Marine mammals are increasingly threatened by interactions with fishing gear, ocean noise, pollution, direct harvest, ship traffic, competition for food with fisheries, and coastal development. Managers must set limits to these sources of human-caused mortality and disturbance to marine mammals without compromising human welfare. Currently, the U.S. Marine Mammal Protection Act limits the allowable number of deaths caused by fisheries with a simple model called Potential Biological Removal. NOAA has also recently committed to developing mapping tools to better understand where underwater noise overlaps with the distribution and density of cetaceans. Although a vast improvement to the status quo, there are still two major limitations associated with these approaches: 1) they do not consider the cumulative impacts of all threats, and 2) they assume largely unrealistic population dynamics. We propose to develop a new framework for setting removal limits that incorporates cumulative impacts, and also allows for more realistic population dynamics, especially with respect to social complexity in marine mammals. Our analyses will provide managers with clear guidelines for managing the threats that marine mammals encounter in space and time.
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