In this year's report on the risk assessment of Norwegian fin fish aquaculture, we have continued the work of compiling contributions from animal welfare and the environmental impacts considered most significant from Norwegian fish farming concerning the risk of reduced sustainability in the thirteen production areas. This provides an easily accessible overview of the overall risk picture in each area, illustrating how animal welfare and environmental impacts in Norwegian aquaculture vary along the coast. Such a presentation would not have been possible without solid and knowledge-based risk assessments as a foundation. The results in this report are based on the knowledge and scientific references published in the "Risk Report Norwegian Fish Farming 2022 - Knowledge Status" as well as "Escaped Farmed Salmon – Risk Assessment and Knowledge Status 2023" and "Sea Lice – Risk Assessment and Knowledge Status 2023" from last year. The entire report series from 2010 can be read here (all in Norwegian):
Risk Report Norwegian Fish Farming
Knowledge Status Risk Report
In essence, we find the greatest challenges related to environmental sustainability and animal welfare on the West Coast, from Ryfylke to Hustadvika (production areas 2 to 5). In these areas, there is a high risk that sea lice infestation could lead to a reduction in wild salmon stocks and the productivity of sea trout that graze in areas with high lice abundance. There is also a moderate to high risk for more vulnerable wild salmon stocks due to additional interbreeding with farmed salmon in most areas. Low escape numbers have been reported in the last two years, contributing to reduced risk if this proves to be a lasting trend. This year, as in the previous year, the farmers report high mortality rates for farmed salmon in the sea,mainly explained by persistent issues with sea lice and diseases. The attack by string jellyfish in the fall of 2023 has also led to increased mortality. From Nordmøre to Bodø, mortality in farmed salmon decreases somewhat and is around the national average of 15-16%. There is a moderate to high risk associated with negative effects of sea lice, especially for sea trout. Throughout the area, there is a moderate to high risk for more vulnerable wild salmon stocks due to further interbreeding with escaped farmed salmon, but few escaped farmed fish have been reported. From Vestfjorden to West-Finnmark, production area 10, Andøya to Senja, stands out with a moderate risk associated with both negative effects of sea lice on wild salmon, high consumption of de-lousing therapeutants deltamethrin and emamectin, and increased vulnerability of wild salmon stocks due to additional interbreeding with escaped farmed salmon. In the northernmost and southernmost production areas (East-Finnmark and the Swedish border to Jæren), the risk associated with production mortality in farmed salmon is considered moderate. The other environmental impacts are considered to contribute little to reduced sustainability, mainly due to the low production in these areas.
Today's farmed salmon are initially well adapted to life in net pens along the entire coast, but gill issues, diseases, delousing operations, and water conditions contribute to increase the risk of mortality in farmed salmon in open cages at sea. The reported figures to the Norwegian Directorate of Fisheries show that a total of 65 million farmed salmon died or were in such poor condition that they were recorded as discards in 2023. This increase from 58 million in 2022 can largely be explained by string jellyfish attacks in the fall of 2023, culling of salmon in production area 8 to prevent the spread of pancreas disease (PD), and also an increase in the number of salmon transferred to sea in 2023 compared to the previous year. Mortality is an imprecise welfare indicator, but it is reasonable to assume that fish that die have experienced poor welfare before death, thus high mortality is considered a sign of poor welfare. Based on production mortality, a clear picture emerges that there is a high risk associated with poor animal welfare for farmed salmon in open cages in production areas 1–5 (Swedish border to Hustadvika). The production mortality for fish released in 2019-2022 has generally been significantly above 15%, and in production areas 2–4 (Ryfylke to Stadt), mortality has been as high as 23–27%. The high mortality is explained, among other things, by the fact that fish on the West Coast have had more sea lice and disease problems and tolerate de-lousing less effectively than farmed fish further north. Due to high mortality for the 2022 generation of salmon in production area 12 (West-Finnmark), we have upgraded the risk of poor animal welfare in this area from moderate to high in this year's report. Rainbow trout production mainly occurs in production areas 3-5 (Karmøy to Hustadvika). The production mortality per generation here typically ranges between 10 and 15%, which is considerably lower than for salmon in the same areas. The risk associated with mortality in rainbow trout at sea is considered moderate in the three production areas with rainbow trout farming.
The risk associated with environmental effects on wild salmonids in this year's report includes further genetic changes resulting from interbreeding with escaped farmed salmon, the impact of sea lice on out-migrating post-smolt salmon and grazing sea trout and sea char, and changes in the occurrence of infectious salmon anemia (ISA) and pancreas disease (PD) in wild fish due to infection from farmed fish.
Five of the production areas are assessed to have a high risk of further genetic changes in wild salmon. This is a downgrade from previous risk assessments, where six production areas had a high risk in the 2023 assessment, and seven in the 2022-2019 assessments. This is because reported escape numbers have decreased, and the National Monitoring Program observes fewer escaped farmed salmon in rivers. However, there are still areas where rivers have a high proportion of escaped farmed salmon (>10%). Both major and minor escape incidents from salmon farming occur regularly, and combined with the innate behavior of salmon, it is likely that some of these escaped farmed salmon will find their way into one or more of our approximately 440 salmon rivers and interbreed with wild salmon in the rivers. Although there is still a lack of knowledge about how much escaped farmed salmon reach the spawning grounds and how robust wild salmon stocks are to interbreeding, we now have a good overview of the degree of interbreeding of farmed salmon in wild salmon populations. Knowledge about why certain salmon stocks seem to be more susceptible to interbreeding than others is limited, but we see that rivers in certain areas are more vulnerable even when escape numbers in the area have been relatively low over time. Escaped farmed salmon can spread over large areas, creating uncertainty about the influence from other production areas. There is a need for more knowledge to identify the origin of escaped farmed salmon recorded in the monitoring program. This will increase our understanding of the dispersal potential of escaped farmed salmon based on the timing and life stage at escape, facilitating more targeted recapture efforts and enhancing understanding of the infection potential in the escape of diseased or infected farmed fish.
Looking at the picture of sea lice infestation on wild salmonids, even though production areas 3 and 4 (Karmøy to Stadt) are particularly vulnerable, there is considered to be a high risk associated with stock-reducing effects on salmon due to high mortality in out-migrating post-smolt salmon caused by sea lice from fish farming in all production areas from 2 to 5 (Ryfylke to Hustadvika), moderate risk in production areas 6-8 (Nordmøre to Bodø) and 10 (Andøya to Senja). In production areas 2–7 (Ryfylke to Nord-Trøndelag with Bindal), the risk of sea lice-induced reduction in productivity of sea trout and sea char is assessed to be high. The fact that there are more areas with high risk for negative effects on sea trout than for out-migrating salmon smolt is not surprising, as sea trout and sea char migrate out and reside in areas with sea lice infestation for a longer period after leaving the rivers. Production areas 2–7 (Ryfylke to Bindal) and production area 10 (Andøya to Senja) encompass the most production-intensive areas along the coast (24–50 tons/km2), and with favorable temperature and salinity conditions for sea lice, this leads to moderate to high lice emissions that increase throughout the summer. For post-smolt salmon, the probability of high lice infestation and subsequent increased mortality will increase with a late migration onset and with increasing distance from the migration start point to open sea. For sea trout and sea char that stay along the coast for an extended period to graze, the infection pressure will be high for much of the grazing season. This is less pronounced in the northernmost production areas where temperatures are lower, and the grazing season is so short that sea lice will develop to adult stages to a lesser extent before the fish return to the river.
The situation of infectious salmon anemia (ISA) shows that for all production areas the risk associated with changes in the occurrence of ISA virus (ISAV) in wild fish due to infection from farmed fish is considered to be low. The complexity and randomness of ISA occurrence in aquaculture make it difficult to determine whether areas with the most outbreaks will also experience more frequent outbreaks in the future, thereby increasing the likelihood of infection to wild fish. For changes in the occurrence of salmonid alphavirus (SAV) causing pancreas disease (PD) in wild fish, the risk is considered low in production areas 1, 2, 5, 7, and 8, moderate in production areas 3 and 4, and high in production area 6. Production areas 2–6 (Ryfylke–Nordmøre and Sør-Trøndelag) are referred to as an "endemic zone" where outbreaks of PD historically have occurred most frequently. Assessments for ISAV and SAV are based on the frequency of reported disease outbreaks, reported escapes in the current production area and adjacent areas, and knowledge from monitoring and mapping of viruses in wild and escaped farmed fish. The knowledge underlying the assessments of changes in the occurrence of infectious salmon anemia (ISA) and pancreas disease (PD) in wild fish is insufficient, and the strength of the knowledge is considered weak for all production areas. There is limited knowledge about the release of ISA virus (ISAV) and salmonid alphavirus (SAV) from the facilities, the robustness of the viruses, the minimum infectious dose, and the degree of spread and dilution of the virus in the areas. While there is some experiential knowledge and data from aquaculture and laboratory experiments with farmed fish, there is none from wild salmonids in their natural habitat. The monitoring by the Institute of Marine Research covers only a limited area, and it is only for out-migrating post-smolt that the monitoring can be said to cover larger parts of the coast.
The assessments of the three environmental impacts on wild salmonids included in this year's report must also be viewed in the context of the status of the wild salmon populations in the area. In areas where many rivers have low harvestable surplus and/or do not achieve the spawning stock target, wild salmon may be less resilient to additional stress through high sea lice-induced mortality on out-migrating post-smolts and further genetic interbreeding resulting from aquaculture activities in the area. For sea trout and sea char, areas with a high density of sea lice will cause the fish to migrate into freshwater earlier than they would without the intense infection pressure. A hypothesis is that reduced feeding time could lead to lower productivity in the populations through reduced growth and reproduction and increased mortality. Additionally, wild fish with a high infestation of lice are also exposed to reduced welfare through wound formation and issues with water and salt balance.
The production of farmed fish varies between production areas. Looking at the number of tons of fish produced per area within the baseline, production area 2 has the highest at 50 tons/km2 in 2023, an increase from 46.3 tons/km2 in 2022, based on preliminary figures from the Norwegian Directorate of Fisheries for 2023. At the other end of the scale, production area 13 has less than 4 tons/km2. The average production was around 23 tons/km2 in both 2022 and 2023. Most of the production occurs in open sea facilities, and both nutrients, feces, and excess feed are directly released into the water and dispersed into the environment. The risk associated with environmental effects due to emissions of dissolved nutrients from fish farming is considered low for all production areas since the calculated increase in phytoplankton production is assessed as low, ranging from 1.5 to 20.6%. None of the areas with monitoring stations in intensive aquaculture zones report poor environmental conditions for nutrients, phytoplankton or macroalgae on hard bottoms. Norwegian coastal and fjord areas are inherently nutrient-poor, and most aquaculture facilities are located in areas with good water exchange, allowing nutrients to quickly spread and dilute.
The risk associated with bottom impact from the discharge of particulate organic material is considered low for 10 of the production areas, but for production areas 3, 4, and 9, it is assessed as moderate. In these production areas, the proportion of environmental surveys in "very poor" or "poor" condition is higher than the average across all the production areas. In some areas, the poor sites are also more clustered. However, both B and C surveys are closely monitored, and in the case of "very poor" condition, mitigation measures are taken with the expectation of an improved condition at the next measurement. Whether the moderate risk for production areas 3, 4, and 9 is a trend or if the condition will improve will be revealed over time. This year, we have assessed the proportion of samples taken on soft bottoms compared to hard bottoms where the B-surveys do not function well. In five production areas, the proportion of samples on hard bottom is over 27%, causing some uncertainty to the risk assessment. Some fjord areas have reduced bottom water turnover. These areas are more susceptible to having low oxygen concentrations at the bottom and are more vulnerable to organic loading. In production area 4, there is such an area of limited water exchange where a relatively high proportion of environmental surveys are in "very poor" or "poor" condition. In general, the impact can be reduced by preventing the settling of particles, either by dispersion or by collecting the organic material before it escapes from the pens.
Several foreign substances are released into the environment from fish farming facilities, with the use of copper as an antifouling agent on the fish farming nets being the most significant. In 2022, the latest year we have consumption data for, 440 tons of copper were registered for use as an antifouling agent in aquaculture. This represents a 74% decrease from the peak year 2019 (1698 tons). At the same time, the consumption of the substitute tralopyril increased by 86% from 2019 to 2022 (from 53 tons to 98 tons). Two other substitutes; zinc pyrithion and copper pyrithion had a consumption of 10 and 5 tons respectively in 2022, approximately the same amount as in 2019. The increase in the consumption of tralopyril and zinc pyrithion/copper pyrithion means that these substances should also be included in future risk assessments. Although copper consumption has significantly decreased in recent years, environmental surveys show that there are still moderate proportions of fish farms with poor environmental conditions regarding copper levels in production areas 2, 3, and 4. Based on the estimated copper emissions being more than halved from 2021 to 2022, we have assessed the risk of transitioning from high to moderate for reduced biodiversity due to copper emissions from fish farming in production areas 3 and 4, and maintained the risk at a moderate level in production area 2. For production areas 6 and 7, we have changed the risk from moderate in 2021 to low in 2022 due to a reduction in copper consumption and a small proportion of facilities with poor environmental conditions in the transition zone in last year's C-surveys. Production areas 1, 5, 8-13 were assessed to have a low risk of reduced biodiversity due to copper emissions in both 2021 and 2022 based on low emissions and good environmental conditions from C-surveys. More information on operational practices related to flushing and the use of anti-fouling agents at each site in each production area will be crucial to increase knowledge strength, reduce uncertainty, and thus also the risk associated with reduced biodiversity using copper and other substances in fish farming. It is recommended that such information be recorded alongside regulations for salmon lice treatment.
A variety of medications are used in Norwegian fish farming, including treatments for internal parasites, bacteria (antibacterial agents), and sea lice, as well as disinfectants and anesthetics. In this risk assessment, only delousing agents have been evaluated due to the expected low probability of negative effects on non-target species from the other groups of medications. The risk of severe effects on non-target species is based on individual assessments of each delousing agent, the number of treatments, the time of year the treatment was conducted, location (including proximity to spawning and shrimp areas), and uncertainty due to lack of knowledge. The risk was assessed as low for 11 of the production areas, but for production areas 4 (Norhordland to Stadt) and 10 (Andøya to Senja), it is considered moderate. In production area 4, the risk is assessed as moderate based on multiple treatments with flubenzurons in the summer and many treatments with emamectin in both winter and summer. In production area 10, the risk is assessed as moderate based on several treatments with deltamethrin in the summer and many treatments with emamectin in both winter and summer. Although emamectin is assessed to have a low effect, the knowledge is weak, and many treatments will increase uncertainty and thus the risk. The use of deltamethrin and flubenzurons in the summer provides a high probability of severe effects on non-target species; increased use of these delousing agents will lead to increased risk. In general, there is an increased risk with the use of bath treatments in the summer compared to the winter because it increases the likelihood of a serious effect on sensitive species in the pelagic. The risk assessment for severe effects of delousing agents on non-target species is based on consumption in 2022. The results of the risk assessment include a discussion on how changes in consumption and operational procedures could lead to alterations in the risk levels for the various production areas. More data on residual concentrations in nature for feed ingredients, as they spread through organic particles to bottom sediment and can enter the food chain, are needed. Analyses of medications such as flubenzurons and emamectin should be included in the required sediment analyses that the aquaculture industry must perform (MOM surveys), made publicly available, like copper values in sediment.
There has been concern about the ecological impact of high fishing intensity of wild wrasse for use in aquaculture and quotas were introduced in 2018. It is still too soon to conclude whether the regional quotas are set at sustainable levels over time since the different wrasse species have very different biology and population dynamics, and not at least because the demand for the different species has been variable as a result of changes in demand and the species-specific size limits. Current evidence supports that there has been little or no change in wrasse populations due to wrasse fishing. In recent years, there has also been a reduction in the transport of wild-caught wrasse into production areas 6 and 7 (Nordmøre to Bindal). Less transport of wrasse over large geographical areas reduces the likelihood of genetic interbreeding in local wrasse populations in case of escape. This issue has been little studied so far, but genetic studies have shown that there has been escape and genetic influence from the Skagerrak population on corkwing wrasse in production areas 6 and 7. However, the transport of wild caught wrasse over large geographical distances with their unknown health status is considered far from the desired state in terms of biosafety. The transport of fish from one area into another is a well-known challenge regarding the introduction and spread of pathogens. Additionally, there is little or no treatment of transport vehicles or transport water before it is discharged into the receiving area. Until now, there have been no major disease outbreaks in farmed or wild fish directly linked to the use of cleaner fish, and the likelihood of disease transmission is assessed somewhat differently between different fishing areas. For the "Sørlandet" fishing area (most of production area 1), the probability is considered low with strong knowledge strength. For the "Vestlandet" and "North of 62 degrees north" fishing areas (northern part of production area 1 through production area 7), the likelihood of disease transmission is considered moderate. The knowledge strength on which these probability considerations are based is considered moderate. Based on experience with other species, we know that the probability of disease transmission during transportation, with subsequent highly severe consequences, should not be considered negligible. Researchers assess that "disease transmission via transport or transport water" is a relevant issue characterized by significant uncertainty and the potential for surprises involving critical consequences. Marked with a black swan in the risk charts.
Finally, it is emphasized that the lack of knowledge in the form of limited monitoring data and research means that we can say little about possible effects of, for example, nutrients, particulate organic material, copper, or delousing agents from fish farming on vulnerable habitats such as mearl beds, eelgrass beds, and kelp forests. The picture becomes even more complex as the effects of climate change are beginning to manifest in marine ecosystems, and current knowledge is weak both on how this will impact different marine species and to what extent environmental stress from aquaculture and other human activities will amplify these changes. Until such knowledge is available and uncertainty is reduced, it is recommended to consider mitigating measures based on the best available knowledge.
The annual report does not include a risk assessment of cod farming. The assessment from 2022 can be read here: Risk Report Norwegian Fish Farming 2022 – Risk assessment