Approaches to understanding the cumulative effects of stressors on marine mammals

Activity: Talk or presentation typesPublic lecture/debate/seminar


Early marine conservation efforts focused on managing the number of fish or whales intentionally killed by humans. During the 20th century, fisheries biology aimed to maintain populations at levels set for efficient harvest. Even where declining catch per unit of fishing effort indicated the need for recovery, managers often failed to maintain healthy stocks of many harvested species. Managing individual species is problematic both because of economic factors and also because changing the abundance of one species may change the ecosystem into a new state that becomes difficult to return to a state that we desire. As we industrialize the oceans, restoring the health of marine species and ecosystems demands understanding the effects of many different stressors, including new stressors that have not received enough attention. Underwater noise has recently been accepted as a significant stressor, as it can lead to the death of some animals and can have broader non-lethal impacts. Focused experiments document precisely how marine species respond to measured dosages of specific sounds, enabling the development of probabilistic dose:response functions. The impacts of noise interact with other stressors such as directed hunt, bycatch, toxic compounds, pathogens, and changes in physical and biological features of the ocean that are affected by climate change. We have neither the data nor the theory required to understand how these stressors are likely to interact, which means that we cannot predict when anthropogenic and natural changes to stressors threaten the survival of some species and the health of marine ecosystems. Rather than managing each stressor or species separately, managing modern marine ecosystems demands analyzing which stressors can be reduced to most effectively recover reduced populations and to maintain healthy ecosystems that will be resilient to combinations of stressors they are likely to face in the future.
Period20 Sept 2018
Event titleScottish Oceans Institute Seminar
Event typeSeminar
Degree of RecognitionLocal