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To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1523-1739.2009.01172.x Byline: RAMŪNAS ŽYDELIS (*[dagger][dagger]), BRYAN P. WALLACE (*[dagger]), ERIC L. GILMAN ([double dagger]), TIMOTHY B. WERNER (s.) Keywords: compensatory mitigation; elasmobranchs; fisheries bycatch; invasive predators; marine conservation; marine mammals; sea turtles; seabirds Abstract: Abstract: Many populations of marine megafauna, including seabirds, sea turtles, marine mammals, and elasmobranchs, have declined in recent decades due largely to anthropogenic mortality. To successfully conserve these long-lived animals, efforts must be prioritized according to feasibility and the degree to which they address threats with the highest relative impacts on population dynamics. Recently, Wilcox and Donlan (2007, Frontiers in Ecology and the Environment) and Donlan and Wilcox (2008, Biological Invasions) proposed a conservation strategy of 'compensatory mitigation' in which fishing industries offset bycatch of seabirds and sea turtles by funding eradication of invasive mammalian predators from the terrestrial reproductive sites of these marine animals. Although this is a creative and conceptually compelling approach, we find it flawed as a conservation tool because it has narrow applicability among marine megafauna, it does not address the most pervasive threats to marine megafauna, and it is logistically and financially infeasible. Invasive predator eradication does not adequately offset the most pressing threat to most marine megafauna populations-fisheries bycatch. For seabird populations, fisheries bycatch and invasive predators infrequently are overlapping threats. Invasive predators have limited population-level impacts on sea turtles and marine mammals and no impacts on elasmobranchs, all of which are threatened by bycatch. Implementing compensatory mitigation in marine fisheries is unrealistic due to inadequate monitoring, control, and surveillance in the majority of fleets. Therefore, offsetting fisheries bycatch with eradication of invasive predators would be less likely to reverse population declines than reducing bycatch. We recommend that efforts to mitigate bycatch in marine capture fisheries should address multiple threats to sensitive bycatch species groups, but these efforts should first institute proven bycatch avoidance and reduction methods before considering compensatory mitigation. Abstract (Spanish): Conservacion de la Megafauna Marina Medianate la Minimizacion de la Captura Incidental de Pesquerias Resumen: Muchas poblaciones de megafauna marina, incluyendo aves, mamiferos y elasmobranquios, han declinado en decadas recientes principalmente debido a mortalidad antropogenica. Para conservar exitosamente a estos animales longevos, los esfuerzos se deben priorizar de acuerdo con la factibilidad y el grado en que atienden las amenazas con los impactos relativos mas altos sobre la dinamica de la poblacion. Recientemente, Wilcox y Donlan (2007) y Donlan y Wilcox (2008) propusieron una estrategia de conservacion de 'mitigacion compensatoria' en la que las industrias pesqueras compensan la captura incidental de aves y tortugas marinas mediante el financiamiento de la erradicacion de mamiferos depredadores invasores de las localidades reproductivas terrestres de estos animales marinos. Aunque este es un metodo creativo y conceptualmente imponente, lo consideramos deficiente como una herramienta de conservacion porque su aplicacion es limitada entre la megafauna marina, no aborda las amenazas mas grandes a la megafauna marina y no es factible logistica y financieramente. La erradicacion de depredadores invasores no compensa adecuadamente la amenaza mas fuerte para la mayoria de las poblaciones de megafauna marina - la captura incidental de pesquerias. Para las poblaciones de aves marinas, la captura incidental de pesquerias y los depredadores invasores son amenazas que se traslapan poco frecuentemente. Los depredadores invasores tienen impactos limitados a nivel poblacion sobre tortugas marinas y mamiferos marinos y no tienen impactos sobre elasmobranquios, todos ellos amenazados por la captura incidental. La implementacion de la mitigacion compensatoria en pesquerias marinas no es realista debido a que el monitoreo, control y vigilancia son inadecuados en la mayoria de las flotas. Por lo tanto, es mas probable que la compensacion de la captura incidental con la erradicacion de depredadores invasores revierta la declinacion de poblaciones y no reduzca la captura incidental. Recomendamos que los esfuerzos para mitigar la captura incidental en las pesquerias marinas deberian atender amenazas multiples a los grupos de especies sensibles a la captura incidental, pero estos esfuerzos primeramente deberian instituir metodos de reduccion de captura incidental antes de considerar la mitigacion compensatoria. Author Affiliation: (*)Center for Marine Conservation, Nicholas School of the Environment, Duke University Marine Laboratory, 135 Duke Marine Lab Road, Beaufort, NC 28516, U.S.A. ([dagger])Center for Applied Biodiversity Science, Conservation International, Arlington, VA 22202, U.S.A. ([double dagger])IUCN Global Marine Programme and University of Exeter Centre for Ecology and Conservation, 2718 Napuaa Place, Honolulu, HI 96822, U.S.A. (s.)New England Aquarium, Central Wharf, Boston, MA 02110 and Biology Department, Boston University, 5 Cummington Street, Boston, MA 02215, U.S.A. Article History: Paper submitted February 22, 2008; revised manuscript accepted September 30, 2008. Article note: ([dagger][dagger]) email zydelis@duke.edu