Maufroy Alexandra, Gaertner Daniel, Kaplan David, Bez Nicolas, Soto M., Assan C., Lucas J., Chassot Emmanuel. (2015). Evaluating the efficacy of tropical tuna purse seiners in the Indian Ocean : first steps towards a measure of fishing effort. In :
17ème groupe de travail sur les thons tropicaux. Victoria : CTOI, 12 p. (Documents de Réunion ; IOTC-2015-WPTT17-14). WPTT : Working Party on Tropical Tunas, 17., Montpellier (FRA), 2015/10/23-28.
Titre du document
Evaluating the efficacy of tropical tuna purse seiners in the Indian Ocean : first steps towards a measure of fishing effort
Année de publication
2015
Type de document
Colloque
Auteurs
Maufroy Alexandra, Gaertner Daniel, Kaplan David, Bez Nicolas, Soto M., Assan C., Lucas J., Chassot Emmanuel
In
17ème groupe de travail sur les thons tropicaux
Source
Victoria : CTOI, 2015,
12 p. (Documents de Réunion ; IOTC-2015-WPTT17-14).
Colloque
WPTT : Working Party on Tropical Tunas, 17., Montpellier (FRA), 2015/10/23-28
The evaluation of the fishing effort exerted by purse seiners on tropical tuna requires a constant monitoring of the changes in individual fishing power of purse seiners due to changes in vessel characteristics, fishing gears or fishing strategies. Also, since the 1990s, increasing numbers of drifting Fish Aggregating Devices have been used by this fleet. As dFADs contribute to a reduction of search times, traditional measures of fishing effort such as search time or fishing time are inappropriate. Here, using logbook data from the French and the Spanish purse seine fleets over 2003-2014, the effects of purse seiners' characteristics (length, the size of the wells, period of construction ) and their use of support vessels on the efficiency of purse seiners are analyzed with GLM models. 3 dimensions of the efficiency of purse seiners are analyzed: monthly catch rates, monthly frequency of fishing sets and monthly distance of fishing sets. Among others, we find that support vessels contribute to an increase in catch rates (+10 tons per day) and in distance between fishing set. In a second steps, the results of the GLM models are used to build 3 indexes of fishing effort that are compared to a simple monitoring of the number of EU purse seiners over 2003-2014. Ours result show that this simple index provide a biased image of the evolution of fishing effort for the purse seine fishery. Though preliminary, they indicate that the main components of fishing power should be taken into account when measuring the fishing effort of tropical tuna purse seiners in the Indian Ocean.
Plan de classement
Ressources halieutiques [040]
Localisation
Fonds IRD [F B010065857]
Identifiant IRD
fdi:010065857
