Research Themes - Human Impacts on Marine Mammals

Presentations

Humans have very wide ranging impacts on marine mammals. The most obvious is the harvesting of marine mammals for commercial or subsistence purposes. Overharvesting has reduced some marine mammal populations to very low levels, resulting in concern for their continued existence eg St Lawrence beluga, blue whale and killer whales. Marine mammals are also taken as incidental catches during commercial fishing activities.

Human activities such as marine mammal-watching, petroleum exploration and commercial shipping may also impact on marine mammals. Considerable work remains to be completed to explore these impacts more fully. Marine mammal watching may impact on marine mammals in cases where too many boats approach the animals and interfere with normal resting, breeding or feeding activities. Petroleum activity such as seismic exploration may cause physical damage to marine mammal hearing or interfere with marine mammal feeding, migration or communication. This may have short term impacts on individual whales or longer term impacts on survival if access to critical feeding zones is limited by high sound levels. Industrial impacts need to be examined on a project by project basis, as well as cumulative impacts. For example current areas off the Nova Scotia are currently known as one of the noisiest areas in the world for seismic exploration with constant, high sound levels recorded as far away as the mid-Atlantic during the summer months. Commercial ship traffic is also associated with very high noise levels and is responsible for much of the noise pollution found in the world's oceans today.

Coastal development also has an impact on marine mammals by increasing marine traffic or through the loss of habitat eg seal haulout sites, or feeding areas from animals. Finally, the dumping of waste into the environment results in the transfer to marine mammals, of parasites normally associated with humans or terrestrial wildlife.