Contributing to Responsible Tuna Management in the Indian Ocean: Updating Catch Reporting for the Sea of Oman and the Arabian Sea

Abstract

The United Arab Emirates (UAE) has a long history and tradition in fishing, yet its role in regional tuna management remains yet to be fully defined. This is the case specifically of tuna species, such as yellowfin, which are highly migratory and require coordinated efforts in the context of a corresponding international governance framework, particularly in ecologically important areas like the Northern Indian Ocean and the Sea of Oman. Data collection and species identification present significant complexities for these species, yet accuracy is crucial for effective conservation and fair allocation of management shares. Although UAE fisheries are partly within the area of competence of the Indian Ocean Tuna Commission (IOTC), the country has only recently begun to give consideration to the process toward participating in this Regional Fisheries Management Organisation (RFMO) which, in turn, would provide for the relevant governance framework for the species examined in this paper. This paper explores the factors behind these developments and assesses their implications for regional tuna management. Based on scientific sampling, we developed estimates of past landing volumes and propose mechanisms for ensuring data collection instrumental to an informed participation by the UAE in the regional tuna management framework under the IOTC. Finally, we explored the implications that this development would have under public international law, departing from the traditional principle “ex facto oritur ius” (Latin: the law arises from facts), which embodies the notion that certain legal consequences attach to particular developments. With regard to the specific developments being addressed by this paper, there could be certain legal consequences for UAE; following the reconstruction of landings and the enhancement of international datasets, we postulate that there would be legal ground for UAE to exercise historical fishing rights and seek a potential allocation of quotas within the framework of IOTC.

1. Introduction

For hundreds, if not thousands, of years people from the UAE have fished in the warm waters of the northern Sea of Oman and into the Arabian Gulf which host a wide variety of ecosystems and species. including tunas and tuna-like species. As a matter of fact, yellowfin tuna (Thunnus albacares Bonnaterre 1788) are historically regarded as a critically important fishery resource across the Indian Ocean basin and have long been utilised for food and commerce [1,2]. Generally regarded as an oceanic species [3] they can often be found mixed with other species, notably bigeye tuna (Thunnus obesus Lowe 1839), when juveniles. Furthermore, they are among those species listed under Annex I of 1982 United Nations Convention on the Law of the Sea (UNCLOS) as highly migratory due to the fact that they constantly move across national and international waters. In some areas of the Indian Ocean, where the continental shelf is narrow, yellowfin tuna may also be found mixed with neritic species, such as longtail tuna (Thunnus tonggol Bleeker 1851) [4]. As a result, it is not uncommon that they are harvested and sold together with other species on local markets. This has made it difficult at times to accurately report their catches, including countries like the UAE which have been among the very first in the region to collect data on its landings. The country’s increasing focus on establishing more comprehensive and modern fisheries policies [5,6], including through improved data collection and stock assessments, has progressively created a platform for a wider engagement by the UAE in regional fisheries management.

Tuna species are globally managed through Regional Fisheries Management Organizations (RFMOs), such as the Indian Ocean Tuna Commission (IOTC) (It is worth clarifying that this article does not address the work of the Regional Commission for Fisheries (RECOFI), as tuna and tuna-like species in the Indian Ocean are under the exclusive mandate of the IOTC. RECOFI, established in 1999 under Article XIV of the FAO Constitution, regularly assesses other fish stocks in its area of competence but has never managed tuna species, since this responsibility was already assigned to IOTC). This paper intends to demonstrate that by looking specifically at data collection and reporting of UAE’s catches of tuna and tuna-like species and analyzing how the empirical results of this scientific research could be instrumental to ultimately inform the potential future involvement of the UAE in the IOTC.

When it comes to IOTC, accurate fisheries data are important for a variety of reasons, including stock assessments purposes, for understanding the social and economic importance of the fisheries for countries, for determining allocation of quotas based on catch history by countries and for contributing important biological information to help better manage species and stocks more widely.

The reporting of yellowfin tuna landings by the UAE would entail a number of interesting considerations which are entirely legitimate since in recent years it has been observed that this species has become quite common at local landing sites in ports facing the Sea of Oman. Because the fishing gears involved (nets and lines) used to harvest all species found in these sites have been in use for decades, observations prompted research as to whether yellowfin tuna landings have deeper roots in UAE (Al Ali, S. personal observation, 2023). In this paper, we explore some of the aspects associated with these considerations, especially when it comes to documenting and reporting yellowfin catches by the UAE to IOTC and evaluate the consequences of these considerations for the wider management of yellowfin stocks (including possible regional sub stocks) and, in turn, for the possible development of enhanced data collection protocols departing from a reconstruction of historical data based on datasets managed by the IOTC and Food and Agriculture Organization of the UN (FAO).

2. Misidentification and Database Management in Documenting and Reporting Yellowfin Tuna Catches

Globally, challenges in data accuracy when reporting tunas and tuna like species catches can arise from various factors, including species misidentification, sampling complexities, and database management issues between entities. Such challenges have occurred several times and were often the results of mistakes made in good faith. In this paper we will revises select cases where such challenges were made by countries in good faith. Because we suppose that in the UAE too these factors may have influenced the reporting of yellowfin tuna catches we will link the results of our findings to ongoing efforts being made by UAE to streamline its data reporting at regional and global levels as will be explained below.

2.1. Misidentification

Correct identification of species is important for a wide range of reasons, including managing threatened species [7], managing vulnerable/choke species [8,9] and ensuring accurate stock assessments across a wide range of species, including tunas. Misidentification can occur on vessels, at land-based landing sites and in the supply chain. In addition, morphological traits such as the extent and distribution of red muscle are useful diagnostic features for distinguishing tuna species. It is not just a biological issue as misidentification may also impact consumer confidence when purchasing seafood [10].

Specifically, misidentification of certain tuna species has been a global issue for quite some time. Bigeye, yellowfin and longtail tuna have similar external features when juveniles and their similarities are well known. For yellowfin and bigeye tuna, the potential for misidentification has been recognised as a risk for stock assessments for several decades [11,12] and been addressed by the publication of detailed guides for field staff [13,14]. Ref. [11] found that fish in the 40–60 cm size range presented the biggest challenges. According to [12], the freshness of the fish can also make identification challenging with poor quality, creating a loss of diagnostic markings, which is an issue in the identification of species at landing sites.

Collette & Nauen (1983) [3] noted that, regarding longtail tuna, ‘Juveniles of this species, bluefin tuna, yellowfin tuna and bigeye tuna are very similar. Some of the records from Japanese waters may therefore be ascribed to misidentification’. Challenges in separating yellowfin from longtail have been confronted across in Japan [15,16], Indonesia [17], New Zealand [18] and India [19], with the latter stating that “Generally the morphological traits to differentiate between these two tuna species appear once the individual matures; hence misidentification of juveniles of these two species is unavoidable”. In general terms, the identification challenges of juvenile bigeye and yellowfin are both well-known and represent a recurrent material consideration in stock assessments (see below).

Distinguishing yellowfin and longtail, especially when dealing with juvenile and similarly sized individuals, presents significant challenges due to their overlapping morphological features and similar body proportions [3]. While yellowfin typically have longer pectoral fins which extend beyond the second dorsal fin, this characteristic is less pronounced in smaller individuals, reducing its reliability as a distinguishing factor [20]. The coloration of both species also contributes to misidentification; the distinctive yellow second dorsal fin of yellowfin tuna is often not fully developed in juveniles, while longtail retains a bluish-black dorsal region, leading to confusion in field assessments [21,22]. Additionally, size alone is an unreliable indicator, as both species exhibit similar growth patterns at smaller sizes, making biometric differentiation challenging without further meristic analysis [23,24]. The issue is further compounded by post-mortem changes, where natural pigmentation fades, making it even harder to distinguish between the two species once they are landed and processed [3,25]. This challenge is particularly evident for juveniles, whereas identification in adult specimens is generally much simpler due to more pronounced diagnostic features.

A key distinguishing characteristic between these two species is the presence of spots on the ventral side of the body. Yellowfin tuna typically exhibit a series of small, dark spots along the lower sides and belly, which can aid in field identification. In contrast, longtail tuna display elongated, pale or colourless spots located on the underside and belly, positioned between the pectoral and anal fins [26]. These ventral markings serve as an important morphological feature to differentiate between the two species, particularly in fresh specimens where post-mortem colour fading has not yet occurred. This difference in belly markings, in combination with fin morphology and body coloration, provides an additional tool for distinguishing between these species in mixed landings. However, in commercial fisheries where both species frequently co-occur, misidentifications are extremely common [26]. Although molecular methods, such as DNA barcoding, provide the most accurate species confirmation, their application in routine fisheries monitoring remains limited due to logistical constraints [27]. To improve species differentiation in fisheries data collection and reporting, a combination of external morphological features, meristic counts (e.g., gill rakers, vertebral counts) and molecular techniques is therefore recommended [28].

In order to better understand a scenario where there could have been a potential misidentification of yellowfin tuna in the UAE, we launched a rigorous analysis on the basis of observations at the local markets which pointed to the landing of yellowfin tuna. After having witnessed such landings on several occasions, DNA analyses were conducted on four specimens which were bought from the Fujairah fresh fish market of the UAE in late January 2025, in accordance with the method set out in Appendix A. At this market all specimens were identified by visual means as longtail based on markings, but DNA analysis showed that three out of four to be yellowfin. The molecular analyses followed the procedures described in Appendix A, which include standard controls to reduce the risk of laboratory error. Morphological evaluation of the specimens was conducted by trained fisheries biologists with experience in tuna and tuna-like species identification. Although it is acknowledged that the sample size is small, these preliminary results illustrate the challenges of accurate reporting in the field, especially when fish may be a few hours old. Most importantly, they also pointed us to what we assumed could have been a wider issue in the UAE in relation to tuna reporting based on data collection at the level of local markets. We fully acknowledge that such a small sample cannot on its own justify broader conclusions. However, the DNA confirmation provided essential validation that misidentification was indeed occurring in UAE markets and served as a trigger for the broader investigation combining structured interviews, field surveys, and dataset cross-checking. Future work should expand molecular sampling to confirm and refine these findings.

Reverting to previous cases of misidentification that took place globally, this would not be surprising since the identification of tuna species in the field is complicated by a number of factors, not the least of which is genetic difference within species that may be expressed in external morphology. Hidyat et al. (2023) [29] found morphological differences between juvenile longtail caught within Indonesia waters and suggested that these may be due to the low level of mixing between sub-populations that may be separated by unsuitable habitat (e.g., deep water) or unfavorable currents for mixing. There is a growing amount of information on population sub-structuring in this as well as other tuna species which may make field identification more challenging (see, for example, ref. [30] for yellowfin tuna in the Indian Ocean). Such differences may be difficult to be recognised by experts and scientists, let alone recently recruited national staff expected to be in charge of monitoring catches at landings sites, especially if expert training is not forthcoming.

Fishers usually do not distinguish between small tunas, which may affect field-based sampling via interviews. In the Philippines, fishers do not distinguish between juvenile yellowfin and bigeye [12], referring to both as ‘carao’ and can also mistake small longtail for yellowfin and Pacific bluefin as well. In Indonesia the Bahasa word ‘tongkol’ is used to describe any species of small tuna [14,31,32] and the same species may have multiple names depending on where it comes from and local languages. Longtail, for example, may also be called tongkol abu–abu, tongkol hitam, or tongkol aya [32]. It is worth emphasizing that in the UAE the term yodar is widely applied to both small-sized yellowfin and longtail (Al Ali, S. personal observation, 2024).

2.2. Reporting Anomalies

Fisheries data have been collected for many decades and there has been considerable change in the funding available, staff training, statistical design of sampling programs and types of information required. Reporting anomalies have been (and remain) an issue in many fisheries worldwide. Some of the reasons entail ill behavior and bad faith, others are the consequence of mistakes and errors. Examples of reporting anomalies include Illegal, Unregulated and Unreported (IUU) fishing [33,34,35], inadequate taxonomic discrimination (as compared to misidentification) [36], deliberate misreporting—or underreporting—by fishers [37] and methodological issues [38].

Looking specifically at methodological issues in the sampling of catches, these are fairly common [39,40,41] especially for small scale fisheries. In this context, samplings by enumerators at landing sites are usually conducted during working hours, particularly in the mornings, as most landings happen in the morning. These samplings have mostly covered tunas caught by the gillnet fleet and the main species landed were longtail. However, due to their small size and the inherent difficulty in distinguishing similar species at juvenile stages, samplings could eventually generate instances reporting anomalies in that, for instance, longtail could be mistakenly identified instead of juvenile yellowfin tuna. This scenario is further complicated, looking at the case of the UAE, by the fact that larger yellowfin caught by handliners are usually not landed until the afternoons, which means that in the mornings larger specimens cannot be used to support accurate reporting of yellowfin tuna. In addition, in those countries where there is growing incidence of recreational fishing activities, in that they may take sizeable quantities of fish as it happens in the UAE, the scenario becomes even more complex since data from recreational fishing activities are often not fully captured by conventional or consistent monitoring programs. The resulting oversights have been causing reporting anomalies in data collection systems globally and regionally. We therefore assumed it was likely that they could have also occurred in the UAE.

2.3. Database Management Issues

The UAE has reported landings of longtail tuna and narrow barred Spanish mackerel (Scomberomorus commerson Lacepède 1800) since 1950 and has progressively added more species in its database, such as Indo Pacific King Mackerel (Scomberomorus guttatus Bloch & Schneider 1801) and Kawakawa (Euthynnus affinis) in 1970, frigate mackerel (Auxis thazard Lacepède 1800) in 1974, and black marlin (Istiompax indica Cuvier 1832)/blue marlin (Makaira nigricans Lacépède 1802)/striped marlin (Tetrapturus audax Philippi 1887) and Indo Pacific sailfish (Istiophorus platypterus Shaw 1792) in 1983. The UAE has consistently communicated such data to the FAO. In addition, the UAE landings of species occurring in the IOTC area of competence have also been routinely reported.

Following initial observations and DNA analysis, we delved into our research by looking at datasets maintained by UAE. Figure 1 presents the official time series of tuna and tuna-like species catches reported to the IOTC from 2005 to 2022, disaggregated by species. The dataset illustrates both overall trends and shifts in species composition over time. Spanish mackerel (Scomberomorus commerson) have consistently dominated the catches, with peak landings exceeding 8000 tonnes in 2010 and 2011, and despite a gradual decline, it remains the most abundant species throughout the period. Frigate mackerel (Auxis thazard) showed highly variable trends, with a pronounced peak in 2012 and a marked increase again in 2022, when catches approached 4000 tonnes—possibly reflecting changes in fishing activity or improvements in species identification and reporting. Longtail tuna (Thunnus tonggol) was the second most abundant species in the early years, with landings above 2000 tonnes between 2005 and 2007, then fluctuating below this level but stabilizing at approximately 1300–1500 tonnes in recent years. Kawakawa (Euthynnus affinis) remained consistently low and stable, typically ranging from 200 to 700 tonnes annually. Indo-Pacific king mackerel (Scomberomorus guttatus) was only reported from 2006 to 2009, peaking at over 2000 tonnes in 2007, and has been absent from the IOTC database since 2010, potentially due to species misidentification at the regional level.

Figure 2 presents the time series of tuna and tuna-like species catches reported to FAO from 2005 to 2022. Spanish mackerel (Scomberomorus commerson) consistently dominates the catch profile, particularly after 2008, with peak landings exceeding 8000 tonnes in 2010 and 2011, and remains the most consistently abundant species throughout the time series. Notably, Indo-Pacific king mackerel (Scomberomorus guttatus) appears prominently in the earlier years (2006–2009), peaking at over 2400 tonnes in 2007—suggesting that it may have been underreported or misidentified in earlier datasets. Its complete absence from the records after 2009 could reflect changes in data reporting or species identification. Frigate mackerel (Auxis thazard) shows substantial interannual variability, with marked peaks in 2012 and again in 2022, when catches reached nearly 4000 tonnes—possibly linked to shifts in fleet dynamics, fishing areas, or improved species identification. Longtail tuna (Thunnus tonggol) exhibits greater year-to-year variation than previously estimated, especially between 2006 and 2008, when it peaked above 2200 tonnes. From 2019 onward, its catches stabilized at approximately 1300–1500 tonnes. Kawakawa (Euthynnus affinis) displays slightly more fluctuation than in earlier data but continues to represent a minor share of the total catch, typically below 700 tonnes annually.

Figure 3 illustrates the difference in reported catch data between the FAO and IOTC datasets for tuna and tuna-like species from 2005 to 2022. Positive values represent catches reported to FAO but not reflected in the IOTC dataset, while negative values indicate the opposite. The discrepancies are most pronounced in two distinct periods: 2006–2009 and 2022.

Between 2006 and 2009, the largest differences are linked to Indo-Pacific king mackerel (Scomberomorus guttatus), with over 2000 tonnes appearing in the FAO dataset but completely absent from the IOTC records. This suggests either past misreporting or species misidentification that was later corrected in IOTC submissions, or it could reflect improvements in reporting to FAO that were not mirrored in IOTC updates. During this same period, smaller positive discrepancies are seen in longtail tuna (Thunnus tonggol) and kawakawa (Euthynnus affinis), while minor negative discrepancies in frigate mackerel (Auxis thazard) and Spanish mackerel (Scomberomorus commerson) may reflect shifting classification or reallocation between species in reports.

The most striking anomaly occurs in 2022, where FAO records show approximately 3300 tonnes more frigate mackerel (Auxis thazard) than IOTC, while IOTC lists about the same volume for Spanish mackerel (Scomberomorus commerson) that does not appear in FAO data. This stark divergence may indicate reclassification issues or inconsistencies in species-level identification in either dataset. Notably, this discrepancy in 2022 could have major implications for regional stock assessments if not resolved, as it affects both total catch volume and species composition.

Overall, the graph reveals several inconsistencies between the two datasets, underscoring the need for harmonized species identification protocols, improved data reconciliation processes, and enhanced communication between national authorities and regional and international reporting systems.

Such conclusions have been drawn specifically when looking at the stark differences in the reporting of Auxis thazard and Scomberomorus commerson in the 2022 IOTC database and which, in our view, might suggest a possible inversion of species. Conversely, the disappearance of Scomberomorus guttatus from 2010 onwards in the FAO dataset highlights a misidentification issue that was subsequently resolved. Mistakes and errors in reporing catches of species tend to happen at the country level and they have a factual impact on datasets maintained by regional and global organizations generating discrepancies, as we have tried to demonstrate. Taking into account that, as far as our analysis goes, the IOTC belongs to the FAO institutional framework and operates pursuant to the provisions of Article XIV of the FAO Constitution and related FAO Basic Texts provisions, such discrepancies can be readily addressed. In the scenario we present in this paper, reported discrepancies of catches for Auxis thazard, Scomberomorus commerson, Scomberomorus guttatus, Thunnus tonggol, and Euthynnus affinis reveal a number of issues that are present in official datasets.

2.4. Overall Implications of Incorrect Data for Fisheries Management

Arguably, it is the implications of reporting anomalies and species misidentification in the stock assessment process that are of greatest concern [37,42] but, in accordance with an ecosystem approach to fisheries management, there may also be wider sustainability issues entailed [43] and, as we present in this paper, there are also potential allocation consequences. Discrepancies between FAO and IOTC datasets could have material implications for both regional stock assessments and future quota allocations. Stock assessments depend on accurate species-specific catch histories; systematic over- or under-reporting of certain species (e.g., Auxis thazard, Scomberomorus commerson) could bias estimates of biomass, fishing mortality, and recruitment. From a governance perspective, quota allocations under IOTC are expected to be based, at least in part, on historical catches. Inaccuracies therefore risk disadvantaging countries such as the UAE, whose actual contribution to regional catches may not be fully reflected in official statistics. Challenges with local terminology and fish names are far from unique to tunas and are a worldwide issue with implications for catch reporting (e.g., sardines in the Philippines [44]), and labelling for consumers in Taiwan [45] and the United States [10]. Identification issues may be compounded by loss of information along the supply chain, confusion over translation of names in other languages and legislated names [45,46]. In addition, from a consumer perspective, misidentification may facilitate laundering of fish and overexploitation [47] with [46] reporting an average of 30% misreporting from their review of 51 published papers.

The work by [12,48,49] was driven by serious concerns in the Western and Central Pacific Fisheries Commission (WCPFC) about the reported catches of bigeye and yellowfin tuna in the Philippines (and Indonesia), due to both the volumes of the catches and the fact that large proportions of such catches comprised juveniles. These factors compounded concerns about inadequate data collection in terms of key biological information and the mixing of yellowfin and bigeye in catch reports and effort. Pedrosa-Gerasmio et al. [50] estimate that the degree of misidentification could be as high as 30% and commented on the challenges for field staff seeking to document catches without access to viewing liver morphology, which is a key indicator.

Misidentification may have implications for fisheries management as well [43,51]. For example, in the Philippines, one of the country’s main commercial sardine species had been recorded as the Indian oil sardine (Sardinella longiceps) since 1908. However, subsequent DNA studies demonstrated that the species was actually the Bali sardinella (Sardinella lemuru) [44]. This taxonomic correction had flow on effects to fisheries management regulations, including the gazettal of an annual closed season.

3. Yellowfin Tuna in the Indian Ocean and the Arabian Sea

For hundreds, if not thousands, of years people from the UAE have fished in the warm waters of the northern Sea of Oman and into the Arabian Gulf which host a wide variety of ecosystems and species. including tunas and tuna-like species. As a matter of fact, yellowfin tuna (Thunnus albacares) are historically regarded as a critically important fishery resource across the Indian Ocean basin and have long been utilised for food and commerce [1,2]. Generally regarded as an oceanic species [3] they can often be found mixed with other species, notably bigeye tuna (Thunnus obesus), when juveniles. Furthermore, they are among those species listed under Annex I of 1982 United Nations Convention on the Law of the Sea (UNCLOS) as highly migratory due to the fact that they constantly move across national and international waters. In some areas of the Indian Ocean, where the continental shelf is narrow, yellowfin tuna may also be found mixed with neritic species, such as longtail tuna (Thunnus tonggol) [4]. As a result of this, it is not uncommon that they are harvested and sold together with other species on local markets.

3.1. Population Structures

Successful management of a fishery includes constraining catches to sustainable limits. Where possible, catch constraints (whether implemented via output or input controls) need to take account of any structuring within the fished stocks such that any overall controls do not put localized populations at risk. In relation to yellowfin tuna, this is a globally distributed species as opposed to longtail tuna, which occurs only in the Indian and western Pacific oceans [3]. Overviews of the biology, ecology, fisheries and management (at the time of publication) can be found in [52,53] for yellowfin and longtail respectively.

With the exception of the Pacific Ocean where it is accepted that there is a western and an eastern stock, it has been assumed for decades that single stocks are to be found in the Indian and Atlantic Oceans. Moreover, it has also been assumed that the stock boundaries conform to administrative boundaries. However, there is a growing body of evidence that there is structuring of both yellowfin and longtail within the Indian Ocean and within the western stock of the Pacific Ocean [46,52,54,55,56].

For yellowfin in the Indian Ocean there are several studies which suggest the existence of at least three stocks. Prior to the application of DNA techniques, studies based on morphometric analyses suggested at least two and possible three stocks of yellowfin in the Indian Ocean (see references [57]. DNA studies have added further to this view. In their study of DNA sampled from yellowfin sourced from around Sri Lanka and the Maldives [57] suggested that there are at least three stocks of yellowfin around India alone.

Fish sampled from landing sites around the coast of India show genetic evidence for three distinct populations of yellowfin [19], including one adjacent to the state of Gujurat in the northern Arabian Sea. Using morphometric analyses [58] identified a sub stock around the Laccadive Ridge based on a smaller spawning size than found in other areas of India.

There is considerable debate about the differences in results from DNA studies and between DNA studies and information from other types of research, including tagging. A number of issues such as sample sizes, age of fish and possible mixing of fish all play a role. Age of fish influences movement and thus there could be mixing if fish are sampled from longline operations versus purse seine. It should also be noted that the average size of gillnet caught fish in Iran waters is smaller than for purse seines [59] (and a substantial reduction in size compared to [60] and are thus younger and less likely to have migrated further. Evidence from both DNA and otolith samples, was reviewed by [56], the latter providing evidence from water chemistry of the areas in which individual animals have been associated.

Carbon and oxygen isotope ratios in otoliths have been used to study the nursery grounds utilised by different populations of young yellowfin [61,62,63]. The work by Fraile et al. (2013) [61] on fish sampled from the western Indian Ocean found that fish from the Somali Coast and the Seychelles were more similar to each other than those from the Mozambique Channel, suggesting two separate nursery grounds. The studies by Artetxe-Arrate et al. (2020 and 2021) [62,63] sampled fish from known nursery grounds across the Indian Ocean to evaluate connectivity with older fish sampled in fishing grounds. The sampling of fish from the waters of Pakistan identified the potential existence of another nursery ground in the northern Arabian Sea as fish from Pakistan waters could not be mapped back to existing known nursery grounds. Whilst it is possible that the isotope ratios may be due to the oceanography of the region it was also proposed that there maybe a separate population of yellowfin in the Arabian Sea. Further support, at least in part, comes from the [56] overview of the Population Structure of Tuna, Billfish and Sharks in the Indian Ocean (PSTBS-IO) project which concluded that for skipjack and yellowfin there was a common pattern of genetic differentiation supporting a conclusion of population structure north and south of the equator for these species.

The need to better integrate the information sourced from different types of studies so as to provide better clarity on stock delineation has been raised by [64]. There are multiple lines of evidence (otolith chemistry, DNA and morphometrics) suggesting that there is likely a subpopulation of yellowfin in the northern Arabian Sea. A more detailed review is warranted as there could be significant management implications.

3.2. Specific Management Implications

For the case of tuna fishing at the level of the UAE, there would be clear management implications associated with accurate identification of species and clarity surrounding stock boundaries, for both yellowfin and longtail. Although the potential UAE take of yellowfin is small if considered at the level of the entire Indian Ocean, there are potential consequences from a stock assessment and management point of view if there is a separate population in the northern Arabian Sea. Furthermore, given the poor status of longtail tuna, there is a need to retrospectively address reported landings of this species as the UAE reported catch may have an influence over broader stock assessment, especially if this species may also have a separate stock in the northern Arabian Sea [59].

An overview of the importance of ensuring that stock boundaries and management arrangements are aligned was provided by [65]. Different stocks may possess genetic, physiological, behavioral characteristics that may have an effect on life cycle traits such as growth rates, fecundity, abundance and disease resistance. Similar points have been made over several decades in the case of Indian Ocean tunas by many authors [19,52,56,57,66,67,68].

Whilst the evidence favoring the identification of discrete stocks within the Indian Ocean at times seems contradictory, there is a growing body of evidence that yellowfin, in particular, is not a panmictic stock in the Indian Ocean and there are defined sub-stocks of both yellowfin and longtail and that more localized management is needed. Indeed, Artetxe-Arrate et al. [63] state that connectivity and mixing rates of yellowfin tuna within the Indian Ocean might be more complex than previously assumed. Ignoring such patterns of connectivity could result in inaccurate estimates of stock productivity and misinterpretation of abundance trends in the stock assessment process. Considering different subpopulations as a unique panmictic population has the potential to increase the risk of mismanagement was cautioned by [52] and they emphasise the need to better align management units and true population structures.

3.3. Documentation of Yellowfin Tuna in UAE

Although there is no official reporting or documented presence of yellowfin tuna (Thunnus albacares) in UAE, according to our analysis of datasets from the IOTC and FAO, as well as available literature, several factors triggered further investigation into the nature of the species’ occurrence in the region with a focus on UAE. A key observation was yellowfin being sold and auctioned at the Abu Dhabi fresh fish market (Al Ali, S., personal observation, 2023–2025), with these fish reportedly originating from various other UAE landing sites. As we have already explained, this anomaly, combined with the morphological similarities to longtail tuna (Thunnus tonggol), the use of the same Arabic names for both species—yodar for adults and gebab for juveniles—and multiple anecdotal reports from both commercial and recreational fishers, raised questions about the species’ true distribution and the potential accuracy of officially reported statistics. Additionally, the growing number of photos and videos shared online—through recreational fishers’ blogs, charter boat websites, and social media platforms—further suggested that there may be a need to conduct a more thorough assessment of the species’ presence in the region.

There is little doubt that yellowfin occurs in the UAE and the fisheries maxim, “if the fish are there, the fisheries will follow,” suggests that where yellowfin exists, targeted or incidental fisheries are likely to develop. Furthermore, the species’ known migratory patterns suggest movement into the Sea of Oman, and the proximity of a likely spawning area in the northern Indian Ocean and the Sea of Oman, off the coasts of Pakistan [19] resonate with the need for a comprehensive reassessment of the total take of yellowfin in the UAE, as current data may not fully capture the species’ actual distribution and exploitation in the region.

3.4. Challenges in Distinguishing Yellowfin and Longtail Tuna

The identification challenges associated with longtail and yellowfin have previously been discussed and these, along with the landing site sampling strategy also previously discussed have likely contributed to the lack of records of yellowfin in UAE catch statistics.

For visual reference, the photo below (Figure 4), taken at the Fujairah landing site in December 2024, presents a side-by-side comparison of yellowfin and longtail, highlighting the differences in ventral spots. These images illustrate the distinct patterns, emphasizing the extreme similarities between the two species when juveniles and the importance of belly markings as a diagnostic feature for accurate species identification. Notably, both fish were sold under the same name, gebab, and with the same price.

3.5. Reporting Anomalies and Misidentification of Yellowfin and Longtail Tuna

A mix of reporting anomalies and misidentification are two of several interrelated factors likely affecting, in our view, data collection and species-specific catch statistics relating to yellowfin and longtail in the UAE and these have been compounded by the database discrepancies identified at the levels of the FAO and IOTC, as reported above.

A large proportion of all tuna species landed in the UAE consists of individuals weighing less than 15 kg, primarily due to the prevalence of small-scale fisheries that operate in relatively nearshore waters using handline and gillnets. The presence of a narrow continental shelf characterises the Indian Ocean (Sea of Oman) side of the UAE ultimately means that the preferred habitats of longtail (shelf living) and yellowfin (open ocean living) may overlap, especially in the juvenile stages of both species. Additionally, there is a high occurrence of juvenile specimens, particularly those under 3 kg, possibly attributed to recruitment from spawning areas in the western Indian Ocean and, possibly, the Sea of Oman.

The use of driftnets by small scale fishers in this overlap zone makes the capture of both species highly likely as both species frequently co-occur in the same fishing grounds.

This challenge is exacerbated by the conditions under which fish are identified: once landed, tuna often exhibit faded coloration, and distinctive morphological markers, such as belly spots and fin shapes, become less pronounced. As demonstrated in this investigation, distinguishing between these species in field conditions proves difficult, leading to inconsistencies in catch records and potential biases in stock assessments. Misreporting is also influenced by fishing practices, patterns, and data collection methodologies. Vessels targeting medium to large yellowfin typically operate during the day, fishing 10 to 50 nautical miles from shore, primarily around Fish Aggregating Devices (FADs) or by tracking seabird activity. These boats usually land their catches late in the evening, often after sunset.

Data collection is conducted through sample surveys by data collectors who begin their work early in the morning, during auction times and the primary landing periods, continuing until early afternoon when the majority of landings occur. The majority of landings are recorded in the morning, as fishing activities—such as some forms of netting, trapping, handlining, bottom fishing, and trolling take place overnight or in the early morning hours. To further improve data accuracy, adjustments are being made to sampling schedules to ensure comprehensive coverage of all landing times, including late-evening landings from vessels targeting yellowfin tuna, which will help to improve the landing estimates.

The combination of these factors has greatly contributed to the underreporting of yellowfin and, likely, also of skipjack tuna (Katsuwonus pelamis Linnaeus, 1758) and bigeye tuna (Thunnus obesus), noting that there have also been identification issues associated with the juveniles of these species versus yellowfin as well in the UAE.

4. An Attempt at Yellowfin Tuna Catches Reconstruction in the UAE

4.1. Data Collection Methods for Fisheries and Catch Estimation

We postulate that in the UAE the misidentification and reporting anomalies of yellowfin tuna we have document might have resulted in data gaps. Recognizing this issue, a comprehensive, multi-source data collection approach was implemented through our research, integrating structured interviews, field observations, and secondary data sources to ensure accurate catch estimation. Data were collected from August 2024 to February 2025, coinciding with the period when yellowfin tuna was observed in wet-fish markets in 2023 and 2024. Initial interviews with selected fishers and traders indicated that this period represents the fishing season. These preliminary findings were confirmed and validated during the field data collection and interviews.

Between September 2024 and February 2025, structured interviews were conducted with key stakeholders involved in the UAE’s tuna fisheries at 11 major ports, from Dibba in the north to Khor Kalba in the south (Figure 5). The survey included 71 commercial fishers, 22 fish traders, and 43 recreational fishers and charter boat managers. Responses were coded and analyzed to identify patterns of misidentification and underreporting, and the most consistent answers were used to refine species-specific estimates. A summary of the questionnaire results is presented in

Table 1. Sample Size by Stakeholder Group.

	Commercial Fishers	Traders	Recreational Fishers & Charter Boats
Total interviews	71	22	43

.

The interviews were conducted using structured questionnaires [70] designed specifically for fishers and traders. The questionnaire for fishers focused on effort-related data, including the number of fishing trips per week, types of fishing gear used, and estimates of the average catch per trip by species, supported by photographs for accurate species identification (but noting previous comments about identification issues). Additionally, fishers were asked to estimate fuel consumption per trip to help infer the distance to fishing grounds. For traders, the questionnaire began with photographs of various tuna species to ensure correct species identification. It then included questions about the frequency of tuna sales and trades per week, along with estimates of the average quantities traded.

To enhance data reliability, consistent questions were posed to multiple respondents from diverse perspectives, allowing for cross-validation of the information. Insights from traders and recreational fisheries and charter operators were particularly valuable in corroborating data provided by commercial fishers.

The estimates were calculated by aggregating catch-per-trip values and multiplying them by the number of active vessels in each gear category, following the methodology outlined in Pinello et al. (2017) [70].

• Field Observations

Direct observations at landing sites and harbours were critical in identifying active tuna fishing vessels and understanding fishing practices. Special attention was given to large, perforated containers submerged beside boats at docks, which are commonly used to store live bait such as horse mackerel and scad (Figure 6). These containers served as visual indicators of tuna fishing activity and were essential in identifying and counting vessels involved in the yellowfin fishery—here defined as the handline fishery that targets yellowfin. In contrast yellowfin is largely a bycatch in the gillnet fishery which targets longtail.

b.

Secondary Data Sources

To complement primary data collection, additional information was gathered from photographs sourced online, fish markets, and the personal archives of fishers. These secondary sources were instrumental in cross-referencing and verifying interview and observational data, thereby enhancing the robustness of the catch reconstruction process.

One of the main challenges in the reconstruction was estimating the number of vessels and fishing trips. This was addressed through field visits, direct observations, and structured interviews with fishers and traders. The results consistently indicated that fisheries activity and effort remained stable over the past five years, a finding confirmed by multiple independent sources. Catch-per-trip values, collected directly at landing sites, were extrapolated to the number of active vessels and trips to calculate total catches. The reconstruction process followed FAO guidelines [70].

Data collected during the fishing season from August 2024 to February 2025 were utilized to reconstruct catch and effort data for the past five years. This reconstruction was based on consistent reports from fishers confirming that catch and effort levels have remained stable over recent years. As a result, the reconstructed data are considered representative and applicable to the preceding five-year period and is presented in the tables below (

Table 2. Reconstructed handline YFT data.

Tot Boats	Kg per Boat/Trip	Trip per Boat/Season	Tonnes/Boat/Season	Total Catch (Tonnes)
369	142	46	6.6	2424

and

Table 3. Reconstructed Skipjack tuna catch data.

Tot Boats	Kg per Boat/Trip	Trip per Boat/Season	Tonnes/Boat/Season	Total Catch (Tonnes)
369	14	46	0.7	242

).

4.2. Findings

The UAE’s yellowfin tuna fishery is characterized by handline fishing using live bait, targeting tuna species located between 10 and 50 nautical miles offshore. Seasonal variations significantly influence fishing techniques and success rates. From August to December, Fish Aggregating Devices (FADs) play a crucial role in attracting tuna, while from January to March, fishers rely on seagull activity to locate tuna schools. A typical fishing trip yields between 40 kg and 500 kg of yellowfin (Figure 7), with the amount varying depending on the port, and the season. Average data were calculated based on the sample data collected through the structured interviews and data are presented in Table 2.

The collected data on yellowfin sizes revealed the presence of three distinct groups: individuals weighing less than 2 kg (gebab), those between 8 and 20 kg (yodar), and larger specimens ranging from 20 to 80 kg (yodar). The larger yellowfin are typically caught between January and March, while smaller individuals are more commonly landed from November to February. Intermediate-sized tuna, weighing between 8 and 20 kg, are predominantly caught from August to December. It remains unclear whether these seasonal patterns are driven by the species’ biological and migratory behaviours or are influenced by the fishing grounds and practices commonly employed by local fishers.

The primary target species is yellowfin but during the same trips fishers may also catch dolphinfish (Coryphaena hippurus Linnaeus 1758), rainbow runner (Elagatis bipinnulata Quoy & Gaimard 1825), and skipjack tuna (Katsuwonus pelamis) (Figure 8). It is worth noting that the skipjack tuna is also absent from all the official datasets analysed. This absence suggests another potential gap in reporting and a likely misidentification.

From November to February, juvenile yellowfin are frequently caught closer to shore, often mixed with longtail (Figure 9). Both species are locally referred to as yodar, contributing to widespread misidentification and inaccuracies in landings data. The ex-vessel price for the yellowfin was reported at USD 1.5–2.5/kg.

While gillnets remain the predominant fishing technique for smaller tunas, handlines are also used. This practice increases the likelihood of mixed-species catches, a phenomenon similarly observed in fisheries in Sri Lanka and Indonesia [71,72].

In summary, two main fishing areas have been identified (Figure 10): a shelf habitat area where gillnets are the main gear and longtail and juveniles of yellowfin are caught, and a ocean habitat area where yellowfin tuna are the main target using handline with live bait.

4.3. Catch Data Reconstruction for Yellowfin and Skipjack Tuna

A comprehensive reconstruction of yellowfin catch was conducted to estimate its total annual catch by the UAE. As reported, this process integrated structured interviews, field observations, and secondary data, focusing on the total number of boats, fishing trips per season (August to March), average catch per trip, and total catch per boat and port. Yellowfin tuna fishing activity along the eastern coast of the UAE involves 11 ports from Dibba in the north to Khor Kalba in the south (Figure 5), and is primarily concentrated in the southern region, particularly around Khorfakkan, Fujairah, and Kalba. An estimated total of 369 boats operate, primarily utilizing handline fishing methods and mostly using live bait. The total reconstructed YFT data from handline fishing alone was estimated at 2424 tonnes per year. During the same data collection campaign and interviews, information on skipjack tuna was also gathered, with catches estimated at 242 tonnes, approximately 10% of the YFT data (Table 3). The average values derived from data collection and used for this estimation are presented in Table 2 and Table 3, respectively.

The reconstruction relied on a set of explicit assumptions. First, we assumed that the average catch per trip, as reported by fishers and validated through landing observations, was consistent across vessels within the same port cluster. Second, we assumed that fishing effort (number of trips per season) has been relatively stable over the last five years, as consistently reported by interviewees. Third, we extrapolated from the sample of 71 commercial fishers to the total active handline fleet of 369 vessels (as identified through harbor observations). This produced estimates of total catch at the national level. While this approach necessarily introduces some uncertainty, the triangulation of interviews, field observations, and secondary photographic evidence provided consistent results, lending confidence to the reconstructed estimates.

Based on field data collection, the percentage of juvenile yellowfin tuna that are sold together and misidentified as longtail, sharing the same name and market price, was estimated at approximately 5% during the months when juvenile yellowfin appear in the landings, specifically from October to March. This estimate was derived from repeated direct observations during these months, where roughly 1 in 20 individuals identified as longtail were, in fact, yellowfin, later confirmed through DNA analysis. While approximate, this figure was further cross-validated by independent observations from market monitoring and trader interviews. The reported catches of longtail during these six months over the past four years ranged between 486 tonnes and 759 tonnes. Therefore, 5% of these catches over six months can be estimated between 24 and 38 tonnes. This amount, which was mistakenly recorded under longtail, should be subtracted from the reported landings of longtail tuna to correct for the reporting anomaly.

4.4. Improving Accuracy in Statistics of Tuna and Tuna-like Species

To enhance both national and international fisheries statistics and support the regional management of key tuna species, we suggest that the following catch data should be integrated into the official UAE records. For yellowfin, the catch has been estimated at 2424 tonnes, based on the methodologies and criteria outlined in Section 3.1 (data collected between August 2024 and February 2025). Additionally, skipjack tuna catches are estimated at 249 tonnes, which is approximately 10% of the yellowfin tuna catch. Incorporating these figures into the official statistics will enhance the accuracy of stock assessments and support the development of sustainable fisheries management strategies within the region. Improved data collection and reporting are essential for aligning with international standards, such as those recently outlined by the IOTC [73], and for landing legitimacy to a potential UAE’s position to have a share in regional fisheries governance [3]. In addition, specific training for data collectors, fishermen, and fish traders is critical to improve species identification, ensure transparent market practices, and address future legal and management challenges linked to misidentification. The revised reconstructed statistics for the past four years resulting from our analysis are presented in

Table 4. Proposed new catch data.

Species Name	2018	2019	2020	2021	2022
Thunnus tonggol—OLD	971	1250	1384	1517	1318
Thunnus tonggol—NEW *	922	1188	1315	1441	1252
Thunnus albacares— NEW **	2473	2487	2493	2500	2490
Katsuwonus pelamis—NEW ***	247	249	249	250	249

* Subtracted 5% from the total catch over a six-month period; ** based on data collected in 2024–2025 + 5% from Thunnus tonggol; *** 10% of Thunnus albacares, based on data collected in 2024–2025.

below.

5. Legal and Regulatory Implications of Ensuring Correct Identification and Reporting

Based on the sections above, and bearing in mind the importance of underpinning the regional management framework with accurate data, we are of the view that there is sufficient evidence that reporting anomalies affected database records of several species. This means that the UEA would be now in a position to update its historical records of landings, especially for yellowfin, based on the time series of recorded catches, as previously presented. In addition to biological and management implications, which we have thoroughly documented, these data also have strong legal implications as they can play a crucial role in the UAE being allocated quota for tuna and tuna like species managed by the IOTC in the future, also bearing in mind that the IOTC is currently in the process of developing a quota allocation system.

By addressing and refining catch reporting practices, as per our advice, the UAE would be well-positioned to actively contribute to ongoing discussions on the development of a quota allocation system by the IOTC, ensuring that its historical fishing activities are accurately represented in future management frameworks. In this regard, it is worth looking at existing legal precedents, specifically within the IOTC, as relating to the resolution of previous reporting anomalies and how these may inform the development of solutions proposed by the UAE.

The IOTC is not new to the situation of reporting anomalies. In 2002, the IOTC Secretariat prepared a document for the fourth session of the IOTC Working Party on Tropical Tunas (WPTT) held in Shanghai, China, from 3 to 11 June 2002, entitled Catches of Artisanal and Industrial Fleets in Indonesia: An Update. At that point in time and as is currently the case with the UAE relative to the IOTC, Indonesia was neither a Contracting Party nor a cooperating non-Contracting Party of IOTC. Furthermore, Indonesia had never reported its catches to the IOTC. In the document referred to, a major review of the catches of Indonesian vessels in the Indian Ocean was provided, expounding how legislative changes in Indonesia, inter alia, had contributed to the distortion of estimated catches by both longline and artisanal fishers.

Returning to the case of Indonesia, longline catch estimates were revised due to inconsistencies in previously reported or estimated data from FAO databases. These inconsistencies stemmed from underreporting and the aggregation of domestic and foreign catches as Indonesian. The corrected estimates showed lower catches in years when foreign longliners dominated the fleet and higher catches in the following years, as all foreign longliners reflagged to Indonesia.

Additionally, catches from 1973 to 1981, previously recorded as aggregated, were re-estimated separately to complete the historical data series. Artisanal catch estimates in Indonesia were on the other hand revised only for years where data were not reported to the IOTC. The new estimates, based on FAO database records, were significantly higher than previous figures. This scenario resonates significantly with the one presented in this article as relating to reporting anomalies of catches of tuna and tuna like species in the UAE as well as in the framework of FAO database records, as it has been already clarified in previous sections.

The fourth session of the IOTC WPTT took note of the information relating to the catch reporting anomalies of Indonesia. This played a critical role in granting Indonesia, some months later, the status of cooperating non-Contracting party to IOTC at the Seventh Session of the Commission (Mahé, Seychelles 2–6 December 2002) granted.

What stands out in the precedent set by Indonesia within the IOTC is the readiness with which the IOTC Secretariat spearheaded the revision of Indonesia’s historical catches and the temporal proximity between this revision and the decision by the IOTC Commission to grant Indonesia admittance to IOTC as a cooperating non-Contracting party. Consequently, it has to be expected that the UAE too would be afforded a chance to address reporting anomalies, should it decide to submit an official request to that effect to the IOTC Secretariat. Also, the UAE should be offered a path towards IOTC membership in due course, first through cooperating non-Contracting Party status and then by pursuing full membership, looking also at the evidence collected as relating to the fact that the UAE has been already participating in the harvesting of tuna and tuna-like species managed by the IOTC.

In purely legal terms, looking at public international law, good faith is always to be presumed. This is a foundational principle rooted in centuries of practice and codified in Art. 2 (2) of the United Nations Charter. It is thereby binding on not only all UN Member States, but also UN organs. Any State alleging that another State did not act in good faith would have to rebut this presumption of good faith by producing convincing evidence to that effect. In other words, the burden of proof to demonstrate a lack of good faith would have to be discharged by the State claiming said lack of good faith.

This means, in practical terms, that any potential reporting anomalies would have legal consequences originating from a specific situation as the one we witnessed and reported. Ex facto, oritur ius. Consequently, in the remit of IOTC this “fact”, as it happened, should be readily accepted in good faith both by the IOTC Secretariat and by IOTC Contracting Parties and lead to legal consequences and entitlements. Should this not happen, the ensuing course of action would not only run counter to the strong scientific basis presented in this article when it comes to the reporting anomalies of catches.

In the case at hand, although any possible mistakes or error made in terms of reporting catches do not concern the validity of an international treaty in and of itself, it does concern the contents of rights and duties expressed in a treaty, being either the 1995 United Nations Fish Stocks Agreement (UNFSA) or the IOTC constitutive agreement, or both. Reasoning by analogy, this could warrant the application of Article 80 of the 1986 Vienna Convention on the Law of Treaties of International Organizations, which concerns the correction of errors in the texts of treaties. It is worth recalling that the first subsection of this provision reads as follows:

1. Where, after the authentication of the text of a treaty, the signatory States and international organizations and the contracting States and contracting organizations are agreed that it contains an error, the error shall, unless those States and organizations decide upon some other means of correction, be corrected:

(a)

by having the appropriate correction made in the text and causing the correction to be initialed by duly authorized representatives;

(b)

by executing or exchanging an instrument or instruments setting out the correction which it has been agreed to make; or

(c)

by executing a corrected text of the whole treaty by the same procedure as in the case of the original text.

Following an exchange of instruments clarifying and correcting the situation as it happened, we postulate that UAE could claim its entitlement to a future allocation of a relevant quota by IOTC based on revised data in due course. No additional formalities of the kind foreseen by Art. 80 (1) (c) would be necessary, as the error does not concern the text of the treaty in question. Nevertheless, based both on the cardinal principle of good faith expounded above, should the IOTC Secretariat or any of its Contracting Parties wish to contest the hypothetical situation that might be presented by the UAE, they would have to support their position with convincing evidence. It should however be specified that any potential application of the abovementioned Article 80 by analogy would be displaced by the application of a lex specialis doctrine, in the event that the relevant RFMO had defined rules on how to address reporting errors of the kind discussed in this article. The lex specialis doctrine requires that where there is a conflict between a general rule of international law and one that is specifically designed or designated to address the details of a given case the latter is to prevail.

IOTC Resolution 10/01, adopted in 2010, requires the development of a quota allocation system (or any other relevant measure) for the sound management of species falling under the competence of the IOTC. To achieve this result, the IOTC created its Technical Committee on Allocation Criteria (TCAC). As of January 2025, the IOTC’s TCAC has convened thirteen formal meetings and one informal meeting. These meetings have not yet produced a final agreement on allocation criteria, but they have yielded several draft proposals for an allocation regime.

The most recent and publicly available of these proposals is the Chair’s draft proposal for an allocation regime (V7). This proposal was presented at the thirteenth meeting of the TCAC, which met in a hybrid capacity from 21 to 24 October 2024 in Bangkok, Thailand. Draft Article 6.9 of the Chair’s draft proposal for an allocation regime (V7) is entitled “Correction for Extenuating Circumstances” and reads as follows:

(1) A CPC whose ability to fish for stocks covered by this Resolution has been severely restrained or impeded by extenuating circumstances may seek to have its allocation for that stock corrected/adjusted or have it, or a portion, carried forward. The CPC shall submit a formal documented request to the IOTC Secretariat at least 60 days before the Commission annual meeting for a decision of the Commission.

(2) Extenuating Circumstances include but are not limited to:

(a)

engagement in war or other military conflicts;

(b)

engagement in civil conflicts;

(c)

wide spread piracy in the fishing area;

(d)

environmental disasters, such as a tsunami;

(e)

spatio-temporal impacts of climate change on fishing once adequate and stable indicators are adopted by the Commission based on advice from the Scientific Committee; and

(f)

global pandemic, which have directly affected the fishing capacity of CPC.

This draft article does not appear to cover scenarios where Contracting Parties and cooperating non-Contracting Parties are trying to have a potential allocation for that stock corrected after having failed to address reporting anomalies. The provision focuses rather on situations where “the ability to fish for stocks […] has been severely restrained or impeded by extenuating circumstances.”

As outlined above this failure has been due to a mix of limited capacity to distinguish one species from the other and the landing site monitoring process and is therefore not directly covered by this provision. In addition, because draft Article 6.9 does therefore not pertain to the situation faced by the UAE at it presently stands, applying the lex specialis doctrine to this case would not seem to be entirely appropriate. As the Chair’s draft proposal for an allocation regime (V7) has not yet been agreed by IOTC, the UAE might also consider requesting observer status to participate in future TCAC meetings and present a request that Article 6.9 is broadened so as to include also the case of catch misreporting among the various scenarios it lists.

Ultimately, in light of information provided in this article as well as of the legal basis for action, we conclude that the UAE would be in position to advance a claim to a quota for tuna and tuna like species managed by IOTC in the future while referring to its historical catches. Fishing rights based on historical catches have been recognized by several international courts and tribunals (ex plurimis, Territorial Sovereignty and Scope of the Dispute (Eritrea/Yemen), Award of 9 October 1998; The Republic of the Philippines v. the People’s Republic of China, PCA Case No 2013-19 in the matter of the South China Arbitration, Award of 12 July 2016 (merits); Award between the United States and the United Kingdom relating to the rights of jurisdiction of the United States in the Bering Sea and the preservation of fur seals of 15 August 1893), including the International Court of Justice (Fisheries case (United Kingdom v. Norway), [1951] ICJ Rep. 138.). These are non-exclusive customary access rights that attach both to the State of the nationality of the individuals and to the individuals of the relevant community of fishers.

The key requirements for the establishment of these rights are: consistent and clearly-defined fishing activities or ‘common patterns of behavior’, often linked with local traditions and customs, which are performed uninterrupted and unobjected for a lengthy period of time. Relying on the reasoning of the Eritrea/Yemen award, the arbitral tribunal in the South China Sea case noted that these rights extended to artisanal fishing, but not to industrial fishing that departs radically from traditional practices. While these rights are not restricted to indigenous peoples, this would seemingly exclude the formation of traditional fishing rights linked to modern distant-water fishing fleets.

The evidence we collected supports the recognition of UAE historical catches leading to the attribution of fishing rights on tuna and tuna-like species. This provides in turn a strong foundation for the UAE to advocate for a fair and representative quota allocation within the IOTC framework, reflecting its long-standing engagement in these fisheries and its commitment to ensuring their sustainability. Providing convincing evidence to claim such rights has already been done and can be done again in the future, based on previous practice.

The Eritrea/Yemen tribunal referred to ‘the most reliable historical and geographical sources, both ancient and modern’, to ‘a variety of sources’ supporting these ‘historical facts’ as ‘submitted in evidence during the arbitral proceedings’ and specifically referred to books on the history of the area and the Red Sea evidencing these activities. On what constitutes “a lengthy period of time”, the tribunal in the Barbados/Trinidad and Tobago arbitration rejected the existence of a purported traditional fishing right based on only eight years of evidence (Arbitration between Barbados and the Republic of Trinidad and Tobago, relating to the delimitation of the exclusive economic zone and the continental shelf between them, decision of 11 April 2006). Judging from the evidence on which the South China Sea and Eritrea/Yemen tribunals relied on to find the existence of these rights, it appears that the relevant practice should span decades and this appears to be the case with the UAE and the catches reported in this articles.

6. Conclusions

In light of the historical evidence, reconstructed catch data, and biological and governance considerations discussed in this paper, it is clear that the UAE holds a legitimate claim to recognition of its historical engagement in tuna and tuna-like fisheries. The analysis highlights both the ecological basis and the policy relevance of correcting past misidentifications and omissions in official records, which have limited the UAE’s visibility within the IOTC framework.

This recognition is not only important for ensuring equitable quota allocation in the future, but also for reinforcing the UAE’s role as a responsible actor in regional and international fisheries governance. By aligning scientific evidence with legal and institutional processes, the UAE can advance its national interest while contributing to the credibility and effectiveness of the IOTC system as a whole.

To further strengthen data quality and reporting, we recommend the adoption of standardized species identification protocols across national and regional systems. These should include harmonized field guides, periodic training, and, where feasible, the integration of molecular tools (e.g., DNA barcoding) for validation. Such measures would help minimize misidentification and ensure greater consistency across reporting frameworks.

Based on the analysis above, the best course of action for UAE could be to communicate with the IOTC Secretariat, as well as with the FAO, so that a process can be initiated to have corresponding official database records revised and to enable the conditions for a quota of species concerned by this revision to be in the future allocated to the UAE by the IOTC. As the IOTC has not yet elaborated a binding regime on quota allocation, UAE might consider to promptly proceed to submit information based on revised data to the IOTC Secretariat in order to assert its entitlement to any future quota of tuna and tuna like species, including all required procedural steps entailed, such as seeking cooperating non-Contracting Party status with the IOTC. This would allow the UAE to benefit from the very beginning from the future quota allocation system under the IOTC in relation to tuna and tuna like species which it has been historically harvesting.

Taking such steps would not only safeguard the UAE’s historical rights but also position the country as a proactive partner in shaping a sustainable and equitable future for tuna fisheries under the IOTC.