Cobb Seamount

Relatively convenient access and an interesting biological setting have made the seamount an object of several scientific cruises and dives.

Cobb Seamount lies 270 mi (430 km) off the coast of Washington, in the 8,500 ft (2,600 m)-deep Cascadia Basin.

[3] Cobb Seamount's slopes average 12° in grade, and are indented by four prominent terraces at various depths; this morphology is partly the result of sub-aerial exposure and wave erosion at sea level and partly due to volcanic processes far below wave base.

[7] The summit of the volcano is dominated by a carpet of Hinnites multirugosus, which forms the base of a dense ecosystem of sponges and other small, sessile organisms.

The species is otherwise scarce in its distribution in the Pacific; its abundance is accommodated by the scarcity of its chief predator, the sea star Orthasterias koehleri.

Red-colored colonies of demosponge and related species predominant the ecosystem, which includes sea urchins, sponges, algae, anemones, and gastropods.

It is known that it has been the site of trawling, gill net, and long-line fishing for some time, mostly by the Japanese and Oregonian fleets.

[8] In 2012, an extensive scientific survey of Cobb Seamount was led jointly by Fisheries and Oceans Canada (DFO) and the United States National Oceanographic and Atmospheric Administration (NOAA).

Red encrusting demosponge of the type found on Cobb Seamount.