Unequal Competition Threatens Southwestern Atlantic Domestic Fisheries

In developing countries, domestic industrial fisheries, although less equipped than DWF, have also improved their technological power over time through innovations such as onboard refrigeration, freezing of catches and the use of synthetic netting materials. Additionally, the industrial fishing sector embraced sensors and satellite technologies to locate fish, monitor gear performance while fishing, help with communications and navigation, thereby enabling safer fishing in the high seas¹⁰. In contrast, many small-scale fisheries (SSF), especially in developing countries, have low investment capacity and strongly rely on fish caught to ensure their food sovereignty, health and economic well-being^11,12. Yet, small-scale fishers in coastal communities are very diverse, ranging from fishers on foot to fishers using canoes or small- to medium-sized wooden and fiberglass boats. Vessels used are characterized by low-tech, travel shorter distances and are equipped with several gears to exploit multiple species. SSF are mostly limited to coastal areas, in the Territorial Seas up to 12 nm^13,14.

Over time, fishing effort in the tropical marine ecosystems of developing countries at lower latitudes increased due to high and strongly criticized subsidies provided by wealthier nations^2,7,8,15,16. In fact, recent estimates show that more than 40% of subsidies to support fisheries in developing countries come from countries with a high to very high Human Development Index (HDI)⁵. Consequently, vessels flagged to high- and upper–middle-income nations are responsible for up to 78% of fishing effort employed in the EEZs of developing countries³. These fisheries often face challenges such as limited data collection, poor management, and insufficient information, despite their critical role in providing income, food security, livelihood, and cultural heritage for diverse coastal communities^15,17,18.

As DWF takes place in distant waters, sometimes illegally and lands its catch in ports of other countries¹⁹, some aspects of this fishing remain blurred. Thus, the scientific community is still unveiling the implications of DWF on the fishing population both in high seas and within EEZs. This includes investigating the interactions, if any, between domestic fleets and foreign-flagged vessels^20,21. Even though¹⁹ found concerning implications for the safety, sustainability of fisheries, and the livelihoods of local fishing workers in African countries, up to date, the degree of overlap between fishing grounds used by large-range foreign-flagged vessels and domestic fleets remains unclear. Additionally, the potential implications of this overlap for catches and for local fish workers remain poorly understood.

Here, we investigated the competition between DWF and domestic fishing fleets in the Southwestern Atlantic Ocean (SWA), focusing on the overlap of fishing areas within Brazil’s coastal waters. Beyond the high seas, we expect to detect overlaps between DWF and domestic industrial fleets operating along the border of the EEZ and the high seas of countries in the region. We carried out the investigation using 15 years of catch and ex-vessel price data from tuna fisheries operating in Brazil, which comprises the largest and most central portion of the tropical, subtropical and temperate coast of the SWA²². Our findings shed light on the interaction of foreign-flagged vessels with domestic fleets in developing countries, steering regulations toward safeguarding the equity and sustainability of the use of fishery resources.

Contributions, trends, and key players

Our results revealed the presence of DWF fleets from 24 countries, excluding Brazil, targeting tuna species in the Brazilian coastal area. African-flagged nations constituted 25% of the countries engaged in DWF operations in the Central Southwest Atlantic (SWA). Asian-flagged countries accounted for 21%, while Caribbean nations represented 17%. Central American and European countries each contributed 13% of the DWF activity in the region. From Oceania, only fleets flagged to Vanuatu were recorded (Table 1). Collectively, these fleets (including the ‘Unknown’ category) landed 741.3 thousand metric tons of tuna species during the study period (2001–2016).

According to the records, 85.6% of all tuna species combined are caught by domestic (Brazilian) fleets (Table 1). However, when focusing on albacore specifically, Taiwanese vessels capture 2.4 times the volume landed by Brazilian vessels (Fig. 1). The Taiwanese fleet also accounts for the second-greatest share of total catch (~10% of the recorded landings). The Japanese fleet accounts for 1.4% of the catches, while the combined catches of the other 22 countries together amount to 3.2% of the total (Fig. S1).

Fishing dynamics and target species

By zooming lens only in the DWF catches, vessels flagged under Taiwan accounted for the majority of the catches (67%), followed by Japan (10%), Belize (5%), and Saint Vincent & the Grenadines (4.1%). The remaining foreign-flagged vessels together represented 13.5% of total distant water fishing catches (Fig. S1, see Supplementary Material).

During the period analyzed, DWF for albacore was mostly conducted by Taiwanese fleets. Brazilian albacore catches declined sharply after 2003, showed a modest increase between 2011 and 2013, but experienced another decline after 2014. The Japanese fleet accounted for the second-greatest share of albacore harvesting among DWF operations, surpassing the catch volumes of domestic Brazilian fleets. The domestic fleet appeared as the main harvester of the bulk of the skipjack tuna, yellowfin and bigeye tuna. DWF on yellowfin tuna was performed mainly by fleets from Saint Vincent & Grenadines, Vanuatu, Taiwan and Belize. Bigeye tuna was caught by DWF performed by fleets from Japan, China, Taiwan, Panamá and Saint Vincent & Grenadines (Fig. 1). In summary, although albacore tuna has been the primary target of DWF in Brazilian waters, yellowfin and bigeye also experienced consistent, albeit minimal, fishing pressure from foreign fleets.

In contrast to catches, the pattern of fishing events targeting tuna species did not indicate broad dominance by domestic fleets. Instead, DWF events conducted by fleets from Japan, Saint Vincent & Grenadines, Portugal, Spain, Colombia, and Vanuatu were particularly prominent (Fig. 2). Notably, fleets from Japan, South Korea, and Belize increased their fishing efforts for bigeye, particularly after 2006. Additionally, DWF events by the Taiwanese fleet demonstrated a more consistent distribution across years and targeted all tuna species.

Throughout the 16-year period, fishing events were conducted annually by domestic fleets (i.e., Brazil), Taiwanese fleets, and those classified as ‘Unknown Fishing Country’. Although the “Unknown” category likely represents a mix of various fleets each year, its persistence highlights the consistent presence of unidentified DWF operations in Central SWA. Half of the 24 countries engaged in DWF in the region maintained activities for over a decade (Fig. 2; Table 1).

Overall, the CPUE (catch per number of fishing events) demonstrated that DWF activities were more efficient than those of domestic fleets (Fig. 3). For albacore tuna, fleets from Uruguay, Taiwan, and Portugal fleets exhibited the highest efficiency. In the case of yellowfin, the most efficient fleets were Uruguay, Belize, Panama, Spain and the ‘Unknown Fishing Country’ category. Similarly, DWF fleets surpassed domestic fleets in efficiency for bigeye tuna, with ‘Unknown Fishing Country’, Spain, Belize and China fleets being particularly notable. In contrast, domestic fleets were only slightly more efficient than DWF fleets for skipjack tuna, and this was limited to the early years of the data set (2001–2008).

The spatial assessment revealed that, until 2011, the overlapping areas exploited by domestic fishing (i.e., Brazil) and DWF were primarily located outside Brazil’s EEZ and its internal boundary. However, from 2012 onwards, this overlap advanced further into the EEZ, even encroaching upon the territorial sea (light blue areas in Fig. 4).

Overall, the prices of all tuna tend to be higher in Japan, France and unknown countries (Fig. 5). The prices for all tuna species were consistently lower inside the EEZ across all years. Although in 2009 and 2010 the prices for skipjack tuna harvested inside the EEZ were marginally higher than those outside the EEZ, the difference was not statistically significant (Fig. 6).

The price reached by tuna species were determined by the captures, by the catch within the EEZ and by the area exploited inside the EEZ (spatial factor). For skipjack in 2004 and albacore in 2002 the spatial fishing ground did not have an effect on the price reached (Tables S1).

The tuna data set evaluated here in the Southwestern Atlantic Ocean highlights increasing competition between domestic fishing fleets (i.e., Brazil) and DWF operations, both in terms of targeted species and fishing areas. Fishing effort for DWF, as measured by fishing events, was notably high (33% higher than domestic fishing effort), primarily driven by Taiwanese fleets, which have consistently operated in the region for over 16 years. As a result, DWF exhibited a significantly higher CPUE compared to domestic fishing fleets. The spatial extent of DWF operations has expanded, encroaching on areas up to the Territorial Sea, intensifying competition with small-scale fishers who depend on these waters. Our findings highlight two key concerns: (1) DWF exhibit higher CPUE than the domestic fleet, though the latter generally achieves greater total catches for most tuna species. However, official landing data may not fully reflect nuances like high catchability with low effort. Stochastic events, such as concentrated tuna stocks harvested with minimal effort, can influence these variations. This was evident in 2015 when the Belize fleet achieved the highest CPUE for skipjack tuna despite lower fishing effort (see Figs. 2 and 3). These findings illustrate the complexities of fishing competition over shared high-seas resources. (2) DWF has increasingly occupied the Brazilian EEZ, surpassing the Territorial Sea and reaching coastal areas. This trend underscores the economic competition DWF imposes on domestic fisheries.

Most fishing operations by well-equipped and long-range foreign vessels are conducted within the EEZs of developing countries, where national industrial fleets also operate³. In such a context, the domestic industrial fishing sector, still in a consolidation phase in many developing countries, is often the first to interact and compete with vessels performing DWF. A key revelation of our study is the relevant presence of DWF fleets from a diverse array of countries, encompassing Africa, South America, Asia, the Caribbean, Central America, and Europe. This multinational participation underscores the global nature of DWF operations and highlights the complex geopolitical and economic motivations driving these activities²³. The substantial quantity of tuna caught by these foreign fleets—totaling 152,542 metric tons over the analyzed period, with an annual average of 9533 ± 2147 metric tons—compared to 634,976 metric tons by Brazilian domestic fleets, highlights the significant impact of foreign fleets on regional marine resources. Nevertheless, DWF vessels operating under flags of convenience—i.e., foreign fleets that obtain national authorizations to operate under different jurisdictions—may account for a significant portion of the fleets operating within the Brazilian EEZ. This could obscure the direct link between tuna landings and the countries officially granting fishing permissions. However, our study is primarily focused on analyzing and discussing the overall pressure exerted by DWF on Brazil’s territorial waters, regardless of these multinational arrangements. While the role of flags of convenience is relevant in understanding the complexities of fleet operations, it does not alter our core findings regarding the increasing competition between DWF and the domestic fishing fleet.

While Brazilian domestic fleets accounted for the majority (86%) of tuna catches, certain species, such as albacore, were disproportionately exploited by foreign fleets, particularly those from Taiwan. However, despite the lax Brazilian fishing rules, the industrial fishery sector operates under a distinct framework of application and control, subject to specific regulations and taxes that do not apply to DWF fleets. This disparity creates an unequal situation, as numerous foreign-flagged fleets enter Brazil’s jurisdictional waters, where domestic industrial fleets must adhere to rules that do not embrace foreign fleets. It is worth mentioning that any non-agreed distant water fishing operation within the EEZ of other countries is undoubtedly illegal fishing. In central SWA, this has largely been the case, with a few exceptions for specific time periods and certain foreign-flagged fleets²⁴.

Consequently, the domestic fishing sector competes locally with fishing carried out by large-range foreign vessels within the EEZ. Examining catch per unit effort (CPUE) by species provides additional insights. While domestic fleets exhibited comparable or slightly higher CPUE for certain species, such as skipjack, DWF fleets are more efficient, particularly in the harvesting of albacore (entire study period) and bigeye tuna (2002–2010). However, the CPUE of most foreign nations fishing within Brazil’s EEZ exceeds that of domestic industrial fisheries, likely reflecting greater efficiency driven by superior technology and advanced fishing capabilities. Although the domestic fishing industry generally captures a higher total volume of tuna species, it is likely to underperform in this competition because of structural limitations, such as lower investment in modern equipment, less specialized training, and restricted access to the subsidies and resources that often benefit foreign fleets. The effort we estimated for Brazilian fishing in the last 5 years (2012–2016) supports this outcome, as it has declined compared to that of most of the 25 countries conducting fishing within the EEZ. Our analysis of tuna prices within and outside the EEZ also pointed out disparities by showing prices consistently lower within the EEZ. Such price dynamics reflect the complex interplay between market forces, supply and demand dynamics, and regulatory frameworks. Understanding these price dynamics is crucial for informing policy decisions aimed at promoting fair competition, sustainable resource management, and equitable economic benefits in the fisheries sector. This imbalance in catch distribution and prices underscores the challenges domestic fisheries face in competing with foreign fleets, particularly in the context of resource conservation and sustainable management.

It is important to bear in mind that SSF, constrained by its structural features, would be expected to perform even worse if encountering and competing with DWF²⁵. Although the SSF face varying levels of vulnerability and technological shortage, their activity remains under-resourced and is conducted exclusively within jurisdictional waters, reaching, at best, the border of the EEZ^12,18. This raises even greater concern, as the encroachment of DWF into traditional territories of the domestic SSF fleet can lead to reduced catchability due to intensified competition for fishing grounds and target species. Moreover, in many developing regions, the long-term collection of quantitative data, statistics, and monitoring for SSF is scant, often misaligned with government priorities, poorly managed, and disconnected from broader fisheries management frameworks²⁶. Central SWA we evaluated follow the same trend: there is a lack of official data on spatial and temporal catches. Also, there is no information from on-board vessels, leaving the actual fishing activities within Brazil’s vast EEZ (3.6 million km²) largely unknown²⁷. Moreover, the Brazilian domestic fleet is composed of multiple fisheries sectors, including industrial, small-scale, and artisanal fleets, which operate under different technological capacities, fishing strategies, and target species beyond tuna. These structural and operational disparities likely influenced the lower efficiency observed in the domestic fleet when compared to DWF, which consists solely of highly industrialized vessels with standardized gear and advanced technology optimized for tuna and other large pelagic fisheries.

SSF sustains millions of livelihoods globally, yet remains highly vulnerable to competition from DWF, especially in low-income coastal regions. Despite contributing significantly to food security and national fish production, SSF are often overlooked in fisheries policies. This gap limits our understanding of the socio-economic and cultural impacts of DWF on small-scale fishers. However, we do know now, as shown here, that by 2016 the DWF had extended into coastal areas of central SWA, fished exclusively by small-scale fishers. This interaction will always be biased towards better performance and profits for large-range foreign fleets. The data we assessed here does not differentiate the domestic fleet between the industrial and small-scale fishing sectors. Given the “smallness” of coastal SSF, characterized by smaller boats that result in lower annual catches²⁸, limited access to tuna stocks, and the lack of SSF data reporting as aforementioned (but see ref. ²⁹), it is reasonable to assume that the estimated CPUE for the domestic fleet predominantly reflects the performance of the industrial fishing sector. Without global regulation to stop the subsidies that allow DWF to remain profitable (as shown by Skerritt et al.⁵), including their encroachment into areas traditionally fished by SSF, the economic, ecological, and social impacts of DWF on coastal communities will deepen poverty and jurisdictional conflicts.

Alone, the great technological and financial advantage of DWF upon domestic fleets, markedly upon SSF, would be an unease concern. However, the spatial assessment conducted in our study reveals concerning trends in the overlapping of fishing activities between domestic and DWF fleets within the Brazilian EEZ. While overlapping occurrences were initially restricted outside the EEZ, our data indicate a significant increase in DWF activities within the EEZ.

Once inside the Territorial Sea, the large-range vessels are often seen by small-scale fishers who identify that DWF capture more, have greater technology and have more autonomy at sea²⁵. To cope with such a challenge, local fishers demand support to acquire larger boats, in an attempt to increase their capacity to capture resources and compete with DWF. Local fishers then claim subsidies³⁰. The presence of DWF not only leads small-scale fishers to such a demand but also presents subsidies as the prone strategy to overcome such inequalities in marine resource exploitation. Fisher’s view is also biased by fisheries policies, despite evidence that the large size does not ensure greater catches in the EU and in the Central SWA^31,32. Fishing authorities often advocate subsidies for fleet improvement and growth as a strategy to increase catches and fishing profits²⁷.

Subsidy-driven policies in fisheries have proven to be neither ecologically nor economically sustainable. However, in many developing countries, including Brazil, they are often politically expedient, with fishing institutions being used as bargaining tools²⁷. While subsidies may temporarily support domestic fleets, they ultimately increase risks to fisheries resources and to small-scale fishers who depend on them for food security and livelihoods^33,34. Instead, investments should be based on the assessment of the current status of fish stocks and the health of marine ecosystems to ensure long-term conservation and sustainability.

The lack of reliable fisheries management and reporting in Central SWA exacerbates this issue, with federal fishing statistics in Brazil having been discontinued since 2011²⁷. This data gap not only obscures the growing competition between DFW and small-scale domestic fleets but also enables illegal and unregulated fishing to thrive. Weak governance, a common problem in many developing nations, further facilitates DWF encroachment into Brazil’s Territorial Seas, undermining national fisheries sovereignty. The absence of accountability prevents Brazil from effectively asserting its interests within Regional Fisheries Management Organizations, such as ICCAT and CCAMLR³⁵, placing the country at a disadvantage in negotiations concerning fishing regulations within its own EEZ. These factors align with our findings, which consistently demonstrate the progressive advancement of DWF into Brazil’s EEZ, intensifying competition with SSF domestic fishers. Therefore, the combination of weak governance, unregulated subsidies, and the absence of robust fisheries data is fostering an environment where DWF fleets continue to expand at the expense of local fishery livelihoods, potentially exacerbating economic and ecological challenges.

Thus, the time has come for global regulations to contribute to building governance in developing countries (including very low-, low- and medium-income nations). If fishing nations cannot protect their EEZ and coastal areas from encroachment and illegal fishing, they rely on global rules to guarantee their sovereignty and prioritize fisheries sustainability and equity. More than ever, the decisions of members of the World Trade Organization (WTO) may steer the direction toward avoiding the subsidies that support overfishing and illegal fishing in poorer nations and adopting regulations to uphold fisheries sustainability and equity¹⁵. Also, the WTO has now agreed to a fisheries subsidies agreement, which the member states are currently (https://www.wto.org/english/news_e/news24_e/ddgae_13mar24_e.htm). Global rules could create mutual accountability and pave the way for developing and poorer nations to build governance and deal with the multiple interests arising from distant water fishing that operates within their territory.

Dataset used and analysis

The study encompasses a significant portion of the Southwestern Atlantic (SWA) region, extending northward from Guyana to the southward Beagle Channel in Tierra del Fuego. This area includes the North Brazil Shelf, Northeastern Brazil, Tropical Southwestern Atlantic, Southeastern Brazil, and the Warm Temperate Southwestern Atlantic Province. Major coastal countries that comprise the SWA include Brazil, Argentina, Colombia, Guyana, Uruguay, and Venezuela. The analyzes covered the entire Brazil coast (7491 kilometer), which covers over 60% of the SWA region and hereafter is referred to as Central SWA (red line in Fig. 7). Note that throughout the text, we will use the acronyms ‘developing countries’ in a broad sense to denote very low-, low- and middle-income nations. The term ‘high-income nation’ refers to wealthy and developed countries.

Data accessed encompassed vessels’ flag, catch (ton), year of operation, number of fishing events/year, tuna species harvested, location (Lat-Long) and ex-vessel price per species from 2001 to 2016. The ex-vessel price is used as an indicator of the ability of DWF fleets to reach markets that pay higher prices, and therefore produce higher economic returns while exploiting the same fishing resources as national fleets. The four main tuna species harvested in the region were included (albacore—Thunnus alalunga, skipjack—Katsuwonus pelamis, bigeye—Thunnus obesus, and yellowfin—Thunnus albacares). The dataset has around 500,000 records, 156,200 for albacore, 59,802 for skipjack, 138,949 for bigeye, and 152,392 for yellowfin. All information on the harvest of tuna species in the Central SWA is drawn from the reconstructed catch database by Sea Around Us (SAU) (seaaroundus.org) and the Fisheries Economics Research Unit (FERU) at the University of British Columbia. SAU uses official reports by member countries to FAO, national statistics and also includes unreported catches, discards, and potentially illegal fishing as sources for reconstructing fishing data¹³.

The flag state was used to distinguish between the domestic fleet and DWF fleets. The domestic fleet included the industrial and small-scale fishery sectors. DWF includes foreign fishing fleets that operate in the EEZ and in its adjacent waters, in the high seas. We established a conservative boundary for surrounding high seas (red line in Fig. 7), extending from 200 to 1000 NM beyond the EEZ border. Fisheries operating beyond this boundary were considered to have a lesser influence on the overlapping dynamics between DWF and domestic fisheries. While tuna species are known for high-seas migrations³⁶, and distant fishing operations beyond the EEZ limits can impact fish stocks within the EEZ and at its borders, our analysis focused on the immediate impact of DWF proximity to the EEZ. The north adjacent area is narrower, as it encompasses the edge of the Amazon basin, where industrial freshwater fishing predominates. All records within the defined red line were included in the analysis.

Fishing events refer to each instance of fishing activity and are used as a proxy for fishing effort^37,38. CPUE is then given by the fishing events performed during the 15-year period in relation to the catches from domestic and DWF. The positioning of domestic and DWF fleets was used to assess the overlap of fishing grounds exploited by each fleet over time, based on their presence and absence. This analysis considered the Brazilian territorial sea (up to 12 miles), EEZ (up to 200 miles) and the high seas off the Brazilian coast (up to 1200 miles).

Based on Bayesian Space models using the stochastic partial differential equation (SPDE) method³⁹, we estimated the variables predicting the price mean of the four tuna species fished in the Central SWA. The ex-vessel price achieved at each operation was the response variable, while the catch, EEZ (in or out of the EEZ), year and location (Lat-Long) were considered predictive variables. Location was treated as a random spatial effect through the SPDE module and the catch, EEZ and year as fixed effects, as follows in equation below (1):

With price equal to the ex-vessel price; geo-location being the positioning (lat-log) of each vessel from both fleets (domestic fishing fleets and DWF); EEZ being the exclusive economic zone, and catch being the fishing capture (in ton).

The models predicting the price for each tuna species were assessed using the Lower Watanabe-Akaike information criterion (WAIC) values to determine the goodness of fit^40,41. Additionally, for models where the EEZ was a significant variable (lower WAIC), we compared the inside and outside EEZ using Bayesian posterior marginal probability^42,43,44. These models use data up to 2010, due to the limited volume of data for modeling after this date.

To visualize and analyze the spatio-temporal dynamics of both DWF and domestic fishing fleets, as well as to capture overlapping variations, the data within Central SWA was spatially structured through a Delaunay triangular mesh and using the Integrated nested Laplace approximations (INLA) statistical package⁴⁵ in the R software⁴⁶. This technique produces different sizes and densities of triangles instead of regular square grids⁴⁷, becoming denser the more observations were provided, and resulting in more accurate predictions and better fit to the contour of the studied area⁴⁸. Additionally, the smooth transition between areas dominated by small triangles (which correspond to the domain of interest) to areas with larger triangles (areas outside the domain and used to avoid boundary effects) avoids errors in the estimation of individual densities^45,47. To include the spatial factor in the model for predicting the price cover of the four species’ fishing areas, 1791 triangular cells were created.