Article

The Cost of Lice: Quantifying the Impacts of Parasitic Sea Lice on Farmed Salmon

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Abstract

Diseases are an important challenge in aquaculture. However, most of what is known about the effect of diseases comes from laboratory experiments. Using a farm-level data set containing sea lice infestation counts for all Norwegian salmon farms over an 84-month period, we empirically investigate the biological and economic impacts of observed levels of infective lice. Sea lice, a common ectoparasitic copepod of salmonids, have been shown to reduce fish growth and appetite and cause substantial costs to salmon farmers worldwide. Our results suggest that the percent of total biomass growth lost per production cycle due to average infestations varies from 3.62 to 16.55%, despite control, and depends on farm location. Using a discrete harvesting model, we simulate the economic impact on farm profits over typical cycles. An average infestation over a typical central region spring-release cycle generates damages of US0.46perkgofharvestedbiomass,equivalentto90.46 per kg of harvested biomass, equivalent to 9% of farm revenues. We estimate that lice parasitism produced US436m in damages to the Norwegian industry in 2011.

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... The lack of accounting for true costs results in spurious extrapolations of estimated loss values. The proper economic analytical method would be to estimate the loss of "profits" due to disease which includes a detailed estimation of cost and returns in the presence and absence of disease (Abolofia et al., 2017;Asche et al., 2021;Kumar, Hedge, et al., 2021). Such estimation would account for net returns in the presence of disease and the profit that could have been earned without the specific disease outbreak (Figure 1). ...
... Adoption of superior aquaculture technologies has imparted increased control over production processes and has allowed for productivity gains and cost efficiencies in aquaculture industries (Asche, 2008;Asche et al., 2012;Kumar & Engle, 2016;Kumar et al., 2018). However, infectious diseases continue to pose significant production and economic risk to the sector (Abolofia, et al., 2017;Cheatham, Kumar, Johnson, et al., 2023). Losses to bacterial diseases remain a serious impediment to the growth and economic viability of the catfish sector-the largest aquaculture industry in the U.S. (Abdelrahman et al., 2023;Khoo et al., 2023;Peterman & Posadas, 2019;Wise et al., 2004). ...
... Such studies that do not account for the effect of reduced yields from disease mortality that increase unit costs of production lead to erroneous extrapolations of estimated loss values. Estimating the loss of "profits" from a disease is a more accurate economic analytical method (Abolofia et al., 2017;Asche et al., 2021) as it can incorporate the price effect, effect due to loss in production and also the change in unit cost of production. However, such estimations would require detailed farm production data that can account for both costs and returns in the presence and absence of a specific disease. ...
Article
Edwardsiellosis of catfish caused by Edwardsiella ictaluri and Edwardsiella piscicida remains one of the most significant diseases in U.S. catfish aquaculture. Economic losses related to this disease are currently unknown. This work sheds light on the losses associated with E. ictaluri and E. piscicida in catfish aquaculture. The robust economic approach employed is grounded in farm-level production data and long-term disease trends in the industry. Direct farm-level economic losses from Edwardsiellosis ranged from −3,485to3,485 to −13,320/ha causing industrywide economic losses of −5.2to5.2 to −17.6 million/year. The lost revenue due to Edwardsiellosis ranged from −8.4to8.4 to −24.8 million/year causing a negative economic impact of −15.5to15.5 to −45.9 million/year. The economic losses and negative impacts of Edwardsiellosis are relatively greater on the foodfish sector compared to the fingerling sector. This work provides a platform for a more accurate estimation of the true economic impacts of diseases for aquaculture sectors for which commercial farm data is available.
... Impacts of salmon lice is one of the main concerns and is now the defining element of the regulatory system in terms of whether production will increase, remain constant or decline in each of 13 production areas (Osmundsen et al., 2020). Managing the salmon lice challenge lead to significant costs to the farmer due to lost biomass as a consequence of reduced growth and increased mortality associated with treatment Walde et al., 2022), possible negative effect of treatment on the filet quality causing down-grading or reclaims, direct treatment costs such as equipment, labour and energy, as well as costs of control and prevention (Abolofia et al., 2017;Costello, 2009;Iversen et al., 2020;Iversen et al., 2017). ...
... The increase in mortality and decrease in fish growth affects the profitability of the farmer as it reduces production (Abolofia et al., 2017). However, there is a large variability in the experienced mortality after different delousing treatments, and the effect on growth can vary substantially between the different delousing treatments Walde et al., 2022). ...
... It is central to the public regulation of the growth of salmon aquaculture industry in Norway, and influence many parts of the ongrowing production and planning of the production of Atlantic salmon at sea (Forskrift om kapasitetsjusteringer, 2022; Forskrift om lakselusbekjempelse, 2016; Produksjonsområdeforskriften, 2017). Several studies have shown the enormous monetary cost associated with salmon lice, and thus highlighted the importance of prioritising the problem both at a macro and microeconomic level (Abolofia et al., 2017;Costello, 2009;Iversen et al., 2020;Liu and Bjelland, 2014;Mustafa et al., 2001;Olaussen et al., 2015). Salmon lice control is a cost to both society, the farmer and the salmon. ...
... The louse has received much focus from industry, academics, and the government over the last three decades leading to better understanding and management but has also been a source of negative perception of the salmon industry by the public (Bron and Bricknell, 2022). Sea louse have been estimated to cost around 9% of farm revenues, the most relevant costs being treatment costs, reduced fish growth, and reduced food conversion efficacy (Abolofia et al., 2017;Costello, 2009). Part of the life cycle of lice is freeliving. ...
... These complicating factors associated with costs and effectiveness, in combination with constantly evolving protocols, differences between salmon producing companies' internal policies on sea lice management measures and sensitivity towards sharing data (Brugere et al., 2017) have led to a lack of quantitative information on sea lice management measures in Scotland. Internationally published studies on economics and effectiveness of sea lice control measures are at a farm level, using a bioeconomic model to simulate the economy of the production (Abolofia et al., 2017;Bjørndal and Tusvik, 2019;Liu et al., 2011;Liu and Bjelland, 2014) or used real farm data on isolated sea lice management measures (Powell et al., 2018). Such methodology provides valuable insights but requires many resources. ...
... For example, if a strict delousing regulation, such as that currently in place in Norway, is motivated by protecting wild salmon, should efficacy not be measured as some effect of a measure deployed in aquaculture on the infestation pressure of sea lice to migrating wild salmon? The break-even point of implementing lice treatment solely based on economic effectiveness for Norwegian salmon farmers is estimated around 7-10 lice per fish which is well over the government regulation (Abolofia et al., 2017). However, quantifying such an association with environment effectiveness is complex, and in Norway there is no evidence that such strict L. salmonis regulations (a threshold of 0.2 lice per fish during the out-migration period) reduces infestation pressures on wild fish (Larsen and Vormedal, 2021). ...
... Farmed salmon are typically reared with few barriers between the fish and the surrounding marine environment, creating a complex set of externalities . Of these, sea lice infestation remains the most harmful of environmental issues within the industry, as measured by the damage costs (Abolofia et al., 2017;Dresdner et al., 2019;Walde et al., 2023), and the impact on the wild salmon populations (Torrissen et al., 2013;Glover et al., 2017;Osmundsen et al., 2020;Hersoug et al., 2021). At farm level, existing solutions for containing this parasite are costly. ...
... These indirect costs could be higher than the direct costs (Misund, 2022). Salmon lice infestations in Norwegian salmon farms amounted to 9% of revenues in 2011 (Abolofia et al., 2017). Given that profit margins have been around 20% to 30% in recent years, this suggests that salmon lice costs are equivalent to between one-third and half of profits, underscoring how costly sea lice can be for both producers and society. ...
... This transition has enhanced production flexibility, thereby facilitating a reduction in CO2 emissions. Similarly, increased flexibility in salmon aquaculture production could potentially facilitate the management of sea lice infestations (Abolofia et al., 2017). It can be argued that FITs should be differentiated to reflect this flexibility in production. ...
... However, as mentioned by Asche et al. (2022) aquaculture production generates a number of negative externalities. For the production of salmon in Norway, the most important externalities are diseases (Fischer et al., 2017), salmon lice 1 (Abolofia et al., 2017) and escapees (Olaussen, 2018;Pincinato et al., 2021). From a practical policy perspective, salmon lice infections has been considered the most important environmental problem in Norway (Ministry of Trade, Industry and Fisheries, 2015). ...
... A number of studies have aimed at analyzing economic issues related to salmon lice in Norway. Specifically, Torrissen et al. (2013) focused on the socioeconomic impacts of salmon lice on wild salmon stocks, while Abolofia et al. (2017) and Olaussen et al. (2015) conducted an empirical investigation of the size of the damage costs of wild stocks. A theoretical analysis of the response by firms to existing entry restrictions related to salmon lice can be found in Oglend and Soini (2020), while Greaker et al. (2020), Osmundsen et al. (2022) and Føre et al. (2022) considered technological innovations as a solution to salmon lice externality problems. ...
Article
The salmon lice-induced mortality of wild salmon stocks that result from aquaculture production can be considered a nonpoint pollution problem. In Norway, this externality is managed using a traffic light system (TLS), and the purpose of this system is to regulate the estimated aggregated salmon lice-induced mortality of wild salmon stocks in a number of production areas. This paper evaluates the TLS and in doing so, we depart from the literature on the regulation of nonpoint pollution problems. We argue that limited perceived influence of individual actions on the mortality of wild salmon stocks, difficulties in obtaining a reliable measure for the aggregated salmon lice-induced mortality and collective punishment of individual actions constitute the major problems of the TLS. As alternatives to the TLS, we discuss a subsidy to reduce the amount of salmon lice and a tax on salmon lice at farm site level.
... year, in part from prophylaxis and treatments against louse, as well as mortality and growth reduction in infested fish (Abolofia et al., 2017). Salmon producers have also come under public scrutiny and government regulation under the 'traffic light system' to reduce the spread of louse and therefore lessen the health risks to wild salmonids (Taranger et al., 2015;Vollset et al., 2018). ...
... Statistical analyses were performed and visualized in R v4.2.2 (R Core Team, 2022) using the tidyverse package(Wickham et al., 2019). A linear mixed effects model (LMM) was used to test the individual and interactive effects of species and number of spiked lice on TDC across all samples (lme4::lmer; Bates et al.,2015). Two subsequent LMMs were created using subsets of the data by species and tested the effects of stage and lice number on L. salmonis and C. elongatus samples separately. ...
Article
Sea lice cause substantial economic and environmental harm to Norway's aquaculture industry and wild salmonid populations. Rapid, accurate quantification of lice larval densities in coastal waters remains the greatest bottleneck for providing empirical data on infestation risk within wild salmon habitats and aquaculture production regions. We evaluated the capability of droplet digital PCR (ddPCR) as an absolute quantification method for the planktonic stages of two parasitic louse species, Lepeophtheirus salmonis (Krøyer) and Caligus elongatus (von Nordman). Results demonstrated linear relationships between the DNA quantity measured and the number of spiked larvae for both species and life stages. However, L. salmonis contained a significantly greater number of DNA copies than C. elongatus individuals and for C. elongatus , nauplii displayed a significantly higher number of DNA copies than copepodids. Our results suggest that ddPCR can effectively enumerate louse larvae, but interpreting ddPCR results differ between the two louse species. Obtaining larval abundance estimates from marine plankton samples will depend on the nauplii to copepodid ratio for C. elongatus , but not for L. salmonis .
... The environmental impact and societal cost that can be associated with health issues in finfish farming have rarely been looked at. These impacts and costs are due to the losses associated to a waste of resources, the additional treatment of biological waste, the cost of treatments and biosecurity measures, and the contamination of wild stocks (Skilbrei 2012;Monir et al. 2015;Abolofia et al. 2017;Just Economics 2021). Studies and reports have recently started to address the issue using a LCA approach. ...
... This difference of perspective could considerably change the estimated opportunity cost. Modeling the distinct consequences of events happening at different growth stages and the responses of the production program has already been done for environmental or economic assessment (Bala and Satter 1989;Château and Chang 2010;Abolofia et al. 2017;Ferreira et al. 2021), but never adapted to LCA to our knowledge. Assessing the environmental opportunity cost of losses and being able to predict the environmental impacts of a farming system under different biological performances thus require a new disaggregated and detailed LCA allowing modification of this performance at different stages in the production cycle. ...
Article
Full-text available
Purpose Mortality and suboptimal biological performance are a widespread problem in finfish farming. The associated losses constitute an environmental opportunity cost that needs to be thoroughly assessed to prioritize actions aiming at reducing the environmental impacts of finfish aquaculture. We here propose and demonstrate the use of a new parameterized and consequential LCA model of sea-trout production designed to assess the environmental opportunity costs of suboptimal biological performances, considering distinct mortalities and biological feed conversion ratios (FCRs) along the rearing process. Methods Primary data was collected in Danish and Italian farms to reconstitute the whole production process for sea-reared trouts. The level of detail allowed us to divide this production into seven different growth stages for which mortality and biological FCR can be assessed and modified. Excretion and valorization of fish sludge were modeled with a calibrated mass-balance model. Together with fish sludge, dead fish was modeled as valorized by anaerobic digestion. The foreground system was linked to the consequential version of ecoinvent 3.8 for which the embedded uncertainty was considered in Monte Carlo simulations. The model was used to assess the current environmental opportunity costs and evaluate the effect of losses happening at different timings along the rearing process. Results and discussion Results showed a low environmental opportunity cost for the current mortality rate of 5% as suppressing this mortality decreased impacts by 3.5 to 5% across impact categories. Decreasing the biological FCR decreased the environmental impacts proportionally. The timing of the losses was shown to greatly influence the environmental opportunity cost, and the same mortality rate happening in the late stages had substantially more impact than in the first stages. The valorization of the dead fish showed a negligible contribution to the reduction of impacts in the current system but showed a substantial contribution in the case of higher mortalities, such as observed for other farms and foreseen in the future. Conclusion The model demonstrated that assessing an opportunity cost by multiplying the lost biomass by a unique impact factor constitutes an oversimplification neglecting the losses timing and the fact that fish biomass is not a marketable product. Even though the current environmental opportunity cost for losses appeared neglectable, suboptimal biological FCR should be tackled. The model and approach can be used to project trout farming within future disease regimes and assess the trade-offs regarding fish health issues and new treatments and practices.
... Sea lice are naturally occurring parasitic copepods that feed on the mucous, blood and skin of both wild and farmed salmonid fish. In high numbers, sea lice may reduce the general health and welfare of their hosts [5][6][7] and can cause significant economic losses to commercial salmonid farms as a result of increased production costs and increased fish mortalities [8][9][10]. Furthermore, sea lice produce large amounts of planktonic larvae and given the nature of the open net-pen salmon farming system, they can disperse via the water currents and infect populations of migrating post-smolts of Atlantic salmon and sea trout (Salmo trutta) and Arctic char (Salvelinus alpinus L.) that stay in coastal waters [11,12]. ...
Article
Full-text available
Aquaculture is expanding globally and the environmental implications associated with this growth, including the increasing use of chemicals in aquatic locations, are an emerging concern for environmental legislators. Veterinary medicinal products (VMP) are used as chemotherapeutants to control sea lice infestations on open-net pen salmon farms and questions have been raised about their potential to cause adverse effects on marine ecosystems. The current study analyses the usage patterns of anti-sea lice VMPs in major salmonid aquaculture regions and reviews the current knowledge on their mode of action, routes into the environment and environmental fate. We subsequently evaluate their hazard potential by performing a toxicity assessment and deriving up-to-date preliminary environmental quality standards (EQS). We demonstrate that the use of anti-sea lice VMPs varies between the major salmon-producing countries, with quantities varying over time and depending on the chemical. Norway and Chile use the highest quantity of chemical treatments, consistent with their higher salmon production capacity, and while the reliance on some chemicals has decreased the use of newly authorised chemicals has increased. Our toxicity assessment revealed that there was sufficient reliable acute toxicity data to derive EQS for five of the selected anti-sea lice VMPs using the probabil-istic method of constructing species sensitivities distribution curves. However, insufficient chronic and sediment toxicity data were available for all chemicals and therefore EQS were derived using the traditional deterministic method. The information presented in this review can guide future research and facilitate better environmental risk assessments of chemotherapeutant used on salmon farms.
... Combating salmon lice is one of the biggest challenges in Atlantic salmon farming [1,2] and has been estimated to cost the salmon farming industry in Norway around 9% of their income [3]. In recent years, there has been a strong focus on the increasing salmon lice problem in the Norwegian aquaculture industry [4], and the large economic losses it causes in the form of lost growth, treatment mortality, reduced feed utilization, secondary infections, downgrading and treatment costs [5][6][7][8]. ...
Article
Full-text available
Acoustic lice treatment (AcuLice) is a newly developed system which uses a composite acoustic sound image with low-frequency sound to remove salmon lice (Lepeophtheirus salmonis) from Atlantic salmon (Salmo salar). The effect of AcuLice treatment on salmon lice dynamics was measured by weekly salmon lice counting at a full-scale production facility from mid-summer 2019 to late-spring 2024. We monitored four production cycles, with AcuLice applied for two of the production cycles and with no AcuLice treatment applied during the other two production cycles as control. This is a follow-up study to our previous work. The numbers of salmon lice treatments and of weeks until the first salmon lice treatment were also compared in the two experimental groups. For the small (sessile and mobile stages) salmon lice, a significantly lower number (mean ± SEM) was shown for the AcuLice group (0.73 ± 0.03) compared with the control group (1.18 ± 0.05). For the mature female salmon lice, a significantly lower number (mean ± SEM) was found for the AcuLice group (0.12 ± 0.01) compared with the control group (0.22 ± 0.03). In addition, the mean (±SEM) number of C. elongatus varied between the two experimental groups and was higher in the control group (0.12 ± 0.01) compared with the AcuLice group (0.03 ± 0.01). In addition, a lower number (mean ± SEM) of salmon lice treatments (1.4 ± 0.17 vs. 4.22 ± 0.20) and a longer production period before the first salmon lice treatment occurred was observed for the AcuLice group (11.2 ± 0.1 weeks) compared with the control group (24.1 ± 2.3 weeks). These data suggest that the use of the AcuLice system significantly reduces the number of salmon lice (by 40–60%) and C. elongatus (by 70%) on farmed Atlantic salmon and reduces the need for traditional salmon lice treatments (by 65%).
... Surface-based salmonid production is often hindered by issues such as sea lice infestation and unsuitable temperatures, which negatively impact growth performance, welfare, and production of salmonids [10][11][12][13][14][15][16][17]. Culturing salmonids in submerged environments is considered an effective strategy to mitigate these challenges. ...
Article
Full-text available
Salmonids, classified as physostomous fish, maintain buoyancy by ingesting air to inflate their swim bladders. Long-term submergence has been shown to cause body imbalance and reduced growth performance in these fish. Previous studies have demonstrated that extended photoperiod can promote growth in salmonids. This study aimed to investigate the regulatory effects of prolonged lighting on the growth of submerged rainbow trout (Oncorhynchus mykiss) by examining the transcriptional expression of genes in the growth hormone (GH)-insulin-like growth factor (IGF) axis. Rainbow trout were individually reared in one of the six environments, defined by the combination of three photoperiods (0L:24D, 12L:12D, and 24L:0D) and two spatial rearing modes (routine and submerged), for 16 weeks. We compared the growth performance of rainbow trout in different environments and further analyzed the transcription profiles and correlations of GH-IGF axis genes in the brain, liver, and muscle. The findings of this study were as follows: growth performance of rainbow trout gradually increased with photoperiod duration. Specifically, final body weight (FBW) and specific growth rate (SGR) increased, while feed conversion ratio (FCR) decreased. Extended photoperiod partially mitigated the adverse effects of long-term submergence on rainbow trout growth. Under 24L:0D photoperiod conditions, growth performance (FBW, SGR, and FCR) in submerged and routine rainbow trout was more closely aligned compared to 0L:24D and 12L:12D photoperiod conditions. In response to variations in the photoperiod, GH-IGF axis genes of rainbow trout exhibited significant transcriptional differences, particularly between treatments with 0L:24D and 24L:0D light exposure. An extended photoperiod facilitated the restoration of the expression of GH-IGF axis genes in submerged rainbow trout towards routine levels, including the up-regulation of sst and sstr2 genes in the brain. Correlation analysis implied differentiation of physiological functions of ghr and igfbp paralogs. This study provided insights into the feasibility of enhancing the growth performance of submerged salmonids through photoperiod manipulation.
... Sea lice infestations pose significant challenges to salmon farming, affecting fish welfare, health, and economic sustainability (Costello 2009, Abolofia et al. 2017). These harmful copepods cause economic losses and productivity issues, making the management of sea lice infestations a pressing concern for the aquaculture industry (Costello, 2009). ...
... The sea louse, Lepeophtheirus salmonis, an ectoparasitic copepod of Atlantic salmon, Salmo salar, is a major pest in aquaculture systems that has been the subject of sustained control efforts, in particular using chemotherapy (Abolofia, Asche & Wilen, 2017). The evolution of drug-resistant sea lice populations was therefore no surprise (e.g. ...
Article
Full-text available
The Anthropocene is seeing the human footprint rapidly spreading to all of Earth's ecosystems. The fast‐changing biotic and abiotic conditions experienced by all organisms are exerting new and strong selective pressures, and there is a growing list of examples of human‐induced evolution in response to anthropogenic impacts. No organism is exempt from these novel selective pressures. Here, we synthesise current knowledge on human‐induced evolution in eukaryotic parasites of animals, and present a multidisciplinary framework for its study and monitoring. Parasites generally have short generation times and huge fecundity, features that predispose them for rapid evolution. We begin by reviewing evidence that parasites often have substantial standing genetic variation, and examples of their rapid evolution both under conditions of livestock production and in serial passage experiments. We then present a two‐step conceptual overview of the causal chain linking anthropogenic impacts to parasite evolution. First, we review the major anthropogenic factors impacting parasites, and identify the selective pressures they exert on parasites through increased mortality of either infective stages or adult parasites, or through changes in host density, quality or immunity. Second, we discuss what new phenotypic traits are likely to be favoured by the new selective pressures resulting from altered parasite mortality or host changes; we focus mostly on parasite virulence and basic life‐history traits, as these most directly influence the transmission success of parasites and the pathology they induce. To illustrate the kinds of evolutionary changes in parasites anticipated in the Anthropocene, we present a few scenarios, either already documented or hypothetical but plausible, involving parasite taxa in livestock, aquaculture and natural systems. Finally, we offer several approaches for investigations and real‐time monitoring of rapid, human‐induced evolution in parasites, ranging from controlled experiments to the use of state‐of‐the‐art genomic tools. The implications of fast‐evolving parasites in the Anthropocene for disease emergence and the dynamics of infections in domestic animals and wildlife are concerning. Broader recognition that it is not only the conditions for parasite transmission that are changing, but the parasites themselves, is needed to meet better the challenges ahead.
... A frontrunner of parasitic infections in the aquaculture industry is sea lice, especially when taking into consideration the detrimental effects they can have on economically significant fish species like the Atlantic salmon [229][230][231]. Sea lice are naturally occurring ectoparasites of fish, though increasing rearing densities have sparked rather high infestation rates in both farmed and wild fish populations during the last decades. ...
Preprint
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Aquaculture has rapidly emerged as one of the fastest growing industries, expanding both on global and on national fronts. With the ever-increasing demand for high biological value protein, the aquaculture industry has established itself as one of the most efficient forms of animal production, proving to be a vital component of global food production, by supplying nearly 50% of the planet’s seafood. As in classic animal production, the prevention of diseases constitutes an enduring challenge associated with severe economic and environmental repercussions. Nevertheless, remarkable strides in the development of aquaculture vaccines have been recently witnessed, offering sustainable solutions to persistent health-related issues challenging resilient aquaculture production. These advancements are characterized by breakthroughs in increased species-specific precision, improved vaccine delivery systems, and innovations in vaccine development, following the recent advent of nanotechnology, biotechnology, and artificial intelligence in the -omics era. The objective of this paper was to assess recent developments and milestones revolving around aquaculture vaccinology and provide an updated overview of strengths, weaknesses, opportunities, and threats of the sector, by incorporating and comparatively discussing various diffuse advances that span across a wide range of topics, including emerging vaccine technologies, innovative delivery methods, insights on novel adjuvants, and parasite vaccine development for the aquaculture sector.
... Sea louse infestation remains one of the most serious challenges to salmon aquaculture in many regions. Infestation with this ectoparasite can pose a risk to salmon health and reduces fish growth, thus decreasing aquaculture productivity (Abolofia et al. 2017). It has also been suggested that such infestations may contribute to declines in wild salmonid populations (Krkosek et al. 2007;Rogers et al. 2013;Nekouei et al. 2018). ...
Article
Full-text available
Objective Efficiently managing sea lice on salmon farms through active surveillance, crucial for lice abundance estimation, is challenging due to the need for effective sampling schemes. To address this, we developed an application that considers infestation levels, farm structure, and management protocols, enhancing the precision of sampling strategies for sea louse abundance estimation. Methods Simulation‐based methods are valuable for estimating suitable sample sizes in complex studies where standard formulae are inadequate. We introduce FishSampling , an open Web‐based application tailored to determine precise sample sizes for specific scenarios and objectives. Result The model incorporates factors such as sea lice abundance, farm pen numbers, potential clustering effects among these pens, and the desired confidence level. Simulation outcomes within this application provide practical advice on how to decide on the number of fish and pens to sample, under varying levels of assumed clustering. Conclusion This approach can be used across the salmon aquaculture sector to improve sampling strategies for sea lice abundance estimation and balance surveillance costs against health objectives.
... A frontrunner of parasitic infections in the aquaculture industry is sea lice, especially when taking into consideration the detrimental effects they can have on economically significant fish species like the Atlantic salmon [230][231][232]. Sea lice are naturally occurring ectoparasites of fish, though increasing rearing densities have sparked rather high infestation rates in both farmed and wild fish populations during the last decades. ...
Article
Full-text available
Aquaculture has rapidly emerged as one of the fastest growing industries, expanding both on global and on national fronts. With the ever-increasing demand for proteins with a high biological value, the aquaculture industry has established itself as one of the most efficient forms of animal production, proving to be a vital component of global food production by supplying nearly half of aquatic food products intended for human consumption. As in classic animal production, the prevention of diseases constitutes an enduring challenge associated with severe economic and environmental repercussions. Nevertheless, remarkable strides in the development of aquaculture vaccines have been recently witnessed, offering sustainable solutions to persistent health-related issues challenging resilient aquaculture production. These advancements are characterized by breakthroughs in increased species-specific precision, improved vaccine-delivery systems, and innovations in vaccine development, following the recent advent of nanotechnology, biotechnology, and artificial intelligence in the -omics era. The objective of this paper was to assess recent developments and milestones revolving around aquaculture vaccinology and provide an updated overview of strengths, weaknesses, opportunities, and threats of the sector, by incorporating and comparatively discussing various diffuse advances that span across a wide range of topics, including emerging vaccine technologies, innovative delivery methods, insights on novel adjuvants, and parasite vaccine development for the aquaculture sector.
... Sea lice are a significant economic pest for farming of Atlantic salmon (Salmo salar) in marine net pen operations. Economic estimates of the annual cost of managing sea lice were about 9% of farm revenues and over $750 million USD in 2012 (Abolofia et al., 2017;Roth, 2015). Sea lice management is complicated by increased resistance to most drug-based treatments (Aaen et al., 2015;Roth, 2015). ...
... Infectious salmon anemia alone costs 2 billion dollars and causes 20000 workers to lose their jobs in Chile (Leung and Bates, 2013). Sea lice infections of salmon in Norway led to a loss estimated at >US$ 400 million in 2011 (Abolofia et al., 2017). Due to these considerable economic risks, disease outbreaks represent one of the main obstacles to the sustainable growth of aquaculture (Subasinghe et al., 2019). ...
Article
The aim of the current study was to isolate and identify potential bacterial pathogens from Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) in Lake Hawassa, Ethiopia. The study was conducted during January to December 2021. A total of 360 Nile tilapia were sampledfrom Lake Hawassa and subjected to bacteriological investigations. The results showed 64.2% prevalence of bacterial infection in Nile tilapia from the lake. Potential bacterial pathogens such as Aeromonas hydrophila, Escherichia coli, Edwardsiella tarda, Vibrio sp,,Bacillus sp., Staphylococcus sp., Salmonella sp., Flavobacterum sp., Pseudomonas sp. and Shigella sp. were isolated. The prevalence of infection in female fish (52.4%) was higher compared to male fish (47.6%). Comparatively higher prevalence was recorded in thesmaller fish group than in the larger ones. The average bacterial loads recorded in various organs such as intestine, skin, gill, liver and kidney were, 4.86±0.56 x 105, 4.72±0.48 x 105, 4.14±0.53 x 105, 3.45±0.23 x 105 and 2.63±0.324 x 105 CFU ml-1 respectively. Significantly high bacterial loads were recorded from the intestine (5.81±0.01 x 105 CFU ml-1) of fishduring the summer season (p<0.05). The results of the study indicated that there is a risk of occurrence of disease outbreak under stressful situations. Moreover, the recovery of these bacteria in the fish which are potentially pathogenic to humans, suggests that if the fish are improperly handled, undercooked or consumed raw, may cause diseases to susceptible individuals. Keywords:Bacterial pathogens, Lake Hawassa, Oriochromis niloticus, Prevalence
... Second, bay-scale issues were addressed through collaboration amongst salmon farming companies within the same area, a strategy that has been used to address common problems such as disease management and water quality [38]. This type of collective action is also required by some eco-certification schemes [59,71]) and demonstrates the role of collective action in both managing common-pool resources [24,38] and protecting private assets, for instance, where the spread of disease and parasites is costly for producers [72][73][74]. Finally, social acceptance of aquaculture is mediated by perceptions of the contribution of aquaculture to local economies including the creation of jobs [13,[75][76][77][78]; therefore, CSR strategies that prioritize the development of local supply chains and creation of local jobs address both social acceptance and cultural ecosystem services through the provision of symbolic value and a sense of place. ...
Article
Aquaculture eco-certification is especially relevant in salmon farming where it has emerged as a popular corporate social responsibility (CSR) strategy, providing global standards that can be applied to a globally traded commodity. However, eco-certification is just one of many CSR strategies used to address seafood sustainability at the corporate level. CSR is important for company image, but it is not clear whether or how these strategies contribute to sustainability outcomes. This paper applies an ecosystem services framework to an analysis of sustainability reporting from top salmon farming companies to identify links between eco-certification, other CSR strategies, and the delivery of ecosystem services. Although eco-certification was used to indicate commitment to sustainability practices across all companies, other CSR strategies, especially practices, power, and partnership, were more frequently and explicitly connected to the delivery of ecosystem services. Results show that individual CSR strategies including eco-certification are not isolated but interact and work in concert to manage the supply of ecosystem services.
... Furthermore, sea lice infestation can have negative impacts on the survival of wild post-smolts, and consequently are believed to contribute to the decline of the wild Atlantic salmon populations Torrissen et al., 2013). The economic cost of sea lice to the global salmonid farming industry was estimated at US$301 million in 2017 (Abolofia et al., 2017). To minimize the economic losses to the industry, improve fish welfare, and to protect wild salmonid populations, monitoring and controlling sea lice numbers on salmon farms is vital. ...
... Saksvik et al. (2001) demonstrated a reduced growth rate in Atlantic salmon Salmo salar L. infected with Eubothrium sp. (Cestoda: Pseudophyllidea) compared with uninfected fish, and Abolofia et al. (2017) found that sea lice, an ectoparasitic copepod, reduce the total biomass growth of farmed salmon. ...
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Nematodes that parasitize salmonids are found in both seawater and freshwater. Unlike seawater species such as those in family Anisakidae, freshwater species have not been well studied. In particular, the influences of these nematodes on the body condition of salmonids remain unclear. We studied the effects of Salmonema cf. ephemeridarum on the body condition of masu salmon Oncorhynchus masou. We found a positive relationship between the number of parasites and fish fork length. In contrast, we found a negative relationship between the body condition (condition factor) of fish and the number of parasites. These results suggest that nematode infection could affect host energy reserves for future growth.
... Infestation with salmon lice represents one of the most serious threats to the salmon farming industry. The salmon louse Lepeophtheirus salmonis and other sea lice genera in the family Caligidae are the economically most important pathogens in salmon aquaculture (Abolofia et al., 2017;Costello, 2006;Torrissen et al., 2013). Salmon lice are ectoparasites that attach to and damage the skin of the fish. ...
Article
Abstract Lufenuron is a benzoylurea insecticide currently in use to combat sea lice infestation in salmon aquaculture in Chile. With pending approval in Norway, the aim of this work was to study the uptake and toxicity of lufenuron in liver tissue of Atlantic salmon. Juvenile salmon weighing 40 g were given a standard 7-day oral dose, and bioaccumu- lation and transcriptional responses in the liver were examined 1 day after the end- of-treatment (day 8) and after 1 week of elimination (day 14). Bioaccumulation levels of lufenuron were 29 ± 3 mg/kg at day 8 and 14 ± 1 mg/kg at day 14, indicating rela- tively rapid clearance. However, residues of lufenuron were still present in the liver after 513 days of depuration. The exposure gave a transient inhibition of transcription in the liver at day 8 (2437 significant DEGs, p-adj < .05), followed by a weaker com- pensatory response at day 14 (169 significant DEGs). Pathways associated with RNA metabolism such as the sumoylation pathway were most strongly affected at day 8, while the apelin pathway was most profoundly affected at day 14. In conclusion, this study shows that lufenuron easily bioaccumulates and that a standard 7-day oral dose induces a transient inhibition of transcription in liver of salmon.
... Perhaps these criteria are being applied arbitrarily because taking their consistent application to its logical conclusion would be extremely problematic. For example, sea lice (Lepeophtheirus spp., Caligus spp.) are ectoparasitic copepods that cost the global salmon farming industry hundreds of millions of dollars annually to control (Abolofia 2017;Stene et al. 2022). This cost is incurred in large part to satisfy animal welfare concerns over the impact of lice infestation on the welfare of wild and cultured salmon (Macaulay et al. 2022), but without any regard for the impact of the treatments on the welfare of the sea lice (Moccia et al. 2020). ...
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Psychology and vision science, university of leicester, leicester, uK; j school of veterinary science, Murdoch university, Perth, wA, Australia; k Department of ichthyology, Faculty of Biology, lomonosov Moscow state university, Moscow, Russia; l school of Biomedical sciences, university of queensland, Australia; m Pepperell Research and consulting, noosaville, qlD, Australia; n Kansas Biological survey, and the Biodiversity institute, the university of Kansas, lawrence, Ks, usA; o emeritus (Retired) Department of Zoology and Physiology, university of wyoming laramie, wY, usA; p Britannia heights, nelson, new Zealand; q Biomed sci, Atlantic veterinary college, university of Pei, charlottetown, canada; r the college of william & Mary, virginia institute of Marine science, Gloucester Point, virginia, usA; s emeritus (Retired) tropical Aquaculture laboratory, university of Florida, Gainesville, usA ABSTRACT The welfare of fishes and aquatic invertebrates is important, and several jurisdictions have included these taxa under welfare regulation in recent years. Regulation of welfare requires use of scientifically validated welfare criteria. This is why applying Mertonian skepticism toward claims for sentience and pain in fishes and aquatic invertebrates is scientifically sound and prudent, particularly when those claims are used to justify legislation regulating the welfare of these taxa. Enacting welfare legislation for these taxa without strong scientific evidence is a societal and political choice that risks creating scientific and interpretational problems as well as major policy challenges, including the potential to generate significant unintended consequences. In contrast, a more rigorous science-based approach to the welfare of aquatic organisms that is based on verified, validated and measurable endpoints is more likely to result in "win-win" scenarios that minimize the risk of unintended negative impacts for all stakeholders, including fish and aquatic invertebrates. The authors identify as supporters of animal welfare, and emphasize that this issue is not about choosing between welfare and no welfare for fish and aquatic invertebrates, but rather to ensure that important decisions about their welfare are based on scientifically robust evidence. These ten reasons are delivered in the spirit of organized skepticism to orient legislators, decision makers and the scientific community, and alert them to the need to maintain a high scientific evidential bar for any operational welfare indicators used for aquatic animals, particularly those mandated by legislation. Moving forward, maintaining the highest scientific standards is vitally important, in order to protect not only aquatic animal welfare, but also global food security and the welfare of humans.
... Aquaculture, one of the fastest-growing food sectors, predominates in LMICs . Interacting biological, environmental, social, and political factors have contributed to diseases that have seriously limited yield, benefits, profit, and food security from the sector, both in LMICs and in higher-income nations, over recent decades (Faruk et al., 2004;Solomieu et al., 2015;Abolofia et al., 2017;Tang and Bondad-Reantaso, 2019;Stentiford et al., 2020Patil et al., 2021;Ward et al., 2021). The role of animal disease as a poverty trap for LMIC farmers, in particular, has been discussed in this contextan improved biosocial evidence basis to understand causality, to design policy, and to drive public-private investment are cornerstones of the Global Burden of Animal Diseases (GBAD) approach to reducing risk (Huntington et al., 2021;Rushton et al., 2021). ...
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Aquaculture now provides half of all aquatic protein consumed globally—with most current and future production occurring in low- and middle-income countries (LMICs). Concerns over the availability and application of effective policies to deliver safe and sustainable future supply have the potential to hamper further development of the sector. Creating healthy systems must extend beyond the simple exclusion of disease agents to tackle the host, environmental, and human drivers of poor outcomes and build new policies that incorporate these broader drivers. Syndemic theory provides a potential framework for operationalizing this One Health approach.
... The most speciose genera in this family are Caligus and Lepeophtheirus, comprising 278 and 124 species, respectively [1]. Sea lice, mainly Caligus rogercresseyi and Lepeophtheirus salmonis, have become widely known due to their negative impact on fish aquaculture, causing skin irritation, ulcerations, anemia, lethargy, weight loss, secondary infections, and mortality in fish [3][4][5]. ...
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Fish–parasite systems could be subject to two scenarios under climate change: (i) increased water temperature might enhance parasite metabolism, allowing the parasite to spread rapidly; (ii) parasitism could decrease if the optimal temperature for growth and transmission is exceeded. Sea lice are parasitic copepods commonly found on marine fish in tropical regions, yet their biology remains poorly investigated. In this study, we analyzed the changes in infection levels and the transcriptomic response of the tropical sea louse Caligus confusus to two seasonal seawater temperatures (30 °C, “warm”, and 21 °C, “cold”). The prevalence of C. confusus was significantly higher in the colder water. A de novo transcriptomic analysis of C. confusus, the first for a tropical sea louse, revealed 426 over-expressed and 1402 down-expressed transcripts at the lower temperature. In particular, we observed over-expression of transcripts encoding vitellogenins (vit-1, vit-2, vit-4, and vit-6) and matrix metalloproteinases (mmp-2 and mmp-9), which are involved in reproduction and development. These results suggest that the cold tropical season physiologically favors C. confusus and that low temperature favors embryo development, which might ultimately lead to a higher prevalence. It is possible, therefore, that climate change could reduce some tropical sea lice populations during extreme warming events.
... The infestation of sea lice (Lepeophtheirus salmonis Krøyer 1837) on farmed salmon (Salmo salar) is now the biggest constraint to sustainable growth for the Norwegian aquaculture industry (Abolofia et al., 2017;Liu and Bjelland, 2014;Todd, 2007;Torrissen et al., 2013). Caligus elongatus is another parasite infecting the salmon and is mainly considered a problem in northern Norway (Hemmingsen et al., 2020). ...
... Along with damage to the fins, skin, and gills, which could lead to infection, they have been shown to reduce fish growth and appetite which cause substantial costs to salmon farmers. It has been estimated that the cost of the damages to the Norwegian salmon farming industry due to lice was US$436 million in 2011 (Abolofia et al., 2017). Whilst dependent on location, they also estimate that the total biomass growth lost per production cycle is between 3.62 and 16.55% despite control measures put in place. ...
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Zooplankton are a key group of organisms at the base of the marine food web and are fundamental to providing a broad range of societal and economic benefits which have previously remained poorly defined. This research addresses this knowledge gap through the provision of a first full assessment of zooplankton ecosystem services and disservices. Anthropogenic stressors such as microplastic pollution, climate change, and fisheries, could negatively affect the marine ecosystem services provided to humans and therefore have a negative impact on human well-being through reduction in food security, livelihoods, income, and good health. Deploying a mixed methodology approach including a semi-systematic literature review and ecological impact assessment, we provide novel evidence of the effects of microplastic pollution (high and low concentrations), fisheries, and climate change on the ecosystem services of three important zooplankton groups (copepods, jellyfish, and krill). We show that the majority of impacts on ecosystem services are negative, with the exception of climate change on jellyfish ecosystem services. Climate change and high microplastic concentration are evidenced to have the most substantial negative impacts on copepods and krill, with accompanying implications for the ecosystem services of climate regulation, water conditions, other materials, science, and entertainment. High microplastic concentration also depressed ecosystem service provision for jellyfish, impacting the services of genetic materials , climate regulation, water conditions, education, and entertainment. Fisheries are also evidenced to have negative impacts on all three zooplankton groups. In the case of jellyfish, climate change is evidenced to have a positive impact on the group's ecosystem service provision in every category except experiential experiences, which is inversely related to increasing population, owing to their negative perception due to sting injuries. The evidence presented in this study shows that by maintaining sustainable fisheries, reducing plastic pollution, and minimising climate change, we will be actively investing in the current and future provision of marine ecosystem services and the human well-being benefits that they provide.
... Until now, no studies have examined the economic impact of severe skeletal anomalies in any fish species. However, a number of recent studies have examined the economic impact of fish diseases (Abolofia et al., 2017;Fernández Sánchez et al., 2021Lafferty et al., 2015;Nor et al., 2019;Peterman & Posadas, 2019). Furthermore, only the investigations of Fernández Sánchez et al. (2021Sánchez et al. ( , 2022 focused on Mediterranean aquaculture, taking into account European seabass, Dicentrarchus labrax, and gilthead seabream, Sparus aurata. ...
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The economic impact of skeletal anomalies in aquaculture farming is a significant issue for the industry, as deformed fish are frequently discarded because of their low survival rate and a variety of other disadvantages, including increased costs, consumer distrust of aquaculture products, and ethical concerns. The goal of this article is to propose a method for calculating the direct costs of severe skeletal anomalies in typical Mediterranean seabream and seabass aquaculture hatcheries using a deterministic static model programmed in MATLAB that simulates their annual operation. Our findings suggest that larger hatcheries experience higher direct costs associated with severe skeletal anomalies but have better financial stability and significantly higher expected profits. Mean results indicate that the annual economic losses of severe skeletal anomalies for seabream and seabass Mediterranean aquaculture are 22.88 million euros per year for a scenario of low severe skeletal anomalies, 65.34 million euros per year for a scenario of medium severe skeletal anomalies, and 115.98 million euros per year for a scenario of high severe skeletal anomalies. Furthermore, some options for increasing the financial stability of the hatcheries are to increase the sale price of fingerlings, reduce the feed conversion ratio, and reduce the feed unit cost.
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The expansion and development of sustainable salmon aquaculture requires research, innovation and, where necessary, regulation to manage environmental impacts. Sea lice are a key concern for marine salmonid fish aquaculture as these parasites adversely affect farmed and wild salmonids. Reducing the risk of harmful infestation levels requires appropriate data to support modelling and inform adaptive management processes. Throughout their life cycle, sea lice occur as either planktonic larvae or as ectoparasites on farmed, wild or sentinel fish host populations. Limited resources require surveillance methodologies and strategies for these stages to be optimized to obtain data that meet the specific needs of control. In this review we assess the different surveillance strategies available to inform the appropriate management of sea lice impacts on wild salmonids. We advocate modelling as the most effective way to use surveillance data, with subsequent model improvements informed by the continued input of collected data. A feedback loop is proposed of identifying/collecting empirical data to improve models, which in turn will direct more focused surveillance for future data collection and so drive adaptive management processes. In the future, surveillance monitoring, as part of an adaptive management regime in Scotland, should build on existing links between stakeholders and policy makers, and use both models and data to help the sustainable development of the aquaculture industry.
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Background Salmonid species have followed markedly divergent evolutionary trajectories in their interactions with sea lice. While sea lice parasitism poses significant economic, environmental, and animal welfare challenges for Atlantic salmon (Salmo salar) aquaculture, coho salmon (Oncorhynchus kisutch) exhibit near-complete resistance to sea lice, achieved through a potent epithelial hyperplasia response leading to rapid louse detachment. The molecular mechanisms underlying these divergent responses to sea lice are unknown. Results We characterized the cellular and molecular responses of Atlantic salmon and coho salmon to sea lice using single-nuclei RNA sequencing. Juvenile fish were exposed to copepodid sea lice (Lepeophtheirus salmonis), and lice-attached pelvic fin and skin samples were collected 12 h, 24 h, 36 h, 48 h, and 60 h after exposure, along with control samples. Comparative analysis of control and treatment samples revealed an immune and wound-healing response that was common to both species, but attenuated in Atlantic salmon, potentially reflecting greater sea louse immunomodulation. Our results revealed unique but complementary roles of three layers of keratinocytes in the epithelial hyperplasia response leading to rapid sea lice rejection in coho salmon. Our results suggest that basal keratinocytes direct the expansion and mobility of intermediate and, especially, superficial keratinocytes, which eventually encapsulate the parasite. Conclusions Our results highlight the key role of keratinocytes in coho salmon’s sea lice resistance and the diverged biological response of the two salmonid host species when interacting with this parasite. This study has identified key pathways and candidate genes that could be manipulated using various biotechnological solutions to improve Atlantic salmon sea lice resistance.
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The Gulf of Maine (GoM) is one of the fastest-warming parts of the world’s oceans. Some species’ distributional shifts have already been documented, especially for commercially-important species. Less is known about species that are not currently exploited but may become so in the future. As a case study into these issues, we focus on lumpfish (Cyclopterus lumpus) because of the recognized and timely need to understand wild lumpfish population dynamics to support sustainable fisheries and aquaculture developments. Using occurrence data from five different fisheries-dependent and -independent surveys, we examined lumpfish distribution over time in the GoM. We found that lumpfish presence was more likely in spring and correlated with deeper waters but not bottom temperature. Since 1980, lumpfish presence has increased over time, moved farther offshore, and shifted northward. Our work provides preliminary information for resource managers to ensure that lumpfish are harvested sustainably for use in emergent lumpfish aquaculture facilities. An understanding of lumpfish occurrence patterns may enable lumpfish aquaculturists to utilize the most local populations, thus maintaining the local genetic integrity of fish slated for release into net pen salmonid farms.
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Sea lice (Lepeophtheirus salmonis [Krøyer, 1838]) are a key issue for salmon aquaculture, contributing to increased mortality for both wild and farmed salmon if no action is taken. Using cleaner fish can be an effective, drug‐free treatment method, and ballan wrasse (Labrus bergylta) is a hardy wrasse species that displays cleaning behavior. With concerns about the overharvest of wild ballan wrasse, many companies farm this species, but the optimal ranges of a wide variety of rearing parameters are still unknown. This study investigated the effect of 6‐week exposure to four dissolved oxygen (DO) levels (125%, 100%, 85%, and 75% DO saturation as the percentage of air) on ballan wrasse. Survival; growth (specific growth rate, SGR); condition factor (CF); and primary (cortisol), secondary (glucose, lactate, magnesium), and tertiary stress indicators (swimming performance) were investigated. There were no differences in SGR, CF, survival, or cortisol level among the groups at the end of the 6 weeks. There was variation in the magnitude of the cortisol response to an acute stressor at the end of the 6‐week period, with the 75% DO treatment exhibiting a 3.3‐fold increase in cortisol compared to a 5.2‐fold increase in the control group (100%), which could suggest chronic stress. Relative critical swimming speed (RUcrit) was measured to investigate swimming performance once all groups were returned to 100% DO saturation. The 75% RUcrit was lower than the 100% treatment (1.7 ± 0.18 body length [BL]/s compared to 2.5 ± 0.16 BL/s). Overall, these results suggest that DO levels of 75% trigger physiological changes and therefore may negatively affect welfare.
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Parasitic sea lice (Copepoda: Caligidae) colonising marine salmonid (Salmoniformes: Salmonidae) aquaculture production facilities have been implicated as a possible pressure on wild salmon and sea trout populations. This investigation uses monitoring data from the mainland west coast and Western Isles of Scotland to estimate the association of the abundance of adult female Lepeophtheirus salmonis (Krøyer) colonising farmed Atlantic salmon Salmo salar L. with the occur- rence of juvenile and mobile L. salmonis on wild sea trout, anadromous S. trutta L. The associations were evaluated using generalised linear mixed models incorporating farmed adult female salmon louse abundances which are temporally lagged relative to dependent wild trout values. The pattern of lags, which is consistent with time for L. salmonis development between egg and infective stage, was evaluated using model deviances. A significant positive association is identified between adult female L. salmonis abundance on farms and juvenile L. salmonis on wild trout. This association is consistent with a causal relationship in which increases in the number of L. salmonis copepodids originating from lice colonising farmed Atlantic salmon cause an increase of L. salmonis abundance on wild sea trout.
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The demand for lumpfish (Cyclopterus lumpus) as a biological control for salmon lice is increasing. However, lumpfish welfare is considered a limiting factor within aquaculture operations. Identifying a noninvasive parameter that measures subclinical stress in lumpfish is a key goal for improving their welfare. The lumpfish is documented to emit green and red biofluorescence within the blue shifted light of their environment. Here we show that lumpfish fluorescence responds to a therapeutic stressor within a controlled experiment. Lumpfish (n = 60) underwent a 3-h freshwater bath therapeutant to evaluate whether fluorescence spectra produced by the species respond to external stimuli. Lumpfish were quickly scanned under a hyperspectral camera (400–1000 nm spectral range) prior to and after treatment. The lumpfish were randomly divided into 3 groups with identical treatment. All groups increased fluorescence emissions, though the level of change depended on whether the averaged, red, or green spectra were analyzed; the control group (n = 20) remained constant. All lumpfish emitted green fluorescence (~ 590–670 nm) while a portion (49%) produced red fluorescence (~ 690–800 nm). As lumpfish fluorescence shifts in response to the applied stressor, this study provides insight into how fluorescence may be incorporated into the welfare management of lumpfish.
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Sea lice are ectoparasites that can be found in high numbers in and around salmon farms, where they are a threat to fish health and can induce high aquacultural costs. Large numbers of suitable hosts facilitate the infection and subsequent release of their planktonic larvae in the surrounding environment where they can potentially infect wild salmonids, including migrating juvenile fish (smolts). Investigating sea lice spatial distribution is generally done using coupled hydrodynamic and particle tracking models. The quality of these numerical tools is critical to identify areas of higher infection risk to valuable wild salmon populations and thus support sustainable salmon aquaculture. While the transport of salmon lice is mainly affected by physical processes, biological behaviours such as vertical swimming can also play an important role. However, a review of previous sea lice studies shows no clear consensus on their swimming abilities and the parameters implemented in sea lice dispersion modelling. Here, we focus on the Diel Vertical Migration (DVM) behaviour, a vertical migration that sea lice perform within a daily cycle. Our sensitivity study of the infectious copepodid phase of sea lice highlights how their retention potential and spatial distribution within a water body are affected by their vertical swimming velocity and maximum swimming depth. In a fjordic system (Loch Linnhe on the West Coast of Scotland), the vertical position of sea lice can affect their horizontal trajectory due to the two-layer exchange flow of the estuarine circulation. At the surface, transport is mainly due to the wind driven circulation, and the residual seaward current. Lower in the water column, the saltier shelf water is drawn into the sea loch. This can potentially increase the retention of sea lice if they dive deep enough to reach those opposing subtidal currents. Therefore, lack of confidence in sea lice DVM parameterisation may introduce inaccuracy in modelled sea lice distribution. Effective sea lice management in aquaculture would benefit from more observational data like farm sea lice count, sea lice swimming laboratory observations, field observation of sea lice vertical distribution and accurate sea lice quantification in the field. This would help to reduce uncertainties derived from sea lice vertical swimming behaviour parameterisation in lice dispersal models.
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ea lice are a major health hazard for farmed Atlantic salmon in Europe, and their impact is felt globally. Given the breadth of ongoing research in sea lice dispersal and population modelling, and focus on research-led adaptive management, we brought experts together to discuss research knowledge gaps. Gaps for salmon lice infection pressure from fish farms were identified and scored by experts in sea lice-aquaculture-environment interactions, at an international workshop in 2021. The contributors included experts based in Scotland, Norway, Ireland, Iceland, Canada, the Faroe Islands, England and Australia employed by governments, industry, universities and non-government organisations. The workshop focused on knowledge gaps underpinning five key stages in salmon lice infection pressure from fish farms: larval production; larval transport and survival; exposure and infestation of new hosts; development and survival of the attached stages; and impact on host populations. A total of forty-seven research gaps were identified, five broad themes emerged with thirteen priority research gaps highlighted as important across multiple sectors. The highest-ranking gap called for higher quality and frequency of on-farm lice count data, along with better sharing of information across sectors. We highlight the need for synergistic international collaboration to maximise transferable knowledge. Round table discussions through collaborative workshops provide an important forum for experts to discuss and agree research priorities.
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Lumpfish (Cyclopterus lumpus) are used as cleaner fish in salmon aquaculture to treat sea lice. However, after 18–24 months and reaching 0.4–0.6 kg, the fish is removed from the salmon cage and usually discarded, which raises social, economic, and environmental challenges, as well as ethical concerns. This paper assesses the viability of marketing lumpfish as food by exploring possible products that can be made from the fish in Vietnamese cuisine, and understanding the stakeholder’s perception and acceptance of the fish. We used a customer co-creation method to investigate market potential, sending a sample of 45 kg of frozen and whole lumpfish from Norway to Vietnam. Researchers, industrial stakeholders, restaurant chefs, and household consumers collaborated to discuss, process, cook, and taste the fish, and the evaluations were assessed before and after consumption. More than 10 Vietnamese dishes were identified as possible use for lumpfish, including grilled, fried, sour soup, hotpot, and several value-added products. Household consumers and restaurant buyers evaluated the fish positively in terms of sensory quality (taste, color, flavor, size, and texture), but the rough skin and sharp thorn are negative aspects. Individual consumers accept the fish and were willing to buy it if the price is reasonable. In contrast, industrial stakeholders evaluated the lumpfish less favorably, citing its soft and mushy texture, sticky smell, and very low fillet-recovery-ratio (only 15.9% of skinless fillet and 16.7% of kama can be obtained from whole-defrosted lumpfish). They also found that the taste of the fish was not delicious and bitter in some value-added products. In addition, this study found that the information relating to lumpfish as a cleaner fish is not an issue in the Vietnamese context.
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Sustainability of aquaculture, an important component of the blue economy, relies in part on ensuring assessment of environmental impact and interactions relating to sea lice dispersing from open pen salmon and trout farms. We review research underpinning the key stages in the sea lice infection process to support modelling of lice on wild salmon in relation to those on farms. The review is split into five stages: larval production; larval transport and survival; exposure and infestation of new hosts; development and survival of the attached stages; and impact on host populations. This modular structure allows the existing published data to be reviewed and assessed to identify data gaps in modelling sea lice impacts in a systematic way. Model parameterisation and parameter variation is discussed for each stage, providing an overview of knowledge strength and gaps. We conclude that a combination of literature review, empirical data collection and modelling studies are required on an iterative basis to ensure best practice is applied for sustainable aquaculture. The knowledge gained can then be optimised and applied at regional scales, with the most suitable modelling frameworks applied for the system, given regional limitations.
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A reliable growth function is a vital part of deriving the optimal harvesting strategy and production plan for any aquaculture operation. The range of environmental and biological conditions along the Norwegian coast suggests that the growth of farmed salmon will differ from one region to another. We estimate an aggregated regional growth function for three different regions in Norway using monthly data from 2005 to 2011. There is currently some variation for the grow-out period, and Atlantic salmon is raised between 16–24 months to reach weights of 2–8 kg. These results indicate that an increase in sea temperature positively affects the growth in the regions of Northern and Central Norway, while an increase in sea temperatures negatively affect the growth in the Southern region.
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Even though most celebrated clusters seem to be in high-cost areas, many econometric studies represent agglomeration externalities as increased primal productivity or reduced cost. While this certainly can be consistent with some observed agglomeration effects, it may be insufficient for the growth of a cluster. The key condition for this is that profitability is higher. The paper tests for agglomeration effects using a profit function approach. This may be particularly important for firms in high-cost clusters, where revenue effects can be as important as productivity and cost effects. The paper tests for both intra- and inter-industry agglomeration externalities using firm-level data.