Acoustics for ecosystem research / Laurent Dagorn

Public ISBD Faire une suggestion d'achat Titre : Acoustics for ecosystem research : lessons and perspectives from a scientific programme focusing on tuna-environment relatioships Type de document : texte imprimé Auteurs : Laurent Dagorn, Auteur Importance : pp. 197-203 Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : Fisheries management now extends from the stock to the ecosystem. The foundation for fisheries management on an ecosystem basis must lie in appropriate modelling of the ecosystems. A prerequisite for such models requires data on the two interactive components of the ecosystem: the biotope (physical environment), and the community of living species. In this context, acoustics become essential, as this tool can provide qualitative and quantitative data on various communities of species, and furthermore allows the seldom-attainable study of their interactions. In fact, acoustics allow the monitoring of entire communities, from plankton to large predators, as well as certain aspects of the physical environment, such as substratum characteristics. Acoustics have been used during the last two decades mainly to provide fishery-independent estimates of stocks. The intention of this paper is to promote the use of acoustics for studying marine ecosystems and to encourage the emergence of new generations of ecosystem models. As an example of integrative research based on acoustic data, we will present the approach and the results of a scientific programme (ECOTAP) carried out to study the tuna pelagic ecosystem in French Polynesia. We then discuss the use of acoustics as a tool for ecosystem-based studies and management. Acoustics for ecosystem research : lessons and perspectives from a scientific programme focusing on tuna-environment relatioships [texte imprimé] / Laurent Dagorn, Auteur . - [s.d.] . - pp. 197-203. Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : Fisheries management now extends from the stock to the ecosystem. The foundation for fisheries management on an ecosystem basis must lie in appropriate modelling of the ecosystems. A prerequisite for such models requires data on the two interactive components of the ecosystem: the biotope (physical environment), and the community of living species. In this context, acoustics become essential, as this tool can provide qualitative and quantitative data on various communities of species, and furthermore allows the seldom-attainable study of their interactions. In fact, acoustics allow the monitoring of entire communities, from plankton to large predators, as well as certain aspects of the physical environment, such as substratum characteristics. Acoustics have been used during the last two decades mainly to provide fishery-independent estimates of stocks. The intention of this paper is to promote the use of acoustics for studying marine ecosystems and to encourage the emergence of new generations of ecosystem models. As an example of integrative research based on acoustic data, we will present the approach and the results of a scientific programme (ECOTAP) carried out to study the tuna pelagic ecosystem in French Polynesia. We then discuss the use of acoustics as a tool for ecosystem-based studies and management.

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Homing abilities of dolphinfish (Coryphaena hippurus) displaced from fish aggregating devices (FADs) determined using ultrasonic telemetry / Laurent Dagorn

Public ISBD Faire une suggestion d'achat Titre : Homing abilities of dolphinfish (Coryphaena hippurus) displaced from fish aggregating devices (FADs) determined using ultrasonic telemetry Type de document : texte imprimé Auteurs : Laurent Dagorn, Auteur Importance : pp. 313-321 Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : We conducted displacement experiments using acoustic tags to study the orientation abilities of dolphinfish (Coryphaena hippurus) around FADs. Eleven fish were passively monitored using coded transmitters and acoustic receivers attached to FADs, while seven others were actively tracked with a vessel using continuous acoustic tags equipped with pressure sensors. Ail thèse 18 dolphinfish were captured close to a FAD and released between 70 and 1720 m from it. Five fish out of the 14 that were displaced at more than 360 m from a FAD (estimated détection range of our acoustic receivers, defining the target area during our experiment) returned to the target area. With one individual successfully returning to the target area after having been released at 1600 m from the FAD, the rate of return of fish released up to this distance was significantly higher than expected if they were moving at random, but many fish released at intermediate distances moved in other directions. Based on detailed statistical analysis of the return score, we estimated that dolphinfish are able to orientale towards a FAD area from at least 820 m. The connection between our définition of thé target area and the association area of dolphinfish around a FAD is discussed, as well as the impact of stress and motivation in the rates of return observed. More experiments should be conducted to improve this first estimate. Specifie experiments should also be designed to more accurately determine the association range of fish around FADs and their motivation to orientale towards FADs. Homing abilities of dolphinfish (Coryphaena hippurus) displaced from fish aggregating devices (FADs) determined using ultrasonic telemetry [texte imprimé] / Laurent Dagorn, Auteur . - [s.d.] . - pp. 313-321. Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : We conducted displacement experiments using acoustic tags to study the orientation abilities of dolphinfish (Coryphaena hippurus) around FADs. Eleven fish were passively monitored using coded transmitters and acoustic receivers attached to FADs, while seven others were actively tracked with a vessel using continuous acoustic tags equipped with pressure sensors. Ail thèse 18 dolphinfish were captured close to a FAD and released between 70 and 1720 m from it. Five fish out of the 14 that were displaced at more than 360 m from a FAD (estimated détection range of our acoustic receivers, defining the target area during our experiment) returned to the target area. With one individual successfully returning to the target area after having been released at 1600 m from the FAD, the rate of return of fish released up to this distance was significantly higher than expected if they were moving at random, but many fish released at intermediate distances moved in other directions. Based on detailed statistical analysis of the return score, we estimated that dolphinfish are able to orientale towards a FAD area from at least 820 m. The connection between our définition of thé target area and the association area of dolphinfish around a FAD is discussed, as well as the impact of stress and motivation in the rates of return observed. More experiments should be conducted to improve this first estimate. Specifie experiments should also be designed to more accurately determine the association range of fish around FADs and their motivation to orientale towards FADs.

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Using local ecological knowledge (LEK) to provide insight on the tuna purse seine fleets of the Indian Ocean usefulfor management / Laurent Dagorn

Public ISBD Faire une suggestion d'achat Titre : Using local ecological knowledge (LEK) to provide insight on the tuna purse seine fleets of the Indian Ocean usefulfor management Type de document : texte imprimé Auteurs : Laurent Dagorn, Auteur Importance : pp. 367-376 Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : The purse seine fishery in the Western Indian Ocean is dominated by Spanish and French vessels that rely heavily on the use of drifting fish aggregation devices (DFADs) to capture tropical tuna species (skipjack, yellowfin and bigeye tuna). This study uses local ecological knowledge (LEK) obtained through standardized interviews of fishing masters to compare and characterize the body of local ecological knowledge, fishing technology and fishing strategies of both fleets, with the goal of obtaining useful information for the management of the fishery. A notable difference between fleets was the number of DFADs actively monitored per vessel at any given time, which was much higher for Spanish vessels (ça. 60 versus 20 DFADs). Spanish vessels also achieved higher vessel CPUE (catch per DFAD set) than their French counterparts. The use of supply vessels to manage, monitor and protect productive DFADs, and the latest satellite-based technology to track and remotely monitor DFAD aggregations is restricted to the Spanish fleet. The French do not use supply vessels and deploy less sophisticated tracking buoys. These technological disparities resulted in some fishing strategy differences between both fleets, but few differences were found in the knowledge of tuna behavior accumulated by the fishers. Using local ecological knowledge (LEK) to provide insight on the tuna purse seine fleets of the Indian Ocean usefulfor management [texte imprimé] / Laurent Dagorn, Auteur . - [s.d.] . - pp. 367-376. Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : The purse seine fishery in the Western Indian Ocean is dominated by Spanish and French vessels that rely heavily on the use of drifting fish aggregation devices (DFADs) to capture tropical tuna species (skipjack, yellowfin and bigeye tuna). This study uses local ecological knowledge (LEK) obtained through standardized interviews of fishing masters to compare and characterize the body of local ecological knowledge, fishing technology and fishing strategies of both fleets, with the goal of obtaining useful information for the management of the fishery. A notable difference between fleets was the number of DFADs actively monitored per vessel at any given time, which was much higher for Spanish vessels (ça. 60 versus 20 DFADs). Spanish vessels also achieved higher vessel CPUE (catch per DFAD set) than their French counterparts. The use of supply vessels to manage, monitor and protect productive DFADs, and the latest satellite-based technology to track and remotely monitor DFAD aggregations is restricted to the Spanish fleet. The French do not use supply vessels and deploy less sophisticated tracking buoys. These technological disparities resulted in some fishing strategy differences between both fleets, but few differences were found in the knowledge of tuna behavior accumulated by the fishers.

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