A roadmap towards monitoring walruses from space

Walruses (Odobenus rosmarus) are experiencing rapid habitat change, concomitant with dramatic sea ice declines in the Arctic. Reduction in sea ice also creates the potential for reduced benthic production and heightened disturbance levels from
increasing levels of shipping traffic in previously ice-covered areas. These stressors are creating a growing need to monitor
how walrus populations are responding under the new conditions, through the production of accurate abundance estimates,
population trend data, and updated distribution information. Most walrus stock assessments rely on counts of walruses at
their terrestrial haul-out sites, which are spread across the Arctic, limiting the spatial and temporal extent at which they can
be surveyed with current tools (boats, planes, and drones). Satellite imagery is an emerging monitoring tool that can sample anywhere on the Earth’s surface and increase survey frequency. Herein, we lay a roadmap towards monitoring walruses
from space by discussing: (1) walrus conservation needs; (2) satellite capabilities in relation to walrus monitoring; and (3)
the current feasibility and future prospects of surveying walruses using space technologies. Satellite imagery has been used
successfully to detect, and in some cases count walruses, highlighting its potential to be a complementary tool to traditional
methods for monitoring walrus distribution. Validation studies and initial population assessments demonstrate the potential
of this new approach.