Wild Fish Stocks Research Articles

Insect-Based Feed Ingredients for Aquaculture: A Case Study for Their Acceptance in Greece.

Simple SummarySince 2017, insects can be used as ingredients in aquafeeds in the EU. However, insect-based aquafeeds are still not broadly accepted by European aquaculture companies. Understanding the beliefs of people associated with the aquaculture sector on the use of insect-based fish diets could assist their adoption. In the present study, we ran a survey among the participants of an aquaculture conference held in Greece, in order to ask them what they think regarding the inclusion of insect meal in aquafeeds. Furthermore, we inquired nine Greek aquaculture and aquafeed companies about this issue. Greece is among the largest farmed fish producers in the EU; however, there are currently no data available on the acceptance of insect-based aquafeeds in Greece. Based on our results, the majority of the respondents were aware and in favor of the inclusion of insects in aquafeeds, mainly due to their potential to lower fishing pressure on wild fish stocks used for fishmeal production and enhance the ecological footprint and sustainability of aquaculture. Moreover, six out of nine companies were favorably disposed towards the use of insects in fish diets and four of them were willing to produce or use such diets. Further studies are warranted towards this direction.Although the inclusion of insects in fish diets is officially allowed in the EU since 2017, insect-based aquafeeds have not been widely adopted by the European aquaculture sector. In order to investigate the perceptions related with adoption trends, it is critical to explore the beliefs of people associated with the aquaculture sector on the use of insects in farmed fish diets. A survey was conducted among 228 participants of an aquaculture conference to explore their perceptions on the inclusion of insect meal in fish diets. Additionally, we investigated the attitudes of nine companies operating in the aquaculture and aquafeed sector in Greece that attended the conference towards this direction. The findings of the conference survey provide evidence that there is a wide-range awareness and acceptance regarding the use of insect-based feeds in farmed fish diets among the respondents. This is mainly driven by the expectations for the decline in fishing pressure on wild fish stocks, the reduction of the ecological footprint and the enhancement of the sustainability of the aquaculture sector. The results of the stakeholder survey show that six out of the nine companies that participated in the survey are favorably disposed towards the use of insect-based feeds. Specifically, four of them stated that they would produce or use aquafeeds based on insects. However, the results highlight the need for further research on the implementation of the wider adoption of insect-based feeds in aquaculture. The present study provides some first insights into the use of insect-based aquafeeds in Greece, for which there are no data available.

The three dimensions of aquaculture’s sustainability in Africa for food safety

Following the exponential increase in Africa's population compared to past decades and the increased need for food production to meet this growing demand in the continent, studies on agricultural research for sustainable food production have been gradually strengthened in the face of climate change, water scarcity and increasing desertification. Aquaculture is a growing sector in Africa and has a major role to play in the role is of primary importance in ensuring food security, while reducing dependence on wild fish stocks that are often overexploited. However, this rapid growth poses challenges to the overall long-term sustainability of the agricultural sector and raises concerns in a number of respects. Sustainable aquaculture implies the integration of all three pillars or dimensions of sustainable development to ensure that this young African industry is economically and environmentally viable, but also that aquaculture farms operate in a socially responsible manner.

Multigenerational exposure to warming and fishing causes recruitment collapse, but size diversity and periodic cooling can aid recovery

Global warming and fisheries harvest are significantly impacting wild fish stocks, yet their interactive influence on population resilience to stress remains unclear. We explored these interactive effects on early-life development and survival by experimentally manipulating the thermal and harvest regimes in 18 zebrafish (Danio rerio) populations over six consecutive generations. Warming advanced development rates across generations, but after three generations, it caused a sudden and large (30-50%) decline in recruitment. This warming impact was most severe in populations where size-selective harvesting reduced the average size of spawners. We then explored whether our observed recruitment decline could be explained by changes in egg size, early egg and larval survival, population sex ratio, and developmental costs. We found that it was most likely driven by temperature-induced shifts in embryonic development rate and fishing-induced male-biased sex ratios. Importantly, once harvest and warming were relaxed, recruitment rates rapidly recovered. Our study suggests that the effects of warming and fishing could have strong impacts on wild stock recruitment, but this may take several generations to manifest. However, resilience of wild populations may be higher if fishing preserves sufficient body size diversity, and windows of suitable temperature periodically occur.

Maturation reaction norm evolution under varying conditions of eco-evolutionary change

Probabilistic maturation reaction norms (PMRNs) are commonly used to infer evolution of maturation age and size in wild fish stocks, but how well estimates from phenotypic data actually reflect underlying genotypes is debated. We used an eco-genetic model of a commercially harvested freshwater fish to simulate populations undergoing various levels of fisheries-induced evolution and density-dependent feedback and evaluated effects on the estimation of PMRNs. We estimated PMRNs from phenotypic data sampled from simulated populations (age, length, and maturation status of individuals), as is done for wild stocks, and compared estimates with the known maturation genotypes of individuals in the simulated population. PMRN estimates were robust to changes in the strength of density-dependent growth and high levels of fisheries-induced evolution. However, our ability to detect slower rates of evolution was limited, especially when individuals matured within a narrow range of ages. Furthermore, low numbers of immature or mature individuals within a given age class limited our ability to robustly estimate midpoints for more than one or two ages, despite our large sample sizes (n = 200 randomly sampled individuals of each age per year), highlighting a challenge with this approach. Nonetheless, this study suggests that the widely applied method of estimating PMRNs from readily available phenotypic data to detect underlying evolution of maturation schedule is robust to some key factors that vary in wild populations.

Wild or Farmed Gilthead Seabream (Sparus aurata)? How To Distinguish between Them by Two-Dimensional Gel Electrophoresis

Because the world's wild fish stocks are limited and the market demand is increasing, fish farming has become an alternative food source and a way to reduce costs for consumers. The sale of farmed as wild fish is a fraudulent practice; it is, therefore, important to find new and alternative tools that can help in the fight against fraud to protect consumers and to ensure food traceability. The proteomic profiles of farmed and wild fish differ. With this study we wanted to identify liver protein markers via two-dimensional electrophoresis that would allow us to distinguish wild from farmed gilthead seabream. The liver samples from 32 gilthead seabream, wild and farmed, were stored at -80°C before protein extraction. The samples were subjected to two-dimensional electrophoresis to detect qualitative and quantitative differences. Proteomic analysis showed a protein spot (molecular weight of ∼34 kDa and isoelectric point of ∼6.9) only in the samples from the wild gilthead seabream; liquid chromatography-tandem mass spectrometry identified the spot as ubiquitin. Ubiquitin could be a valid marker to differentiate wild from farmed gilthead seabream; it could be used to ensure continuous monitoring throughout the entire commercial chain and to fight commercial fraud.

Multidimensional aquaculture investor index: Black Sea riparian countries

ABSTRACT The demand for fish products in Black Sea riparian countries has been intensively growing annually by 4% since 2000. This demand was predominantly covered by importation and/or capture fisheries. To reduce pressure on the wild fish stocks of the shared sea basin, regional and national development plans are aiming to stimulate aquaculture production. However, there is a scarcity of instruments that allow assessment of the situation on the regional level to capture the multidimensional nature of such activity. A Composite Indicator or so-called Index has been recognized as one of the best ways to investigate the complex system statement and reveal areas of concern. The aim of this study was (1) to construct a Composite Indicator, (2) to analyze conditions created for aquaculture establishments, (3) to reveal competitive advantages and pitfalls in each country, and (4) to determine possible drivers of countries with better performance such as Turkey and Bulgaria.

Progress and challenges in eliminating illegal fishing

AbstractIllegal fishing is a widespread, global phenomenon that is affecting already heavily depleted wild fish stocks, threatening marine habitats and contributing to marine pollution through discarded fishing gear. Many different measures have been implemented by nation states to deter and prevent illegal fishing. These include coastal surveillance and policing, policies and regulation, and education. In this paper, we examine the case of Australia through an analysis of regulative arrangements, policies and guidelines that form the governance framework to better understand the changing seascape of illegal fishing. We argue that joint efforts with neighbouring states such as Indonesia and regional fisheries management authorities have contributed to a decrease in illegal fishing in and around the Australian EEZ. Finally, we discuss current and future challenges, opportunities, recent advancements and technological approaches for reducing illegal fishing around the world.

Modelling and forecasting of catfish species yield from Mangochi artisan fisheries of lake Malawi in Malawi

Most of the wild fish stocks in Malawi either are fully or over exploited. This challenge underpins importance of forecasting using available data to support sustainable fisheries management. The study aimed at modelling and forecasting Catfish (Mlamba) species yield from artisan fishery on Lake Malawi in Mangochi District as they are becoming important food fish due to decline of more important fish species such as Oreochromis(Chambo). The study was based on secondary data on fish catches between1976 and 2012, collected from Fisheries Research Unit of the Department of Fisheries in Malawi. The study considered Autoregressive Integrated Moving Average (ARIMA) processes to select an appropriate stochastic model for forecasting the species yield. Appropriate models were chosen based on ARIMA (p, d, q). Autocorrelation function (ACF), Partial autocorrelation (PACF), Akaike Information Criteria (AIC), Box-Ljung statistics, correlogram of residual errors, distribution of residual errors, ME, RMSE, MAPE and MAE. Selected model was ARIMA (0, 0, 1) for forecasting artisan landings of Catfish from Lake Malawi in Mangochi District from 2013 to 2022. Based on the chosen model, forecast for artisan Catfish landings showed mean of 352 tonnes and mean of actual catches was 362 tonnes. However, catches in year 2022 are projected to be 360 tonnes, slightly below the actual catches mean but above 236 tonnes in 2010, assuming other factors remain constant. Confidence intervals of the forecasts included a zero and as such over exploitation of the species cannot be ruled out. Landings of the fishery will increase to 360 tonnes and remain stable through year 2022 necessitating fisheries management consideration to improve the trend. Policy makers should secure sustainable exploitation of Catfish species, among artisan fishery in the study area by controlling all fishing effort that lands the species such as gillnets, beach seines, open water seines among others.

Streptococcus iniae associated mass marine fish kill off Western Australia.

Streptococcus iniae causes high mortality in cultured and wild fish stocks globally. Since the first report in captive Amazon river dolphins Inia geoffrensis in 1976, it has emerged in finfish across all continents except Antarctica. In March 2016, an estimated 17000 fish were observed dead and dying along a remote 70 km stretch of the Kimberley coastline north of Broome, Western Australia. Affected species included finfish (lionfish Pterois volitans, angelfish Pomacanthus sp., stripey snapper Lutjanus carponotatus, sand bass Psammoperca waigiensis, yellowtail grunter Amniataba caudavittata, damselfish Pomacentridae sp.), flatback sea turtles Natator depressus, and olive (Aipysurus laevis) and black-ringed (Hydrelaps darwiniensis) sea snakes. Moribund fish collected during the event exhibited exophthalmia and abnormal behaviour, such as spiralling on the surface or within the water column. Subsequent histopathological examination of 2 fish species revealed bacterial septicaemia with chains of Gram-positive cocci seen in multiple organs and within brain tissue. S. iniae was isolated and identified by bacterial culture, species-specific PCR, Matrix-Assisted Laser Desorption Ionisation Time-Of-Flight (MALDI-TOF) and biochemical testing. This is the first report of S. iniae associated with a major multi-species wild marine fish kill in Australia. Extreme weather events in the region including a marked decrease in water temperatures, followed by an extended period of above-average coastal water temperatures, were implicated as stressors potentially contributing to this outbreak.

Value creation through innovation in the primary sector

Purpose Innovation is a growing topic. The primary sector is also a subject that has great importance in the global economy. However, limited research has been conducted linking these two subjects. This paper aims to start bringing them together. Design/methodology/approach The method selected is a systematic literature review presenting a thorough analysis of the existing discussions and a summary of the findings to identify future research opportunities. Findings Innovation has played and will continue to play an essential role in the success of fisheries. The fishing industry is in crisis. A decline in wild fish stocks, regulations and quota management are some of the factors that drive the need to innovate. The discussions of innovation in this industry are non-technological, which is an emerging field with opportunities for further research. There is a strong focus on fisheries sustainability. The main theoretical frameworks discussed in the literature are common property theory, cooperation and competition theory and diffusion of innovation. Emerging environmental sustainability frameworks are also becoming an essential element in the primary sector. Research limitations/implications This paper focuses on peer-reviewed publications based on the results of the searches from selected keywords, recognizing that the literature evaluated may not cover the full spectrum of themes related to this subject. Originality/value Innovation is usually linked to high tech and fast-moving industries. This paper tries to broaden this paradigm and evaluate it from a different perspective, with a focus on the primary sector.

Review Article: The impacts of COVID-19 pandemic on aquatic food production: A review

The novel pandemic disease has been evaluated as a global health emergency by the World Health Organization (WHO) due to its rapid spread worldwide. In many countries, the established restrictive measures on the movement and travel have had adverse economic outcomes, including a substantial drop in both jobs and salaries, in these communities. The economic consequences of the COVID-19 have severely affected the aquatic food supply chain, i.e. the fishers, aquaculture farmers, processing, and marketing sector due to the decrease in consumer purchasing power. There is increasing evidence that the farmers are not able to sell their products which lead to the live fish stocks increasing and therefore higher costs for feeding. In contrast, a fall in demand and selling price of aquatic food has resulted in a decline in fishing activities, which may give wild fish stocks a chance to recover. This review aims to summarize the impacts of the novel coronavirus disease (COVID-19) on aquatic food production.

Stability of lipids during wet storage of the marine diatom Porosira glacialis under semi-preserved conditions at 4 and 20\xa0\xb0C

Cultivation of diatoms may help alleviate the pressure on wild fish stocks for marine nutrient availability in aquaculture feed and for human consumption. However, the lipids in microalgae biomass are easily deteriorated, both trough lipolysis and degradation of polyunsaturated fatty acids (PUFA). Proper storage conditions are therefore necessary to maintain the lipid quality. Additionally, the storage conditions must have a low cost and facilitate further processing of the biomass. In this study, we investigated the formation of free fatty acids, changes in lipid classes, and fatty acid composition of the psychrophilic marine diatom Porosira glacialis under storage. The wet biomass was stored for 14 days at 4 and 20 °C with either heat treatment, formic acid, or benzoic acid addition, and a control sample. Heat-treated and formic acid samples had the lowest rate of free fatty acid formation during storage. Mainly, polar lipids were hydrolyzed to free fatty acids and this occurred fastest at 20 °C. The fatty acid composition remained stable in heat-treated samples during storage, whereas a loss of PUFA was observed in the other treatments. The lack of effect from benzoic acid indicates that the loss of lipid quality stems from endogenous enzymes rather than exogenous organisms. Heat treatment and formic acid appeared to effectively reduce lipase activity, and potentially lipoxygenase and similar enzymes that affect the fatty acids. The low pH of the formic acid samples seems to have a negative effect on the PUFA content, in particular at 20 °C.

Omega-3 index and blood pressure responses to eating foods naturally enriched with omega-3 polyunsaturated fatty acids: a randomized controlled trial

Diets low in seafood omega-3 polyunsaturated fatty acids (PUFAs) are very prevalent. Such diets have recently been ranked as the sixth most important dietary risk factor—1.5 million deaths and 33 million disability-adjusted life-years worldwide are attributable to this deficiency. Wild oily fish stocks are insufficient to feed the world’s population, and levels of eicosapentaenoic acid and docosahexaenoic acid (DHA) in farmed fish have more than halved in the last 20 years. Here we report on a double-blinded, controlled trial, where 161 healthy normotensive adults were randomly allocated to eat at least three portions/week of omega-3-PUFA enriched (or control) chicken-meat, and to eat at least three omega-3-PUFA enriched (or control) eggs/week, for 6 months. We show that regular consumption of omega-3-PUFA enriched chicken-meat and eggs significantly increased the primary outcome, the red cell omega-3 index (mean difference [98.75% confidence interval] from the group that ate both control foods, 1.7% [0.7, 2.6]). Numbers of subjects with a very high-risk omega-3 index (index < 4%) were more than halved amongst the group that ate both enriched foods. Furthermore, eating the enriched foods resulted in clinically relevant reductions in diastolic blood pressure (− 3.1 mmHg [− 5.8, − 0.3]). We conclude that chicken-meat and eggs, naturally enriched with algae-sourced omega-3-PUFAs, may serve as alternative dietary sources of these essential micronutrients. Unlike many lifestyle interventions, long-term population health benefits do not depend on willingness of individuals to make long-lasting difficult dietary changes, but on the availability of a range of commonly eaten, relatively inexpensive, omega-3-PUFA enriched foods.

Ranching in river Ganga: A protocol of practices for indigenous carps germplasm enhancement and conservation in river

River ranching of fish species is one of the managerial techniques to conserve the native germplasm in the open waters. In the recent years most of the rivers worldwide including the river Ganga have been facing serious pressure including water abstraction, water obstruction, pollution and climate change. In this backdrop, river ranching of the identified indigenous carp species through artificial breeding of native brooders of Labeo catla (Catla), Labeo rohita (Rohu), Cirrhinus mrigala (Mrigal) and Labeo calbasu (Calbasu) were carried out in Ganga. The seeds of these species were raised to more than 100mm size before ranching to reduce the chances of natural mortality. More than 30 lakh fingerlings were ranched at different sites of the middle (Pryagraj to Farakka) and lower stretches (Farakka to Howrah) of river Ganga with the objective to enhance the IMC population keeping the native germplasm unpolluted. This study describes a protocol of river ranching of fish seeds through artificial breeding of wild fish stocks, nursery managements and release and may be suitable for other rivers also. Key words River Ganga; Conservation; Ranching; IMC; NMCG

Fish as feed: Using economic allocation to quantify the Fish In : Fish Out ratio of major fed aquaculture species

Efficiency assessments of marine ingredient use in aquaculture are required to fully understand their contribution to global seafood supply and their impacts on all UN Sustainable Development Goals. Fish In: Fish Out (FIFO) ratios have become the principal metric used to ensure aquaculture does not negatively impact wild fish stocks. However, several approaches have been advocated to calculate the FIFO ratio and there have been criticisms that the different approaches employed lead to over- or under- estimates of the dependence of aquaculture on marine ingredients. Critically, FIFO does not align with Life Cycle Assessment as a measure of other environmental impacts. In this paper we present an alternative method to calculate the FIFO ratio based on the principle of economic allocation (economic Fish In: Fish Out – eFIFO) as commonly used in Life Cycle Assessments. Economic allocation acts as a proxy for the nutritional value of ingredients and places higher importance on the more limiting co-products generated and their relative demand. Substitution of marine ingredients by alternate feed ingredients has significantly reduced the amount of fishmeal and fish oil in aquafeed formulations for most farmed fish species, resulting in a continually decreasing FIFO ratio. Results show that most aquaculture species groups assessed in this study are net producers of fish, while salmon and trout aquaculture are net neutral, producing as much fish biomass as is consumed. Overall, global fed-aquaculture currently produces three to four times as much fish as it consumes. Tracking historical prices of fish oil against fishmeal, the relative higher price of fish oil leads to relatively higher allocation of fish to fish oil compared to fishmeal. This leads to relatively higher eFIFO for species with high fish oil requirements.

Links and Trade-Offs between Fisheries and Environmental Protection in Relation to the Sustainable Development Goals in Thailand

The fisheries sector significantly contributes to global food security, nutrition, and livelihood of people. Its importance for economic benefits, healthy diets, and nutrition, and achieving sustainable food systems is highlighted by several Sustainable Development Goals (SDGs), i.e., SDG 1 (No Poverty), SDG 2 (Zero Hunger), and SDG 14 (Life Below Water). However, due to unprecedented population levels, the contribution of the fisheries sector to fulfills these roles is challenging, particularly given additional concerns regarding environmental well-being and sustainability. From this perspective, this study aims to identify the links and trade-offs between the development of this sector and the environmental sustainability in Thailand via a critical analysis of their trends, current ecological impacts, and more importantly, their contributions to several individual SDGs. A time-series of Thailand’s fisheries production from 1995 to 2015 indicates a recent reduction from around 3.0 million tons in 1995 to 1.5 million tons in 2015 of wild fish and shellfish from marine and freshwater habitats. The maximum sustainable yield of these species has been exceeded. Conversely, Thailand’s aquaculture production has continued to grow over the last decade, resulting in a reduction of mangrove forest area, wild fish stocks, and water quality. While capture fisheries and aquaculture production significantly contribute to several SDG targets, there are potential trade-offs between their development and the achievement of SDGs within the planet dimension, i.e., SDG 6 (Clean Water and Sanitation), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), SDG 14, and SDG 15 (Life on Land). On the one hand, the mitigation of overfishing will be beneficial for the targets of SDG 14, leading to more sustainable resource management. On the other hand, it might cause a decrease in the volume of marine catches and economic and social profits. We conclude that the SDGs can serve as a framework for both policymakers and industrial workers to monitor and compromise on regulations that will optimize productivity in the context of sustainable development.

Numerical Study on Hydrodynamic Responses of Floating Rope Enclosure in Waves and Currents

Enclosure aquaculture is a healthy and ecological aquaculture pattern developed in recent years to relieve the pressure due to the wild fish stock decline and water pollution. The object of this paper was a floating rope enclosure, which mainly consisted of floaters, mooring lines, sinkers and a net. In order to optimize mooring design factors, the hydrodynamic responses of the floating rope enclosure with different mooring systems in combined wave-current were investigated by experimental and numerical methods. Physical model experiments with a model scale of 1:50 were performed to investigate the hydrodynamic characteristics of a floating rope enclosure with 12 mooring lines. Based on the lumped mass method, the numerical model was established to investigate the effects of mooring design factors on the mooring line tension, force acting on the bottom, and the volume retention of the floating rope enclosure. Through the analysis of numerical and experimental results, it was found that the maximum mooring line tension of the floating rope enclosure occurs on both sides of the windward. Increasing the number of mooring lines on the windward side is helpful to reduce the maximum mooring line tension. Waves and current both have an influence on the mooring line tension; in contrast, currents have a more obvious effect on the mooring line tension than waves. However, the influence of the wave period on the maximum mooring line tension is small. The force endured by the bottom of the floating rope enclosure also changes periodically with the wave period. Yet, the maximum force endured by the bottom of floating rope enclosure occurred at the windward and leeward of the structure. The volume retention of the floating rope enclosure increased with the increasing amount of mooring lines.

Using Decision Analysis to Balance Angler Utility and Conservation in a Recreational Fishery

AbstractRecreational fisheries are often managed to provide satisfying fishing experiences for anglers while conserving wild fish stocks. However, managing recreational fisheries is difficult because fish populations are often infrequently monitored and fishing effort is uncontrolled; moreover, a satisfying fishery may draw many anglers, which may lead to enhanced risk of overfishing. Furthermore, external pressures will also affect fisheries, leading to fishery collapses despite the best intentions of management. Any management decision about regulations and habitat alteration will have effects on angler satisfaction and conservation. Decisions should be made with the intention of achieving fisheries objectives despite the uncertainties that arise from sampling data, ecosystem processes, and external factors, yet they must be defensible to stakeholders and the public. We show herein how decision analysis can be used to evaluate and communicate the relative efficacy of management decisions that are made to achieve fisheries management objectives by using a variety of commonly collected field data. We used a wild kokanee population at risk of overfishing as a case study and evaluated the medium‐term effects of fishing regulations and habitat alterations on conservation and angler utility objectives. Using a flexible age‐structured model, we determined that these two objectives are often at odds, where management actions leading to high angler utility in this fishery also lead to high conservation risk. Overall, decision analysis helps to communicate these tradeoffs and makes it clear how particular decisions were made. Decision analysis is not new, but it is often underused in recreational fisheries. This work demonstrates how it may streamline decisions, even for infrequently monitored fisheries, and lead to better fisheries overall.

Production dynamics reveal hidden overharvest of inland recreational fisheries

Recreational fisheries are valued at $190B globally and constitute the predominant way in which people use wild fish stocks in developed countries, with inland systems contributing the main fraction of recreational fisheries. Although inland recreational fisheries are thought to be highly resilient and self-regulating, the rapid pace of environmental change is increasing the vulnerability of these fisheries to overharvest and collapse. Here we directly evaluate angler harvest relative to the biomass production of individual stocks for a major inland recreational fishery. Using an extensive 28-y dataset of the walleye (Sander vitreus) fisheries in northern Wisconsin, United States, we compare empirical biomass harvest (Y) and calculated production (P) and biomass (B) for 390 lake year combinations. Production overharvest occurs when harvest exceeds production in that year. Biomass and biomass turnover (P/B) declined by ∼30 and ∼20%, respectively, over time, while biomass harvest did not change, causing overharvest to increase. Our analysis revealed that ∼40% of populations were production-overharvested, a rate >10× higher than estimates based on population thresholds often used by fisheries managers. Our study highlights the need to adapt harvest to changes in production due to environmental change.

Endangered wild salmon infected by newly discovered viruses.

The collapse of iconic, keystone populations of sockeye (Oncorhynchus nerka) and Chinook (Oncorhynchus tshawytscha) salmon in the Northeast Pacific is of great concern. It is thought that infectious disease may contribute to declines, but little is known about viruses endemic to Pacific salmon. Metatranscriptomic sequencing and surveillance of dead and moribund cultured Chinook salmon revealed a novel arenavirus, reovirus and nidovirus. Sequencing revealed two different arenavirus variants which each infect wild Chinook and sockeye salmon. In situ hybridisation localised arenavirus mostly to blood cells. Population surveys of >6000 wild juvenile Chinook and sockeye salmon showed divergent distributions of viruses, implying different epidemiological processes. The discovery in dead and dying farmed salmon of previously unrecognised viruses that are also widely distributed in wild salmon, emphasizes the potential role that viral disease may play in the population dynamics of wild fish stocks, and the threat that these viruses may pose to aquaculture.