Humpback whale (Megaptera novaeangliae)

Abstract To effectively protect and manage marine mammals, contemporary information on their abundance and distribution is essential. Several factors influence present-day insight including the accessibility of the study area and the degree of difficulty in locating and studying target species. The offshore waters of the Gulf of Alaska are important habitat to a variety of cetaceans yet have remained largely unsurveyed due to its remote location, vast geographic area, and challenging environmental conditions.

Mortality from collisions with vessels is one of the main human causes of death for large whales. Ship strikes are rarely witnessed and the distribution of strike risk and estimates of mortality remain uncertain at best. We estimated ship strike mortality for blue humpback and fin whales in U.S. West Coast waters using a novel application of a naval encounter model. Mortality estimates from the model were far higher than current minimum estimates derived from stranding records and are closer to extrapolations adjusted for detection probabilities of dead whales.

Managing marine species effectively requires spatially and temporally explicit knowledge of their density and distribution. Habitat-based density models, a type of species distribution model (SDM) that uses habitat covariates to estimate species density and distribution patterns, are increasingly used for marine management and conservation because they provide a tool for assessing potential impacts (e.g., from fishery bycatch, ship strikes, anthropogenic sound) over a variety of spatial and temporal scales.