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3. Diving into the vertical dimension of elasmobranch movement ecology.

Author

Andrzejaczek, Samantha, Lucas, Tim, Goodman, Maurice, Hussey, Nigel, Armstrong, Amelia, Carlisle, Aaron, Coffey, Daniel, Gleiss, Adrian, Huveneers, Charlie, Jacoby, David, Meekan, Mark, Mourier, Johann, Peel, Lauren, Abrantes, Kátya, Afonso, André, Ajemian, Matthew, Anderson, Brooke, Anderson, Scot, Araujo, Gonzalo, Armstrong, Asia, Bach, Pascal, Barnett, Adam, Bennett, Mike, Bezerra, Natalia, Bonfil, Ramon, Boustany, Andre, Bowlby, Heather, Branco, Ilka, Braun, Camrin, Brooks, Edward, Brown, Judith, Burke, Patrick, Butcher, Paul, Castleton, Michael, Chapple, Taylor, Chateau, Olivier, Clarke, Maurice, Coelho, Rui, Cortes, Enric, Couturier, Lydie, Cowley, Paul, Croll, Donald, Cuevas, Juan, Curtis, Tobey, Dagorn, Laurent, Dale, Jonathan, Daly, Ryan, Dewar, Heidi, Doherty, Philip, Domingo, Andrés, Dove, Alistair, Drew, Michael, Dudgeon, Christine, Duffy, Clinton, Elliott, Riley, Ellis, Jim, Erdmann, Mark, Farrugia, Thomas, Ferreira, Luciana, Ferretti, Francesco, Filmalter, John, Finucci, Brittany, Fischer, Chris, Fitzpatrick, Richard, Forget, Fabien, Forsberg, Kerstin, Francis, Malcolm, Franks, Bryan, Gallagher, Austin, Galvan-Magana, Felipe, García, Mirta, Gaston, Troy, Gillanders, Bronwyn, Gollock, Matthew, Green, Jonathan, Green, Sofia, Griffiths, Christopher, Hammerschlag, Neil, Hasan, Abdi, Hawkes, Lucy, Hazin, Fabio, Heard, Matthew, Hearn, Alex, Hedges, Kevin, Henderson, Suzanne, Holdsworth, John, Holland, Kim, Howey, Lucy, Hueter, Robert, Humphries, Nicholas, Hutchinson, Melanie, Jaine, Fabrice, Jorgensen, Salvador, Kanive, Paul, Labaja, Jessica, Lana, Fernanda, Lassauce, Hugo, Lipscombe, Rebecca, Llewellyn, Fiona, and Macena, Bruno

Abstract

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements.

Published
2022

7. Biodegradable drifting fish aggregating devices: Current status and future prospects

Author

Zudaire, Iker, Moreno, Gala, Murua, Jefferson, Hamer, Paul, Murua, Hilario, T. Tolotti, Mariana, Roman, Marlon, Hall, Martin, Lopez, Jon, Grande, Maitane, Merino, Gorka, Escalle, Lauriane, C. Basurko, Oihane, Capello, Manuela, Dagorn, Laurent, Ramos, Maria Lourdes, Abascal, Francisco J., Báez, José Carlos, Pascual-Alayón, Pedro J., Déniz, Santiago, and Santiago, Josu

Published
2023
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9. Lessons learnt from the first large-scale biodegradable FAD research experiment to mitigate drifting FADs impacts on the ecosystem

Author

Murua, Hilario, Zudaire, Iker, Tolotti, Mariana, Murua, Jefferson, Capello, Manuela, Basurko, Oihane C., Krug, Iñigo, Grande, Maitane, Arregui, Igor, Uranga, Jon, Ferarios, Jose Maria, Sabarros, Philippe, Ruiz, Jon, Baidai, Yannick, Ramos, Maria Lourdes, Báez, Jose Carlos, Abascal, Francisco, Arrizabalaga, Haritz, Moreno, Gala, Dagorn, Laurent, and Santiago, Josu

Published
2023
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11. Quantifying the impact of habitat modifications on species behavior and mortality: A case study of tropical tuna.

Author

Dupaix, Amaël, Dagorn, Laurent, Deneubourg, Jean‐Louis, and Capello, Manuela

Subjects
YELLOWFIN tuna, FRAGMENTED landscapes, ENVIRONMENTAL degradation, FISH mortality, RANDOM walks, HABITAT modification
Abstract

Ecosystems and biodiversity across the world are being altered by human activities. Habitat modification and degradation are among the most important drivers of biodiversity loss. These modifications can have an impact on species behavior, which can, in turn, impact their mortality. While several studies have investigated the impacts of habitat degradation and fragmentation on terrestrial species, the extent to which habitat modifications affect the behavior and fitness of marine species is still largely unknown, particularly for pelagic species. Since the early 1990s, industrial purse seine vessels targeting tuna have started deploying artificial floating objects—Drifting Fish Aggregating Devices (DFADs)—in all oceans to increase tuna catchability. Since then, the massive deployment of DFADs has modified tuna surface habitat, by increasing the density of floating objects, with potential impacts on tuna associative behavior and mortality. In this study, we investigate these impacts for yellowfin tuna in the Indian Ocean. Using an individual‐based model based on a correlated random walk and newly available data on DFAD densities, we quantify for the first time how the increase in floating object density, due to DFAD use, affects the percentage of time that yellowfin tuna spend associated, which, in turn, directly impacts their availability to fishers and fishing mortality. This modification of tuna associative behavior could also have indirect impacts on their fitness, by retaining tuna in areas detrimental to them or disrupting schooling behavior. Hence, there is an urgent need to further investigate DFAD impacts on tuna behavior, in particular, taking social behavior into account, and to continue regulation efforts on DFAD use and monitoring. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Reply to: Shark mortality cannot be assessed by fishery overlap alone

Author

Queiroz, Nuno, Humphries, Nicolas E., Couto, Ana, Vedor, Marisa, da Costa, Ivo, Sequeira, Ana M. M., Mucientes, Gonzalo, Santos, António M., Abascal, Francisco J., Abercrombie, Debra L., Abrantes, Katya, Acuña-Marrero, David, Afonso, André S., Afonso, Pedro, Anders, Darrell, Araujo, Gonzalo, Arauz, Randall, Bach, Pascal, Barnett, Adam, Bernal, Diego, Berumen, Michael L., Lion, Sandra Bessudo, Bezerra, Natalia P. A., Blaison, Antonin V., Block, Barbara A., Bond, Mark E., Bonfil, Ramon, Bradford, Russell W., Braun, Camrin D., Brooks, Edward J., Brooks, Annabelle, Brown, Judith, Bruce, Barry D., Byrne, Michael E., Campana, Steven E., Carlisle, Aaron B., Chapman, Demian D., Chapple, Taylor K., Chisholm, John, Clarke, Christopher R., Clua, Eric G., Cochran, Jesse E. M., Crochelet, Estelle C., Dagorn, Laurent, Daly, Ryan, Cortés, Daniel Devia, Doyle, Thomas K., Drew, Michael, Duffy, Clinton A. J., Erikson, Thor, Espinoza, Eduardo, Ferreira, Luciana C., Ferretti, Francesco, Filmalter, John D., Fischer, G. Chris, Fitzpatrick, Richard, Fontes, Jorge, Forget, Fabien, Fowler, Mark, Francis, Malcolm P., Gallagher, Austin J., Gennari, Enrico, Goldsworthy, Simon D., Gollock, Matthew J., Green, Jonathan R., Gustafson, Johan A., Guttridge, Tristan L., Guzman, Hector M., Hammerschlag, Neil, Harman, Luke, Hazin, Fábio H. V., Heard, Matthew, Hearn, Alex R., Holdsworth, John C., Holmes, Bonnie J., Howey, Lucy A., Hoyos, Mauricio, Hueter, Robert E., Hussey, Nigel E., Huveneers, Charlie, Irion, Dylan T., Jacoby, David M. P., Jewell, Oliver J. D., Johnson, Ryan, Jordan, Lance K. B., Joyce, Warren, Keating Daly, Clare A., Ketchum, James T., Klimley, A. Peter, Kock, Alison A., Koen, Pieter, Ladino, Felipe, Lana, Fernanda O., Lea, James S. E., Llewellyn, Fiona, Lyon, Warrick S., MacDonnell, Anna, Macena, Bruno C. L., Marshall, Heather, McAllister, Jaime D., Meÿer, Michael A., Morris, John J., Nelson, Emily R., Papastamatiou, Yannis P., Peñaherrera-Palma, Cesar, Pierce, Simon J., Poisson, Francois, Quintero, Lina Maria, Richardson, Andrew J., Rogers, Paul J., Rohner, Christoph A., Rowat, David R. L., Samoilys, Melita, Semmens, Jayson M., Sheaves, Marcus, Shillinger, George, Shivji, Mahmood, Singh, Sarika, Skomal, Gregory B., Smale, Malcolm J., Snyders, Laurenne B., Soler, German, Soria, Marc, Stehfest, Kilian M., Thorrold, Simon R., Tolotti, Mariana T., Towner, Alison, Travassos, Paulo, Tyminski, John P., Vandeperre, Frederic, Vaudo, Jeremy J., Watanabe, Yuuki Y., Weber, Sam B., Wetherbee, Bradley M., White, Timothy D., Williams, Sean, Zárate, Patricia M., Harcourt, Robert, Hays, Graeme C., Meekan, Mark G., Thums, Michele, Irigoien, Xabier, Eguiluz, Victor M., Duarte, Carlos M., Sousa, Lara L., Simpson, Samantha J., Southall, Emily J., and Sims, David W.

Published
2021
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14. Reply to: Caution over the use of ecological big data for conservation

Author

Queiroz, Nuno, Humphries, Nicolas E., Couto, Ana, Vedor, Marisa, da Costa, Ivo, Sequeira, Ana M. M., Mucientes, Gonzalo, Santos, António M., Abascal, Francisco J., Abercrombie, Debra L., Abrantes, Katya, Acuña-Marrero, David, Afonso, André S., Afonso, Pedro, Anders, Darrell, Araujo, Gonzalo, Arauz, Randall, Bach, Pascal, Barnett, Adam, Bernal, Diego, Berumen, Michael L., Lion, Sandra Bessudo, Bezerra, Natalia P. A., Blaison, Antonin V., Block, Barbara A., Bond, Mark E., Bonfil, Ramon, Braun, Camrin D., Brooks, Edward J., Brooks, Annabelle, Brown, Judith, Byrne, Michael E., Campana, Steven E., Carlisle, Aaron B., Chapman, Demian D., Chapple, Taylor K., Chisholm, John, Clarke, Christopher R., Clua, Eric G., Cochran, Jesse E. M., Crochelet, Estelle C., Dagorn, Laurent, Daly, Ryan, Cortés, Daniel Devia, Doyle, Thomas K., Drew, Michael, Duffy, Clinton A. J., Erikson, Thor, Espinoza, Eduardo, Ferreira, Luciana C., Ferretti, Francesco, Filmalter, John D., Fischer, G. Chris, Fitzpatrick, Richard, Fontes, Jorge, Forget, Fabien, Fowler, Mark, Francis, Malcolm P., Gallagher, Austin J., Gennari, Enrico, Goldsworthy, Simon D., Gollock, Matthew J., Green, Jonathan R., Gustafson, Johan A., Guttridge, Tristan L., Guzman, Hector M., Hammerschlag, Neil, Harman, Luke, Hazin, Fábio H. V., Heard, Matthew, Hearn, Alex R., Holdsworth, John C., Holmes, Bonnie J., Howey, Lucy A., Hoyos, Mauricio, Hueter, Robert E., Hussey, Nigel E., Huveneers, Charlie, Irion, Dylan T., Jacoby, David M. P., Jewell, Oliver J. D., Johnson, Ryan, Jordan, Lance K. B., Joyce, Warren, Keating Daly, Clare A., Ketchum, James T., Klimley, A. Peter, Kock, Alison A., Koen, Pieter, Ladino, Felipe, Lana, Fernanda O., Lea, James S. E., Llewellyn, Fiona, Lyon, Warrick S., MacDonnell, Anna, Macena, Bruno C. L., Marshall, Heather, McAllister, Jaime D., Meÿer, Michael A., Morris, John J., Nelson, Emily R., Papastamatiou, Yannis P., Peñaherrera-Palma, Cesar, Pierce, Simon J., Poisson, Francois, Quintero, Lina Maria, Richardson, Andrew J., Rogers, Paul J., Rohner, Christoph A., Rowat, David R. L., Samoilys, Melita, Semmens, Jayson M., Sheaves, Marcus, Shillinger, George, Shivji, Mahmood, Singh, Sarika, Skomal, Gregory B., Smale, Malcolm J., Snyders, Laurenne B., Soler, German, Soria, Marc, Stehfest, Kilian M., Thorrold, Simon R., Tolotti, Mariana T., Towner, Alison, Travassos, Paulo, Tyminski, John P., Vandeperre, Frederic, Vaudo, Jeremy J., Watanabe, Yuuki Y., Weber, Sam B., Wetherbee, Bradley M., White, Timothy D., Williams, Sean, Zárate, Patricia M., Harcourt, Robert, Hays, Graeme C., Meekan, Mark G., Thums, Michele, Irigoien, Xabier, Eguiluz, Victor M., Duarte, Carlos M., Sousa, Lara L., Simpson, Samantha J., Southall, Emily J., and Sims, David W.

Published
2021
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15. Both environmental conditions and intra- and interspecific interactions influence the movements of a marine predator

Author

Mourier, Johann, Soria, Marc, Silk, Matthew, Demichelis, Angélique, Dagorn, Laurent, Hattab, Tarek, Mourier, Johann, Soria, Marc, Silk, Matthew, Demichelis, Angélique, Dagorn, Laurent, and Hattab, Tarek

Abstract

Animal movements are typically influenced by multiple environmental factors simultaneously and individuals vary in their response to this environmental heterogeneity. Therefore, understanding how environmental aspects, including biotic, abiotic and anthropogenic factors, influence the movements of wild animals is an important focus of wildlife research and conservation. We apply exponential random graph models (ERGMs) to analyse movement networks of a bull shark population in a network of acoustic receivers and identify the effects of environmental, social or other types of covariates on their movements. We found that intra- and interspecific factors often had stronger effects on movements than environmental variables. ERGMs proved to be a potentially useful tool for studying animal movement network data especially in the context of spatial attribute heterogeneity.

Published
2024
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17. Direct assessment of tropical tuna abundance from their associative behaviour around floating objects.

Author

Baidai, Yannick, Dupaix, Amaël, Dagorn, Laurent, Gaertner, Daniel, Deneubourg, Jean-Louis, Duparc, Antoine, and Capello, Manuela

Subjects
BIGEYE tuna, SKIPJACK tuna, YELLOWFIN tuna, BASIC needs, SPECIES
Abstract

Managing populations of wild harvested species requires the ability to regularly provide accurate abundance assessments. For most marine species, changes in abundance can only be monitored indirectly, using methods reliant on harvest-based indices, with significant inherent limitations surrounding the estimation and standardization of harvest effort. Tropical tunas are some of the most exploited marine species in the world and are among several species in critical need of alternative methods for estimating abundance. Addressing this concern, we developed the Associative Behaviour-Based abundance Index (ABBI), designed to provide direct abundance estimates for animals, which exhibit an associative behaviour with aggregation sites. Its implementation in the western Indian Ocean on skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares) and bigeye tuna (Thunnus obesus), revealed similar trajectories in their relative abundance. The ABBI stands as a potentially promising alternative to enhance traditional tropical tuna stock assessments methods, as well as a new opportunity to assess the abundance of other wild species that display an associative behaviour with physical structures found in their natural environment. [ABSTRACT FROM AUTHOR]

Published
2024
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21. Quantifying the interplay between environmental and social effects on aggregated-fish dynamics

Author

Capello, Manuela, Soria, Marc, Cotel, Pascal, Deneubourg, Jean-Louis, and Dagorn, Laurent

Subjects
Physics - Biological Physics, Physics - Data Analysis, Statistics and Probability, Quantitative Biology - Quantitative Methods
Abstract

Demonstrating and quantifying the respective roles of social interactions and external stimuli governing fish dynamics is key to understanding fish spatial distribution. If seminal studies have contributed to our understanding of fish spatial organization in schools, little experimental information is available on fish in their natural environment, where aggregations often occur in the presence of spatial heterogeneities. Here, we applied novel modeling approaches coupled to accurate acoustic tracking for studying the dynamics of a group of gregarious fish in a heterogeneous environment. To this purpose, we acoustically tracked with submeter resolution the positions of twelve small pelagic fish (Selar crumenophthalmus) in the presence of an anchored floating object, constituting a point of attraction for several fish species. We constructed a field-based model for aggregated-fish dynamics, deriving effective interactions for both social and external stimuli from experiments. We tuned the model parameters that best fit the experimental data and quantified the importance of social interactions in the aggregation, providing an explanation for the spatial structure of fish aggregations found around floating objects. Our results can be generalized to other gregarious species and contexts as long as it is possible to observe the fine-scale movements of a subset of individuals., Comment: 10 pages, 5 figures and 4 supplementary figures

Published
2011
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29. Unintended effects of single-species fisheries management

Author

Tolotti, Mariana, Guillotreau, Patrice, Forget, Fabien, Capello, Manuela, Dagorn, Laurent, Tolotti, Mariana, Guillotreau, Patrice, Forget, Fabien, Capello, Manuela, and Dagorn, Laurent

Abstract

Ecosystem-based management is widely recognized as the path to achieve sustainability of ecosystem services. Tuna Fisheries Management Organizations have incorporated an ecosystem approach into their mandate, but their decision-making process essentially relies on individual stock assessments. This study investigates possible unintended consequences of management measures that primarily focus on single target species. In 2016, the Indian Ocean Tuna Commission (IOTC) adopted a plan for rebuilding yellowfin tuna stock. We examined the impacts that this measure might have had on the fishing strategy of purse seine fleets and on silky shark mortality, their main elasmobranch bycatch. The economic dimension of this possible ecological impact was also explored. Logbook and observer data from the French fleet, coupled with IOTC data from Spain, Seychelles and Mauritius, were used. After the implementation of the measure, an increase on the number of fish aggregating device (FAD) sets and an expansion of the fishing effort were observed. These resulted in a 35% increase on silky shark bycatch for the French fleet and a 18% increase for all fleets combined. Based on the estimated catches, the mean forgone consumptive value of silky shark bycatch was evaluated at US$ 1.6 million. Taking the conservation value into account, the social cost of this forgone ecosystem service could increase up to USD 14 million. This work is a first exploration into to the socioeconomic dimension of trade-offs between the use of FADs in tuna purse seine fisheries and shark bycatch and can be applied to other FAD-associated species.

Published
2023
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30. Improving sustainable practices in tuna purse seine fish aggregating device (FAD) fisheries worldwide through continued collaboration with fishers

Author

Murua, Jefferson, Moreno, Gala, Dagorn, Laurent, Itano, David, Hall, Martin, Murua, Hilario, Restrepo, Victor, Murua, Jefferson, Moreno, Gala, Dagorn, Laurent, Itano, David, Hall, Martin, Murua, Hilario, and Restrepo, Victor

Abstract

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 knowledge-exchange workshops organized by the International Seafood Sustainability Foundation (ISSF), referred to as “ISSF Skippers Workshops”, where scientists, fishers, and key stakeholders examine and develop together ways and tools to minimize fishery impacts. Workshops organized since 2010 have reached fleet members in 23 countries across Asia, Africa, the Americas, Europe, and Oceania, with over 4,000 attendances, mostly skippers and crew, operating in the Indian, Atlantic, and Pacific oceans. Structured and continued open transparent discussions on ocean-specific options to minimize FAD associated bycatch, ghost fishing and marine pollution have produced an array of novel co-constructed solutions and a better understanding of ecosystem and fishery dynamics. Dedicated at sea research cruises in commercial purse seiners have enabled testing some of the ideas proposed in workshops. Results obtained were then communicated back to fishers for a double loop learning system resulting in solution refinement and/or adoption. Furthermore, fishers’ increased trust and stewardship have stimulated unprecedented large-scale science-industry research projects across oceans, such as multi-fleet biodegradable FAD trials, the adoption and widespread use of non-entangling FADs, and the development and adoption of best practices for the safe handling and release of vulnerable bycatch. This model of collaborative research is broadly applicable to other natural resource conservation fields. Support for long-term inclusive programs enabling harvesters to proactively collaborate in impact mitigation research contributes to improved scientific

Published
2023
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31. Macroeconomic impact of an international fishery regulation on a small island country

Author

Guillotreau, Patrice, Dissou, Yazid, Antoine, Sharif, Capello, Manuela, Salladarré, Frédéric, Tidd, Alex, Dagorn, Laurent, Guillotreau, Patrice, Dissou, Yazid, Antoine, Sharif, Capello, Manuela, Salladarré, Frédéric, Tidd, Alex, and Dagorn, Laurent

Abstract

This paper examines the macroeconomic impact of a tuna fishing regulation on a small island economy that relies heavily on tourism and fishing for 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, proposes a 72-day moratorium on dFADs, but this resolution faces opposition from many contracting parties, particularly developing countries. To understand the reasons for this opposition, a recursive multi-sector 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 in 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 trend in real Gross Domestic Product after seven years. Such an impact would have wide-ranging 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. JEL codes: Q22, D68, E65

Published
2023
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33. Lessons learnt from the first large-scale biodegradable FAD research experiment to mitigate drifting FADs impacts on the ecosystem

Author

European Commission, Food and Agriculture Organization of the United Nations, Murua, Hilario, Zudaire, Iker, Tolotti, Mariana, Murua, Jefferson, Capello, Manuela, Basurko, Oihane C., Krug, Iñigo, Grande, Maitane, Arregui, Igor, Uranga, Jon, Ferarios, Jose Maria, Sabarros, Philippe, Ruiz, Jon, Baidai, Yannick, Ramos, María Lourdes, Báez, José Carlos, Abascal, Francisco Javier, Arrizabalaga, Haritz, Moreno, Gala, Dagorn, Laurent, Santiago, Josu, European Commission, Food and Agriculture Organization of the United Nations, Murua, Hilario, Zudaire, Iker, Tolotti, Mariana, Murua, Jefferson, Capello, Manuela, Basurko, Oihane C., Krug, Iñigo, Grande, Maitane, Arregui, Igor, Uranga, Jon, Ferarios, Jose Maria, Sabarros, Philippe, Ruiz, Jon, Baidai, Yannick, Ramos, María Lourdes, Báez, José Carlos, Abascal, Francisco Javier, Arrizabalaga, Haritz, Moreno, Gala, Dagorn, Laurent, and Santiago, Josu

Abstract

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 results of the first large-scale biodegradable FAD project in the Indian Ocean to develop and implement the use of non-entangling biodegradable dFADs. The bioFAD tested were fully non-entangling without netting minimizing completely the risk of entanglement. Tested bioFADs significantly contribute to the reduction of the synthetic plastic-based materials, increase the use of biodegradable materials and reduce the total material weight used in FADs, reducing their overall ecosystem impacts. The results of testing 771 bioFADs in real fishing conditions, showed that the fishing performance regarding presence/absence of tuna around dFADs, first day of tuna detection, proportion of FADs occupied by tuna, biomass aggregation underneath the FADs and catch per set between bioFADs and conventional dFADs were similar. This provides support for the efficacy of bioFADs regardless of the degradation experienced by the biodegradable materials tested. Although some bioFADs lasted up to one year, the degradation of the biodegradable material was important and some bioFADs lost their original structure after the study period, suggesting the need to find alternative designs for bioFADs that will suffer less structural stress than those bioFADs made of biodegradable material but with conventional design. The lessons learnt in this large-scale trial will contribute to refining the future designs of biodegradable FADs.

Published
2023

34. Biodegradable drifting fish aggregating devices: Current status and future prospects

Author

Abascal, Francisco Javier [0000-0002-8550-8617], Báez, José Carlos [0000-0003-2049-0409], Pascual-Alayón, Pedro José [0000-0001-9834-4693], Deniz, Santiago [0000-0002-9431-4785], Zudaire, Iker, Moreno, Gala, Murua, Jefferson, Hamer, Paul, Murua, Hilario, T. Tolotti, Mariana, Roman, Marlon, Hall, Martin, Lopez, Jon, Grande, Maitane, Merino, Gorka, Escalle, Lauriane, C. Basurko, Oihane, Capello, Manuela, Dagorn, Laurent, Ramos, María Lourdes, Abascal, Francisco Javier, Báez, José Carlos, Pascual-Alayón, Pedro José, Deniz, Santiago, Santiago, Josu, Abascal, Francisco Javier [0000-0002-8550-8617], Báez, José Carlos [0000-0003-2049-0409], Pascual-Alayón, Pedro José [0000-0001-9834-4693], Deniz, Santiago [0000-0002-9431-4785], Zudaire, Iker, Moreno, Gala, Murua, Jefferson, Hamer, Paul, Murua, Hilario, T. Tolotti, Mariana, Roman, Marlon, Hall, Martin, Lopez, Jon, Grande, Maitane, Merino, Gorka, Escalle, Lauriane, C. Basurko, Oihane, Capello, Manuela, Dagorn, Laurent, Ramos, María Lourdes, Abascal, Francisco Javier, Báez, José Carlos, Pascual-Alayón, Pedro José, Deniz, Santiago, and Santiago, Josu

Abstract

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 contribute to the global marine litter problem. Transitioning to biodegradable and non-toxic materials that have a faster rate of decomposition, and are free of toxins and heavy metals, relative to synthetic materials, has been prescribed as an important part of the solution to reducing marine pollution from industrial tuna fisheries that rely on dFADs. This review of the current state of dFADs considers aspects related to the use of biodegradable materials in their construction, including; regulations related to dFAD materials, trials of biodegradable designs and materials and future alternatives. During the last decade, regulatory measures at tuna Regional Fishery Management Organizations (tRFMOs) have gradually moved towards the clear recommendation to use biodegradable materials in dFAD construction together with other measures limiting the number of active dFADs and the use of netting materials. However, to provide operational guidance, more clarity is needed, starting with a standardised definition of biodegradable dFADs among tRFMOs. Research involving dFAD natural and synthetic materials is required, along with improved data collection for monitoring the transition of dFAD materials against specified standards for biodegradable dFADs. In addition, alternative and complementary actions need to be explored to contribute to minimising adverse effects of dFADs on the environment. Acknowledging the current difficulties for the implementation of fully biodegradable dFADs in tuna fisheries, a stepwise process towards the implementation of commercially viable biodegradable dFADs should be considered.

Published
2023

35. Quantifying the impact of habitat modifications on species behavior and mortality: case-study on floating objects and tropical tuna

Author

Dupaix, Amaël, Dagorn, Laurent, Deneubourg, Jean-Louis, Capello, Manuela, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), CENOLI, Université Libre de Bruxelles, and Université libre de Bruxelles (ULB)

Subjects
Fish Aggregating Device, correlated random walk, [SDE.MCG]Environmental Sciences/Global Changes, purse-seine fisheries, exploited species, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, individual-based model, [SDE.ES]Environmental Sciences/Environmental and Society, global change, associative behavior
Abstract

Ecosystems and biodiversity across the world are being altered by human activities. Habitat modification and degradation is among the most important drivers of biodiversity loss. These modifications can have an impact on species behavior, which can in turn impact their mortality. With around 5 million tons fished yearly, tuna species represent more than 7 % of global marine fish capture, of which two third are captured by purse seine vessels. Because several pelagic fish species, such as tuna, associate with floating objects, fishers have started deploying their own floating objects – Drifting Fish Aggregating Devices (DFADs) – in the early 1990s to increase tuna catchability. Since then, the massive deployment of DFADs has modified tuna habitat, by increasing the density of floating objects, with potential consequences on tuna associative behavior. This use of DFADs by purse seine fisheries is a major concern and it offers an important case study to assess the impact of habitat modifications on species behavior and mortality. In this study we use an individual-based model, based on a correlated random walk calibrated on passive acoustic tagging data, to determine a general relationship between DFAD density and the time tuna spend between two associations with a DFAD. Using this general relationship and fisheries data in the Indian Ocean, we predict that the increase of floating object density, due to DFAD use, strongly increases the percentage of time tuna spend associated, which directly impacts tuna availability to fishers and fishing mortality. This modification of tuna associative behavior could also have indirect impacts on their fitness, by retaining tuna in areas detrimental to them or disrupting schooling behavior. Hence, there is an urgent need to further investigate DFAD impacts on tuna behavior, in particular taking social behavior into account, and to continue regulation efforts on DFAD use and deployments.

Published
2023

37. The challenge of assessing the effects of drifting fish aggregating devices on the behaviour and biology of tropical tuna

Author

Dagorn, Laurent, Dupaix, Amaël, Filmalter, John, Baidai, Yannick, Bodin, Nathalie, Capello, Manuela, Chassot, Emmanuel, Demarcq, Hervé, Deneubourg, Jean-Louis, Fonteneau, Alain, Forget, Fabien, Forrestal, Francesca, Gaertner, Daniel, Hall, Martin, Holland, Kim, Itano, David, Kaplan, David, Lopez, Jon, Marsac, Francis, Maufroy, Alexandra, Moreno, Gala, Muir, Jeff, Murua, Hilario, Roa-Pascuali, Liliana, Pérez, Géraldine, Restrepo, Victor, Robert, Marianne, Schaefer, Kurt, Sempo, Grégory, Soria, Marc, Ménard, Frédéric, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), South African Institute for Aquatic Biodiversity (SAIAB), National Research Foundation [South Africa] (NRF), African Marine Expertise, Seychelles Fishing Authority (SFA) (SFA), Université des Seychelles, Sustainable Ocean Seychelles (SOS), Indian Ocean Tuna Commission (IOTC), CENOLI, Université Libre de Bruxelles, Université libre de Bruxelles (ULB), Consulant, Saint-Malo, Southeast Fisheries Science Center (SEFC), NOAA National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA), Inter-American Tropical Tuna Commission (IATTC), Hawai'i Institute of Marine Biology (HIMB), Opah Consulting, ORTHONGEL, International Seafood Sustainability Foundation (ISSF), Collecte Localisation Satellites (CLS), Institut Océanographique Paul Ricard, Six-Fours-les-Plages, France, Dynamique et durabilité des écosystèmes : de la source à l’océan (DECOD), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and Aix Marseille Univ., Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography

Subjects
ecological effects, fisheries management, tuna, [SDV.SA.STP]Life Sciences [q-bio]/Agricultural sciences/Sciences and technics of fishery, fish behaviour, ecological trap, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, DFAD
Abstract

Though fisheries have intensively used drifting fish aggregating devices (DFADs) over the last three decades to facilitate their catch of tropical tunas, assessing the consequences of the presence of DFADs at sea on tuna behaviour and biology is a challenge. The use of DFADs has resulted in a major increase in the number of floating objects, which are spatially heterogeneous at sea. To date, no scientific consensus exists regarding the effects of DFADs on the large-scale movements and behaviour of tuna, mainly due to the difficulty of disentangling the respective roles of DFADs and environmental factors. Some biological indices show that tuna condition is lower when associated to a floating object than in a free-swimming school. It is not possible, however, to elucidate whether this is the cause or result of the association, or if it affects the fitness of individuals in the long term. Further scientific progress would require (i) the collection of time series of indicators to monitor habitat change, individual behaviour, individual fitness and population dynamics, and (ii) experimental studies to identify the underlying behavioural and biological processes involved the associative behaviour. The extent of the modification of the surface habitat by the massive deployment of DFADs and the current uncertainty of the possible long-term consequences on the individual fitness and dynamics of tuna populations argue for the need for increased awareness of this issue by Regional Fisheries Management Organisations regulating tuna fishing.

Published
2023

38. Fine-scale vertical movements of oceanic whitetip sharks (Carcharhinus longimanus)

Author

Tolotti, Mariana, Bauer, Robert, Forget, Fabien, Bach, Pascal, Dagorn, Laurent, and Travassos, Paulo

Subjects
Time series analysis -- Usage, Oceanic whitetip shark -- Physiological aspects, Animal locomotion -- Observations, Zoology and wildlife conservation
Abstract

Abstract--Time series of depth data, obtained for 6 oceanic whitetip sharks (Carcharhinus longimanus) tagged with pop-up satellite archival tags, were analyzed in detail. The aim was to improve our knowledge [...]

Published
2017
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41. Drifting Fish Aggregating Devices (DFADs) as ecological traps: no evidence displayed by a long-term analysis of yellowfin tuna condition

Author

Dupaix, Amaël, Dagorn, Laurent, Duparc, Antoine, Guillou, Aurélie, Deneubourg, Jean-Louis, Capello, Manuela, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), CENOLI, Université Libre de Bruxelles, and Université libre de Bruxelles (ULB)

Subjects
industrial tuna fisheries, floating objects, relative condition factor, [SDE.MCG]Environmental Sciences/Global Changes, Indicator log, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Indian Ocean, [SDE.ES]Environmental Sciences/Environmental and Society, Thunnus albacares
Abstract

Human-induced habitat modifications can severely impact the biology and behavior of wild species. Drifting Fish Aggregating Devices (DFADs), used by industrial purse seine tropical tuna fisheries, significantly increased the number of floating objects found in the open ocean, with which tropical tuna associate. This habitat change raised concerns over the risk of modifying the behavior and altering the biology of tuna and other associated species (the so-called ecological trap hypothesis). Relying on a time-series of more than 25,000 length-weight samples collected in the western Indian Ocean (1987-2019), we reject the hypothesis that the body condition (Le Cren’s relative condition factor Kn) of yellowfin tuna (Thunnus albacares) decreased concurrently with the increased number of DFADs. This result suggests the absence of negative long-term impacts of DFADs on the biology of tuna. As other factors may have counteracted possible negative effects of DFADs, we recommend a long-term monitoring of habitat, biological and behavioral parameters of tunas to detect any critical change.

Published
2022

43. Swimming depth of dolphinfish (Coryphaena hippurus) associated and unassociated with fish aggregating devices

Author

Whitney, Nicholas M., Taquet, Marc, Brill, Richard W., Girard, Charlotte, Schwieterman, Gail D., Dagorn, Laurent, and Holland, Kim N.

Subjects
VEMCO Inc., Communications equipment, Fishes, Fisheries -- International economic relations, Fish industry -- International economic relations, Cellular transmission equipment, Telecommunications equipment, Zoology and wildlife conservation
Abstract

Abstract--Dolphinfish (Coryphaena hippurus), large pelagic predators and important fishery targets, frequently associate with floating debris or manmade fish aggregating devices (FADs). We tagged 8 dolphinfish with pressure-sensitive ultrasonic transmitters and [...]

Published
2016
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44. A model based on data from echosounder buoys to estimate biomass of fish species associated with fish aggregating devices

Author

Lopez, Jon, Moreno, Gala, Boyra, Guillermo, and Dagorn, Laurent

Subjects
Animal populations -- Measurement, Tunas (Fishes) -- Distribution, Sonobuoys -- Usage, Company distribution practices, Zoology and wildlife conservation
Abstract

Abstract--Most of the drifting fish aggregating devices (DFADs) used in industrial tropical tuna purseseine fisheries are equipped with satellite linked echosounder buoys, which provide fishing crews with remote, accurate geolocation [...]

Published
2016
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45. Fishing for the Microbiome of Tropical Tuna

Author

Gadoin, Elsa, primary, Desnues, Christelle, additional, d’Orbcastel, Emmanuelle Roque, additional, Bouvier, Thierry, additional, Auguet, Jean-Christophe, additional, Dagorn, Laurent, additional, Moroh, Jean-Luc, additional, Adingra, Antoinette, additional, and Bettarel, Yvan, additional

Published
2022
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