3 research outputs found

    Distribuci贸n estival y abundancia de la gran manta raya (Mobula mobular) en el mar Adri谩tico: datos de base para un marco de gesti贸n iterativo

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    The giant devil ray (Mobula mobular) is a poorly understood protected endemic species of the eastern Atlantic-Mediterranean region. However, to date there are no range-wide management actions in place. This paper provides the first overview of the summer distribution and abundance of this species and other Myliobatiformes within the Adriatic Sea based on an aerial survey. Although the survey麓s primary targets were cetaceans and sea turtles, the study showed that it was possible to use the survey to monitor other species. Abundance estimates are derived using conventional distance sampling analysis. Giant devil rays were observed mainly in the central-southern Adriatic (88% of total sightings). A total of 1595 giant devil rays were estimated in the central-southern Adriatic Sea [coefficient of variation(CV)=25%, uncorrected estimate for perception and availability bias]. When corrected for availability bias the number of specimens was estimated at 3255 (CV=56%). Population growth rate was estimated using life history traits and a sensitivity analysis was conducted to evaluate the benefit of improving biological knowledge on this data-poor species. A power analysis showed that a long-term commitment to an aerial survey would be necessary to monitor population trends. Conservation implications and future work, including how the study could be used to conduct an ecological risk assessment are discussed.La manta raya gigante (Mobula mobular) es una especie end茅mica protegida poco conocida de la regi贸n del Atl谩ntico oriental-Mediterr谩neo. Sin embargo hasta la fecha no hay acciones de gesti贸n que cubran todo su rango. Este art铆culo proporciona la primera visi贸n de conjunto de la distribuci贸n y abundancia estival de esta especie y otras Myliobatiformes en el mar Adri谩tico basada en un censo a茅reo. Aunque los objetivos principales del censo eran cet谩ceos y tortugas marinas, el estudio mostr贸 que era posible usar el censo para monitorizar otras especies. Las estimas de abundancia se derivaron utilizando an谩lisis convencional de muestreo de distancias. Las manta rayas gigantes se observaron principalmente en el Adri谩tico central y sur (88% de los avistamientos totales). Se estimaron un total de 1595 mantas rayas gigantes en el mar Adri谩tico central-sur (CV=25%, estima no corregida para los sesgos de percepci贸n y de disponibilidad). Cuando se corrigi贸 para el sesgo de disponibilidad el n煤mero de espec铆menes se estim贸 en 3255 (CV=56%). La tasa de crecimiento de la poblaci贸n se estim贸 usando aspectos de la historia natural y se realiz贸 un an谩lisis de sensibilidad para evaluar el beneficio de mejorar el conocimiento biol贸gico de esta especie de la que hay tan pocos datos. Un an谩lisis de potencia mostr贸 que ser铆a necesario un compromiso a largo plazo para realizar censos a茅reos para monitorizar las tendencias de la poblaci贸n. Se discuten las implicaciones para la conservaci贸n y trabajo futuro, incluyendo c贸mo se podr铆a utilizar este estudio para llevar a cabo una evaluaci贸n ecol贸gica de riesgo

    Summer distribution and abundance of the giant devil ray (<em>Mobula mobular</em>) in the Adriatic Sea: Baseline data for an iterative management framework

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    The giant devil ray (Mobula mobular) is a poorly understood protected endemic species of the eastern Atlantic-Mediterranean region. However, to date there are no range-wide management actions in place. This paper provides the first overview of the summer distribution and abundance of this species and other Myliobatiformes within the Adriatic Sea based on an aerial survey. Although the survey麓s primary targets were cetaceans and sea turtles, the study showed that it was possible to use the survey to monitor other species. Abundance estimates are derived using conventional distance sampling analysis. Giant devil rays were observed mainly in the central-southern Adriatic (88% of total sightings). A total of 1595 giant devil rays were estimated in the central-southern Adriatic Sea [coefficient of variation(CV)=25%, uncorrected estimate for perception and availability bias]. When corrected for availability bias the number of specimens was estimated at 3255 (CV=56%). Population growth rate was estimated using life history traits and a sensitivity analysis was conducted to evaluate the benefit of improving biological knowledge on this data-poor species. A power analysis showed that a long-term commitment to an aerial survey would be necessary to monitor population trends. Conservation implications and future work, including how the study could be used to conduct an ecological risk assessment are discussed
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