Indian Ocean Tuna Commission Research Articles

Macroeconomic impact of an international fishery regulation on a small island country

This paper examines the macroeconomic impact of regulating tuna fishing on a small island economy that relies heavily on tourism and fishing for its foreign exchange earnings. While there is scientific consensus to limit the use of drifting fish aggregating devices (dFADs) worldwide, there is no agreement on their optimal number at sea. Resolution 23/02, adopted by the Indian Ocean Tuna Commission (IOTC) in February 2023, proposed a 72-day moratorium on dFADs, but this resolution has met with resistance from many contracting parties, including developing countries. To understand the reasons for this resistance, a recursive, multi-sectoral dynamic general equilibrium model is developed for the Republic of Seychelles, a small tuna-dependent country. The model assesses the short- and medium-term macroeconomic impacts of a seasonal dFAD closure for the Indian Ocean tuna fishery. The analysis suggests that a 12% decline in canned tuna exports would result in a −8.8% deviation from the real gross domestic product trend after seven years. Such an impact would have far-reaching effects on the domestic economy, affecting all components of aggregate demand. Consequently, the economy would become more dependent on tourism, which has shown its vulnerability during the recent pandemic crisis. The study highlights the importance of considering social and economic aspects in sustainable fisheries management and provides insights into the potential consequences of dFAD regulations for small island economies.

Bycatch in drift gillnet fisheries: A sink for Indian Ocean cetaceans

AbstractIn 1992, the UN banned the use of large‐scale pelagic driftnets on the high seas (UNGA Resolution 46/215). Three decades later, however, drift gillnets remain one of the primary fishing gears in the Indian Ocean, accounting for approximately 30% of tuna catches in this ocean. Recent estimates indicate that several million small cetaceans have been killed in Indian Ocean gillnets over the past few decades. National agencies and the regional fisheries management organization charged with managing tuna fisheries, the Indian Ocean Tuna Commission, have yet to effectively document the bycatch of small cetaceans in these fisheries. Here, we review current information on cetacean bycatch in Indian Ocean drift gillnets and propose potential solutions to this important conservation issue.

Virtual Voting in rfmos: A Procedural Odyssey at the Indian Ocean Tuna Commission

Abstract This article examines, from the perspective of international institutional law, the variety of procedural problems which arose following an online vote by secret ballot taken by the Indian Ocean Tuna Commission (iotc) in 2021. By providing a detailed case-study of this novel instance of practice and the challenges it represents, this article aims to contribute to a better understanding of the institutional governance and procedural legal framework of regional fisheries management organizations (rfmo s). It first analyses the vote and the challenge to its validity. This article then constructs a taxonomy of the various procedural irregularities that were found to have occurred, the responsibility of institutional actors for their occurrence, and their legal consequences. The final substantive sections of this article examine how the iotc ultimately dealt with the situation and what potential role the available dispute settlement procedures could have had in addressing the discussed procedural irregularities.

Ecological risk assessment in the southern Indian Ocean: Towards better seabird bycatch mitigation

Abstract Fisheries bycatch has been identified as the most serious threat to many seabird species and there is an increasing awareness of the responsibility of fisheries management bodies to include the impact on non‐target species in their management and regulatory frameworks. In 2022, an ecological risk assessment (ERA) for seabirds and fisheries was presented to the Scientific Committee of the Southern Indian Ocean Fisheries Agreement (SIOFA). This ERA identified 32 seabird species that regularly occurred in the SIOFA Area, of which 11 were determined as being at high risk. This high‐risk group included 10 albatross species that have the greatest likelihood of interacting with SIOFA managed fisheries in Subareas 1, 2 and 3b (west of 40° E) where they overlap with the pelagic longline fishery. Although the pelagic longline fishery for Ruvettus pretiosus is the largest fishery under the auspices of SIOFA, in terms of catch and number of vessels, the existing management measures of SIOFA focused on demersal fisheries and did not include any mitigation requirements for pelagic longlines. In response to the outcomes of the ERA, a proposed amendment to SIOFA's management measures was presented by France to the Meeting of Parties of SIOFA and led to the revision of SIOFA's seabird bycatch mitigation measures in respect of pelagic longlines, making them consistent with those agreed by the Indian Ocean Tuna Commission. Regulatory diffusion, the increased likelihood of adoption of regulation by one agency if that regulation has been adopted by another agency, contributed to the relatively rapid transition from the identification of the risk posed by pelagic longline vessels to the change in regulations to address those risks in SIOFA.

Reconstructing past fisheries catches for large pelagic species in the Indian Ocean

Comprehensive catch data are fundamental to support the sustainable management of large pelagic fisheries. However, catch data reported by the Indian Ocean Tuna Commission (IOTC) on behalf of its member countries currently under-represent the extent of these fisheries in the Indian Ocean. We reconstructed fisheries catches of large pelagic species for the Indian Ocean from 1950 to 2020, aiming to improve the comprehensiveness of existing reported data and to provide more ecologically relevant datasets for research and management uses. We reconstructed catches for 42 countries operating five major gear groups (longline, purse seine, gillnet, pole-and-line, and other gears) in the large pelagic fisheries. Reconstructed catches were 30% higher than the data reported by the IOTC. We demonstrated that distant-water fishing fleets historically dominated large-scale industrial fishing but were gradually replaced by fleets flagged to Indian Ocean rim countries. Our results also indicated an average discard rate of ~14% over the 1950-2020 period, primarily attributable to extensive discarding practices associated with longline and gillnet vessels. Reporting over time has improved only for tunas, whereas shark catches still remain under-reported, accounting for 51% of total unreported landings and discards in 2020. We confirmed substantial taxonomic aggregation in the data reported by the IOTC on behalf of its member countries, masking important patterns and trends and further complicating the sustainable management of exploited species in the Indian Ocean. We recommend substantially increased observer coverage and far better and stronger support by all member countries to improve the fisheries statistics in the IOTC.

Effects of Climate Variability on Two Commercial Tuna Species Abundance in the Indian Ocean

Oceanic temperature fluctuations are one of the leading factors affecting marine fish populations. Indian Ocean Dipole (IOD), characterized as the sea surface temperature (SST) anomaly change, is an ocean–atmosphere interactive process causing interannual climate variability in the Indian Ocean. Influences of the IOD on the tuna catch rates are supported by previous research. Yet, there remains limited information about the impacts on the abundance of tuna stocks. In this study, we used the standardized Catch Per Unit Effort (CPUE) index to present the stock abundance and compared the effects of the IOD on the bigeye tuna (Thunnus obesus) and yellowfin tuna (Thunnus albacares) among different management areas of the Indian Ocean Tuna Commission (IOTC). Results show significant correlations between IOD events on both species’ abundance in the tropical western Indian Ocean. However, in the tropical eastern Indian Ocean and the southern Indian Ocean, neither bigeye nor yellowfin tuna abundances were significantly correlated by the IOD. For the whole Indian Ocean, IOD was significantly correlated uniquely with the yellowfin tuna abundance. Our results emphasized the importance of evaluating the climate variability effects over fisheries abundance species by species and per fishing areas analyses.

David against Goliath? The rise of coastal states at the Indian Ocean Tuna commission

Tuna regional fisheries management organizations (RFMOs) have long suffered from the domination of distant water fishing nations (DWFNs) in decision-making processes. The Indian Ocean Tuna Commission (IOTC) is no exception. In recent years, coastal states of the Indian Ocean (IO) have tried to change this dynamic - led by countries like the Maldives, Kenya, South Africa, and Australia - to deliver greater benefits to the region, including East Africa. These countries are gathered under the informal group of G16 and have increasingly improved their involvement in the IOTC. Here, we ask how the rise of the G16 benefited coastal States through participation and collective understanding in the Indian Ocean. To do this, we analyzed proposals submitted by the G16 for conservation and management measures and the participant lists of the Commission meetings in the past ten years. Our results show that, individually and collectively, the G16 has played a significant role in shaping the IOTC’s rules. The coastal States have established a good representation, with only a handful of Members absent in some years. Unveiling the efforts of coastal countries is essential to guide further capacity building in the region in terms of negotiations. We also call for international oversight of the actions of DWFNs, such as the EU, whose efforts often differ markedly from their claims of being sustainability champions. The G16’s work is essential to keep the coastal States of the Indian Ocean in the driver’s seat for managing Indian Ocean fisheries to benefit future generations.

Indian Ocean Tuna Commission Climate Change Resolution: A quiet interaction of ocean and climate change legal regimes

Regional Fisheries Management Organisations (RFMOs) are struggling to take appropriate actions for climate change adaptation and mitigation. Recent reports of the Intergovernmental Panel on Climate Change highlighted the impacts of climate change on marine ecosystems and fisheries, and at the same time, the Indian Ocean Tuna Commission (IOTC) recently adopted a legally binding Resolution on climate change. This article briefly analyses the main provisions of the Resolution. It also highlights the importance of this Resolution as an example of the interaction between ocean and climate change legal regimes. This article argues that the Resolution is an initiative in the right direction. The IOTC needs to take proactive steps to implement the Resolution considering the challenges the RFMOs face in climate action generally.

Subsidies and allocation: A legacy of distortion and intergenerational loss

One of the greatest threats to the conservation of transboundary stocks is the failure of Regional Fisheries Management Organizations (RFMOs) to equitably allocate future fishing opportunities. Across RFMOs, catch history remains the principal criterion for catch allocations, despite being recognized as a critical barrier to governance stability. This paper examines if and how subsidies have driven catch histories, thereby perpetuating the legacy of unfair resource competition between distant water fishing nations (DWFNs) and coastal States, and how this affects ongoing allocation negotiations in the Indian Ocean Tuna Commission (IOTC). Using limited publicly available data on subsidies to Indian Ocean tuna fleets, we show that subsidies have inflated catch histories of many DWFN's. As long as historical catch remains the key allocation criterion, future fishing opportunities will continue to be skewed in favor of DWFNs, in turn marginalizing half of the IOTC member States, which collectively account for a paltry 4% of the current catch. Without better transparency in past subsidies data, accounting for this distortion will be difficult. We provide alternative allocation options for consideration, with our analysis showing that re-attributing DWFN catch to the coastal State in whose waters it was caught may begin to alleviate this historical injustice.

Analysis of At-Haulback Mortality and Influencing Factors of Indian Ocean Swordfish (Xiphias gladius)

The at-haulback mortality of swordfish (Xiphias gladius), a highly migratory fish, in the Indian Ocean during tuna longline fishery is a concern of the Indian Ocean Tuna Commission Fisheries Management. We obtained the data of 1144 swordfish recorded in 1925 operations in the Indian Ocean by Chinese tuna longline observers from 2012–2018. A generalized linear model was used to analyze the at-haulback mortality of swordfish and the potential influencing factors. The overall mortality rate of swordfish was 64.0%, and the average female size was 166.3 cm (SD = 32.5 cm), with an observed at-haulback mortality rate of 64.3%. The average male size was 155.1 cm (SD = 25.6 cm), which was smaller than females. The observed at-haulback mortality rate was 63.6%. No significant difference was observed between the sexes. Quarter, longitude, hook type, and Lower Jaw-Fork Length (LJFL) had a significant effect on the at-haulback condition when fish were retrieved onboard. Longitude and LJFL had a significant effect on the at-haulback mortality of swordfish. When the capture position was closer to the east, the at-haulback mortality decreased and LJFL increased. The interaction term of hook type and LJFL had a significant effect on at-haulback mortality. When using the circle hook and other hook types, the greater the LFJL, the greater the mortality rate; the opposite was true for Japanese tuna hooks. We provide information for understanding the at-haulback mortality of swordfish bycatch by Chinese tuna longline fishing fleets in the Indian Ocean and its influencing factors, which will help the future conservation and management of swordfish.

Status and challenges for sustainable billfish fisheries in the Western Indian Ocean.

Billfish species (families Istiophoridae and Xiphiidae) are caught in artisanal, recreational, and commercial fisheries throughout the Western Indian Ocean region. However, data and information on the interactions among these fisheries and the ecology of billfish in the WIO are not well understood. Using an in-depth analysis of peer-reviewed articles, grey literature, observation studies, and authors’ insider knowledge, we summarize the current state of knowledge on billfish fisheries in 10 countries. To describe historical and current trends, we examined fisheries statistics from governmental and non-governmental agencies, sportfishing clubs’ reports, diaries of sportfishing captains, and the catch and effort databases of the Indian Ocean Tuna Commission. We highlight two key points. First, billfish fisheries in the Western Indian Ocean are highly diverse, comprising two distinct segments—coastal and oceanic. However, data are poor for most countries with significant gaps in information especially for sport and artisanal fisheries. Second, the evidence assembled showed that billfish species have immense social, cultural, and economic value. Swordfish are targeted by both large-scale and semi-industrial fisheries, while other billfish species, particularly marlin, are highly sought after by sport fisheries in most countries. Our paper provides a comprehensive review of billfish fisheries and available information in the context of the WIO underscoring the need to strengthen data collection and reporting, citizen science, and collaborative sustainable development and management of billfish.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11160-022-09725-8.

Environmental controls of billfish species in the Indian Ocean and implications for their management and conservation

AbstractBackground and aimBillfish are epipelagic marine predators facing increasing pressures such as overfishing and rising global temperatures. Overfishing is a major concern, as they are caught by industrial longline fishers targeting tuna. Billfish are targeted by multiple fishing sectors, which provides food, socio‐economic and cultural benefits. To support effective billfish management and conservation, it is essential to understand their spatial distribution and the environmental factors that may influence it.LocationThe focus of this study is the Indian Ocean (IO), where there are gaps in understanding the interactions between fisheries and billfish distribution. Three of six billfish species are at risk from overfishing. Therefore, determining their distribution is crucial to their management and conservation.MethodsUsing Ocean Biogeographic Information System (OBIS) occurrence data, Indian Ocean Tuna Commission (IOTC) catch data, and environmental covariates, we applied species distribution models to investigate the spatial extent of the realized niches of six billfish species in the IO. We also determined the role and relative importance of environmental drivers. Moreover, we evaluated the association between species’ spatial distribution and the fishing effort distribution.ResultsWe found niche partitioning and overlap among the six species identified spatial distribution, with higher species richness in the northern region of the IO and off the East coast of Africa. Temperature, mixed layer depth and salinity were identified as the most important predictors of species distribution, with moderately warm and stable environments preferred by most billfish species. Areas with high species richness and high fishing effort overlap were primarily found in the Areas Beyond National Jurisdiction (ABNJ). In contrast, areas with high species diversity richness and low fishing effort were found mainly in the Exclusive Economic Zone (EEZ).Main conclusionSpatial overlap between fishing effort and billfish projected distribution suggests inadvertent fishing pressure on billfish populations as they are caught together with targeted tuna. Spatial distribution transcends maritime zones, reinforcing a need to formulate effective management policies for marine areas beyond national jurisdictions.

Scientific Research and Its Influence in Decision-Making of Tuna Regional Fisheries Management Organizations: Case Studies in the Atlantic Ocean and Indian Ocean

Scientific research has played an important role in the conservation and management of high seas fisheries resources since the adoption and entry into the force of the 1982 United Nations Convention on the Law of the Sea (UNCLOS). In addition, regional fisheries management organizations (RFMOs) have become the most important platform in addressing fisheries-related issues under the contemporary international fisheries legal regime, which also includes the responsibility to ensure that their decisions have to properly incorporate recommendations of scientific research into their decisions. This paper aims to analyze, from a legal aspect, how scientific research plays its role in the formation and adoption of conservation and management measures (CMMs) in RFMOs and finds that scientific research has become an essential and integral part of both International Commission on the Conservation of Atlantic Tunas (ICCAT) and the Indian Ocean Tuna Commission (IOTC). Although, on some occasions, these recommendations will not be totally accepted and adopted by the Commission due to social, economic, and political considerations, the results from scientific research have become the basis for issues related to conservation and management measures discussed in RFMOs and will be more influential if the Scientific Committee provides a more concrete recommendation to the Commission.

Common but differentiated rights and responsibilities in tuna fisheries management

AbstractThe UN Law of the Sea Convention (LOSC) and one of the implementing agreements of the Convention—the UN Fish Stocks Agreement (UNFSA)—mandates all states to cooperate in the management of highly migratory and straddling fish stocks. In doing so, the UNFSA specifies that the special requirements of developing states need to be taken into account. To date, except in the Western and Central Pacific Fisheries Commission (WCPFC), there is no formal mechanism to identify these differential responsibilities in tuna regional fisheries management organizations (RFMOs). Although some conservation and management measures exempt small‐scale and artisanal fishing vessels, power imbalances within RFMOs tend to favour the interests of more developed and larger distant water fishing nations over those of small developing coastal states. To facilitate the implementation of differentiated responsibilities as mandated in UNFSA, in this study we develop a three‐step framework that could be applied in the case of new conservation and management measure proposals. The framework has also been tested based on two developing countries and compared with a developed state in the Indian Ocean Tuna Commission and the adopted resolutions in 2019. To facilitate better transparency and equitable decision‐making processes across RFMOs, this framework could be adapted based on member states' fisheries management objectives and target and non‐target species.

Disentangling politics in the Indian Ocean Tuna Commission

Regional Fisheries Management Organizations (RFMOs) require countries with diverse objectives, aspirations, and interests to cooperate to sustainably manage transboundary fish stocks. These organizations are often subjected and are held responsible for overfishing, slow management responses and failure to follow scientific evidence. Disappointing performance is often attributed to a ‘black box of politics’ or a ‘lack of political will’ among members. Disentangling the politics and motivations behind RFMO decision-making is crucial in understanding how they function and why they might fail. Here, we analysed eight socio-economic indicators to identify the priorities of 30 members of the Indian Ocean Tuna Commission (IOTC) and conducted 41 interviews with key stakeholders to understand their engagement strategies. This study also focuses on how different actors engage, negotiate, and leverage their political power in the development and adoption of Conservation and Management Measure proposals. Our results demonstrate that socio-economic interests, political and economic influences, and management priorities converge on IOTC members to inform their negotiation positions. Even though individual domestic interests drive the decisions taken by members, we identified 34 unique entities that influence member decisions in the IOTC. Additionally, members with tuna interests influence other members, in particular developing States. Further, the decisions by members are not necessarily based on tuna management but tied to sovereignty, foreign aid, and other development aspects outside the realm of the RFMO decision-making. Our findings also indicate the importance of defining clear ownership of the resource and the critical role of various stakeholders.

How the Indian Ocean Tuna Commission Addresses the IUU Fishing Challenge: Is It Working?

How the Indian Ocean Tuna Commission Addresses the IUU Fishing Challenge: Is It Working?

A comparative study on habitat models for adult bigeye tuna in the Indian Ocean based on gridded tuna longline fishery data

AbstractUsing the gridded fishery data to estimate the habitat preferences of bigeye tuna (Thunnus obesus) in the Indian Ocean is challenging, as it is still not clear what type of model is appropriate to make reliable habitat predictions. In this study, we tested two classes of habitat models: Generalized Additive Models (including Gaussian distribution GAM, Poisson distribution GAM, Negative Binomial distribution GAM, Tweedie class distribution GAM, and Zero‐inflated distribution GAM) and Maximum Entropy Model (MaxEnt) for forecasting the habitat of bigeye tuna in the Indian Ocean, using the 5°×5° monthly gridded fishery data from 2008 to 2015 provided by Indian Ocean Tuna Commission (IOTC) and the environmental factors (i.e., the vertical temperature, salinity, dissolved oxygen concentration, thermocline depth, vertical shear of ocean current, concentration of sea surface chlorophyll‐a (chl‐a), and the eddy kinetic energy (EKE)). We compared the models’ fitting ability, predictive performance, predicted results, and the ecological interpretation within the models. The results showed (1) GAMs provided better model fit and predictive performance than MaxEnt; (2) GA‐GAM showed the best model fit performance by using the log transformation of the standardized CPUE as response variable; (3) TW‐GAM was suitable for predicting the habitat of adult bigeye tuna with the over‐dispersed fishery datasets. (4) Results suggested that the vertical temperature, dissolved oxygen concentration, and thermocline depth could be used as reliable predictors in forecasting the spatial‐temporal distribution of the adult bigeye tuna in the Indian Ocean.

Understanding Barriers in Indian Ocean Tuna Commission Allocation Negotiations on Fishing Opportunities

Tuna Regional Fisheries Management Organizations (RFMOs) have been given an arduous mandate under the legal framework of the United Nations Fish Stocks Agreement. Member states with different interests and objectives are required to cooperate and collaborate on the conservation and management of tuna and tuna-like species, which includes the allocation of fishing opportunities. It is well understood that the main RFMO allocation disagreements are the inability to agree on a total allowable catch, the lack of willingness to accept new members, disagreement on who should bear the conservation burden, and non-compliance with national allocations owning to perceived inequities. Addressing these elements is crucial for any organization if it is to sustain its credibility stability and legitimacy. This paper identifies additional barriers facing an equitable allocation process at the Indian Ocean Tuna Commission (IOTC). These challenges are multi-faceted and include institutional, political, and scientific barriers in the ongoing allocation negotiations, and further inhibit effective negotiation and resolution adoption as a whole. After almost 10 years of negotiations, the process has progressed little, and without agreement on these barriers it will be a challenge to adopt a stable systematic allocation process.

Interactions Between a Large Marine Protected Area, Pelagic Tuna and Associated Fisheries

The efficacy of large marine protected areas (MPA) for the conservation of mobile pelagic species is widely debated. Here, we quantified spatial and temporal trends in standardised catch per unit effort (CPUE) of two target pelagic species, yellowfin (Thunnus albacares) and bigeye tuna (Thunnus obesus) in the Indian Ocean to analyse the impact of the British Indian Ocean Territory (BIOT) MPA’s creation in 2010. We applied generalised additive mixed effects models to historical BIOT longline fishery logbooks and official catch and effort statistics from the Indian Ocean Tuna Commission (IOTC) to standardise CPUEs and to evaluate long-term trends and distribution patterns across the equatorial Indian Ocean. We find that trends in population indices from within BIOT prior to the MPA’s establishment mirror those of the wider Indian Ocean. We also suggest that there may be behavioural plasticity within the yellowfin tuna stock, with some individuals possibly undertaking alternative migration patterns or exhibiting residency behaviour within BIOT. Yet, we find no direct evidence of any improvement in standardised CPUE indices of either species in the area surrounding the BIOT MPA, eight years after its establishment. The average size of yellowfin and bigeye tunas caught both increased after the MPA’s establishment. These patterns were also evident across the equatorial Indian Ocean, suggesting that any MPA effect is in combination with other regional drivers, such as behavioural changes in the fishing fleets in response to the threat of Somali Piracy. We therefore conclude that BIOT MPA may be providing local conservation value to tunas, but it is not significant enough to halt the overall regional decline in yellowfin tuna stocks. Thus, we emphasise that large MPAs should be considered in conjunction with other fishery management regulations and wider regional processes, rather than as a silver bullet, in order to provide the conservation and management benefits needed for mobile species like tunas.

Implementation of the UNCLOS 1982 in Utilization of Highly Migratory Species By Indonesia

Indonesia is one of the producers of tuna and tuna species (tuna, skipjack, and mackerel tuna), which are increasing every year. Its geographical location and area of its many Exclusive Economic Zones (EEZs) bordering many neighboring countries, requires Indonesia to implement the CLS 1982 provisions on far-migratory fish. In this connection, Indonesia implements two forms. Firstly, in the form of legislation, which Indonesia has issued about 17 regulations, starting from the level of the Law to the Ministerial Regulation. Secondly, Indonesia has been active as a member of regional fisheries organizations whose territory borders on the Indonesian EEZ. Consequently, from the issuance of this Ministerial Regulation, Indonesia must carry out fisheries monitoring on board, to meet the higher quality data needs. So that Indonesia is faced with carrying out monitoring on fishing vessels operating in the convention area of the RFMOs, namely the Indian Ocean Tuna Commission, the Commission for Southern Blue Fin Tuna Conservation, and the Central and Western Pacific Fisheries Commission. In order to optimize this implementation, Indonesia needs to prepare officials, facilities, and infrastructure that can support the compliance and enforcement of legislation that has been issued. Indonesia should immediately formulate fisheries policies in the high seas outside the Indonesian EEZ, which involve and benefit Indonesian fishermen.