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What are the difficulties in studying marine mammal movements?

One difficulty in studying marine mammal movements is attaching the instruments to the animals.  Instruments are attached to the fur of pinnipeds using epoxy glue.

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When the pinniped is large, it is usually sedated so that it will not be overly stressed (and will not hurt the researchers while being handled!). Instruments are retrieved by clipping the fur attached to the instrument. Because pinnipeds molt their fur once a year, scientists have to make sure that the instrument is attached at a time of year when the fur will not be molted.

It is more difficult to attach instruments to cetaceans, because they cannot be captured on land, as pinnipeds can be. It is also quite difficult to attach an instrument to a cetacean's smooth skin.  In some cases, instruments are attached to cetaceans with a suction-cup device, by driving a boat close to the animal and shooting the instrument using a cross-bow. In some cases, smaller cetaceans can be captured and restrained in the water, and instruments attached to the dorsal fin. In all cetaceans and pinnipeds alike, streamlining is a big concern, because scientists do not want the instrument to be a great energy burden for the animal.

Often, instruments on cetaceans only stay on for a short period of time (less than 10 hours, compared to several months for instruments glued onto pinniped fur). It is also difficult to retrieve instruments from cetaceans. Many instruments are designed so that they will drop off after a certain amount of time, and they have radio transmitters and flotation devices so that they can be retrieved after they have dropped off the animal.

Why study marine mammal movements?

  • To locate marine mammals (historically to hunt them; more recently, to aid with their conservation)
  • To learn about their role in the marine ecosystem
  • To help us understand more about their life history
  • To understand where and how far they go in different seasons
  • To balance the effects of human activities with the conservation of marine mammal species and their habitat

The study of marine mammal movements provides us with both the scientific knowledge and appreciation to conserve their populations. If you think about it, people have always studied the distribution and migratory behavior of animals, both marine and terrestrial, in order to hunt them. The earliest information on the movements of marine mammals came from traditional knowledge of indigenous hunters as well as from commercial sealers and whalers; however, that information only provided locations of animals at one point in time. The use of modern technology, such as satellite transmitters and dive recorders, provides scientists with non-lethal method of collecting extensive data on the distribution and migratory behavior of marine mammals over long periods of time.

Information on the movement and diving behavior of free-ranging marine mammals helps us understand what the seasonal boundaries of their movements are, and how they use their habitat. Knowledge of how marine mammals interact with their environment fosters an understanding about how human interactions affect the marine environment. Human activities ranging from whale watching to commercial shipping (which creates a great deal of underwater noise) to commercial fishing all have potential impacts on marine mammals and their habitat. In each of these potential areas of conflict, detailed knowledge of the movement patterns of marine animals is essential to balancing the effects of human activities with the conservation of these species and their habitat.

Studies involving modern technology provide a window into the fascinating behavior of marine mammals. Through telemetry based observations, we are able to follow the first migrations of a fur seal pup, the movements of groups of beluga whales through the arctic ice, or the continuous diving of elephant seals and sperm whales to depths of 3280.8 feet (1000 meters) or more. Ideally, information gained from these instruments will help to give us both the knowledge and the appreciation to conserve these populations.

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Information within the education website should not be cited in scientific journals or publications.

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