Contribution of China’s bivalve aquaculture to world’s essential amino acid production

Abstract

Bivalve aquaculture are environmentally friendly high-quality protein, but quantitative data on protein and essential amino acid (EAA) production from bivalve aquaculture remain limited. This study assesses the long-term production of protein and EAAs from bivalve aquaculture in China, the world’s leading producer of farmed bivalves, over the period from 2004 to 2023. The findings reveal that bivalves are rich in proteins and EAAs. Current bivalve aquaculture in China produces 411 thousand tonnes of protein, sufficient to meet the recommended protein intake of 22.5 million sedentary adults, and 72 thousand tonnes of EAAs, fulfilling the EAA requirements of 15.36 million individuals. Among bivalves, scallops stand out as the top choice for consumers prioritizing EAAs, as they contain the highest levels of protein and nearly all individual EAAs. By highlighting the nutritional and environmental benefits of bivalve farming, this study underscores its potential as a key component of sustainable food systems.

Introduction

The global human population has doubled in just half a century, reaching 8.22 billion in 2025¹, and is projected to rise to 11 billion by the end of the 21st century². This rapid population growth, combined with urbanization, rising incomes, and increasing demand for nutritious food, has significantly increased the demand for animal proteins. Global demand for animal protein is expected to surge from 202 million tonnes in 2018 to at least 500 million tonnes by 2050, with aquatic animal protein demand rising from 80 million tonnes to 130 million tonnes in the same period^3,4. Currently, the majority of animal protein is sourced from livestock farming and wild capture fisheries, with land-based livestock and aquatic animals contributing 84.7% and 15.3%, respectively, to the total animal protein supply⁵.

Proteins are macromolecules essential for survival, growth, and physiological functions in humans and animals. Composed of amino acids (AAs), proteins nutritional quality depends on AA composition. AAs play vital roles in muscle and organ development, as well as in synthesizing enzymes, hormones, nucleic acids, and immune components. Based on the body’s ability to synthesize them de novo, AAs are classified into essential amino acids (EAAs) and non-essential amino acids. EAAs, including threonine (Thr), cystine (Cys), methionine (Met), valine (Val), isoleucine (Ile), leucine (Leu), phenylalanine (Phe), tryptophan (Trp), and lysine (Lys), cannot be synthesized in sufficient quantities by the body and must be obtained through diet⁶. The recommended average requirement (EAR) and dietary allowance (RDA) for protein in healthy adults are 0.66 g and 0.83 g per kg of body weight per day, respectively^7,8. While no upper limit has been established, excess protein is likely catabolized⁹.

The production of animal protein from livestock farming contributes 12–15% of direct global greenhouse gas (GHG) emissions and 30% of indirect GHG emissions from land use¹⁰. However, increasing protein production from crops, livestock, and freshwater aquaculture is unlikely to meet future demand due to declining yields, limited land and water resources, and intense competition^3,11–14. Although aquatic animal protein production contributes only 6% of the GHG emissions compared to terrestrial animal protein⁵, the expansion of wild capture fisheries and fish mariculture is constrained by overexploited fish stocks (>90% of stocks are overfished^15,16) and a heavy reliance on unsustainable fishmeal and fish oil¹⁷.

Bivalves are an important source of high-quality animal protein, with protein content exceeding that of land-based sources like pork, beef, and chicken¹⁸. They are particularly rich in amino acids and demonstrate high digestibility (>90%)^19–21. In recent decades, bivalve aquaculture has experienced remarkable growth, now representing >20% of global aquaculture production, with China contributing >85% of the total production¹⁵. Unlike finfish and shrimp aquaculture, bivalve farming operates without external feed inputs, making it one of the most environmentally sustainable protein source with a low carbon footprint (1.2 Mt CO₂e per Mt of production), compared to fish (2.4–4.3 Mt CO₂e per Mt) and shrimp (6.7–7.5 Mt CO₂e per Mt) aquaculture²².

Despite these advantages, quantitative data on the contribution of proteins and EAAs from bivalve aquaculture remain limited. This study aims to address this gap by quantifying the production of proteins and EAAs from China’s bivalve aquaculture sector, the world’s largest bivalve producer, using two decades of production data (2004–2023) from the China Fisheries Statistical Yearbook and amino acid profiles of key aquaculture species. The findings highlight China’s expanding role in global protein and EAA production and provide practical insights for enhancing bivalve aquaculture to meet rising nutritional demands.

Results

Protein nutritional quality of bivalves

The indices of protein nutritional quality of bivalves are summarized in Table 1. Scallops and razor clams exhibited significantly higher flesh content (30.00 ± 2.24% and 30.00 ± 2.35%, respectively; P < 0.05) compared to other bivalves, which ranged from 17.78% to 23.09%. Scallops also demonstrated superior protein content (16.25 ± 1.45 g/100 g flesh), total amino acids (63.23 ± 5.59 g/100 g protein), and essential amino acids (23.27 ± 3.15 g/100 g protein), significantly exceeded those of other bivalves (protein content: 11.00–14.80 g/100 g flesh; total AA: 29.02–45.14 g/100 g protein; EAA: 13.17–18.79 g/100 g protein; P < 0.05). Clams recorded the lowest protein content (P < 0.05), while razor clams had the lowest total and essential amino acid levels (P < 0.05).

Table 1.

Protein nutritional quality of bivalves

	Flesh content (%WW)	Protein content (g protein/100 g flesh)	Total AAs (g/100 g protein)	EEAs (g/100 g protein)	Thr (g/100 g protein)	Cys+Met (g/100 g protein)	Val (g/ 100 g protein)	Ile (g/ 100 g protein)	Leu (g/ 100 g protein)	Phe+Trp (g/ 100 g protein)	Lys (g/ 100 g protein)
Mussels	22.5 ± 1.92b	12.80 ± 0.20c	45.14 ± 9.00b	17.19 ± 3.95b	2.00 ± 0.67c	2.33 ± 2.33a	2.29 ± 0.40c	2.34 ± 0.11c	3.84 ± 0.78c	4.30 ± 0.37c	3.15 ± 0.18 d
Oysters	17.78 ± 1.51c	11.60 ± 2.70 cd	38.75 ± 7.77c	14.00 ± 2.90c	1.17 ± 0.86 d	0.65 ± 0.71d	1.23 ± 0.89 d	1.14 ± 0.82 d	1.92 ± 1.26 d	1.65 ± 0.95e	1.95 ± 1.36e
Clams	23.09 ± 1.88b	11.00 ± 2.00 d	38.05 ± 7.92c	18.45 ± 6.62b	3.10 ± 1.27b	2.45 ± 1.30a	3.23 ± 1.19b	2.87 ± 1.03b	5.29 ± 2.41b	5.09 ± 2.11b	5.38 ± 2.40b
Razor clams	30.00 ± 2.35a	14.80 ± 2.30b	29.02 ± 7.33 d	13.17 ± 5.21c	0.62 ± 0.12e	0.06 ± 0.01e	0.48 ± 0.09e	0.45 ± 0.08e	0.79 ± 0.11e	1.13 ± 0.14e	0.50 ± 0.21 f
Scallops	30.00 ± 2.24a	16.25 ± 1.45a	63.23 ± 5.59a	23.27 ± 3.15a	3.93 ± 0.64a	2.16 ± 0.66b	3.53 ± 1.08a	3.44 ± 0.71a	6.51 ± 1.72a	5.44 ± 1.06a	6.07 ± 2.13a
Cockles	20.00 ± 1.89bc	14.50 ± 2.10b	35.92 ± 10.30c	18.79 ± 3.13b	3.20 ± 0.57b	1.20 ± 0.47c	2.70 ± 0.49c	2.60 ± 0.39bc	3.90 ± 0.44c	2.80 ± 0.51 d	4.70 ± 0.67c

Modified from Song et al. (2024).

Different letter indicating significant differences (P < 0.05)

Among specific essential amino acids (EAAs), scallops contained significantly higher levels of Thr, Val, Ile, Leu, Phe+Tyr, and Lys compared to other bivalves (P < 0.05). In contrast, clams and mussels were rich in Cys+Met (P < 0.05). Razor clams consistently showed the lowest EAA concentrations across all EAA (P < 0.05).

Long-term trend (2004 to 2023) of farmed bivalve production in China

China’s farmed bivalve production increased by over 50% from 2004 to 2023, rising from 9.51 million tonnes to 14.95 million tonnes annually (Fig. 1). Oysters were the largest contributor (38%), followed by clams (35%), scallops (13%), mussels (6%), razor clams (6%), and cockles (2%) (Fig. 1A).

Fig. 1. Bivalve aquaculture production in China from 2004 to 2023.

A The production of different bivalves in China from 2004 to 2023. B The production of bivalves from different provinces of China from 2004 to 2023.

At the provincial level, Shandong accounted for the highest share of bivalve aquaculture production (29%), followed by Fujian (21%), Liaoning (15%), Guangdong (13%), Zhejiang (7%), Guangxi (7%), Jiangsu (5%), Hebei (3%), and Hainan (<1%) (Fig. 1B).

Long-term trend (2004 to 2023) of animal protein production from China’s bivalve aquaculture

Farmed bivalve protein production in China increased by 55% over two decades, increasing from 265 thousand tonnes in 2004 to 411 thousand tonnes in 2023. Clams (29.94 ± 1.28%) and oysters (28.12 ± 2.17%) were the primary contributors, followed by scallops (22.79 ± 1.60%), razor clams (10.64 ± 1.02%), mussels (6.57 ± 0.85%), and cockles (2.94 ± 0.27%) (Fig. 2A).

Fig. 2. Animal protein production in China from 2004 to 2023.

A The animal protein production of different bivalves in China from 2004 to 2023. B The animal protein production of bivalves from different provinces of China from 2004 to 2023.

Provincially, Shandong led bivalve protein production (32.06 ± 0.92%), followed by Fujian (18.06 ± 1.33%), Liaoning (16.29 ± 1.37%), Guangdong (11.58 ± 1.21%), Zhejiang (7.59 ± 0.86%), Guangxi (5.24 ± 0.42%), Hebei (4.59 ± 0.92%), Jiangsu (4.46 ± 0.62%), and Hainan (0.11 ± 0.05%) (Fig. 2B).

Long-term trend (2004 to 2023) of essential amino acids production from China’s bivalve aquaculture

Essential amino acid (EAA) production from China’s farmed bivalves increased by 57% from 2004 to 2023, rising from 46 thousand tonnes to 72 thousand tonnes. Clams (30.19 ± 1.28%) and scallops (30.07 ± 1.87%) were the largest contributors to EAA production, followed by oysters (22.28 ± 1.86%), razor clams (7.88 ± 0.78%), mussels (6.46 ± 0.76%), and cockles (3.11 ± 0.29%) (Fig. 3A).

Fig. 3. Essential amino acid production in China from 2004 to 2023.

A The essential amino acid production of different bivalves in China from 2004 to 2023. B The essential amino acid production of bivalves from different provinces of China from 2004 to 2023.

At the provincial level, Shandong contributed the most to EAA production (32.87 ± 7.61%), followed by Liaoning (17.22 ± 4.14%), Fujian (14.43 ± 3.54%), Guangdong (10.07 ± 2.49%), Zhejiang (6.17 ± 1.62%), Hebei (5.68 ± 1.74%), Guangxi (4.45 ± 1.09%), Jiangsu (4.12 ± 1.10%), and Hainan (0.10 ± 0.05%) (Fig. 3B).

Percentage of total variation in bivalve weight production, protein production, and EAA production attributed to bivalve groups and provinces

The results of revealed that bivalve group explained 23.5% of the variance in wet weight production (P < 0.05), 15.8% of the variance in protein production (P < 0.05), and 15.9% of the variance in EAA production (P < 0.05). Province accounted for 22.4% of the variance in wet weight production (P < 0.05), 27.8% of the variance in protein production (P < 0.05), and 27.2% of the variance in EAA production (P < 0.05).

Discussion

Unlike lipids and carbohydrates, the human body lacks specialized storage mechanisms for protein. Proteins are primarily utilized in critical biochemical processes, such as deamination (removal of amine group from amino acids), or catabolized for energy during severe nutrient deprivation²³. Consequently, it is essential to consume foods rich in amino acids, particularly essential amino acids (EAAs), which must be obtained from dietary sources to compensate for these losses. If a protein source is deficient in one or more EAAs, higher protein consumption is required to meet EAA requirements. Seafood is particularly effective for fulfilling EAA requirements due to its amino acid profile closely matching human nutritional needs, supporting both growth and health maintenance^20,24,25.

In the context of climate change, prioritizing food production systems with lower greenhouse gas (GHG) emissions has become imperative. Among aquatic species, bivalve aquaculture emerges as one of the most environmentally friendly options, characterized by the lowest carbon footprint^26,27. Remarkably, bivalve aquaculture accounts for ~20% of total aquaculture production while contributing only with 7% of global aquaculture GHG emissions⁵. This is largely due to bivalves’ ability to obtain nourishment directly from planktonic and detrital sources in their environment, eliminating the need for additional feed^28,29. Furthermore, many studies suggest that bivalve aquaculture acts as a carbon sink, enhancing carbon sequestration through shell formation and sediment deposition^30–32 and increasing carbon storage in surrounding waters³³. However, some researchers argue that bivalve aquaculture may function as a carbon source^26,34,35, underscoring the need for further investigation to resolve these contrasting findings and better understand bivalves’ role in marine carbon cycling.

As mentioned earlier, China is the largest producer of bivalve aquaculture, accounting for over 85% of global farmed bivalve production¹⁵. Studying the contribution of China’s bivalve aquaculture to protein supply not only can provide valuable guidance for other nations. In addition, since the production of farmed bivalves varies across China’s coastal provinces, it offers insignts into how environmental and policy drivers can effectively promote the development of bivalve aquaculture in other coastal regions. Between 2004 and 2023, China’s bivalve production increased by 5.44 million tonnes, driven primarily by oysters (52%), clams (29%), and scallops (15%). Provinces such as Shandong (28%), Liaoning (25%), and Fujian (17%) were the main contributors to this growth. Notably, provincial factors explained a higher proportion of variance in protein (27.8% versus 15.8%) and EAA (27.8% versus 15.9%) production compared to bivalve group factors. This expansion was facilitated by China’s “Blue Granary” initiative, which prioritizes sustainable seafood production³⁶ and advancements in artificial seed breeding techniques in certain provinces, especially in Shandong³⁷. These innovations have made China’s bivalve aquaculture almost entirely reliant on hatchery-produced seeds³⁸. Additionally, rising demand for high-quality animal protein, spurred by improved living standards, further boosted production³⁹. China’s remarkable success in expanding bivalve aquaculture offers valuable lessons for other nations, and knowledge and technological transfer should be promoted through international collaborations.

In 2023, China’s bivalve aquaculture produced 411 thousand tonnes of protein, sufficient to meet the adequate protein intake of 22.5 million sedentary adults (based on 50 g/capita/day⁴⁰). From an EAA perspective, bivalve aquaculture produced 72 thousand tonnes of EAAs, fulfilling the EAA requirements of 15.36 million people (based on 12.845 g/capita/day for an adult male weighing 70 kg and 177 cm tall⁴¹). Among bivalves, scallops exhibit the highest protein content and quality, with superior levels of EAAs and nearly all individual EAAs, except for Cys+Met, making them the most recommended bivalve choice for EAA-focused consumers^20,42. Beyond amino acids, bivalves are also rich in omega-3 long-chain polyunsaturated fatty acids, essential nutrients, polysaccharides, and bioactive compounds, offering numerous health benefits^43–46. Thus, bivalve aquaculture represents a vital source of high-quality animal protein to support a growing global population.

Despite its potential, bivalve aquaculture production efficiency can be further improved. For instance, while farmed scallops account for only 13% of total bivalve production, they contribute 23% of the protein and 30% of the EAA output. In contrast, oysters constitute 38% of production but provide only 28% of the protein and 22% of the EAAs. Shifting cultivation toward species with higher protein and EAA content could enhance overall efficiency. Although bivalve farming is one of the fastest-growing food sectors, it remains concentrated in tropical regions, with China producing over 85% of the world’s farmed bivalves¹⁵. Gentry et al.⁴⁷ estimated that over 1.5 million km² of ocean could be developed for bivalve farming, with most countries utilizing less than 1% of suitable areas. Expanding aquaculture into other coastal regions could significantly increase protein and EAA production. For example, in Shandong Province, China’s largest bivalve farming area, production could be increased by 4.66 times without exceeding ecological carrying capacity⁴⁸. Similarly, regions such as Hebei, Jiangsu, Zhejiang, and Guangxi have untapped potential, while Tianjin and Shanghai have minimal bivalve farming activity. These findings underscore the significant potential for sustainable expansion of bivalve aquaculture to meet rising protein and EAA demands^3,49.

It is worth noting that this study reliance on the Statistical Yearbook of China’s Fisheries may underestimate the carbon sink potential of bivalves, as national yearbooks often overlook small-scale farming. More accurate estimations could be achieved by incorporating data from provincial or local databases. In addition, this study relies on aggregated meta-analysis data, which provides only a general overview of protein production from bivalve aquaculture. Since the protein quantity and quality of bivalves vary by species, future research should use species-specific data to assess protein production more precisely.

In conclusion, despite their relatively low meat content, bivalve are rich in proteins and EAAs. Currently, China’s bivalve aquaculture produces 411 thousand tonnes of protein, equivalent to the adequate protein intake of 22.5 million sedentary adults, and 72 thousand tonnes of EAAs, meeting the EAA requirements of 15.36 million people. Among bivalves, scallops are the most recommended for consumers seeking high-quality EAAs, given their superior protein content and EAA profile. Bivalve aquaculture is not only environmentally friendly but also holds immense potential to address the growing demand for high-quality protein from the sea. This article provides an overview of trends in protein and EAA production in China, offering valuable insights for advancing bivalve aquaculture. By focusing on strategies to enhance protein and EAA supply, bivalve aquaculture can play a pivotal role in meeting the increasing global demand for sustainable, high-quality protein.

Methods

Data extraction

Annual production data of bivalve aquaculture in China over two decades (2004–2023) were extracted from the Statistical Yearbook of China’s Fisheries. The dataset included marine bivalve production figures for all coastal provinces except Shanghai and Tianjin, where bivalve production was not recorded due to these regions’ minimal fisheries contribution to GDP (dominated by industry and services) falling below the yearbook’s reporting threshold.

Protein nutritional quality indicators, including protein content, total amino acids, essential amino acids (EAAs), and AA score for individual EAAs (threonine [Thr], cystine + methionine [Cys + Met], valine [Val], isoleucine [Ile], leucine [Leu], phenylalanine + tyrosine [Phe + Tyr], and lysine [Lys]), were derived from a comprehensive meta-analysis of global bivalve amino acid profiles²⁰. Specifically, these raw data were sourced from the following studies: Miletić et al.⁵⁰, Şengör et al.⁵¹, Chen et al.⁵², Babu et al.⁵³, Chi et al.⁵⁴, Asha et al.⁵⁵, Abirami et al.⁵⁶, Jamaluddin et al.⁵⁷, Tabakaeva and Tabakaev⁵⁸, Chakraborty et al.⁵⁹, Zhu et al.⁶⁰, Peralta et al.⁶¹, Huang et al.⁶², Tan et al.⁴², Trisyani and Yusan⁶³, Moniruzzaman et al.⁶⁴, Bityutskaya et al.⁶⁵, Lee et al.⁶⁶, Hong et al.⁶⁷, and Chasquibol et al.¹⁹.

Proteins and essential amino acid production calculations

Using the annual production data from the Statistical Yearbook of China’s Fisheries and the protein nutritional quality indicators from Song et al.²⁰, the production of marine bivalve proteins (a) and EAAs (b) was calculated as follows:

Production of proteins for each bivalve group (thousand tonnes) = Annual production (million tonnes) x flesh content in wet weigh (%WW) x protein content (g protein/100 g flesh)/10,000.

Production of EAAs for each bivalve group (thousand tonnes) = Production of proteins for each bivalve group (thousand tonnes) × EEA content (g/100 g protein)/100.

Statistical analysis

All results were expressed as mean ± standard deviation (SD). Statistical analyses were performed using SPSS software (version 26) with a significance set at P < 0.05 unless otherwise noted. Prior to analysis, production and protein nutritional variables were tested for normality using the Kolmogorov-Smirnov test and for homogeneity of variance using Levene’s test. Significant differences in protein and EAA production among different bivalve groups and provinces were evaluated using one-way ANOVA, followed by Tukey’s HSD post-hoc tests for pairwise comparisons.

Author contributions

Hong Zhang prepared Figure 1 to 3 and revised the manuscript. Leiheng Huang, Cong Luo, Zexin Li, and KhaiHang Choong prepared Table 1 and performed project administration. Kit-Leong Cheong provides supervision. Karsoon Tan drafted and edited the manuscript.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Competing interests

The authors declare no competing interests.