Evaluating the drivers and consequences of sub-lethal impacts in cetacean populations
Project Lead: Joshua Stewart
From a management and conservation perspective we are typically focused (with very good reason) on acute threats to species and populations, such as fisheries and other impacts that cause direct mortalities. Our lab has recently been studying sub-lethal impacts, or stressors that do not result directly in mortalities, but which may still affect individual fitness and ultimately population viability and trends. In a recent study with collaborators from NOAA, Woods Hole Oceanographic Institution, and the New England Aquarium, we found that sub-lethal entanglements in fishing gear are stunting the growth of critically endangered North Atlantic right whales. In a follow-up study, we found that smaller body sizes may contribute to lower reproductive output, further imperiling this declining population. The drone-based aerial photogrammetry methods used in this study allow for extremely precise measurements of body size. As drone technology becomes more advanced, we are finding countless opportunities to put these powerful tools to work collecting information on size structure, body condition, individual behaviors, and fine-scale movements and habitat use of marine vertebrates.
Related projects: (1) Linking Southern Resident killer whale nutritive condition to salmon availability. (2) Integrating eastern North Pacific gray whale demographic and condition data to understand dramatic population fluctuations.