacted by fish farms was small compared to the numbers that return to BC (> 7,000) and accounted for <6% of all types of reported entanglements in BC. Human intervention was required to release humpback whales at fish farms, which points to the need to have well-established protocols to minimize entanglements and maximize successful releases.

Health prediction for king salmon via evolutionary machine learning with genetic programming

ABSTRACT King (Chinook) salmon is the only salmon species farmed in Aotearoa New Zealand and accounts for over half of the world's production of king salmon. Determining the health status of king salmon effectively is important for farming. However, it is a challenging task due to the complex biotic and abiotic factors that influence health. Evolutionary machine learning algorithms have shown their superiority in learning models for challenging tasks. However, they have not been investigated for health prediction in king salmon farming. This paper focuses on data processing and machine learning algorithm design to develop king salmon health prediction models in Aotearoa New Zealand. Particularly, this paper proposes a king salmon health prediction method based on genetic programming which is an evolutionary machine learning algorithm. The results show that genetic programming achieves the best overall performance among all examined typical machine learning algorithms for most trials. Further analyses show that genetic programming can automatically detect important features for learning classifiers for king salmon health classification tasks effectively, and can also learn potentially interpretable models. Our results are an important step forward in developing health prediction tools to automatically assess health status of farmed king salmon in Aotearoa New Zealand.

Equity zombies in Canada’s blue economy: a critical feminist analysis for equitable policy implementation

IntroductionOcean equity is a key aim of blue economy frameworks globally and is a pillar of the international High Level Panel for A Sustainable Ocean Economy. However, the Panel offers only a general definition of ocean equity, with limited guidance for countries. Canada, as a party to the High Level Panel’s blue economy agenda, is developing its own blue economy strategy, seeking to reshape its ocean-based industries and advocate for new ones. How equity will be incorporated across scales is not yet known but has implications for how countries like Canada will develop their ocean-based industries. This raises important questions, including what are Canada’s equity commitments in relation to its blue economy and how will they be met? Currently, the industries identified in Canada’s emerging blue economy narratives are governed through both federal and provincial legislation and policies. These will shape how equity is implemented at different scales.MethodsIn this paper, we examine how the term equity is defined in relevant federal and provincial legislation and look to how understandings of equity found in critical feminist, environmental justice, and climate justice scholarship could inform policy and its implementation within Canada’s blue economy. We focus on two industries that are important for Canada’s blue economy: offshore oil and marine salmon aquaculture in the Canadian province of Newfoundland and Labrador. We investigate how existing legislation and policy shapes the characterization, incorporation, and implementation of equity in these industries.Results and discussionOur analysis highlights how a cohesive approach to ocean equity across the scales of legislation and policy is needed to ensure more robust engagement with social and environmental equity issues in blue economy discourse and implementation.

Genetic architecture and accuracy of predicted genomic breeding values for sea lice resistance in the St John River aquaculture strain of North American Atlantic salmon

Sea lice infections cause significant economic losses in Atlantic salmon (Salmo salar) farming. The objectives of this study were to (1) estimate the heritability of resistance to sea lice in the USDA's breeding program for North American (N.A.) Atlantic salmon; (2) elucidate the genetic architecture of sea lice resistance; and (3) assess the accuracy and bias of predicted breeding values for sea lice resistance using cross-validation analysis (CVA) and progeny testing of selection candidates (PTSC). Fish from year-class (YC) 2014 n=967 and YC 2018 n=941 were challenged with sea lice (Lepeophtheirus salmonis) and genotyped with the new USDA 50K SNP chip developed for the N.A. Atlantic salmon. Heritability estimates for sea lice count in the two year-classes were between 0.07 and 0.10. GWAS with weighted ssGBLUP (wssGBLUP) highlighted the polygenic architecture of the trait. With CVA, the genomic prediction methods x¯=0.54 had higher accuracy of predictions than the pedigree-based method x¯=0.43; and ssGBLUP had the highest accuracy of BV predictions (0.50–0.62) among the genomic prediction methods. With PTSC approach, the pedigree-based method PBLUP had higher estimated accuracy than the genomic prediction methods (0.48 vs. 0.30). Bias of BV predictions with CVA x¯=0.87range0.57−1.06 was lower than with PTSC x¯=1.22range0.44−2.35. Our retrospective assessment of the accuracy of indirect sib-based selection to improve sea lice resistance in the St John River aquaculture stock that is commonly used for farming of Atlantic salmon in North America demonstrated that substantial genetic gains can be obtained. Due to the polygenic architecture of the trait, the estimated accuracy of the ssGBLUP model was better than the wssGBLUP model. In our assessment, a larger training sample size will be needed to achieve optimal results with the whole genome-enabled selective breeding method due to the polygenic architecture of sea lice resistance coupled with low heritability of the trait.