Seafood holds promise for helping meet nutritional needs at a low climate impact. Here, we assess the nutrient density and greenhouse gas emissions, weighted by production method, that result from fishing and farming of globally important species. The highest nutrient benefit at the lowest emissions is achieved by consuming wild-caught small pelagic and salmonid species, and farmed bivalves like mussels and oysters. Many but not all seafood species provide more nutrition at lower emissions than land animal proteins, especially red meat, but large differences exist, even within species groups and species, depending on production method. Which nutrients contribute to nutrient density differs between seafoods, as do the nutrient needs of population groups within and between countries or regions. Based on the patterns found in nutritional attributes and climate impact, we recommend refocusing and tailoring production and consumption patterns towards species and production methods with improved nutrition and climate performance, taking into account specific nutritional needs and emission reduction goals.

Aquaculture is the fastest growing food sector worldwide, mostly driven by a steadily increasing protein demand. In response to growing ecological concerns, life cycle assessment (LCA) emerged as a key environmental tool to measure the impacts of various production systems, including aquaculture. In this review, we focused on farmed salmonids to perform an in-depth analysis, investigating methodologies and comparing results of LCA studies of this finfish family in relation to species and production technologies. Identifying the environmental strengths and weaknesses of salmonid production technologies is central to ensure that industrial actors and policymakers make informed choices to take the production of this important marine livestock to a more sustainable path. Three critical aspects of salmonid LCAs were studied based on 24 articles and reports: (1) Methodological application, (2) construction of inventories, and (3) comparison of production technologies across studies. Our first assessment provides an overview and compares important methodological choices. The second analysis maps the main foreground and background data sources, as well as the state of process inclusion and exclusion. In the third section, a first attempt to compare life cycle impact assessment (LCIA) and feed conversion ratio (FCR) data across production technologies was conducted using a single factor statistical protocol. Overall, findings suggested a lack of methodological completeness and reporting in the literature and demonstrated that inventories suffered from incomplete description and partial disclosure. Our attempt to compare LCA results across studies was challenging due to confounding factors and poor data availability, but useful as a first step in highlighting the importance of production technology for salmonids. In groups where the data was robust enough for statistical comparison, both differences and mean equalities were identified, allowing ranking of technology clusters based on their average scores. We statistically demonstrated that sea-based systems outperform land-based technology in terms of energy demand and that sea-based systems have a generally higher FCR than land-based ones. Cross-study analytics also strongly suggest that open systems generate on average more eutrophying emissions than closed designs. We further discuss how to overcome bottlenecks currently hampering such LCA meta-analysis. Arguments are made in favor of further developing cross-study LCA analysis, particularly by increasing the number of salmonid LCA available (to improve sample sizes) and by reforming in-depth LCA practices to enable full reproducibility and greater access to inventory data.

The seafood sector is facing difficulties to meet the increasing demand for product greenhouse gas emission (GHG) assessments. We quantified GHGs of important seafood products of Norway, the world's second largest seafood exporter. We present results and improvement options for products of farmed salmon and wild‐caught shrimp, king crab, cod, and herring, followed to their dominating markets, based on detailed data for 2017. To enable more frequent monitoring, without engaging in a full assessment, we then suggest a simplified approach, focusing on the main drivers of production‐related emissions. The simplified approach is used to analyze temporal trends from 2007–2017 for fisheries and 1990–2017 for salmon aquaculture. Finally, the simplified approach was compared to the comprehensive assessment for 2017 to define species‐specific upscaling factors. Results show that salmon and crustacean products in 2017 caused higher emissions than cod and herring products, with feed and fuel use being the main emission drivers, whereas airfreighted products had the highest emissions of all products. Large improvement potential from average to best performers within each production system exists. The simplified approach shows that the fuel‐use intensity of Norwegian fisheries has increased by almost 50% for shrimp over the past decade whereas it has decreased for fish by 20% for demersal species such as cod and 5–10% for pelagic species such as herring. Feed‐related emissions for salmon, on the other hand, have increased by almost 30% during the same period, because of an increasing feed conversion ratio and increased inclusion of emission‐intensive feed inputs.

Salmon is a nutritious and popular food among consumers predominantly in wealthy countries around the world. Since the mid-1990s farmed salmon production has exceeded wild salmon harvest, and is now 80 % of total global salmon supply. The environmental impacts of farmed salmon are frequently discussed and consumers are faced with a multitude of choices even after deciding to have salmon for dinner: species, production method, origin, product form. We present life cycle impacts of fresh and frozen salmon products, originating in purse seine fisheries for pink salmon and gill net fisheries for sockeye salmon in Alaska, when sold on markets in Europe and the United States. Norwegian salmon products are then modelled to the same markets in fresh and frozen form, based on literature data. Impact categories included were greenhouse gas emissions, marine eutrophication, marine ecotoxicity and land use. A fish in, fish out ratio is also calculated and differences in content of nutrients and contaminants described. Frozen products from wild sockeye and pink salmon had the lowest emissions in both markets. For consumers in the U.S. and Europe, wild salmon products have 46-86 % and 12-71 % lower greenhouse gas emissions than farmed Norwegian salmon, respectively, depending on species and product form. Farmed salmon also had higher land use, marine ecotoxic and eutrophying emissions and fish in, fish out ratio. Important differences exist in nutritional and contaminant content between the three types of salmon production. Improvement options as well as an optimized supply chain are modelled showing greenhouse gas reduction opportunities of 40-50 % also for the best performing chains. Results can be used as a baseline for improved data collection and emission reductions. Recommendations for consumers, industry and policymakers who can facilitate and even drive development towards more sustainable salmon products are provided.

Achieving a sustainable global food chain is becoming particularly acute as modern Western diets are adopted in a growing number of countries and cultures around the world. Understanding the consequences that this shift has on health and sustainability is important. This exploratory study is the first to apply the life cycle assessment (LCA) methodology to analyze the sustainability implication of ongoing dietary shifts in Greenland, where locally hunted seal meat is increasingly being replaced by imported livestock products, primarily pig and poultry produced in Denmark. This dietary shift, indirectly driven by international trade bans such as the EU seal product ban, has sustainability implications. To inform and support more comprehensive analyses and policy discussions, this paper explores the sustainability of these parallel Greenlandic food supply chains. A quantitative comparison of the greenhouse gas emissions of Greenlandic hunted seal and Danish pig and poultry is complemented by a qualitative discussion of nutrition, cultural food preferences, animal welfare, and the use of land, pesticides and antibiotics. Although the variability in the life cycle inventory data collected from Greenlandic hunters was considerable, greenhouse gas emissions of seal meat were consistently lower than those of imported livestock products. Emissions of the latter are dominated by biogenic emissions from feed production and manure management, while these are absent for seal meat, whose emissions instead are dominated by fossil fuel use. The implications of these results for sustainable national food policies in a modern global context as well as important areas for additional research are discussed.