Vessel strikes are a major source of mortality and injury for large whales around the world. The chance of a vessel strike occurring depends on the co-occurrence or overlap of whales and vessels in space and time, with risk increasing as the densities of both ships and whales increase. Both the likelihood and severity of a vessel strike vary based on vessel characteristics (e.g., size, speed) and the species and behavior of the whale involved. Vessel strike avoidance depends on the ability for a whale to be detected, and the time for a vessel to enact a maneuver to avoid a whale. Thus, current efforts to reduce vessel strike risk in the U.S. depend on both relocating shipping lanes away from key whale habitat (i.e. reducing co-occurrence of whales and vessels) and implementing voluntary or mandatory speed restrictions in key areas. Reduced vessel speeds are known to reduce severity of collisions and also likely reduce the probability of collisions by increasing reaction times and chances for whale detection by boaters. For more detailed information and scientific citations, please see the full FAQ document linked below.