Análisis de la pesca de atún con palangre en el Golfo de México durante las fases de luna nueva y llena

Data from the long-line fishery in the Gulf of Mexico during 2001 was analyzed with the aim of detecting differences during full and new moon phases. A preference for fishing during new moon is observed although the catches of yellowfin tuna, Thunnus albacares (aimed specie), and of bluefin tuna, Thunnus thynnus, in terms of catch per unit effort (CPUE), was similar in both periods. In addition catches of sailfish, Istiophorus albicans, swordfish, Xiphias gladius, and marlins (Makaira and Tetrapturus) were also analyzed, all as a group. Differences are detected with billfishes (incidental catch with commercial value), detecting higher CPUE values during full moon, although significant differences were observed only in the case of swordfishes (P=0.005). Two areas of high effort concentration were detected (one of them relatively coastal). During new moon both areas had high effort concentrations; however, with full moon effort was concentrated only in the coastal area. Both zones are located in deep waters, off the continental platformSe analizó información de la pesca con palangre del Golfo de México durante el 2001, con la finalidad de detectar las diferencias en la pesca durante las fases de luna llena y luna nueva. Se observó que hay una preferencia a pescar en luna nueva, aunque la captura de atún aleta amarilla, Thunnus albacares (especie objetivo) y la de atún aleta azul, Thunnus thynnus, en términos de captura por unidad de esfuerzo (CPUE), no mostró diferencias. Se analizó además la captura de pez vela, Istiophorus albicans, pez espada, Xiphias gladius, y marlines en conjunto (géneros Makaira y Tetrapturus). Con los peces picudos (captura incidental de más valor comercial) generalmente se observaron diferencias, con una CPUE mayor durante la fase de luna llena, sin embargo sólo en el caso del pez espada hubo diferencias significativas (P=0.005). Se observó que la pesca se concentra en dos zonas, una de ellas muy alejada de la costa. En luna nueva las dos áreas tienen alta concentración de esfuerzo, a diferencia de la fase de luna llena, cuando esa concentración de esfuerzo sólo se observó en la zona costera. Ambas zonas se localizan en aguas profundas fuera de la plataforma continental

A first approach to the management of the incidental catch of the eastern Pacific Mexican tuna fleet

The information registered by the Mexican Tuna Management and Dolphin Protection Program (PNAAPD) observers on board the Mexican tuna vessels was used to make a basic statistical analysis of the incidental catch of the Mexican eastern Pacific fleet, and to evaluate different aspects of the spatial and seasonal closure strategy. Twenty spatial and seasonal units were identified and hierarchically classified by set-type into four categories (explosive, avoidable, preventive and acceptable) based on two criteria: the incidental catch per set and the number of sets. Incidental catch reduction curves were created. Finally, and example of incidental catch reduction was performed for the mahi-mahi (dolphin-fish) Coryphaena hippurus and C. aquisells, considering the reduction percentage of incidental catch and main objective species catch (yellowfin tuna, Thunnus albacares), and the number of spatial and seasonal units closed. Log-sets are the type of sets that contribute with the gratest amount of incidental catch, except for billfishes. Of the five analyzed areas, those located off the coasts of Mexico can be considered as those with lower risk for most of the species incidentally caught throughout the year. The direct strategy for most of the management objectives is to eliminate or reduce the number of log-sets for the Mexican tuna fleet, throughout the whole zone or in specific units, resulting in a significant incidental catch reduction and a minimal effect on the yellowfin catch. The choice among five alternatives, none better than the others, establishing the units to be closed and the order to do so to reduce the incidental catch, rests in the decision-makers, and is a function of their preferences in respects to the different criteria used to evaluate the alternatives

Descarte y captura incidental de la flota atunera mexicana menor de 363 tm de capacidad de acarreo en 1996

Due to the importance of fishing in a responsible manner, following FAO's Code of Conduct for Responsaible Fishing, there is the need to estimate the incidental catch and discard of all fisheries worldwide. The fishing logbooks of the mexican tunaboats with less than 363 metric tons of carrying capacity were analyzed to estimate the level of tuna discards and incidental catches during 1996. Due to the absence of scientific observers aboard, direct and indirect methods were used. The tun discard estimate varied fro 190 to 230 metric tons, and the incidental catch estimate from 146 to 262 metric tons of different species or group os species. The discard estimate represents approximately 1.3 to 1.6% of total catch, and the incidental catch estimate about 1.0 to 1.8%. These levels are low compared to worldwide and other tun fisheries discard and incidental catch estimates, but the damage they cause to the populations affected are subject to further population dynamic studies.Debido a la importancia de realizar actividades pesqueras responsables, de acuerdo al Código de Conducta para l Pesca Responsable de la FAO, es de gran necesidad el contar con estimaciones de la captura incidental y descartes en todas las pesquerías a nivel mundial. En el presnte trabajo se aalizaron bitácoras de pesca de embarcaciones atuneras mexicanas menores de 363 tm de capacidad de acarreo para obtener una estimación del nivel de descarte de atunes y captura incidental en 1996. Debido  a la ausencia de observadores científicos a bordo, se utilizaron métodos directos e indirectos para las estimaciones. Se estimó un descarte de atunes con un intervalo de 190 a 230 toneladas métricas, y captura incidental con un intervalo de 146 a 262 toneladas métricas de diferentes especies o grupos de especies. El descarte representa entre el 1.3 y 1.6% de la captura total, y la captura incidental entre el 1.0 y 1.8%. Estos niveles resultan bajos comparados con los niveles mundiales y con los de otras pesquerías de túnidos, pero el daño que causan a las poblaciones está sujeto a estudios futuros sobre la dinámica poblacional de cada especie descartada o capturada incidentalmente