Résumé: Despite major advances in our capacity to measure marine larval connectivity (i.e. the pattern of transport of marine larvae from spawning to settlement sites) and the importance of these measurements for ecological and management questions, uncertainty in experimental estimates of marine larval connectivity has been given little attention. We review potential uncertainty sources in empirical larval connectivity studies and develop Bayesian statistical methods for estimating these uncertainties based on standard techniques in the mark-recapture and genetics literature. These methods are implemented in an existing R package for working with connectivity data, ConnMatTools, and applied to a number of published connectivity estimates. We find that the small sample size of collected settlers at destination sites is a dominant source of uncertainty in connectivity estimates in many published results. For example, widths of 95% CIs for relative connectivity, the value of which is necessarily between 0 and 1, exceeded 0.5 for many published connectivity results, complicating using individual results to conclude that marine populations are relatively closed or open. This “small sample size” uncertainty is significant even for studies with near-exhaustive sampling of spawners and settlers. Though largely ignored in the literature, the magnitude of this uncertainty is straightforward to assess. Better accountability of this and other uncertainties is needed in the future so that marine larval connectivity studies can fulfill their promises of providing important ecological insights and informing management questions (e.g. related to marine protected area network design, and stock structure of exploited organisms). In addition to using the statistical methods developed here, future studies should consistently evaluate and report a small number of critical factors, such as the exhaustivity of spawner and settler sampling, and the mating structure of target species in genetic studies.

Résumé: Although marine reserves represent one of the most effective management responses to human impacts, their capacity to sustain the same diversity of species, functional roles and biomass of reef fishes as wilderness areas remains questionable, in particular in regions with deep and long-lasting human footprints. Here we show that fish functional diversity and biomass of top predators are significantly higher on coral reefs located at more than 20 h travel time from the main market compared with even the oldest (38 years old), largest (17,500 ha) and most restrictive (no entry) marine reserve in New Caledonia (South-Western Pacific). We further demonstrate that wilderness areas support unique ecological values with no equivalency as one gets closer to humans, even in large and well-managed marine reserves. Wilderness areas may therefore serve as benchmarks for management effectiveness and act as the last refuges for the most vulnerable functional roles.

Résumé: The North Atlantic right whale (NARW) (Eubalaena glacialis) is one of the world's most threatened whales. It came close to extinction after nearly a millennium of exploitation and currently persists as a population of only approximately 500 individuals. Setting appropriate conservation targets for this species requires an understanding of its historical population size, as a baseline for measuring levels of depletion and progress toward recovery. This is made difficult by the scarcity of records over this species' long whaling history. We sought to estimate the preexploitation population size of the North Atlantic right whale and understand how this species was distributed across its range. We used a spatially explicit data set on historical catches of North Pacific right whales (NPRWs) (Eubalaena japonica) to model the relationship between right whale relative density and the environment during the summer feeding season. Assuming the 2 right whale species select similar environments, we projected this model to the North Atlantic to predict how the relative abundance of NARWs varied across their range. We calibrated these relative abundances with estimates of the NPRW total prewhaling population size to obtain high and low estimates for the overall NARW population size prior to exploitation. The model predicted 9,075-21,328 right whales in the North Atlantic. The current NARW population is thus <6% of the historical North Atlantic carrying capacity and has enormous potential for recovery. According to the model, in June-September NARWs concentrated in 2 main feeding areas: east of the Grand Banks of Newfoundland and in the Norwegian Sea. These 2 areas may become important in the future as feeding grounds and may already be used more regularly by this endangered species than is thought. Una Estimacion Espacialmente Explicita de la Abundancia Previa a la Caza de la Ballena Franca del Atlantico Norte en Peligro de Extincion La ballena franca del Atlantico Norte (BFAN) (Eubalaena glacialis) es una de las ballenas mas amenazadas del mundo. Su extincion estuvo proxima despues de casi un milenio de explotacion y actualmente persiste una poblacion de aproximadamente 500 individuos. El establecimiento de objetivos de conservacion apropiados para esta especie requiere del entendimiento del tamano historico de la poblacion como la linea base para la medida de los niveles de disminucion y el progreso hacia la recuperacion. Esto se dificulta por la escasez de registros sobre la larga historia de la caza de esta especie. Buscamos estimar el tamano poblacional previo a la explotacion de la ballena franca del Atlantico Norte y entender como se distribuia esta especie a lo largo de su extension. Usamos un conjunto de datos espacialmente explicitos sobre las capturas historicas de las ballenas francas del Pacifico Norte (BFPN) (Eubalaena japonica) para modelar la relacion entre la densidad relativa de ballenas francas y el ambiente durante la temporada de verano de alimentacion. Cuando asumimos que las dos especies de ballenas francas seleccionan ambientes similares, pudimos proyectar este modelo hacia el Atlantico Norte y asi poder predecir como la abundancia relativa de las BFAN vario a lo largo de su extension. Calibramos estas abundancias relativas con los estimados del tamano poblacional total previo a la caza de las BFPN y asi obtener estimados altos y bajos para el tamano poblacional general de las BFAN previo a la explotacion. El modelo predijo la existencia de 9, 075 – 21, 328 ballenas francas en el Atlantico Norte. La poblacion actual de BFAN es entonces <6 % a la capacidad de carga historica del Atlantico Norte, por lo que tiene un potencial enorme para la recuperacion. De acuerdo al modelo, entre junio y septiembre, las BFAN se concentraron en dos areas de alimentacion principales: al este de los Grandes Bancos de Terranova y en el Mar de Noruega. Estas dos areas pueden volverse importantes en el futuro como sitios de alimentacion y puede que ya sean usadas por esta especie de manera mas regular de lo que se cree. Resumen