Hilario Murua

• PhD
• International Seafood Sustainability Foundation

Current efforts to mitigate impacts on threatened elasmobranch species in tuna fisheries focus primarily on best handling and release practices for individuals caught in the gear or arriving on deck. Releasing elasmobranchs fast is key as prolonged ventilatory restriction results in reduced survival. Yet, because handling large sharks and mobulid r...

The objective of this project was to obtain scientific advice for the purpose of implementing the EUPOA on sharks as regards the facilitation of monitoring fisheries and shark stock assessment on a species-specific level in the high seas. The study was focused on major elasmobranch species caught by both artisanal and industrial large pelagic fishe...

Neritic tunas and tuna-like species are an important resource for many coastal nations1 worldwide supporting both commercial and artisanal fisheries, but little is known about their population structure at a spatial scale required for effective fisheries management. In this study, we use Next Generation Sequencing methods to investigate the genetic...

Yellowfin tuna (Thunnus albacares) supports the second largest tuna fishery worldwide, and in the Indian Ocean, it is overfished and subject to overfishing. This situation presents a significant challenge to fisheries management, requiring effective measures to rebuild and then maintain the stock at sustainable levels. A single stock of yel-lowfin...

This document reviews the biological knowledge and conservation status of whale sharks at both the global and regional levels. It also provides a detailed analysis of whale shark interactions with purse seine fisheries in the Atlantic Ocean. Although scientific data about this species is limited, the available information on whale shark life histor...

Purse‐seine tropical tuna fishing in the eastern tropical Pacific Ocean (EPO) results in the bycatch of several sensitive species groups, including elasmobranchs. Effective ecosystem management balances conservation and resource use and requires considering trade‐offs and synergies. Seasonal and adaptive spatial measures can reduce fisheries impact...

Among the various challenges facing tropical tuna purse seine fleet are the need to reduce fuel consumption and carbon footprint, as well as minimising bycatch of vulnerable species. Tools designed for forecasting optimum tuna fishing grounds can contribute to adapting to changes in fish distribution due to climate change, by identifying the locati...

The age‐structured assessment model available in the MSEtool R package assesses stock status and exploitation for varying data availability, from limited to rich datasets. We investigated model accuracy in relation to data availability, population exploitation levels, initial population assumption and fishery selectivity misspecification. Estimates...

Purse‐seine fishers using drifting fish aggregating devices (dFADs), mainly built with bamboo, plastic buoys, and plastic netting, to aggregate and catch tropical tuna, deploy 46,000–65,000 dFADs per year in the Pacific Ocean. Some of the major concerns associated with this widespread fishing device are potential entanglement of sea turtles and oth...

Yellowfin tuna Thunnus albacares stock assessments use age-structured models; therefore, accurate methods for ageing the catch are required. Age estimation techniques need to be validated at the population level to ensure accuracy. However, otolith-based age estimates of yellowfin tuna have never been validated in the Indian Ocean. The current stud...

Numerous policy and international frameworks consider that “destructive fishing” hampers efforts to reach sustainability goals. Though ubiquitous, “destructive fishing” is undefined and therefore currently immeasurable. Here we propose a definition developed through expert consultation: “Destructive fishing is any fishing practice that causes irrec...

Fishers have intensively used drifting fish aggregating devices (DFADs) over the last three decades to facilitate their catch of tropical tunas. DFADs increase purse‐seine efficiency, potentially increasing tuna fishing mortality. They could also have impacts on tuna natural mortality and reproductive potential, and assessing the consequences of th...

To clarify potential trans-oceanic connectivity and variation in the natal origin of albacore tuna (Thunnus alalunga) from the southwest Indian Ocean (SWI) and the southeast Atlantic (SA), lifetime otolith elemental signatures were assessed from 46 adults sampled from Reunion Island, and 26 juveniles(group 2+) sampled from two locations along the A...

There has been growing concern over the sustainability of marine megafauna exposed to bycatch fishing mortality. This study assembled databases of mitigation methods for at-risk species exposed to pelagic longline, tuna purse seine and drift gillnet fisheries. The databases enable the discovery of bycatch mitigation methods and enable accounting fo...

Otolith stable isotopes suggest limited east to west connectivity of yellowfin tuna (Thunnus albacares) in the Indian Ocean Abstract For stock assessment purposes in the Indian Ocean, a single stock of yellowfin is considered by the Indian Ocean Tuna Commission (IOTC). However, the degree of connectivity and mixing rates are still uncertain, althou...

Natural geochemical markers in the otolith of yellowfin tuna (Thunnus albacares) were used to establish nursery-specific signatures for investigating the origin of fish captured in the western Atlantic Ocean (WAO). Two classes of chemical markers (trace elements, stable isotopes) were used to first establish nursery-specific signatures of age-0 yel...

The oceanography of the Labrador Sea is well studied because of its globally important deep‐water convection that oxygenates the deep ocean and drives climate‐regulating ocean currents. However, little is known about the fish communities that inhabit this area, particularly beyond the depths accessible to standard research surveys and commercial fi...

There is growing concern over the conservation status of sharks and relatives exposed to fishing mortality. The Food and Agriculture Organization of the United Nations in 1999 adopted the International Plan of Action for the Conservation and Management of Sharks (IPOA) which provides nations with advice on adopting and implementing national plans....

There is growing concern over the conservation status of sharks and relatives exposedto fishing mortality. The Food and Agriculture Organization of the United Nations in1999 adopted the International Plan of Action for the Conservation and Managementof Sharks (IPOA), which provides nations with advice on adopting and implementingnational plans. An...

The structure, materials and designs of drifting Fish Aggregating Devices (dFADs) have generally remained rudimentary and relatively unchanged since they first came into use in the 1980 s. However, more recently, dFADs have been increasing in dimensions and the prevailing use of plastic components. Abandoned, lost or discarded dFADs can therefore c...

1. Substantial global population declines in pelagic sharks have led to the introduction of management and conservation measures, including gear restrictions and no-retention policies, to curb declines and encourage stock recovery. As the rate of discarding sharks increases, there is a growing need to understand prognostic factors that influence th...

More than a decade of bottom-up collaborative workshops and research with fishers from the principal tropical tuna purse seine fleets to reduce ecological impacts associated with the use of fish aggregating devices (FADs) has yielded novel improved sustainable fishing practices in all oceans. This integrative effort is founded on participatory know...

Fisheries bycatch is the foremost threat to the conservation of many marine species. Evaluation of alternative bycatch management strategies can account for the relative strength of evidence, contribution to achieving objectives, costs to commercial viability, likelihood of compliance and tradeoffs from multispecies conflicts. This study describes...

Drifting Fish Aggregating Devices (dFADs) are currently made with synthetic and non-biodegradable materials contributing to the increase of marine litter and other potential ecosystem impacts. Tuna RFMOs have promoted the research and progressive replacement of existing FADs by non-entangling biodegradable FADs (bioFADs). Here, we present the resul...

Fishers and scientists in the tropical Pacific, Atlantic and Indian Oceans are jointly designing biodegradable fish aggregating devices (bio-FADs) that are efficient for fishing. The tactic followed by most fishers to construct bio-FADs is to maintain the same conventional drifting FAD (dFAD) design (i.e., large, submerged net panels hanging from a...

Integrated stock assessments consist of fitting several sources of catch, abundance, and auxiliary biological information to estimate parameters of equations that describe the population dynamics of fish stocks. Stock assessments are subject to uncertainty, and it is a common practice to characterize uncertainty using alternative hypotheses and ass...

Fishing activity is closely monitored to an increasing degree, but its effects on biodiversity have not received such attention. Using iconic and well-studied fish species such as tunas, billfishes, and sharks, we calculate a continuous Red List Index of yearly changes in extinction risk over 70 years to track progress toward global sustainability...

Chemical fingerprints in otoliths are commonly used as natural habitat markers in fishes. Alternatively, the first dorsal fin spine can provide valuable chemical information and may be more suitable for studying (i) endangered fish species that cannot be sacrificed for their otoliths or (ii) fishes for which otoliths might not be available because...

Satellite-linked buoys used by tropical tuna purse-seine vessels on drifting fish aggregating devices (DFADs) provide a continuous stream of information on both the ocean characteristics and the presence and size of fish aggregations associated with DFADs, enabling the study of pelagic communities. This unprecedented amount of data is characterized...

Oceanic whitetip shark (Carcharhinus longimanus) is an important top predator in pelagic ecosystems currently classified as globally Critically Endangered by the International Union for the Conservation of Nature. This species is incidentally caught by fisheries targeting highly migratory tunas and billfishes throughout the Indian Ocean. Understand...

Tuna Regional Fisheries Management Organizations (RFMOs) are responsible for conservation and sustainable management of transboundary tuna resources in Exclusive Economic Zones and Areas Beyond National Jurisdiction (ABNJ). The data collected and analyses performed by tuna RFMOs are one of the main sources of scientific information supporting the m...

O III SIBECORP será constituído por uma programação abrangente, envolvendo 106 Trabalhos (53 pôsteres, 34 apresentações orais e 19 palestras) que versam sobre temas relevantes no Brasil; Argentina; Espanha; Portugal; Colômbia; Chile; Peru e México. Os palestrantes e debatedores convidados são pesquisadores de prestígio no Brasil ou atuantes em dive...

The use of fish aggregating devices (FADs) in tropical tuna fisheries has increased significantly during recent decades. Concurrently, concern about juvenile tuna mortality, bycatch, and marine debris associated with FAD fisheries increased, and this led to the implementation of FAD management measures and more sustainable designs (e.g., non-entang...

The pelagic fisheries beyond the continental shelves are currently managed with a range of tools largely based on regulating effort or target catch. These tools comprise both static and dynamic area‐based approaches to include gear limitations, closed areas and bycatch limits. There are increasing calls for additional area‐based interventions, part...

Commercial fisheries can discard a considerable volume of sharks and rays, which, as a group, are of high conservation concern. In Western Australia (WA), commercial shark fishing commenced in the 1940s; however, catch time series are not available for discarded species. The present study quantified catch (i.e. dead individuals) time series of disc...

Different fishing strategies have been adopted in the last decades by tropical tuna purse seiners fleet, including fish aggregating device (FAD) and free-swimming school (FSC) fishing strategies, which has raised issues about the different carbon footprint of those fishing modes. Here we show the activity and energy patterns of a Spanish tuna purse...

Yellowfin tuna (Thunnus albacares) is a highly exploited species in the Indian Ocean. Yet, their stock structure is still not well understood, hindering to assess the stock at a suitable spatial scale for management. Here, young-of-the-year (<4 months) yellowfin tuna otoliths were collected in 2018 and 2019, from four major nursery areas in the Ind...

Yellowfin tuna of the Indian Ocean is overfished, and a better understanding of the stock structure is needed to enable sustainable management. Here, otolith δ18O values of young-of-the-year fish from known nursery areas of the equatorial Indian Ocean (West, Central and East) were used to establish a reference isotopic signature to predict the orig...

arising from n. Queiroz et al. Nature https://doi. Many shark species worldwide are vulnerable to overexploitation due to fishing. Using only the horizontal spatial overlap between the space use of 23 satellite-tracked shark species and the fishing distribution of pelagic longline fisheries tracked using an automatic identification system, Queiroz...

The chemical composition of otoliths (earbones) can provide valuable information about stock structure and connectivity patterns among marine fish. For that, chemical signatures must be sufficiently distinct to allow accurate classification of an unknown fish to their area of origin. Here we have examined the suitability of otolith microchemistry a...

The distribution of the spinetail devil ray Mobula mobular in the eastern tropical Atlantic remains poorly known compared to the Pacific and Indian Oceans. We used fisherydependent data and generalized additive models to examine the environmental characteristics associated with the presence of M. mobular in the eastern Atlantic Ocean. Results revea...

Background Micromilled fish otoliths (ear bones) have been widely used for stable oxygen (δ¹⁸O) and carbon (δ¹³C) isotope analysis. The first dorsal fin spine is routinely used for ageing in the eastern Atlantic bluefin tuna (ABFT) population; however, stable isotope analysis remains unapplied in this hard structure. The objective of the present pr...

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...

Skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tuna are the target species of tropical tuna fisheries in the Indian Ocean, with high commercial value in the international market. High fishing pressure over the past three decades has raised concerns about their sustainability. Understanding life history stra...

Tunas sustain important fisheries that face sustainability challenges worldwide, including the uncertainty inherent to natural systems. The Kobe process aims at harmonizing the scientific advice and management recommendations in tuna regional fisheries management organizations (RFMOs) toward supporting the sustainable exploitation of tunas globally...

The present document aims at summarizing ongoing research by ISSF on the reduction of the impacts of Drifting Fish Aggregating Devices´ (DFADs) structure on the ecosystem, particularly on the use of biodegradable DFADs. ISSF is collaborating with physical oceanographers from the Insitute de Ciències del Mar (CSIC, Spain) experts in oceanic currents...

The Spanish tuna purse seine freezer fleet targeting tropical tuna in the Indian Ocean is one of the most important fleets in the world. The present study firstly describes the history and evolution of this fishery (including its current status, following the economic crisis and the upsurge of Somali piracy of this last decade), and secondly descri...

Despite bycatch of elasmobranch (sharks and rays) being a major concern in most fisheries worldwide, there is a lack of knowledge on their spatio-temporal species distribution, biology (life stage and sex-ratios), as well as their at-haulback mortality rate. Observer data from the French and Spanish tropical purse-seine tuna fisheries operating in...

Man-made floating objects in the surface of tropical oceans, also called drifting fish aggregating devices (DFADs), attract tens of marine species, including tunas and non-tuna species. In the Indian Ocean, around 80% of the sets currently made by the EU purse-seine fleet are on DFADs. Due to the importance and value of this fishery, understanding...

Investigating the relationship between species and environmental conditions is key for the correct management of highly migratory large pelagic species like silky shark (Carcharhinus falciformis). This species is currently ranked as vulnerable by the International Union for Conservation of Nature and the population trend may be decreasing globally....

The EU project BIOFAD was launched in August 2017 and is coordinated by a Consortium comprising three European research centers: AZTI, IRD and IEO. The ISSF is also actively collaborating by providing the biodegradable materials needed to test biodegradable dFADs. This project is seeking to develop and implement the use of non-entangling and biodeg...

This document presents the work that a panel of scientists is conducting to attempt producing estimates of levels of key by-catch species by ICCAT fisheries. It follows up on previous work conducted in the Indian Ocean, which led to the publication of estimates of catch of endangered, threatened and protected species (ETP) by IOTC fisheries, includ...

The implementation of an Ecosystem Approach Fisheries Management (EAFM) in ICCAT has been slow and patchy, as it lacks a long-term plan, vision and guidance on how to operationalize it. Ecosystem plans are needed to formalize the process of operationalizing the EAFM by identifying and formalizing ecosystem goals and objectives, planning actions bas...

The present document summarizes the activities organized and conducted by ISSF with the support of the FAO GEF Common Oceans Tuna Project to reduce the impact of the structure of Fish Aggregating Devices (FADs) on the ecosystem. ISSF’s research activities to reduce the impact caused by FAD structures and move towards the use of biodegradable FADs a...

Pelagic sharks are an important bycatch in pelagic fisheries, especially for drifting longlines targeting swordfish. In the Cabo Verde Archipelago (tropical NE Atlantic), pelagic shark catches can reach a significant proportion of the total catches. Due to the increased concern on the status of pelagic shark species, this study was developed to enh...

Species distribution models (SDMs) are used for a variety of scientific and management applications. For species associated with drifting fish aggregating devices (DFADs), such as tuna, spatial models can help tuna Regional Fisheries Management Organizations (t-RFMOs) understand their habitat characteristics and dynamics. DFADs are monitored and tr...

The Arctic, due to its extensive ice cover and remoteness, sees comparatively low amounts of industrial fishing. The only areas with many months of ice-free water are off far western Russia and in the waters near the Hudson Bay; partially as a result, all AIS fishing is concentrated in these regions. According to the Global Fisheries Landing Databa...

AIS use in this region is dominated by vessels from the United States of America (trawlers in their majority), largely because most other countries in the region have a very low use of AIS. Class A reception is poor in the Gulf of Mexico, missing much of the fishing activity in that zone, but better in the southern and eastern parts of the region....

Most of the fishing activity detected by AIS included fleets from Morocco and distant water fleets from Europe and Asia. In contrast, little activity by west African nations was seen because few vessels in these fleets carry AIS. Trawling, the most important activity identified by AIS in the region, showed clear concentration patterns along the coa...

Based on AIS data, most fishing in the Southern Ocean is conducted by distant water fleets using Class A devices with good reception quality across the region. CCAMLR fishery data reports show that bottom-set longliners and mid-water trawlers are predominant, accounting for 68 percent and 32 percent of fishing days in 2016, respectively. Fishing ac...

In the northern portion of the Western Indian Ocean region, the ability to map fishing activity through AIS data is limited by poor AIS reception and low levels of AIS use in artisanal and semi-industrial fleets from coastal countries. Throughout the region, gillnet is one of the main fishing gears for the artisanal and semi-industrial fleets, but...

Class A AIS device reception is good throughout the area, except in northern areas around the Bay of Bengal. However, Class B AIS device reception is good only in the southern half of the Indian Ocean, and very poor in the northern half including the Bay of Bengal. Fishing activity in the eastern Indian Ocean is poorly represented by AIS data, even...

AIS use in FAO Area 61 is dominated by the Chinese fleet. Because of poor AIS reception in the western part of this region and the difficulties accessing regional fleet registries to verify GFW vessel classification, the usefulness of AIS data to identify the fishing level activity by gear type is very limited in this area. AIS identifies fishing a...

This comparison highlights that Automatic Identification System (AIS)-based methods to estimate fishing effort such as the Global Fishing Watch (GFW) methodology can provide the general pattern of relative distribution of fishing effort intensity. These results were obtained in an area where coverage is quite good in general and with good vessels r...

AIS use is good in the high seas, especially for distant water fleets, but low in the coastal regions. Class A reception is good across the region, while Class B performs well except for vessels operating just outside the South American EEZs. Coastal AIS data, including the highly productive Peruvian fleet fishing anchoveta, is poorly represented i...

Fishing in the Northeast Pacific is dominated by the fleets of the United States of America and Canada, both of which have a high adoption of AIS by larger vessels. AIS Class A reception is excellent, but Class B device reception is medium to poor in most of the area. Trawlers are the most important gear in FAO Area 67, where AIS data highlight wel...

A better understanding of the stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean is needed to ensure the sustainable management of the fishery. In this study, carbon and oxygen stable isotopes (d13C and d18O) and trace elements (138Ba, 55Mn, 25Mg and 88Sr) were measured in otoliths of young-of-the-year (YOY) and age-1 yellowf...

A better understanding of the stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean is needed to ensure the sustainable management of the fishery. In this study, carbon and oxygen stable isotopes (δ¹³C and δ¹⁸O) and trace elements (¹³⁸Ba, ⁵⁵Mn, ²⁵Mg and ⁸⁸Sr) were measured in otoliths of young-of-the-year (YOY) and age-1 yellowf...

Multiannual management plans are increasingly used to manage fishery systems in Europe. Initially, they were focused on single species, however in the last decade mixed-fishery management plans have emerged to ensure sustainable exploitation of stocks and ecosystems. Quantitative evaluations of the management plans are generally focused on data-ric...

Tuna Regional Fisheries Management Organizations have committed to adopting an ecosystem approach to fisheries management (EAFM). Yet their progress has been relatively slow and patchy, lacking a long-term vision and a formalized plan to prescribe how fisheries will be managed from an ecosystem perspective. We argue that one of the impediments in t...

The EU project BIOFAD was launched in August 2017. This 28-months EU project is coordinated by a Consortium comprising three European research centers: AZTI, IRD (Institut de recherche pour le développement) and IEO (Instituto Español de Oceanografía). The International Seafood Sustainability Foundation (ISSF) is also actively collaborating by prov...

Fisheries are constrained by ecosystem productivity and management effectiveness. Climate change is already producing impacts on marine ecosystems through overall changes in habitats, productivity and increased variability of environmental conditions. The way how these will affect fisheries is under debate and, also there is uncertainty on the best...

In this working paper, we address the ecosystem component consisted of "non-retained sharks and rays" to support the development of an ecosystem report card in the IOTC region. This group includes sharks and ray species that are not retained due to retention bans or due to their low or no commercial value. The interaction between these non-retained...

In support of the IOTC ecosystem report card, we estimated several indicators which could be used to measure progress towards monitoring the impacts of IOTC fisheries on and the state of the "Food web/Trophic relationships" ecosystem component. An ecosystem approach requires understanding the ecological effects of removing all animals through fishi...