Fish and other aquatic foods (blue foods) present an opportunity for more sustainable diets 1,2 . Yet comprehensive comparison has been limited due to sparse inclusion of blue foods in environmental impact studies 3,4 relative to the vast diversity of production 5 . Here we provide standardized estimates of greenhouse gas, nitrogen, phosphorus, freshwater and land stressors for species groups covering nearly three quarters of global production. We find that across all blue foods, farmed bivalves and seaweeds generate the lowest stressors. Capture fisheries predominantly generate greenhouse gas emissions, with small pelagic fishes generating lower emissions than all fed aquaculture, but flatfish and crustaceans generating the highest. Among farmed finfish and crustaceans, silver and bighead carps have the lowest greenhouse gas, nitrogen and phosphorus emissions, but highest water use, while farmed salmon and trout use the least land and water. Finally, we model intervention scenarios and find improving feed conversion ratios reduces stressors across all fed groups, increasing fish yield reduces land and water use by up to half, and optimizing gears reduces capture fishery emissions by more than half for some groups. Collectively, our analysis identifies high-performing blue foods, highlights opportunities to improve environmental performance, advances data-poor environmental assessments, and informs sustainable diets.The food system is a major driver of environmental change, emitting a quarter of all greenhouse gas (GHG) emissions, occupying half of all ice-free land, and responsible for three quarters of global consumptive water use and eutrophication 3,6 . Yet, it still fails to meet global nutrition needs 7 , with 820 million people lacking sufficient food 8 and with one in three people globally overweight or obese 9 . As a critical source of nutrition 8,10 generating relatively low average environmental pressures 1,2,11,12 , blue foods present an opportunity to improve nutrition with lower environmental burdens, in line with the Sustainable Development Goals to improve nutrition (Goal 2), ensure sustainable consumption and production (Goal 12), and sustainably use marine resources (Goal 14).Blue foods, however, are underrepresented in food system environmental assessments 13 and the stressors considered are limited 4 such that we have some understanding of GHG emissions 14,15 , but less of others such as land or freshwater use 16 . Where blue foods are included, they are typically represented by only one or a few broad categories (see, for example, refs. 3,17,18), masking the vast diversity within blue food production. Finally, estimates combining results of published life cycle assessments undertaken for different purposes, and consequently using incompatible methodologies 19,20 , cannot be compared reliably. It is therefore critical to examine the environmental performance across the diversity of blue foods in a robust, methodologically consistent manner to serve as a benchmark within the rapidly evolving se...

SummaryThis study aims to assess the environmental impacts of canned sardines in olive oil, by considering fishing, processing, and packaging, using life cycle assessment (LCA) methodology. The case study concerns a product of a canning factory based in Portugal and packed in aluminum cans. It is the first LCA of a processed seafood product made with the traditional canning method. The production of both cans and olive oil are the most important process in the considered impact categories. The production of olives contributes to the high environmental load of olive oil, related to cultivation and harvesting phases. The production of aluminum cans is the most significant process for all impact categories, except ozone depletion potential and eutrophication potential, resulting from the high energy demand and the extraction of raw materials. To compare to other sardine products consumed in Portugal, such as frozen and fresh sardines, transport to the wholesaler and store was added. The environmental cost of canned sardines is almost seven times higher per kilogram of edible product. The main action to optimize the environmental performance of canned sardines is therefore to replace the packaging and diminish the olive oil losses as much as possible. Greenhouse gas emissions are reduced by half when plastic packaging is considered rather than aluminum. Frozen and fresh sardines represent much lower environmental impacts than canned sardines. Nevertheless, when other sardine products are not possible, it becomes feasible to use sardines for human consumption, preventing them from being wasted or used suboptimally as feed. Keywords:canning industrial ecology life cycle assessment (LCA) packaging sardines seafood processing Supporting information is available on the JIE Web site

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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.

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.