Pascal Bach

Pascal Bach
Institute of Research for Development | IRD · Environment and Resources Department

About

171
Publications
29,283
Reads
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1,780
Citations
Additional affiliations
January 2013 - present
Institute of Research for Development
Position
  • Head of Department
Description
  • Monitoring fisheries data and observer program (human and EMS) of tropical large pelagic fisheries. Research on mitigation measures to reduce bycatch or to increase post-release survival. Indicators aiming to quantify fisheries impacts on the ecosystem.
January 2006 - December 2012
Institute of Research for Development
Position
  • Senior Researcher
Description
  • Quantifying adverse ecological impacts of open ocean fisheries (purse seine and longine)
January 2005 - December 2005
Institute of Research for Development
Position
  • Senior Researcher
Description
  • Catchability of pelagic fish exploited by pelagic longline fisheries
Education
September 1982 - December 1985
Université de Montpellier
Field of study
  • Marine Ecology
September 1980 - June 1982
Institut des Sciences de l'Ingénieur de Montpellier
Field of study
  • Freshwater dynamic and ecology

Publications

Publications (171)
Article
Full-text available
Some toothed whale species have gotten used to stealing or damaging fish that have been captured by the fishing equipment of fishers. This stealing is called depredation, and it is a problem for both fishers and toothed whales in all the oceans of the world. Fishers lose their catch and must work harder, and the whales can get injured and forget ho...
Article
Full-text available
High-resolution multibeam sonar allows estimating movements of pelagic fish schools at short range. Taking advantage of this methodology, we calculated a Straightness Index (SI) to quantify the proportion of schools migrating actively from those residents in lagoon channels. This information enhances our knowledge of both fish school displacements...
Article
Full-text available
Blue shark (Prionace glauca) is amongst the most abundant shark species in international trade, however this highly migratory species has little effective management and the need for spatio-temporal strategies increases, possibly involving the most vulnerable stage or sex classes. We combined 265,595 blue shark observations (capture or satellite ta...
Article
Recent comparative studies of billfishes (Istiophoridae and Xiphiidae) have provided evidence of differences in the form and function of the rostra (bill) among species. Here, we report the discovery of a new structure, lacuna rostralis, on the rostra of sailfish Istiophorus platypterus, which is absent on the rostra of swordfish Xiphias gladius, s...
Article
Elasmobranchs make up a significant part of bycatch in pelagic longline fisheries, whose induced mortality can be a major threat to endangered species. It is therefore crucial to understand the drivers of at-vessel mortality (AVM) for this fishing gear in order to enhance post-release survival. To this end, we analysed scientific data collected dur...
Article
Full-text available
106,107 ✉ replying to A. V. Harry & J. M. Braccini Nature https://doi.org/10.1038/s41586-021-03463-w (2021) Our global analysis 1 estimated the overlap and fishing exposure risk (FEI) using the space use of satellite-tracked sharks and longline fishing effort monitored by the automatic identification system (AIS). In the accompanying Comment, Harry...
Article
This article is a response to Murua et al.'s Matters Arising article in Nature, "Shark mortality cannot be assessed by fishery overlap alone," which arose from arising from N. Queiroz et al. Nature https://doi.org/10.1038/s41586-019-1444-4 (2019).
Article
The predominant policy for remedying the world fishing crisis aims at maximum sustainable yield (MSY) by adjusting gear selectivity and fishing effort to maintain sustainable stock levels. The yellowfin tuna (Thunnus albacares) fishery in the Sea of Oman has experienced intense increases in removals since 1980, with particularly high levels since t...
Article
Full-text available
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...
Article
Full-text available
Fisheries observer programs represent the most reliable way to collect data on fisheries bycatch. However, their limited coverage leads to important data gaps that preclude bycatch mitigation at the basin scale. Habitat models developed from available fisheries observer programs offer a potential solution to fill these gaps. We focus on tropical tu...
Article
Full-text available
Fisheries can profoundly affect bycatch species with 'slow' life history traits. Managing bait type offers one tool to control species selectivity. Different species and sizes of marine predators have different prey, and hence bait, preferences. This preference is a function of a bait's chemical, visual, acoustic and textural characteristics and si...
Article
Billfishes are well-known for their distinctive elongated rostra, a.k.a. bills. The functional significance of billfish rostra has been frequently discussed and the recent discovery of an oil gland (glandula oleofera) at the base of the rostrum in swordfish, Xiphias gladius , has added an interesting facet to this discussion regarding the potential...
Article
Full-text available
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...
Article
The La Pérouse seamount (60 m depth) has so far been poorly studied despite it being a short distance (160 km) from Réunion Island. As part of the MADRidge project, a multidisciplinary cruise was conducted to evaluate the effect of this shallow seamount on the local hydrology and ecology. Current measurements, temperature and chlorophyll-a profiles...
Article
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...
Article
Full-text available
Albacore tuna (Thunnus alalunga) exhibit patchy concentrations associated with biological process at a wide range of spatial scales, resulting in variations in their catchability by fishing gears. Here we investigated the association of catch variation for pelagic longlines in the South Pacific Ocean with oceanographic mesoscale structures (in hori...
Article
Full-text available
Linking morphological differences in foraging adaptations to prey choice and feeding strategies has provided major evolutionary insights across taxa. Here, we combine behavioural and morphological approaches to explore and compare the role of the rostrum (bill) and micro-teeth in the feeding behaviour of sailfish (Istiophorus platypterus) and strip...
Conference Paper
Full-text available
It is widely accepted that the identification of small to medium sizes of frozen bigeye (Thunnus obesus, BET) and yellowfin (Thunnus albacares, YFT) tunas is an especially difficult task, mainly at fork lengths (FL) under 50 cm. This is due to the fin damage, discoloration, skin abrasion and distortion of crushing during the storage process. For th...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
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...
Article
Full-text available
Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of...
Technical Report
Full-text available
The Working Group on Technology Integration for Fishery-Dependent Data (WGTIFD) met in Copenhagen, Denmark, 7-9 May 2019 for its first meeting in its three-year multi-annual cycle. WGTIFD has diverse membership including technology service providers, academic and gov-ernmental marine institutions, and non-profit environmental organizations, across...
Chapter
Full-text available
Tout objet flottant à la surface des océans est susceptible d'attirer les thons tropicaux. Au début des années 1990, cette observation a pous-sé les pêcheurs à déployer des objets flottants artificiels (« dispositifs de concentration de poissons » ou DCP) pour concentrer les poissons et les capturer plus facilement avec de grands filets appelés sen...
Chapter
Full-text available
152 agriculture durable et sécurité alimentaire Vers des appâts plus durables À l'échelle mondiale, la pêche à la palangre pélagique a le même poids économique que la pêche à la senne utilisée pour les thons. Elle cible préférentiellement les thons et les espadons de grande taille mais elle peut entraîner des dommages collatéraux, notamment chez le...
Article
Comment, depuis plusieurs décennies, la recherche scientifique contribue-t-elle au développement des pays du Sud ? À travers plus de 100 succès emblématiques de la recherche en partenariat, cet ouvrage nous plonge au coeur des grandes questions de développement : oeuvrer pour des sociétés plus justes, lutter contre les maladies, faire face aux risq...
Conference Paper
Full-text available
Observer programs have been implemented for many years in tuna purse seine fisheries to assess their impact on pelagic ecosystems by monitoring tuna discards and bycatch among which sensitive species such as sharks or rays. On board observers estimate discards using sampling and extrapolation methods when counting exhaustively is not possible. Howe...
Technical Report
Full-text available
This paper presents an update for the period 2008-2017 of the bycatch estimations for the European and Seychelles tuna purse seine fishery operating in the Indian Ocean. Bycatch data were collected by observers onboard. Given the situation of piracy in the area, the coverage of observers decreases progressively during the first part of the series,...
Article
Full-text available
Depredation in marine ecosystems is defined as the damage or removal of fish or bait from fishing gear by predators. Depredation raises concerns about the conservation of species involved, fisheries yield and profitability, and reference points based on stock assessment of depredated species. Therefore, the development of accurate indicators to ass...
Data
Review of the available literature about depredation impacting pelagic longline fisheries. Target species abbreviations: Billfish (BIL): Swordfish (SWO); Unidentified shark species (SHK); Tuna species (TUN). Predator species abbreviations: Killer whale (KW); False killer whale (FKW); Short-finned pilot whale (SFPW); Unidentified shark species (SHK)...
Data
Maximum DPUE. Maximum DPUE in number of depredated fish per 1000 hooks (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Standard deviation of DPUE. Standard deviation of DPUE in number of depredated fish per 1000 hooks (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Standard deviation of DR. Standard deviation of DR in % (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Coefficient of variation of DR. Coefficient of variation of DR in % (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Minimum DR. Minimum DR in % (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Mean DPUE. Mean DPUE in number of depredated fish per 1000 hooks (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Minimum DPUE. Minimum DPUE in number of depredated fish per 1000 hooks (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Mean DR. Mean DR in % (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Median DR. Median DR in % (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Maximum DR. Maximum DR in % (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Median DPUE. Median DPUE in number of depredated fish per 1000 hooks (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Data
Coefficient of variation of DPUE. Coefficient of variation of DPUE in number of depredated fish per 1000 hooks (left: 2004–2010, right: 2011–2015; blue: toothed whale depredation, green: shark depredation). (TIF)
Article
Full-text available
In order to comply with the different regulations and commitments requesting the presence of scientific observers onboard French purse seiners, and since it is not possible to embark more than one observer during a fishing trip, ORTHONGEL has imagined and implemented since July 2013 a program to facilitate and optimize the boarding of well-trained...
Article
In 2017, a total of 12 French vessels operated in the eastern Atlantic Ocean with 1 Bait Boat, 10 Purse Seiner and 1 supply vessel deploying FAD and managing a part of the FAD stock in the water. The total capacity weighted by the months of activity for each vessel is 9 907 t. The total nominal effort in 2017 was of 2794 fishing days and 2335 sets....
Conference Paper
Full-text available
Electronic monitoring system (EMS) was recently implemented on French tropical tuna purse seiners to complement observer program both in the Indian and Atlantic Oceans. The main objective was to test the efficiency and the potential of the EMS compared to regular observer programs. 'Mixed' trips involving both EMS and on-board observers were conduc...
Article
Full-text available
The costs and benefits of group living often depend on the spatial position of individuals within groups and the ability of individuals to occupy preferred positions. For example, models of predation events for moving prey groups predict higher mortality risk for individuals at the periphery and front of groups. We investigated these predictions in...
Article
Full-text available
The blue shark (Prionace glauca) is the most frequently captured shark in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. As part of cooperative scientific efforts for fisheries and biological data collection, information from fishery observers, scientific projects and surveys, and from recreational fisheri...
Article
Full-text available
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 of the vertical behavior of this species. Individuals were tagged in the Atlantic Ocean (n=5) and In- dian Ocean (n=1) between 2011 and 2012. Deployment...
Article
Full-text available
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 of the vertical behavior of this species. Individuals were tagged in the Atlantic Ocean (n=5) and Indian Ocean (n=1) between 2011 and 2012. Deployment p...