Nathalie Bodin

Data for Ecosystem and Ocean Health (DEAL)

The Republic of Seychelles is located in Western-Central Indian Ocean, and marine capture fisheries play a key role in the country’s economic and social life in terms of food security, employment, and cultural identity. The Seychellois are among the highest per capita fish-consuming people in the world, with a high reliance on fish for protein. How...

Trace elements and δ¹⁵N values were analysed in micronekton (crustaceans, fishes and squids) sampled in the south-western Indian Ocean. Myctophids were associated with high concentrations of arsenic at La Pérouse and MAD-Ridge seamounts, and with lead and manganese at MAD-Ridge and in the Mozambique Channel. The difference in cadmium, copper and zi...

The concentrations of 13 trace elements were determined in 1032 muscles of 54 small-scale fisheries species collected from the Seychelles waters between 2013 and 2019. Overall, profiles were dominated by zinc (Zn) > arsenic (As) > iron (Fe) > copper (Cu) > selenium (Se), with the spiny lobsters, spanner crab and octopus exhibiting the highest level...

The Republic of Seychelles is one of six African Small Island Developing States (SIDS) and has a marine-based economy reliant on fisheries and international tourism. Seychelles has been flagged by the United Nations as highly vulnerable to climate change. Climatic threats are compounded with population declines of key fishery species. A progressive...

Background - Along with the development of the tropical tuna purse-seine fishery from the 1960s in the Atlantic Ocean and from the 1980s in the Indian Ocean, many projects and studies have been conducted to improve knowledge about the biology, migrations and dynamics of the stocks of target and non-target (i.e. bycatch) species taken in these fishe...

Climate change is transforming coral reefs, threatening supply of essential dietary micronutrients from small-scale fisheries to tropical coastal communities. Yet the nutritional value of reef fisheries and climate impacts on micronutrient availability remain unclear, hindering efforts to sustain food and nutrition security. Here, we measure nutrie...

Mercury (Hg) concentrations and stable isotope values (δ13C and δ15N) were investigated in micronekton collected from La Pérouse and MAD-Ridge seamounts, Reunion Island and the southern Mozambique Channel. Organisms occupying epipelagic habitats showed lower Hg concentrations relative to deeper dwelling benthopelagic ones. Increasing Hg concentrati...

Concentrations, profiles and muscle-liver distribution of halogenated natural products (HNPs) and anthropogenic persistent organic pollutants (POPs) were investigated in five large pelagic fish species and one smaller planktivore fish species from the Western Indian Ocean. Analysis of swordfish muscle from the Seychelles revealed the predominance o...

La sécurité alimentaire, qui est la garantie de l’approvisionnement et de la qualité des aliments tout en gérant les ressources de manière durable, est intrinsèquement liée à la connaissance de la biologie et l’écologie des espèces consommées. Dans un contexte de dérèglement climatique menaçant la salubrité des produits de la mer, il est donc néces...

Tunas are among the most traded and valued fish species, and good traceability of tuna products in the world market is needed to protect both consumers and tuna stocks. To that purpose, high-resolution proton nuclear magnetic resonance (¹H NMR) spectroscopy combined with multivariate data analysis was used to investigate the molecular components of...

Understanding ecosystem service change necessitates an understanding of the social and ecological dimensions of ecosystem services and how they contribute to the well‐being of different people. These empirical research gaps persist across the tropics and in coastal environments, posing a challenge for small island states that depend on ecosystem se...

Tropical tunas are largely consumed worldwide, providing major nutritional benefits to humans, but also representing the main exposure to methylmercury, a potent neurotoxin that biomagnifies along food webs. The combination of ecological tracers (nitrogen and carbon stable isotopes, δ¹⁵N and δ¹³C) to mercury concentrations in tunas is scarce yet cr...

Tuna factory purchases data constitute a complementary source of independent information in support of IOTC tuna fisheries analyses. This novel data source is aimed to be used routinely for future assessment and to cross-verify and reduce uncertainties in the currently available statistical data (in particular for what concerns species composition)...

Spiny lobsters (P. penicillatus, P. longipes and P. versicolor) are heavily dependent on habitats like coral reefs, known to be highly vulnerable to climate change-driven degradation. Yet, little is known about their trophic ecology and their adaptive capacity to a changing environment. In this study, we used fatty acids (FA) analysed in the hepato...

Spiny lobsters (Panulirus longipes, P. penicillatus and P. versicolor) are an important resource in Seychelles, where they inhabit coastal carbonate and granite reefs that have been impacted by multiple coral bleaching events over the past two decades. Little is known about their biology and ecology in this region. Interspecific competition for foo...

The little information available on fuel consumption and emissions by high seas tuna fisheries indicates that the global tuna fleet may have consumed about 2.5 Mt of fuel in 2009, resulting in the production of about 9 Mt of CO2-equivalent greenhouse gases (GHGs), i.e., about 4.5-5% of the global fishing fleet emissions. We developed a model of ann...

Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (δ15N) are primarily used to estimate trophic position while carbon is...

How the size of female yellowfin tuna (Thunnus albacares) affects their spawning capability and fecundity is still an open and unresolved question due to the difficulties in investigating these complex effects in highly migratory pelagic marine fish species. However, this information is key to understanding the reproductive potential and resilience...

A total of 5478 fishes were sampled between 2009 and 2020 to assess length–weight, length–length and weight–weight relationships in 39 marine species from 10 families caught in the Seychelles waters by the artisanal fishery. Two types of length (total length TL, fork length FL) and three types of weight (whole weight WT, gutted weight GW and gilled...

Albacore tuna (Thunnus alalunga) is an important target of tuna fisheries in the Atlantic and Indian Oceans. The commercial catch of albacore is the highest globally among all temperate tuna species, contributing around 6% in weight to global tuna catches over the last decade. The accurate assessment and management of this heavily exploited resourc...

Swordfish (Xiphias gladius) is a major marine resource of high economic value to industrial and artisanal fisheries. As a top predator with a long lifespan, it is prone to accumulate high levels of contaminants. The bioaccumulation of a wide range of both legacy and emerging persistent organic contaminants was investigated in the muscle, liver and...

The diet of albacore Thunnus alalunga from their spawning ground in the waters of Mauritius was investigated. The stomach contents of 249 albacore individuals, caught by industrial longliners and artisanal fishers, was analysed, and the dominant prey taxa were selected for lipid and fatty acid (FA) analysis. The FA profiles of prey were compared wi...

Tuna and billfish are large pelagic fish of ecological importance in open oceans. As top predators with a long lifespan, they are prone to exposure to various contaminants such as persistent organic pollutants (POPs) and contaminants of emerging concern. In this study, three pollutant families were investigated, including polychlorinated biphenyls...

Fatty acids (FAs) are a common tool to investigate trophic ecology due to the transfer of several FAs across trophic levels. However, some dietary FAs are modified to maintain homeostasis. Therefore, for trophic purposes, there is the question of whether to separate lipid fractions into fatty acids that are physiologically regulated (structural, po...

The SEYFISH project (Nutrients and Contaminants in Seychelles fisheries resources) is led by the Seychelles Fishing Authority (SFA) and co-funded by the French National Research Institute for Sustainable Development (IRD) and the SFA. The Seychelles are considered as a hotspot of marine biodiversity, with emblematic ecosystems including coral reef...

Albacore tuna (Thunnus alalunga) is a highly economically important species in the western Indian Ocean. However, knowledge of its ecological and nutritional characteristics, essential for proper management of the species, is lacking in the region. The trophodynamics of the Indian Ocean albacore was thus examined using known fatty acid trophic mark...

A global dataset of carbon stable isotope (δ13C) values from yellowfin, bigeye, and albacore tuna muscle tissue (n = 4275) was used to develop a novel tool to infer broad-scale movement and residency patterns of these highly mobile marine predators. This tool was coupled with environmental models and lipid content (C:N ratio) of tuna muscle tissues...

The trophic ecology of albacore tuna in the western Indian Ocean and adjacent Atlantic waters based on stomach content analysis, using a reconstituted length and weight of prey approach, was studied. From a total of 686 non-empty stomachs, collected between 2001 and 2015 across three biogeographic provinces, we described the diet composition of alb...

In the Seychelles, spiny lobsters are one of the main resources for artisanal fisheries. Although policies have been established, stocks have kept decreasing in the recent years, and the reason for this stock decline remains unidentified. Diet is a major component of ecological niche, especially for sympatric species like Seychelles spiny lobsters,...

Seafood is known to be a healthy food source for humans, as it provides numerous essential macro- and micro-nutrients. However, seafood is also identified in human diet as a major exposure route to toxic chemical contaminants , such as persistent organic pollutants (POPs) and non-essential trace elements. Fish are indeed exposed to these chemicals...

Seafood is known to be a healthy food source for humans, as it provides numerous essential macro- and micro-nutrients. However, seafood is also identified in human diet as a major exposure route to toxic chemical contaminants , such as persistent organic pollutants (POPs) and non-essential trace elements. Fish are indeed exposed to these chemicals...

United Nations declaration “Transforming our World: The 2030 Agenda for Sustainable Development” and its seventeen sustainable Development Goals (SDG), emphasises the need to achieve food security and improved nutrition for all in a sustainable manner. The continual rapid increase in the global population, coupled with increased industrial food pro...

Seafood is known to be a healthy food source for humans, as it provides numerous essential macro- and micro-nutrients. However, seafood is also identified in human diet as a major exposure route to toxic chemical contaminants , such as persistent organic pollutants (POPs) and non-essential trace elements. Fish are indeed exposed to these chemicals...

Considerable uncertainty remains into how increasing atmospheric CO2 and anthropogenic climate changes are affecting open‐ocean marine ecosystems from phytoplankton to top predators. Biological time series data are thus urgently needed for the world’s oceans. Here, we use the carbon stable isotope composition of tuna to provide a first insight into...

The Northern Mozambique Channel is a treasure of unique oceanography, rich coral reefs, migrating tuna, and whales, bounded by the Comoros, France, Madagascar, Mozambique, Seychelles, and Tanzania. Its living resources are relatively intact and of great importance for food and livelihood security and the developing economies of its surrounding coun...

The Northern Mozambique Channel (NMC) is a tropical area of ~ 1 million km² where pelagic fisheries supply proteins to more than 9 million people living in Comoros, Mayotte, and along the coasts of Mozambique, Tanzania and Madagascar. Although uncertain, statistics suggest that about 20,000 mt of tropical tuna and other pelagic fish are annually ca...

As long lived top predator in marine pelagic ecosystems, billfish such as swordfish bioaccumulate high levels of mercury (Hg) with reported concentrations higher than in their fellows, tuna and tuna-like species, and exceeding from time to time the recommended safety limits. Billfish are thus among the more appropriate bioindicator species for moni...

Oral presentation on a global-scale analysis of trophic interactions in co-occurring tropical tuna using stable isotope analyses

As long lived top predator in marine pelagic ecosystems, billfish such as swordfish bioaccumulate high levels of mercury (Hg) with reported concentrations higher than in their fellows, tuna and tuna-like species, and exceeding from time to time the recommended safety limits. Billfish are thus among the more appropriate bioindicator species for moni...

The SEYFISH project (Nutrients and Contaminants in Seychelles fisheries resources) is led by the Seychelles Fishing Authority (SFA) and co-funded by the French National Research Institute for Sustainable Development (IRD) and the SFA. The Seychelles are considered as a hotspot of marine biodiversity, with emblematic ecosystems including coral reef...

We investigated the effect of the freeze-drying process and rehydration on the lipid class composition of fish and shellfish tissues, and the effect of short- and long-term storage of freeze-dried samples on the FA composition of yellowfin tuna muscle. We found no effect of rehydration prior to extraction on the lipid class composition of both fish...

Various protocols are currently used to study marine lipids, but there is a growing interest in working on dry samples that are easier to transport. However, reference protocols are still lacking for dry samples. In order to make recommendations on this use, lipid classes and fatty acids (FA) obtained from six analytical protocols using two differe...

Aim We examined potential environmental drivers of broad‐scale spatial patterns in the trophic structure of marine ecosystems as represented by nitrogen stable isotopes in globally distributed marine predators. Additionally, we assessed the effects of spatial scale on the predictive capabilities of environmental variables. Location Global oceans....

In the Gulf of Guinea, bigeye Thunnus obesus (BET) and yellowfin tuna Thunnus albacares (YFT) are important for commercial fisheries and play a prominent ecological role as top predators. Using fatty acid profiles and carbon and nitrogen stable isotopes we examined their niche partitioning in this understudied region. Niche overlap was high (>70%),...

Lipid composition in the reproductive and somatic tissues were investigated for female albacore tuna, Thunnus alalunga, in the western Indian Ocean, between latitude 18-21°S and longitude 56-60°E, from January 2014 to March 2015. Highest total lipids (TL) were found in the gonads of spawning-capable females (SCP) (mainly phospholipids, PL, triacylg...

Tuna are marine apex predators that inhabit the tropical and sub-tropical waters of the Indian Ocean where they support socially and economically important fisheries. Key component of pelagic communities, tuna are bioindicator species of anthropogenic and climate-induced changes through modifications of the structure and related energy-flow of food...

Yellowfin tuna, Thunnus albacares, is one of the most important seafood commodities in the world. Despite its great biological and economic importance, conflicting evidence arises from classical genetic and tagging studies concerning the yellowfin tuna population structure at local and global oceanic scales. Access to more powerful and cost effecti...

In 2017, a first attempt has been done to describe some IOTC datasets (dealing with stock assessment model outputs Nieblas et al. [2017] and fishing catch, effort, size class Barde et al. [2017]). Since, the method has been improved to make it more generic and reusable with other data sources. This paper gives an update of this work and focuses on...

Yellowfin tuna (Thunnus albacares; YFT) is an apex marine predator inhabiting tropical and sub-tropical pelagic waters. It supports the second largest tuna fishery in the world. Here, we review the available literature on YFT to provide a detailed overview of the current knowledge of its biology, ecology, fisheries status, stock structure and manag...

Predator populations are in decline globally. Exploitation, as well as habitat degradation and associated changes in prey availability are key drivers of this process of trophic downgrading. In the short term, longevity and dietary adaptability of large‐bodied consumers can mask potential sublethal effects of a changing prey base, producing a delay...

We describe the methodological approach developed to collect and manage a large range of biological and ecological data for large pelagic species sampled throughout several routine monitoring and research programs conducted in the Indian Ocean in the last decades. To cover the large habitats of occurrence of tuna and tuna-like species, collaboratio...

The reproductive biology of albacore tuna, Thunnus alalunga, in the western Indian Ocean was examined through analysis of the sex ratio, spawning season, length-at-maturity (L50), spawning frequency and fecundity. From 2013 to 2015, a total of 923 female and 867 male albacore were sampled. A bias in sex ratio was found in favor of females with fork...

Number of fish per oocyte developmental stage or ovarian phase by 3-cm interval fork length (LF) used for maturity analysis of female albacore tuna in the western Indian Ocean based on histology. In the first criterion, immature fish were viewed as containing the most advanced oocyte stage the primary growth (PG) stage, cortical alveolar (CA) and v...

Morphometric data for tropical tunas caught with purse seine have been collected in the Indian Ocean over the last decades through routine sampling at processing factories and research projects. We estimate the parameters of allometric relationships between fork length (cm) and total weight (kg) for bigeye (Thunnus obesus), skipjack (Katsuwonus pel...

Sex-ratio, size at maturity, spawning period and fecundity of bigeye tuna (Thunnus obesus) in the 1 western Indian Ocean. 2 3 1, Abstract 12 Opportunistic sampling of bigeye tuna (Thunnus obesus; BET) was conducted in the western Indian 13 Ocean from 2010 to 2015 to study important reproductive traits (i.e., sex-ratio, size at maturity, 14 spawning...

The lipid composition of somatic and reproductive tissues was determined for female skipjack tuna Katsuwonus pelamis caught in the western Indian Ocean between latitude 10° N and 20° S and longitude 40° and 70° E. The highest total lipid (TL) contents were in the liver and gonads, with white muscle levels approximately three-fold lower. Three lipid...

The GERMON project had several aims i) to understand the populations’ structure between albacore tuna southwest of the Indian Ocean and southeast Atlantic, ii) to determine the origin of juveniles observed in South Africa iii) to improve the understanding of the biology field (Size/Size and Size/Weight; reproduction and feeding area; trophic linkag...

This paper provides information on the length-length (fork-length, FL with pectoral length, PL and first dorsal length, LD1) and length-weight relationships of albacore tuna (Thunnus alalunga) in five regions of the Western Indian Ocean. Data were obtained for a total of 923 female and 867 male albacore, caught by different fishing gears, and sampl...