In many seas around the world, cuttlefish go through a yearly migration from the deeper waters, ~100m, when the sea surface temperatures begin to drop from late Autumn onwards to the shallows to breed. If you ever see a cuttlefish it will be in the shallows during this breeding phase when the waters are warmest. This probably allows the hatchlings a good temperature to grow in with lots of food around. This much we know. We do not know anything about what they do during the winter months in the cool dark winter waters. Fisheries data suggests they are eating and maybe even mating but this evidence only comes from dead animals that have been trawled.
In addition, in UK waters, there are at least two species which are very rarely seen been by humans, the 'Pink cuttlefish' (Sepia orbignyana) and 'Elegant cuttlefish' (Sepia elegans), live all year round in the deeper water and do not migrate to the very shallows to breed. The ROV is a key tool in discovering what these amazing animals are up to when they are out of sight of the SCUBA community.
The pictures below show how bathymetric data can aid us in determining where best to send the ROV to int the deeper waters.
Originally posted on National Geographic Open Explorer to cephalopodcitsci.