Global consumption of threatened freshwater eels revealed by integrating DNA barcoding, production data, and trade statistics

Abstract

Fisheries resources depend on natural ecosystems, yet their sustainable management is often limited by uneven regional capacities and the pressures of international trade. High demand from certain regions can lead to overexploitation in others, highlighting the need to understand global consumption patterns of key aquatic species. This study introduces an integrated approach that combines DNA barcoding of freshwater eel (Anguilla spp.) products collected from end markets in 11 countries/regions with global production and trade statistics. We estimate that over 99% of eels consumed worldwide belong to three IUCN-listed threatened species: the American eel, Japanese eel, and European eel. Consumption was heavily concentrated in East Asia—particularly China, Japan, and South Korea—where supply volumes far exceed those of other regions. Our approach yields the most comprehensive quantitative global estimate to date of eel species composition in consumption, offering essential insights for the conservation and sustainable management of this highly exploited group.

Introduction

Food resources are essential for sustaining human societies, yet their management and conservation face significant challenges. Unlike agricultural products, such as vegetables and livestock, fisheries resources rely heavily on natural ecosystems, reproducing and sustaining themselves without direct human intervention. As a naturally derived resource, fisheries hold the potential for sustainable utilisation if managed appropriately¹. However, disparities in fisheries management across regions—stemming from variations in resources such as funding, expertise, and scientific knowledge—pose critical challenges^2,3. These disparities are often magnified through international trade, where high demand from certain regions drives overexploitation in others. As of 2021, nearly 90% of the global marine fish stocks were either overexploited or at their maximum sustainable limits⁴, and such cases are more often observed in the global south⁵. Moreover, strong demand from foreign countries sometimes facilitates IUU (illegal, unreported, and unregulated) fishing. Although fish and fish products are among the most globally traded food commodities, and they have a crucial role in food security and economic activity, these benefits are undermined by a range of challenges, including overexploitation and/or IUU fishing⁶.

Addressing these issues is paramount for achieving both sustainable resource use and global biodiversity conservation and requires an understanding of international consumption trends of target fish species. However, understanding trade and consumption on a global scale is challenging when multiple fish species with similar morphological features are traded and consumed worldwide. Although customs in each country record trade statistics, such information is not usually species-specific, and fish are often traded after being prepared as fillets or ready-to-eat products that are difficult to identify by species morphologically. To overcome this challenge, species identification using DNA barcoding has been conducted on seafood sold in restaurants and retail markets^7–9, and DNA is becoming a promising tool for identifying fish species in end markets. This method is powerful for detecting mislabeling and/or illegal sourcing because exact species can be identified from the food sold in markets^10,11. Moreover, species composition in a specific market can be estimated by analysing multiple samples. However, understanding the market on a global scale is challenging because the species composition obtained from different countries cannot be directly aggregated to calculate overall proportions, as the volumes of distribution vary greatly between countries and regions. Because some taxonomic groups of fish species are caught and traded worldwide, understanding the market on a global scale requires a method for aggregating species composition across different markets.

Quantitative data, such as production statistics and customs records of imports and exports, provide critical insights for understanding global market trends on a quantitative scale. For economically important fish species, many countries record capture and aquaculture production volumes and report them to the FAO. Additionally, customs offices worldwide use standardised six-digit Harmonized System (HS) codes to document the import and export volumes of commodities¹². However, these quantitative records, particularly trade statistics, often fail to differentiate between similar species. For example, despite being a large taxonomic group comprising over 400 species in total, squid (Order Teuthida) and cuttlefish (Order Sepiida) are grouped under the same HS codes, with no distinction made between individual species. Therefore, production and trade data, which enable quantitative analyses but often fail to identify species, and, DNA barcoding, which can identify species but lacks the capacity for large-scale quantitative analyses, are complementary tools. By integrating DNA barcoding with the analysis of production and trade data, it becomes possible to comprehensively understand the market dynamics of specific taxonomic groups on a global scale.

This study attempts to estimate global-scale species composition using both DNA barcoding and production and trade data of one well known type of fishes. Freshwater eels of the genus Anguilla provide a compelling example, due to their complexities surrounding fisheries, aquaculture, trade, and conservation. Comprising 16 species distributed at least partly on all continents except Antarctica, these eels are fished, farmed, traded, and consumed as food globally^13–16. Although they are among the most commercially important freshwater fish species worldwide, and despite advances in aquaculture, reproduction and production of seedling in captivity remains confined to experimental laboratory settings¹⁷. This means that all eels in global trade originate from wild populations, because farmed eels, which constitute the majority of those consumed, are raised from recruitment-stage juveniles (called glass eels) captured in natural habitats as they enter freshwater after being born in the sea¹⁸ (Fig. 1). This reliance on wild-caught juveniles for farming—combined with their high market value—has resulted in international trade dynamics comparable to those of precious commodities.

Fig. 1.

Eel life cycle and consumption through aquaculture. Left and right images represent the eel life cycle and consumption of eels through aquaculture, respectively. Aquaculture farming solely relies on wild-caught juveniles called glass eels. Photos of spawning adult and eggs were taken by the IRAGO Institute, photos of glass eels and the yellow eel were taken by R. Uchiyama, and photos of leptocephalus, silver eel, and eel feeding were provided by M. Miller.

Among the 12 species of freshwater eels assessed by the IUCN, 10 are classified as endangered or near-threatened, reflecting the severe pressures they face. Key drivers of their population declines include habitat modification, the spread of pathogens, and overexploitation¹⁹. International trade plays a pivotal role in shaping consumption patterns, often redirecting demand to less-regulated regions or species. For example, the European eel (Anguilla anguilla) has suffered significant population declines partly due to demand in East Asia, leading to its listing in Appendix II of CITES in 2007 and subsequent implementation of trade restrictions^14,16. These measures have inadvertently spurred poaching, smuggling, and shifts in demand to other eel species, such as the Indonesian shortfin eel (A. bicolor) and the American eel (A. rostrata)^15,20,21. Understanding these complex interactions is essential for developing effective conservation policies.

Strong demand for freshwater eels and the decline of their populations underscore the urgent need for comprehensive research into the global market of freshwater eels to inform sustainable management strategies. Several studies have investigated eel consumption in specific regions, such as North America²², Europe²³, and Hong Kong^24,25, and Singapore²⁶, and recently, a meta-analysis was conducted to understand broader global markets²⁰. These studies have demonstrated the species composition of eels distributed in markets of certain countries and regions, but they have not provided an understanding of the global-scale eel market. This is because the focus of the most studies was limited to a specific country or region^22–26, or methods to quantitatively compare species composition across different countries were not used²⁰. To address these gaps, we conducted worldwide sampling of eels and products made from them, including those from East Asia, Europe, North America, Oceania, and Southeast Asia. Additionally, our recent work integrated genetic species identification with the analysis of trade and production data, providing novel insights into the eel market in Japan²⁷. Expanding this approach globally offers a unique opportunity to illuminate the international consumption patterns of freshwater eels, many of which are threatened.

We established two simple research questions on a global scale, which are what eel species are being consumed, and who (countries/regions) is consuming them, to advance the conservation and sustainable management of freshwater eels. To answer these questions, we conducted species identification of live eels and prepared products sold in the markets of 26 cities across 11 countries/regions by applying DNA barcoding methods. We also estimated the domestic supply volume, which reflects consumption volume, of freshwater eels for each country based on production and trade data. By weighting the species composition with domestic supply volume in each country/region, we estimated the current composition of eel species consumed on a global scale. By combining DNA barcoding methods with analyses of production and trade data, we provide a comprehensive overview of global eel consumption. Our findings offer critical insights into the intersections of fishery, aquaculture, trade, and sustainability, contributing to the broader understanding that is necessary for effective conservation interventions.

It is important to note that in addition to the production data compiled and reported to the FAO by each country/region, there are also independent datasets available in East Asia, where eel production and consumption are particularly prominent¹³. The Informal Consultation on International Cooperation for Conservation and Management of Japanese Eel Stock and Other Relevant Eel Species (hereafter referred to as the Informal Consultation), which consists of government agency representatives from China, Japan, South Korea, and Taiwan, has held annual meetings since 2012, during which they compile eel production data²⁸. In some countries, there are substantial discrepancies between the production volumes reported to the FAO and those reported to the Informal Consultation. Therefore, this study examined eel consumption using both datasets (see Materials and Methods for details).

Results

Species composition and labeling in each country/region

282 samples of eel or eel products were collected from 26 cities across 11 countries/regions (see Fig. 2 for examples), and 279 were successfully identified to species level through molecular analysis (see Appendix I for details). The remaining three samples could not be identified for unclear reasons. The genetic analysis of the samples that were collected from supermarkets, convenience stores, wet-markets, and fast-food chains and restaurants detected four species of Anguilla among the samples: American eel, Japanese eel (A. japonica), European eel, and Indonesian shortfin eel. Of the 279 identified samples, American eel was the most frequently detected species, accounting for 54.1% of eel products, followed by Japanese eel (44.1%) and European eel (1.4%). The number of Indonesian shortfin eel products was very limited (n = 1; in Hong Kong), accounting for only 0.4% of the total samples. Both American eel and Japanese eel were found in all countries/regions except Taiwan, where only three samples were collected (Fig. 3). In China, France, Japan, and the UK, Japanese eel was the most dominant species, whereas American eel was the most dominant in the other seven countries/regions. The number of European eel samples was small (n = 4), consisting of two samples from China and two from Japan. It should be noted that the absence of European eel from the samples collected in Europe, its natural distribution area, is likely due to the exclusion of traditional products such as smoked eel from sampling. This bias was corrected using fisheries and aquaculture production data from Europe (see Materials and Methods for details).

Fig. 2.

Examples of collected eel samples. (a): prepared kabayaki product collected in Singapore (ID: S24-003), (b): traditional Chinese eel dish (ID: C25-010), (c): traditional Japanese dish, kabayaki over rice (ID: J25-019), (d): fresh eels sold in a Hong Kong wet-market (ID: H24-018). In the photo a, any information that could identify the manufacturer or importer is concealed by grey rectangles.

Fig. 3.

Species composition of eels by country. Green dots indicate the cities where samples were collected. The pie charts represent the species composition of the samples collected in each country. The numbers in parentheses indicate the sample size. Note that ”Whole sample"simply shows the overall species composition of all collected samples and does not account for the supply volume in each country.

For the 224 kabayaki samples (see Fig. 2 for examples) purchased at retail outlets, the eels were assumed to have been farmed in the country of origin indicated on the product label, as eels are often processed near the farms where they are cultured. Of these, 68%, 25%, and 1% were produced in China, Japan, and Taiwan, respectively. The remaining 5% did not indicate the country of origin (Table 1). Outside Japan, products from Japan were found only in Singapore (n = 2) and the US (n = 3). Similarly, outside Taiwan, products from Taiwan were only found in Hong Kong (n = 1). All kabayaki products collected in Australia, Canada, China, France, Spain, and the UK were produced in China when the country of origin was indicated. When examining species composition by country of production, among the 152 products manufactured in China, American eel accounted for 74%, Japanese eel for 24%, and European eel for 2%. For the 56 products from Japan and the 3 products from Taiwan, all were entirely composed of Japanese eel (100%).

Table 1.

List of numbers of samples analysed for species identification and production countries of kabayaki.

Country/region	Number of total samples	Number of kabayakisamples	Country of kabayakiorigin (%)
			China	Japan	Taiwan	Unknown
Australia	19	18	100.0	0.0	0.0	0.0
Canada	9	6	100.0	0.0	0.0	0.0
China	31	14	78.6	0.0	0.0	21.4
France	6	2	100.0	0.0	0.0	0.0
Hong Kong	18	11	36.4	0.0	9.1	54.5
Japan	156	133	61.9	38.1	0.0	0.0
Singapore	12	10	60.0	20.0	0.0	20.0
Spain	7	6	100.0	0.0	0.0	0.0
Taiwan	3	3	66.7	0.0	0.0	33.3
UK	5	4	100.0	0.0	0.0	0.0
US	16	16	81.3	18.8	0.0	0.0
Total	282	224	68.3	25.0	0.9	6.3

"Country/region"indicates the country or region where the samples were obtained. Among all samples, those with recorded country of origin were exclusively manufactured in China, Japan, or Taiwan.

Among the 224 kabayaki products, 9% (n = 20) carried species labelling (Table 1). The labelled species were American eel (n = 13) and Japanese eel (n = 7). In all cases, the species names indicated on the labels matched the species identification results obtained in this study, and no mislabelling was detected (see Appendix I for details). By region, the proportion of products with species labelling was relatively high in Europe, ranging from 50 to 100%.

Domestic supply volume

Based on an analysis of production and trade data, the global eel supply volume between 2020 and 2022 was calculated (Table 2, Fig. 4) (see Appendix II for details). When calculated using FAO production data from the 38 countries that reported fisheries and aquaculture production information, the annual average supply in the whole world was approximately 286,000 t.

Table 2.

Domestic eel supply and export volumes in the 11 countries/regions where samples were collected for species identification, with other top 10 countries.

Country/region		Domestic supply volume						Expot (t)
		FAO data			Informal Consultation data
		Total (t)	% global	per capita (g)	Total (t)	% global	per capita (g)
Countries/regions investigated in this study	Australia	537.9	0.19	20.8	537.9	0.44	20.8	13.4
	Canada	1,054.9	0.37	27.7	1,054.9	0.87	27.7	268.5
	China	171,995.1	60.17	119.1	7,401.5	6.10	5.1	97,050.7
	France	431.3	0.15	6.6	431.3	0.36	6.6	364.4
	HongKong	3,236.6	1.13	427.7	3,236.6	2.67	427.7	274.9
	Japan	54,993.9	19.24	436.2	54,993.9	45.35	436.2	101.8
	Singapore	684.3	0.24	116.0	684.3	0.56	116.0	58.2
	Spain	519.7	0.18	11.1	519.7	0.43	11.1	278.5
	Taiwan	1,809.6	0.63	79.5	1,809.6	1.49	79.5	1,714.8
	UK	301.2	0.11	4.4	301.2	0.25	4.4	187.6
	USA	7,038.9	2.46	21.1	7,038.9	5.80	21.1	1,903.5
	11 countries/regions	242,603.5	84.87	111.1	78,009.8	64.33	35.7	102,216.0
Other top 10 countries in supply volume	Malaysia	5,489.1	1.92	167.4	5,489.1	4.53	167.4	3,386.4
	Netherlands	3,145.5	1.10	183.2	3,145.5	2.59	183.2	1,551.6
	Philippines	1,809.7	0.63	16.3	1,809.7	1.49	16.3	0.1
	Russia	4,510.3	1.58	30.9	4,510.3	3.72	30.9	93.5
	South Korea	18,812.9	6.58	366.7	18,812.9	15.51	366.7	79.6
Global total		285,864.3	100.00	36.2	121,270.7	100.00	15.4	133,531.9

Domestic eel supply was calculated as the sum of production and import volumes minus export volumes and represents the average values from 2020 to 2022. Due to significant discrepancies in aquaculture production volumes for China between the FAO and the Informal Consultation, data from both sources are presented. Regardless of the data source, the countries/regions where sampling was conducted accounted for 60% to 80% of the global eel supply. Per capita eel supply was calculated by dividing the domestic eel supply for each country, as shown in the table, by the average population of that country from 2020 to 2022.

Fig. 4.

Eel supply volume by country. The values represent the average supply volume from 2020 to 2022. Supply volume was calculated by adding production and import volumes and subtracting export volumes. For East Asia, where eel supply is particularly high, discrepancies exist between FAO data and data from the Informal Consultation. The map based on FAO data is shown at the top, while the map based on“Informal Consultation”data is shown at the bottom. Countries shaded in gray indicate that data were unavailable. Note that the scales shown on the right side of the graph differ between the top and bottom.

The domestic supply volume for each country was calculated by adding its production and import volumes and subtracting its export volume. The countries with the highest domestic eel supply were China (171,995 t), followed by Japan (54,994 t), South Korea (18,813 t), the United States (7039 t), and Malaysia (5489 t). The per capita annual eel supply averaged 36.2 g worldwide, with Japan having the highest supply at 436.2 g per capita, followed by Hong Kong (427.7 g per capita), South Korea (366.7 g per capita), Macao (278.8 g per capita), and the Netherlands (183.2 g per capita). Of the top five countries/regions, four were in East Asia. In China, the per capita domestic supply was 119.1 g, ranking eighth globally. In contrast, when calculated using Informal Consultation data, the global average eel supply between 2020 and 2022 was approximately 121,000 t, with Japan having the highest domestic supply, followed by South Korea, the United States, China (7402 t), and Malaysia. The per capita annual eel supply averaged 15.4 g worldwide. In China, the per capita domestic supply was 5.1 g, ranking below 40th place globally.

Based on FAO data, China’s aquaculture production was approximately 250,000, 255,000, and 282,000 t in 2020, 2021, and 2022, respectively, while according to Informal Consultation data, it was 82,000, 92,000, and 120,000 t for the same years (see Apendix II for details). This resulted in a difference of approximately 160,000 t between the two figures for each year. This discrepancy accounted for more than 50% of the total global eel supply based on FAO data and 130% of the total global eel supply when using Informal Consultation data (Table 2). Between 2020 and 2022, China’s annual eel exports averaged approximately 97,000 t (Table 2), representing 69.7% of the recorded global eel exports. In 2021, China’s export volume was 111,000 t, exceeding the aquaculture production volume reported to the Informal Consultation for the same year²⁸ (92,000 t).

Species composition on a global scale

The species-specific supply volume for each country was calculated based on domestic supply and species composition. By summing these values, the species composition of the eel market across the 11 surveyed countries and regions was integrated into an international scale. As a result, regardless of the data source used, the most abundant eel species distributed in the 11 surveyed countries was the American eel, followed by the Japanese eel and the European eel. Specifically, when calculated based on FAO data, the species composition was 75.3% American eel, 18.0% Japanese eel, 6.7% European eel, and 0.02% Indonesian shortfin eel (Fig. 5). In contrast, when calculated using Informal Consultation data, the respective proportions were 52.7%, 43.5%, 3.6%, and 0.2%.

Fig. 5.

Species compositions of eels consumed globally, estimated from the two data sources for 2020 to 2022. Left and right panels are based on the data from the FAO and the Informal Consultation, respectively. The species composition observed in 11 countries where end markets were surveyed was weighted by the domestic eel supply volume (considered as an approximation of consumption volume) calculated from production and trade data for each country. The species-specific eel consumption volume was then estimated. For the EU and the UK, adjustments were made using European eel fisheries and aquaculture production volumes, as traditional preparations such as smoked eel, which are expected to contain European eel, were not included in the collected samples (see Materials and Methods for details). Ratio of shortfin eel, A. bicolor, is difficult to detect due to its small value (0.02 or 0.2%).

Discussion

In recent years, genetic species identification studies focusing on seafood distributed in end markets have become increasingly common^7–9. These studies have contributed to improving traceability within seafood supply chains. However, no previous research has combined species identification with production and trade data to estimate global species composition in consumption. To link species composition in individual countries/regions to a comprehensive understanding of global markets, it is necessary to trace products back from the end market and integrate information on fisheries and aquaculture production, as well as international trade. This study pioneers an integrated approach to unveil the global consumption patterns of a commercially important fish group, providing essential insights for conservation and sustainable management.

For the three-year average volume from 2020 to 2022, the global eel supply was estimated to be approximately 286,000 t based on FAO data, and approximately 121,000 t based on data from the Informal Consultation, representing a 2.4-fold difference between the two data sources. This discrepancy primarily arises from a 160,000-t difference in China’s reported aquaculture production, making it difficult to determine the actual figure. As mentioned previously, the Informal Consultation is a framework established for the purpose of eel resource management, comprising China, Japan, South Korea, and Taiwan. Each year, these four participants report basic data relating to eels, including aquaculture production volumes. Among these, the production volumes reported by China exhibit a substantial discrepancy when compared to the figures reported to the FAO. Consequently, this study conducted analyses using both data sources.

Based on the Informal Consultation, in 2021, China’s aquaculture production (92,000 t) accounted for only approximately 80% of the export volume (111,000 t). One possible explanation for this discrepancy, whereby the export volume exceeds the production volume, is that exports of other eel-like fishes such as swamp eels may have been misclassified as Anguilla eels. Another possibility is that eels imported from abroad are processed in China and then re-exported. However, China’s average annual eel import volume from 2020 to 2022 was approximately 7,000 tonnes, which is insufficient to account for the 19,000 t gap between 9,200 and 11,100 t. Moreover, several additional factors must also be considered. China captures Japanese glass eels domestically. According to Informal Consultation, between 2020 and 2022, 5 to 38 t of glass eels were annuary fished in China²⁸. In addition, in 2022 alone, at least 157 tonnes of American eel juveniles were reportedly imported into East Asia for aquaculture²¹. Furthermore, EUROPOL has estimated that up to 100 t of juvenile European eels were illegally transported from the EU to China between 2017 and 2018²⁹. In Japan, aquaculture production of eels has been estimated to be 700 to 1200 times the weight of the glass eels used as seed stock¹⁸. Since eels are typically raised to a larger size before harvest in China compared to Japan¹³, it can be inferred that if 200 t of juvenile eels were stocked for aquaculture, the resulting production could exceed 200,000 tonnes. Based on FAO data, China’s average aquaculture production between 2020 and 2022 was approximately 263,000 tonnes, whereas the Informal Consultation data estimated it at around 98,000 tonnes. Considering the recorded export volumes and the international movement of eel seedlings, the Informal Consultation data are likely to underestimate actual production for China. On the other hand, it cannot be ruled out that the FAO data may also be overestimated. To obtain a more accurate estimate of the global eel supply, it is essential to improve the precision of estimates for China’s aquaculture production.

By region, East Asia exhibited the highest supply volume. The six East Asian countries and regions for which production and/or trade data were available—China, Hong Kong, Japan, Macao, South Korea, and Taiwan—accounted for 87.8% of the global eel supply based on FAO data, and 71.3% based on Informal Consultation data. Although freshwater eels are caught and traded globally, previous studies and reports have indicated that East Asia is the centre of global demand for eels^13–16,21. This study reinforces the findings of these previous studies and reports by using fisheries and aquaculture production data, alongside international trade data from countries across the world. The predominance of eel consumption in East Asian countries may be attributed to both cultural and economic factors—namely, the high culinary demand for eels in the region and the financial capacity to obtain eel products from global markets. A deeper examination of these underlying drivers is essential for informing future strategies for the sustainable management of Anguilla species worldwide.

When examining domestic supply volumes by country, FAO data indicate that China ranks first, followed by Japan and South Korea. However, based on Informal Consultation data, Japan ranks first, followed by South Korea and the United States, with China in fourth place. Nevertheless, in both cases, East Asian countries consistently occupy the highest ranks. According to a report by TRAFFIC, Japan’s annual eel supply was estimated at over 150,000 t between 2000 and 2002, accounting for approximately 70% of global production at the time. However, from 2007 onwards, China may have become the world’s largest eel consumer¹³. This estimation was based on FAO data and is broadly consistent with the findings of the present study. There is a 27.5-fold discrepancy in China’s domestic supply volume depending on the data source, making it difficult to provide a highly accurate estimate of eel consumption in China. Nonetheless, it is clear that China is one of the world’s leading eel-consuming countries. Japan’s domestic supply volume is nearly three times that of South Korea, making Japan the largest or second-largest eel-consuming country in the world. South Korea also ranks considerably higher than the United States, with approximately 2.7 times the domestic supply volume, indicating that it is also a major eel-consuming country. Particular attention should be paid to the domestic supply volume in Russia. The average domestic supply volume in Russia between 2020 and 2022 was approximately 4500 t; however, this was largely due to the exceptionally low volume recorded in 2022, which was only 14 t (see Appendix II for details). In contrast, the domestic supply volume was approximately 6400 t in 2020 and around 7300 t in 2021, comparable to that of the United States. The sharp decline in supply volume in 2022 is due to the absence of reported trade data for Russia that year. Overall, the only three countries where domestic eel supply is likely to exceed 10,000 t are China, Japan, and South Korea. Furthermore, as China accounts for 70% of the world’s total eel exports, these three countries can be considered to play a central role in global eel consumption.

When comparing per capita eel supply, Japan ranked first regardless of the data source, with an annual per capita supply of 436 g, followed by Hong Kong at 428 g, South Korea at 367 g, and Macao at 279 g. Excluding the Netherlands, which ranked fifth with 184 g, four of the top five countries/regions were in East Asia. The per capita supply in these countries was substantially higher than the global average of 36 g (based on FAO data) or 15 g (based on Informal Consultation data), highlighting the strong cultural and culinary preference for eating eel in East Asia. These results suggest that the large eel supply in East Asia is not only a consequence of the region’s large population, including China, the most populous country in the world, but also reflects the cultural significance and strong consumer preference for eel as a food ingredient. While the popularity of eel in Japan is widely recognised^18,30,31, the similarly high popularity of eel in Hong Kong, South Korea, and Macao has received considerably less attention. This study provides important insights not only into eel supply but also into the popularity of eel across different countries/regions, based on a quantitative analysis that incorporates production, trade, and population data.

As indicated in a previous report¹³, the domestic supply volumes estimated in this study can be considered roughly equivalent to domestic consumption volumes. Based on the results of this study and previous research, the answer to one of the two research questions—"who (countries/regions) is consuming eels"—can be summarised as follows. Both in terms of total supply volume and per capita supply, East Asia stands out as the region with the highest eel consumption in the world. The country consuming the largest amount of eels is either China or Japan; however, due to the uncertainty in the data, it is not possible to determine this with certainty.

Regarding the other research question,"what eel species are being consumed,"this study found that, in the 11 countries and regions where eel products were sampled, the most consumed species was the American eel, followed by the Japanese eel and the European eel, regardless of the production data source (i.e., FAO or Informal Consultation). Although only 11 countries were selected for analysis out of all countries worldwide, the domestic supply volume of these countries accounted for 84.9% of the global eel supply based on FAO data, and 64.3% based on Informal Consultation data. As these countries represent the majority of the global eel supply, the species composition of eels supplied to their markets can be considered broadly reflective of the global species composition. Nevertheless, some eel species were overlooked. In this study, the number of samples obtained from certain regions, such as Africa and Southeast Asia, was very limited. These regions are known to be habitats of anguillid eel species other than American, European, and Japanese eels. Therefore, if eel products had been collected from these areas, the species composition would likely have been more diverse. For example, in Southeast Asia, several species, such as A. marmorata and A. celebesensis, are known to be caught and consumed¹⁸, and other examples include A. australis and A. reinhardtii, which inhabit the Southern Hemisphere³². Although these species were not detected in the samples collected in this study, they have been reported to be consumed and, in some cases, traded internationally. In the following, we mainly focus on the three most consumed eel species worldwide. However, even if their consumption volumes are smaller, the remaining 13 Anguilla species should also be subject to surveillance in order to prevent potential overexploitation in the event of a sudden increase in demand.

The production data used in this study showed significant discrepancies in China’s aquaculture production. Nevertheless, regardless of whether FAO or Informal Consultation data were used, the ranking of the most consumed eel species worldwide—American eel, followed by Japanese eel, and then European eel—remained unchanged. Therefore, it is unlikely that variations in China’s aquaculture production would alter this order. Another important factor to consider is the situation in South Korea, which has one of the highest domestic eel supply volumes globally but was not included in this study. Based on FAO and UN Comtrade data, the average domestic supply volume in South Korea between 2020 and 2022 was 18,813 t, while average aquaculture production was 14,553 tonnes. According to reports from the South Korean government²⁸, more than 80% of eels farmed domestically are Japanese eel, while American eel accounts for only about 1%, and European eel is not farmed at all. Because domestic aquaculture production accounts for 77% of the total supply, and more than 80% of aquaculture production consists of Japanese eel, the majority of eels distributed in South Korea—at least more than 60%—are estimated to be Japanese eel. According to FAO data, the difference between the global supply volumes of American eel and Japanese eel exceeds 40,000 t, whereas the figure is less than 10,000 t based on the Informal Consultation data. If the majority of eels consumed in South Korea are Japanese eel, and the Informal Consultation data are accurate, the global consumption volumes of the two species could be comparable. However, as discussed above, the Informal Consultation data are likely to underestimate actual production. Based on these considerations, even when taking into account discrepancies in China’s aquaculture production data and the species composition in South Korea, the global species composition of eels in circulation is still most likely dominated by American eel, followed by Japanese eel, and then European eel. Consequently, this study revealed that regardless of the data source used, more than 99% of eels consumed globally belong to species classified as threatened in the IUCN Red List.

It is known that the target eel species tend to shift depending on population status and conservation measures^15,33. Following the decline in juvenile Japanese eel catches and the CITES regulation, along with the EU’s trade ban on European eel, other regions, such as Southeast Asia and the Americas, have become increasingly important sources of juvenile Anguilla spp. ^15,16. In a recent study²⁰, American eel was found to be the most dominant species in terms of composition. However, that study did not include investigations of the Chinese and Japanese markets, which were identified as the most significant eel markets globally. Moreover, the study did not adopt methods that allow quantitative comparisons of species composition across different countries or regions.

Our previous study on trade statistics also indicate that American eel is the most intensively captured juvenile eel species for aquaculture²¹. Finally, the present study substantiated the hypotheses by combining species identification of products distributed in end markets with production and trade data. By employing a mixed-method approach that integrates species identification with the analysis of production and trade data, the present study successfully revealed the global-scale species composition of consumed eels.

The finding of this study—that the majority of eels consumed globally belong to threatened species—raises serious concerns about the conservation and sustainable use of these Anguilla species. While the decline of Anguilla populations is driven by multiple factors beyond consumption—such as the loss and degradation of accessible habitats and the impact of pathogens—there is general consensus within the scientific community that consumption remains one of the major contributors to population declines^17,19,34.

As previously highlighted in published reports^13,15, one of the most concerning issues when investigating international eel consumption is the uncertainty surrounding production data. The discrepancy between reported figures, ranging from 50 to 130% of the estimated total global supply, presents a fundamental obstacle to the effective management of Anguilla species. If these inconsistencies remain uncorrected, further market research and supply chain analysis will be necessary to obtain a more accurate understanding of eel exploitation. Furthermore, given that only 38 countries currently report their production data to the FAO, it is desirable for more eel range states to provide fisheries and aquaculture production data in the future. With regard to trade data, a system is also needed to distinguish trade volumes from different taxonomic groups, such as swamp eels.

Among the three major eel species, the American eel, which is currently the most consumed eel species globally, has seen a sharp increase in exports to East Asia in recent years. This surge is driven by the population decline of the Japanese eel and the restrictions imposed on the international trade of the European eel under CITES¹⁵. In Canada, the total allowable catch for glass eels is limited to approximately 10 tonnes at the national level; however, in 2022, around 40 tonnes were reportedly imported into Hong Kong from Canada²¹. Numerous crimes related to glass eel fishing have also been reported^35,36, indicating that the strong demand in East Asia is likely affecting the Atlantic coast of North America.

For Japanese eel, various illegal activities related to the capture and trade of glass eels have been reported^13,18. Additionally, the Informal Consultation publishes annual statistics on stocking volumes; however, it has been pointed out that catch volumes were likely overreported during the 2013–2014 fishing season, which serves as the baseline year for quota setting¹⁸. Significant discrepancies between the aquaculture production data reported to the FAO and those reported to the Informal Consultation further exacerbate concerns, particularly since the aquaculture production reported by the Informal Consultation exceeds recorded export volumes. This raises considerable uncertainty regarding the reliability of Japanese eel production data. Furthermore, the accuracy of trade data is also compromised by reports of glass eel smuggling for aquaculture purposes^13,18. To ensure the conservation and sustainable use of this species, it is essential to strengthen enforcement against illegal activities and to establish more reliable and transparent statistical reporting systems.

Focusing on the European eel, a species classified as Critically Endangered on the IUCN Red List, the species composition by country becomes even more noteworthy. In this study, the presence of European eel was detected only in China and Japan. Studies published within the past five years identified European eels in certain quantities in Hong Kong, the United States, Europe, North Africa, and Southeast Asia^20,22–26. However, this study revealed that the consumption of European eel is now almost exclusively limited to the two countries. Furthermore, previous investigations demonstrated that alongside Japanese eels, European eels were identified as the dominant species in Japan around 2014^37,38. However, in this study, the ratio of the European eel was only 1% in Japanese market. The European eel was included in Appendix II of CITES in 2007, and since 2009, any international trade involving European eel has required export permits. After the CITES listing, EUROPOL estimated that up to 100 tonnes of juvenile European eels were illegally transported from the EU between 2017 and 2018²⁹. To conserve this species, the destination of these eels should be identified in future investigations.

This study focused on the three most widely consumed eel species globally, American eel, Japanese eel, and European eel. However, species with extremely limited habitats and/or populations, such as the Luzon eel (A. luzonensis), could be significantly affected even by relatively small levels of consumption. Additionally, historical trends suggest that declines in the stocks of certain species, or the introduction of stricter management measures, may shift demand towards alternative species. Therefore, continuous monitoring is necessary to identify which eel species are being consumed globally and which countries or regions are driving this consumption.

This study, together with previous research, has revealed the extensive exploitation of eels at a global scale. Beyond eels, fisheries resources are widely traded across international borders. The international trade of fisheries resources presents two major challenges. The first challenge is the emission of greenhouse gases associated with transportation. In this study, more than 80% of the eel products obtained in the United States and Canada were identified as American eel, and all products with a labelled country of origin were found to be from China. This indicates that glass eels caught in North and Central America are imported to China via Hong Kong²¹, where they are farmed and processed before being exported back to the Americas for consumption. Compared to farming and distributing glass eels domestically, such international trade is likely to result in a significantly larger carbon footprint. Similar patterns were observed in countries within the natural distribution range of eels, such as those in Europe and Australia, where American and Japanese eels—species originating from outside their natural ranges—were frequently found in the market. To the best of our knowledge, no life cycle analysis (LCA) of eel products has been published to date. Future research should explore sustainable consumption patterns that minimise environmental impacts, considering not only the effects on eel populations, but also greenhouse gas emissions.

The second challenge is impacts on biodiversity and/or human society in the country of origin. It has been known that international trade sometimes harms the population of the exploited species^39,40,41 and the ecosystems in the country of origin^42–44. Lenzen et al.⁴⁵ suggested eco-labeling as one of the possible solutions, however, so far, there is no freshwater eel species that is ensured to be consumed sustainably. The result obtained in this study that 99% of eels consumed worldwide are threatened species, indicates that it is almost impossible for consumers to choose ‘sustainable’ eel products. Moreover, among the eel products examined in this study, only 9% were labeled with species-specific information. Excluding those in the EU and the UK, the vast majority of products lacked species labeling.

The conservation and sustainable use of freshwater eels present significant challenges, and achieving these goals is obviously not a straightforward path. However, this study, which has analysed the current consumption patterns on a global scale, contributes to taking one step toward that objective.

Materials and Methods

Target taxonomic group

Freshwater eels, belonging to the genus Anguilla, are catadromous fish that spawn in offshore oceanic waters. Their leaf-like leptocephalus larvae migrate to freshwater and estuarine habitats, where they metamorphose into ‘glass eels^46,47‘. These eels spend most of their lives in continental waters for varying numbers of years until they begin sexual maturation and migrate from freshwater or estuarine habitats to their spawning areas^48,49. They are thought to be semelparous, spawning only once in their spawning areas in the high seas before dying¹⁷.

Glass eels are intensively captured and traded internationally for aquaculture¹³. After farming, eels may be further traded globally, either as live specimens or as prepared products. The trade spans multiple life stages, creating significant challenges for traceability from catch to plate^16,50.

Species identification in global markets

To reveal the species composition of eels sold for consumption in global markets, 282 samples of eels and eel products (Fig. 1) were collected from 26 cities across 11 countries/regions between September 2023 and January 2025, among East Asia, Europe, North America, Oceania, and Southeast Asia (Table 1, Fig. 2, see Appendix for details). Eels and their products were purchased from retail outlets such as supermarkets, convenience stores, and wet-markets, as well as from dining establishments such as fast-food chains and restaurants offering traditional local eel cuisines. The products primarily consisted of Japanese-style grilled eel (kabayaki) (n = 226), but also included raw eel meat, dishes containing eel, and desserts incorporating eel (n = 56) (Table1, see Appendix I for details). It should be noted that, at the time of purchasing raw eel meat, the individuals were already dead; therefore, this study does not require ethical approval for experiments involving live vertebrates. Species composition of a major portion of the samples collected in Japan (133/155) has been published as part of a separate study about eel comsumption in Japan²⁷.

Eel is generally consumed either by dining at restaurants that serve eel dishes or by purchasing processed products at retail outlets for home consumption. Accordingly, this study primarily collected samples from restaurant dishes and processed products available at retail stores. However, during field visits, it became evident that in countries and regions such as China and Hong Kong, there is a cultural tradition of purchasing live or fresh eel at fish markets for home preparation. Therefore, raw eel samples were also included in these locations. In contrast, in the European sample collection, certain traditional processed products—such as smoked eel, which enjoys relative popularity—were intentionally excluded. This decision was made due to concerns that these products, which often contain European eel²⁰, might violate national regulations if transported across borders. The exclusion of European eel from the samples collected in Europe was addressed in the section Domestic supply and global species composition.

Species identification of the collected samples was conducted using DNA barcoding. It is known that external morphological features alone are insufficient to identify all 16 species of the genus Anguilla, even when the specimens are alive⁵¹. This limitation is especially pronounced for processed products, where species identification based on external morphology becomes extremely challenging. Furthermore, HS codes used for recording international trade do not specify eel species. In regions such as East Asia, where multiple eel species are being farmed, it is also difficult to infer species from customs records. Therefore, genetic analysis is essential for species identification of eels and eel products.

From each eel or eel product, a small tissue sample was excised and stored in 95–100% ethanol. When relevant, the product’s name, price, country of origin were recorded (see Appendix I for details). Country of origin, where the product was produced, was indicated on the most products perchased at retail outlets, except live eels purchased in wet-markets. For kabayaki, which is typically prepared directly from live eels, it is reasonable to assume the eel was farmed in the country of origin indicated in the label of the product. However, for futher processed food such as kabayaki over rice or sushi, it is questionable whether the eels were farmed in the country of origin indicated in the lavel because using imported kabayaki to produce those dishes is possible. Therefore, country of origin was taken into account only for kabayaki.

For samples collected from China, genetic species identification was conducted by Hangzhou Youkang Biotechnology Co., Ltd., while the remaining samples were analysed at National Taiwan University. Total DNA was extracted for DNA barcoding using the EasyPure Genomic DNA Spin Kit (Bioman, Taiwan), and the DNA concentration was measured using a Nano-300 micro-spectrophotometer (Medclub Scientific Co., Ltd., Taiwan). The extracted DNA was stored at −20 °C until PCR amplification. A 1000 bp fragment of the cytochrome b gene was amplified using specifically designed primers: forward primer Cytb-F (5’-GAT GCC CTA GTG GAT CTA CC-3’) and reverse primer Cytb-R (5’-TAT GGG TGT TCT ACT GGT AT-3’), as adapted from Han et al.⁵². The resulting PCR products were sequenced using either cytb-F or cytb-R by Genomic Bio-tech Inc., Taiwan, following the method outlined by Lin and Han⁵³. Following the removal of low-quality sequences at both ends, the obtained Cytb sequences were subjected to BLAST analysis using the National Center for Biotechnology Information (NCBI) database (blastn algorithm) for sequence alignment and identification. A sequence similarity threshold of > 99.8% and an e-value of < 1 × 10⁻5 were used for species-level identification.

Domestic eel fisheries and aquaculture production

For each country in the world, annual fisheries and aquaculture production volumes of freshwater eels between 2020 and 2022—the three most recent years for which data is available—were obtained from the FAO database when available (https://www.fao.org/statistics/en). A total of 38 countries reported fisheries and aquaculture production to the FAO. Some countries reported zero production despite being within the natural range of freshwater eels. Additionally, several eel range states did not report any eel production to the FAO. This issue is discussed earlier in this paper.

For East Asia, China, Japan, South Korea, and Taiwan hold an annual meeting called the Informal Consultation on International Cooperation for Conservation and Management of Japanese Eel Stock and Other Relevant Eel Species (Informal Consultation) to cooperate on the international management of eel resources, including the Japanese eel²⁸. Since 2014, this meeting has annually published the upper limits on glass eel stocking volumes for aquaculture for each participating country²⁸. However, these limits are not legally binding. In the"Joint Press Release"published after each meeting, the outcome is described using the term“common view”rather than terms indicating a formal agreement, such as“Agreement”or“Understanding”²⁸. During the annual meetings, each participant reports basic statistics, including data on eel fisheries production, aquaculture production, glass eel catches, and glass eel stocking volumes for aquaculture. These statistics are publicly available online. The most notable issue concerning the data from the Informal Consultation lies in the fact that China’s aquaculture production figures differ significantly from those reported to the FAO, whereas for the other three countries, the differences between the two data sources are negligible. Since China has the world’s largest aquaculture production of freshwater eels regardless of the data source, this inconsistency should not be overlooked. Therefore, both data sources were evaluated in the analysis.

International trade statistics

Similar to the production data, annual export and import volumes between 2020 and 2022 were obtained for each country from the UN Comtrade Database (https://comtradeplus.un.org/), a global trade statistics database maintained by the United Nations Statistics Division (UNSD). Trade volumes of freshwater eels were extracted based on HS codes. Since HS codes for eels are not species-specific and are generally assigned according to the form in which the eels are traded, we obtained import/export volumes for the following categories:"live fish – Eels (Anguilla spp.)"(0301.92),"Fish, fresh or chilled – Eels (Anguilla spp.)"(0302.74; freshly caught or kept chilled but unprocessed),"Fish, frozen – Eels (Anguilla spp.)"(0303.26; frozen whole or in parts), and “Prepared or preserved fish – Eels” (1604.17; Japanese-style grilled eel kabayaki and other ready-to-eat products). It should be noted that the code 1604.17 is not specifically assigned for genus Anguilla and may include non-freshwater eel fishes whose common names include ‘eel’, such as conger eels (genus Conger) and swamp eels (family Synbranchidae). Following the methodology used in a previous report¹³, this study also treated all items reported under code 1604.17 as belonging to the genus Anguilla. As a result, the trade volume of Anguilla species derived from 1604.17 may have been overestimated compared to the actual volume. Possibility for overestimation is discussed in the Discussion section. The HS system also includes broader categories such as fish fillets and other fish meat (0304; whether or not minced) and fish, dried, salted, or in brine (0305). However, these categories were excluded from this study because eels are not distinguished from other fish within these classifications. HS codes can vary across different time periods and countries. To ensure consistency, this study employed the HS Nomenclature 2022 Edition⁵⁴ as a standardized reference. Of the 143 countries for which eel trade data were available, two reported zero for both export and import of eels during the three-year period.

The HS codes do not distinguish between different life stages of eels, meaning that both glass eels used as aquaculture seed and fully grown eels sold for consumption are classified under the same code if their trade form is identical. As a result, the"live fish – Eels (Anguilla spp.)"category used in this study to calculate domestic supply includes not only eels shipped for consumption after aquaculture but also wild-caught glass eels that were traded for farming purposes. However, while eels sold for consumption after aquaculture typically weigh 150–200 g or over¹³, glass eels used as aquaculture seedlings, such as Japanese eel glass eels, weigh only around 0.2 g⁵⁵. Therefore, although glass eels are included in the reported trade volume, their inclusion is unlikely to significantly affect the calculation of domestic supply.

Domestic supply and global species composition

The total volume of domestic supply, which can infer domestic consumption volume, was calculated as the annual average for the period between 2020 and 2022 using the following formula:

1

where ​ represents the average domestic eel supply volume in country i between 2020 and 2022, is the average production volume of eels in country i from industry type j (fishery or aquaculture), is the average volume of eels imported into country i as product type k (i.e., live, fresh, frozen, or processed), and ​ is the average volume of eels exported from country i as product type k. For product type k, the weight of"Prepared or preserved fish – Eels"recorded in customs data (1604.17) is lower than the original live weight because processed eels are typically baked or smoked and do not retain their heads, internal organs, or vertebrae. Following a previous report¹³, a weight reduction rate of 81%, 74%, and 60% was assumed to estimate the original weight of the eels prior to processing for “Fish, fresh or chilled – Eels (Anguilla spp.)”, “Fish, frozen – Eels (Anguilla spp.)”, and"Prepared or preserved fish – Eels", respectively. For"live eels,"no processing, such as heating or filleting, is involved. Therefore, the values recorded in customs data were directly used in the calculations.

In some countries, the domestic supply volume yielded negative values. In most of these cases, eel production was not reported to the FAO, which is likely the reason for the negative values. Since negative supply volumes are not realistic, all such values were treated as zero. In China, despite its reported production, there was a year in which the domestic supply volume was negative when calculated based on the Informal Consultation data. This issue is further examined in the Discussion section. Except for China, none of the 11 countries where eel species identification was conducted had a negative domestic supply volume.

Based on the domestic supply volumes and population in each country, per capita domestic eel supply was calculated. Same as the domestic supply, average populations during 2020–2022 were used for estimation. Population data was retrieved from the State of World Population^56–58.

To estimate the species composition of eels consumed on a global scale, the species composition obtained through sampling in 11 countries/regions was weighted by the domestic eel supply volume of each country. Specifically, the species composition ratio of each country was multiplied by its domestic supply volume to calculate the consumption volume of each eel species in that country. For the European eel, the sampling conducted in France, Spain, and the UK was subject to bias. A previous study in the UK revealed that European eel was predominantly used in traditional eel dishes in Europe, such as smoked eel and jellied eel²⁰. However, in this study, the samples collected in Europe mainly consisted of eel dishes prepared in a Japanese style, such as kabayaki and sushi. To compensate for the omission of European eel samples in the UK, France, and Spain, the production volumes of European eels were additionally estimated and incorporated into the calculations for these three countries.

With few exceptions, no other eel species are known to inhabit the natural distribution range of the European eel, which includes Europe and North Africa⁵⁹. Additionally, eel aquaculture in Europe relies entirely on the stocking of wild-caught European glass eels, indicating that the European eel is the only species farmed in the region⁶⁰. Therefore, eels caught or farmed domestically in these countries can be assumed to be European eels. Similarly, eels exported from these countries are also considered to be the same species. For imported eels, those sourced from other countries within the natural range of the European eel are likely to be the same species, whereas eels imported from outside its natural range, such as from Asia, are unlikely to be European eels, necessitating species identification that was conducted in this study. Therefore, the species compositions of eels distributed in these three countries were estimated while accounting for the proportion of European eels. Specifically, the domestic supply volumes of European eels in these three countries were estimated using the following formula:

2

where represents the average supply volume of European eels in country i within the natural distribution range of the species between 2020 and 2022, and is the average volume of eels imported into country i from non-European eel range states as product type k.

For France, Spain, and the UK, the supply volume of European eels was calculated using the above method. The supply volumes of other eel species were estimated by subtracting the European eel supply from the total domestic supply and then applying the species composition ratios obtained from the species identification results in this study. The European eel and other eel supply volumes calculated for these three countries were combined with the species-specific supply volumes of the other eight countries/regions where species identification was conducted to determine the overall species composition. Finally, the species-specific supply volumes of eels in the 11 countries were aggregated to derive the global-scale species composition of eels consumed.

Author contributions

K. K. contributed conceptualization, data curation, formal analysis, funding acquisition, investigation, and writing—original draft. H. S. contributed data curation, investigation, and writing—review & editing. Y.S. H. contributed data curation, funding acquisition, and writing—review & editing.

Funding

Asahi Glass Foundation,Japan Society for the Promotion of Science,JP22H00371,Chuo University,National Science and Technology Council,NSTC 111-2313-B-002-016-MY3

Data availability

Data used in this study is provided as supplementary materials.

Declaration

Competing interests

The authors declare no competing interests.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-025-15458-y.