As the human population looks set to reach 10 billion people by 2050¹, our food systems will be under intense pressure to produce animal protein for an increasing population². Faced with plateauing wild fishery catches³ and high impacts from land-based agriculture^4,5, momentum is building to look towards marine aquaculture to meet the growing protein demand^6,7. The relative sustainability of marine aquaculture compared with land-based meat production⁸ and the human health benefits of diets rich in fish⁹ make it even more pressing that we consider aquaculture’s potential. Oceans represent an immense opportunity for food production, yet the open ocean environment is largely untapped as a farming resource.

The majority of existing aquaculture takes place on land, in freshwater and in nearshore marine waters¹⁰. However, problems, such as high resource use, pollution and habitat destruction have created a generally negative reputation for aquaculture in several countries^11,12 and pose challenges for continued expansion. Open-ocean aquaculture appears to have several advantages over the more traditional culturing methods, including fewer spatial conflicts and a higher nutrient assimilation capacity^13,14, highlighting the opportunities for sustainable marine development. However, large-scale open-ocean farms are not yet common, making adaptive management and careful research an essential element of sustainable marine aquaculture expansion.

Despite the perception that marine aquaculture has high growth potential^15,16, little is known about the extent, location and productivity of potential growing areas across the globe. Most of the research on marine aquaculture potential has focused on specific species¹⁷ and/or specific regions^18,19, and there remains an important need to assess the more general growing potential across locations. To rectify this shortfall, we drew on physiology and growth theory coupled with environmental data to quantify and map the global potential for fish and bivalve aquaculture. These categories represent two major types of culture: fed aquaculture, where food is provided from an external source, and unfed aquaculture, where nutrition comes from the environment. We focused on quantifying a realistic biological baseline given the diversity of existing ocean uses, thus providing novel insight into the potential global aquaculture production and the role it might play in addressing future food security. Ultimately, the economic and social constraints of aquaculture may limit production, and their inclusion in future research will help further refine realistic production potential.

To characterize aquaculture’s potential, we used a three-step approach (see Methods). First, we analysed the relative productivity for each 0.042 degree² patch of global ocean for both fish and bivalve aquaculture. To do this, we constrained the production potential for each of 180 marine aquaculture species (120 fish and 60 bivalves) to areas within their respective upper and lower thermal thresholds using 30 years of sea surface temperature data (Supplementary Fig. 1). We then calculated the average (multi-species) growth performance index (GPI) for each patch for all suitable fish and bivalve species, resulting in a spatially explicit assessment of the general growing potential for each aquaculture type (Supplementary Fig. 2). GPI is derived from the von Bertalanffy growth equation and uses species-specific parameters (growth rate and maximum length²⁰) to create a single metric to describe the growth potential of a species²¹. GPI has been used frequently to assess growth suitability for culture and is particularly useful for fed species or those not subject to food limitations^22,23,24. Locations with a high GPI are expected to have better growth conditions for a spectrum of aquaculture species and, thus, are well suited to development. Using a multi-species GPI average to assess growth potential provides a more general growth suitability metric than is possible when making detailed assessments for a single species. This approach is especially useful given the fast rate at which new species are being developed for aquaculture and the shift in focal species between nearshore and offshore cultures^14,25,26. Moreover, using GPI averages across species provides a conservative assessment, since we are considering an average rather than the maximum growth potential.

Second, once the production potential was determined, we removed unsuitable areas with certain common environmental or human-use constraints. We excluded areas with unsuitable growing conditions due to low dissolved oxygen (fish only) and low phytoplanktonic food availability (bivalves only). We also eliminated areas at > 200 m depth because they are generally too deep (and thus expensive) to anchor farms, and areas already allocated to other uses, including marine protected areas, oil rigs and high-density shipping areas (Supplementary Fig. 5 and Supplementary Table 1). We acknowledge that advancing technology may alleviate some of these constraints through innovative farm designs that allow for deeper mooring and submerged farming structures. However, these constraints reflect the current common industry practice and provide a more conservative and economically realistic projection of potential. For the third and final step, we estimated the idealized potential production per unit area by converting the average (multi-species) GPI into biomass production, assuming a low stocking density is used and the farm design is uniform across space.