Satellites can be useful for several monitoring tasks. Ocean colour spectre can be used to identify and estimate the amount of phytoplankton in the skin (~1 m) layer. Several climate variables can be monitored (e.g. ice cover, cloud cover, heat radiation, sea surface temperature). Marine mammals, polar bears and seabirds can be traced with attached transmitters.
Aircraft surveys can also be used for monitoring several physical parameters associated with the sea surface as well as observations of mammals at the surface. Along the Norwegian coast, ship-of-opportunity supply weekly the surface temperature along their path.
Tagging of fish and marine mammals has been used for many years to track the horizontal migration and vertical movement. The tags have historically been markers that only can give information about starting location and recapture location, but now electronic markers can monitor several parameters, such as position (through satellite signals when at surface), in situ temperature and salinity.
