GoKawiilContribution of aquatic invertebrates to global nutrient supplies
Global capture and aquaculture statistics
To estimate the contribution of invertebrates to global animal capture fisheries and aquaculture production, we used 2019 reconstructed marine fisheries landings data from the Sea Around Us website25 and reported inland fisheries and aquaculture production from the Food and Agriculture Organization26. Reported inland fisheries, which are probably an underestimate of true inland fisheries production28, were analysed separately from marine capture fisheries throughout the Article, owing to the absence of globally standardized reconstruction datasets for freshwater systems. We used 2019 data in the main text because it is the latest year available with catch reconstructions. However, as a sensitivity analysis, invertebrate contributions were also estimated for other years (2014–2019). We found our invertebrate contribution results were consistent across years (Extended Data Fig. 3). The Sea Around Us uses officially reported landings from international and national fisheries statistics authorities as a baseline. Reconstructions are then performed by adding estimated unreported catches (such as landed illegal catches) using various literature sources. FishStatJ inland fisheries and aquaculture production26 data of territories and land areas were reported at the country level. Aquaculture and inland fisheries production species, reported using the Aquatic Sciences and Fisheries Information System (ASFIS) taxonomic reference system in FishStatJ, were converted to scientific species and species groups names (for example, rainbow trout to Oncorhynchus mykiss)60. Aquatic invertebrates in production data included mollusks (such as clams, mussels, oysters, scallops, cockles, snails, abalone, whelks, conchs, octopus, squid and cuttlefish), crustaceans (such as shrimp, prawns, crabs, lobsters and crayfish), sea cucumbers, sea urchins, sea worms, sponges and jellyfish (Supplementary Table 4). Marine capture fisheries and aquaculture production estimates shown throughout this Article (Fig. 1a and Extended Data Fig. 2) are global estimates derived from a total of 208,728 and 2,507 observations, encompassing 2,304 and 492 unique species (not only invertebrates) and 282 and 206 unique countries, respectively. Similarly, invertebrate-specific estimates for marine capture fisheries and aquaculture production shown throughout the Article (Fig. 1b and Extended Data Fig. 4) are global estimates derived from a total of 28,358 and 624 observations, encompassing 552 and 150 unique species and 252 and 124 unique countries, respectively.
Assigning nutrient composition data to aquatic foods
Nutrient concentration estimates per 100 g and edible proportions for each individual entry in global data (for example, fish and invertebrates) were assigned using raw muscle tissue samples within the AFCD12. We selected 30 nutrients that are important for public health13: 13 minerals (calcium, chromium, copper, iodine, iron, magnesium, manganese, molybdenum. phosphorous, potassium, selenium, sodium and zinc), 11 vitamins (A, C, D, E, B 1 (thiamin), B 2 (riboflavin), B 3 (niacin), B 5 (pantothenic acid), B 6 , B 9 (folate) and B 12 (cobalamin)), 5 versions of essential fatty acids (total monounsaturated fatty acids (MUFAs), total omega 3 fatty acids, total omega 6 fatty acids, DHA and EPA, and ALA), and protein. We included total protein and not specific essential amino acids because the dataset that we are using is currently being updated for those nutrients (for example, validating units and conversions). Moreover, we did not include other nutrients, such as cobalt and arachidonic acid, because they lacked established RNI reference values. Mean nutrient composition estimates and edible proportions were assigned hierarchically on the basis of the closest taxonomic resolution (Supplementary Fig. 2). In other words, for any given nutrient, if a species had species-specific nutrient composition observations in AFCD, we assigned that value. However, if no observed nutrient concentrations were available at the species level, we assigned the mean of the next taxonomic level (such as genus). To obtain nutrient supplies or yields, nutrient concentrations per 100 g were multiplied by equivalent units in live weight. Note that we used live weights for our main analyses (that is, extrapolating the nutrient content from muscle tissue to live weight volumes), but also performed a sensitivity analysis using edible weight (for example, multiplying live weights by edible proportions; Extended Data Fig. 2). We grouped nutrient supplies and total catch or production volumes separately for invertebrates and fish, and calculated the percentage of nutrient supplies coming specifically from invertebrates. We separately did this for different sectors, taxa, years and countries or EEZs. Note that, similar to finfish5, country- or EEZ-specific nutrient yields are not strongly correlated with the average nutrient concentration of their catches (Supplementary Figs. 7 and 8), indicating, for example, that a country or EEZ with high nutrient yields does not necessarily target the species with most nutrient concentrations.
Estimating public health relevance of aquatic foods
Nutrient supplies were converted to the number of yearly requirements met by dividing nutrient-specific nutrient supplies from aquatic invertebrates by their estimated RNI, averaged across available demographic groups (gender and age; Supplementary Table 3). When available, we used the recommended dietary allowance61. However, when such data were not available, we used adequate intake61 estimates or values reported in the literature: 433 mg per day for DHA and EPA (that is, average between different studies reviewed)62 and 48.8 g per day for MUFAs (that is, 20% of total energy recommended intake assuming that a gram of MUFA represents 9 kcal)63,64. Note that for total omega 6 fatty acids, we used recommended intakes reported for linolenic acids; and for total omega 3 fatty acids, we used the sum of ALA and DHA and EPA recommended intakes (that is, 1,633 mg per day). Yearly nutrient supplies were divided by yearly requirements, ensuring that units were the same and assuming 365 days (for example, yearly requirements in tonnes = daily requirements in tonnes × 365). Our approach estimates the number of nutrient requirements met exclusively from the nutrients available from aquatic invertebrates. While we acknowledge that people eat other foods and do not meet their nutritional adequacy exclusively from aquatic invertebrates, this enabled us to compare the importance of aquatic invertebrates across nutrients with a standardized unit relevant for public health.
Predictive model of invertebrate nutrient concentrations
To estimate the variability and potential drivers of nutrient content in aquatic invertebrates, we first updated and validated species-specific invertebrate nutrient concentration samples within AFCD. A total of 13,888 samples from 465 invertebrate species were compiled, updated and validated (for example, reviewing source studies or food composition tables for accuracy, and adding extra information (for example, sample preparation, relative weight)). Specifically, food part (that is, the body part that was sampled for nutrient concentration) and food processing (that is, mechanical or chemical processes that transform the animal to the form before consumption) were validated (for example, examining categorizations for accuracy and disaggregating processing from sample preparation; Supplementary Table 1). Sample sizes and species varied by nutrient (Supplementary Table 2).
We next merged species-specific nutrient data with ecological and environmental trait information available from SeaLifeBase27. Traits were assigned hierarchically, using species-specific data when available or the mean or most common category of the closest taxonomic group (for example, genus). Taxonomic level assignment of traits is shown in Supplementary Fig. 9. We included available traits related to energetic demand, thermal regime, habitat and environment that are likely to influence the nutrient composition of aquatic invertebrates (Supplementary Table 1).
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