SMRU > Research > Distribution
Understanding the distribution of marine mammals helps us to understand their ecology: why they choose to be in one place rather than another. There are numerous ways in which we make use of distributional data, and the work involved here informs many other areas of work within the SMRU and elsewhere.
A large part of SMRU’s work has historically revolved around the instrumentation of marine mammals, using a variety of telemetry devices to study both their underwater behaviour and their distribution.
The distribution of marine mammals has also been studied extensively by the use of sightings data, and more recently by the use of passive acoustic monitoring. Sightings data collected from platforms of opportunity and from dedicated surveys have been combined, for example, to produce maps of cetacean distribution based on the number of animals seen per hour of observation. Dedicated surveys are able to generate estimates of absolute abundance by geographical area, enabling trends in density through time to be analysed, with obvious conservation and management benefits.
Passive acoustic methods include arrays of hydrophones towed behind ships, or fixed to the seabed, as well as self contained individual recording devices that log cetacean echo-location clicks. Acoustic arrays are used to track the movements of individual animals, while self contained units are more useful in determining trends in habitat use.
Seal distribution is routinely monitored photographically by SMRU through annual aerial surveys of haul-out sites and breeding colonies. Distribution data are also used in population modelling to understand the linkages between breeding groups, and the ways in which populations are dispersed
Positional data from Argos tags has enabled Jason Matthiopoulos and others to generate at-sea habitat usage maps for UK seals.
Seal distribution maps have been used by Callan Duck to advise Scottish Natural Heritage and Joint Nature Conservation Committee on the best locations for designating Special Areas of Conservation (SACs) for seals.
Elephant seal distribution in the Southern Ocean has been studied by Mike Fedak, Lars Bohme, Bernie McConnell, and others using satellite telemetry. The distribution and behaviour have been related to oceanographic conditions (see SEAOS).
Phil Hammond has co-ordinated two EU funded large scale surveys of cetaceans in NW European waters that provide benchmark data on the distribution and abundance of cetaceans in this area.
Simon Northridge has used sightings data to generate maps of cetacean distribution in NW Europe.Paddy Pomeroy and others have used the distribution of breeding seals in aerial photos along with high resolution GIS based models of breeding colonies to identify preferred habitat and predict future use.