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.

Increased levels of “background” sound which can elevate the overall soundscape can mask sounds produced by animals to communicate with each other and locate food, which can lead to changes in behavior and increased stress. The frequency (“pitch”), intensity (“volume”), and duration of sound influence whether an animal may be affected. Marine mammals have a range of hearing capabilities and thus may be affected by anthropogenic (human-caused) sound in different ways. Characteristics of individual animals (such as their age, life history status, behavioral state at time of exposure) can also influence their behavioral response to sound exposure. Discrete, loud sounds and longer-duration sounds can also potentially damage the hearing capabilities of marine mammals, either temporarily or permanently or cause non-auditory injury or even death. For more detailed information and scientific citations, please see the full FAQ document linked below.

Climate change is a global phenomenon that is causing changes in ocean currents, temperature, and chemistry. This can affect marine species in a variety of ways, including through changes in their distribution and health, as well as changes to the structure of marine food webs. Climate change may impact the location, timing (phenology), and abundance of lower trophic level organisms (e.g., planktonic algae, zooplankton) on which fishes, birds, marine mammals, and other species eat. This may particularly affect large whales that require substantial quantities of food for survival and reproduction. To date, most known impacts to marine mammals from changing environmental conditions are due to changes in the relationships between predators and prey. Climate change may also have secondary consequences for marine mammals including impacts to their migratory patterns, energetic reserves, and stress levels. If these impacts are severe, population level consequences could occur. For more detailed information and scientific citations, please see the full FAQ document linked below.