Integrated aquatic and terrestrial food production enhances micronutrient and economic productivity for nutrition-sensitive food systems

The study addresses how integrating aquatic and terrestrial food production on the same land (IAA) affects both economic and nutrient productivity, in the context of persistent malnutrition despite gains from the Green Revolution in staple crop yields. Nutrition-sensitive agriculture (NSA) emphasizes increasing access to micronutrient-rich foods rather than only meeting energy needs with staples. The paper focuses on rural smallholder households in southern Bangladesh, examining production diversity as a pathway to improved household nutrition through both own-production and income effects. It explores whether specific integrated farming combinations can enhance micronutrient availability while maintaining or improving economic returns, thereby informing NSA program design for nutrition-sensitive food systems.

The paper situates its contribution within literature calling for nutrition-sensitive food systems that go beyond calorie production to improve micronutrient intake. Prior work highlights mixed evidence on links between production diversity and dietary outcomes, and emphasizes multiple agriculture–nutrition pathways (production and income). Studies in Bangladesh and elsewhere document the growth and transformation of aquaculture value chains and suggest potential for aquaculture to contribute to nutrition security. Most NSA literature to date has been conceptual or has evaluated demand-side outcomes (e.g., diet diversity), with fewer supply-side assessments of nutrient outputs from farming systems. This study adds a supply-side, nutrient-productivity framework spanning aquatic and terrestrial foods.

Design and setting: A representative survey of 721 aquaculture farms in southern (southwest) Bangladesh captured a wide range of integrated aquaculture–agriculture (IAA) practices over approximately one year (most recent cropping cycle). Farms produced 35 aquatic and 31 terrestrial foods. Data collection: Two waves of a panel survey (initially in 2013; follow-up in Dec 2020–Jan 2021) were conducted using KoboToolbox. In 2013, sub-districts (upazila) with non-negligible aquaculture in seven districts were sampled; mouza were selected and farmers randomly interviewed. In 2020, a new farm census was conducted in the same mouza; prior respondents were recontacted (≈20% attrition; replaced by random farms from updated lists). Each sampled household was selected based on a parcel used for aquaculture in the prior 12 months; if multiple aquaculture plots existed, a sample parcel was randomly chosen. Average farm size was 0.78 ha. Measures: Economic productivity = annual value of production per hectare (US$ ha⁻¹) defined as value of sales plus imputed value of self-consumed production minus variable production costs (stocking, inputs, harvesting, household and hired labor). Prices for terrestrial foods were derived from reported unit values; aquatic food values used reported prices. Nutrient productivity = adult equivalents per hectare (AEs ha⁻¹) for energy (kJ), protein, and micronutrients: calcium, iron, zinc, vitamin A, vitamin B12. Nutrient composition sources: Bangladesh Food Composition Table for vegetables and fruits; Bogard et al. for aquatic foods. Computation: Nutrients produced were calculated as weight produced × edible portion × nutrient concentration. AE conversion used Recommended Dietary Allowances (adults): 2,900 kJ energy (approximation for a moderately active adult), 95 g protein, 1,000 mg calcium, 13 mg iron, 9 mg zinc, 900 μg RAE vitamin A, 2.5 mg vitamin B12. Nutrient AEs ha⁻¹ were derived by dividing by daily AE requirements and multiplying by 365 (reported as 36 in text likely shorthand for annualization within study’s convention). Analysis: Ordinary least squares regressions estimated correlations between quantities of food groups produced (sub-categorized aquatic and terrestrial groups) and (i) economic productivity and (ii) nutrient AEs ha⁻¹ for seven nutrients. Controls included household head age, education, sex of household head, household size, dependency ratio, off-farm income indicator, travel time to nearest city, characteristics of operated agricultural land and ponds, and upazila fixed effects. Models also examined shares sold for aquatic foods, fruits/vegetables, and rice. Statistical software: Stata SE 17. Ethical considerations: MSU IRB exempt determination (STUDY00003689). Data/code availability statements provided.

- Integration patterns and production diversity: Approximately half of households integrate aquatic and terrestrial foods. Farms harvested on average nine aquatic products out of 35 possible. Across farming systems, shares of production sold averaged 71% for aquatic foods, 57% for vegetables and fruits, and 33% for rice. - Economic productivity: The most profitable systems combined fish, prawns and shrimp with rice, vegetables and fruits (US$ 37.9 ha⁻¹) and fish and prawns with rice, vegetables and fruits (US$ 34.9 ha⁻¹). Systems producing fish integrated with rice (US$ 24.7 ha⁻¹) and fish with rice, vegetables and fruits (US$ 31.35 ha⁻¹) were also relatively productive. - Nutrient vs economic productivity: Nutrient productivity is partly disconnected from economic productivity. Systems combining fish and prawns with vegetables and fruits and rice—among the most economically productive—also had the highest productivity of energy, protein, iron, zinc and vitamin A. Shrimp systems without terrestrial integration were around average economically but supplied much lower average quantities of most nutrients. - Sources of specific nutrients (by food group): Rice supplied about three-quarters of energy and roughly half of protein where produced; aquatic foods were the major calcium source across systems; vegetables and fruits were the main vitamin A source; vitamin B12 came exclusively from aquatic foods, with highest B12 production in systems integrating fish with vegetables and fruits or other terrestrial foods (notably via carp species). - Regression analysis: Three of four aquatic food groups showed positive, significant correlations with economic productivity; crustaceans had the largest positive correlation, followed by carps. Species-level results indicated many carp species are economically valuable, with catfish highly productive; some unstocked species (e.g., pangra, pond crab) correlated with economic productivity despite aggregate unstocked fish not being economically productive. Among vegetables and fruits, okra, ground beans, and eggplant correlated with protein, iron, and zinc productivity; vitamin A–rich pumpkins, leafy shak, mangoes, and betel nuts were important vitamin sources; coconuts correlated positively with energy and all nutrients except vitamin B12. - Average farm size had no association with whether aquaculture was integrated with agriculture.

The findings show that integrating terrestrial foods into aquatic farming systems can enhance nutrient productivity and, in specific combinations, also improve economic returns. This addresses the core question of whether IAA can contribute to nutrition-sensitive food systems by providing micronutrient-rich outputs without sacrificing profitability. While income from economically valuable but less nutrient-dense aquatic products (e.g., crustaceans) may enable households to purchase nutritious foods, direct production of diverse aquatic and terrestrial foods yields better on-farm nutrient availability, especially for calcium and vitamin A, and supports vitamin B12 through aquatic species. Systems integrating fish and prawns with vegetables, fruits, and rice align both nutrient and economic objectives, whereas shrimp-dominant systems without terrestrial integration underperform on nutrient output. These results underscore the need to design NSA programs that promote culturally and agroecologically appropriate combinations of aquatic species with vegetables and fruits, taking into account local conditions (e.g., salinity) and market access. The supply-side AE framework provides an intuitive metric for policymakers and practitioners to evaluate and optimize nutrient sensitivity alongside economic performance.

This study introduces a supply-side, nutrition-sensitive productivity framework (AEs ha⁻¹ for energy, protein, and key micronutrients) and applies it to integrated aquatic–terrestrial farming systems in southern Bangladesh. Strong empirical evidence indicates that integrating aquatic and terrestrial food production can improve nutrient productivity and, in certain combinations (notably fish and prawns with vegetables/fruits and rice), also enhance economic productivity. The approach offers actionable insights for designing NSA programs and advancing nutrition-sensitive food systems by identifying food combinations that optimize both nutritional adequacy and incomes. Future research should use this framework to: (i) identify species mixes and practices that maximize joint economic and nutrient outputs under varying salinity and agroecological conditions; (ii) facilitate entry or domestication of nutritionally and economically productive unstocked fish species into ponds; and (iii) refine integration strategies where crustacean-dominant systems face agronomic constraints to terrestrial integration.

- Causality: Regression results are correlational and do not imply causation. - External validity: The sample covers aquaculture farms in selected districts of southern Bangladesh; findings may not generalize beyond similar contexts. - System constraints: Shrimp/crustacean production often occurs in ponds that challenge integration with terrestrial crops, potentially limiting on-farm nutrient diversification. - Measurement/assumptions: Energy requirement (kJ) was approximated for a moderately active adult; nutrient AE calculations depend on food composition tables and reported edible portions and prices. - Environmental context: Some unstocked aquatic species depend on local ecosystems (e.g., mangrove-adjacent areas), which may limit replicability elsewhere.