Gorgonian corals become rockfish communities
Photograph by Lou Lehmann – Text by Neil McDaniel
Gorgonian corals are common in the cold waters off Canada’s Pacific and Atlantic coasts, but they usually dwell in deep, dark water well beyond SCUBA depths. But on the Pacific coast, a few species are found in surprisingly shallow water, especially where subsea ridges force deep ocean currents toward the surface.
This specimen is a large fan of Primnoa pacifica, commonly known as the red tree coral. It’s widespread in the deep water of coastal B.C., but in Knight Inlet this striking coral can be found as shallow as 50 feet (15m); it’s the only known site on Canada’s west coast where it can be seen on SCUBA. These gorgonian fans grow in extensive ‘thickets’, providing complex vertical relief that forms important refuge for rockfish, such as the dark rockfish pictured here.
At Knight Inlet, some fans reach six feet (2m) tall and more than eight feet (2.5m) across, and are estimated to be between 100 and 150 years old. The inner skeleton of Primnoa is heavily calcified and the fans feel tough and wiry to the touch. However, they are easily destroyed by bottom-contact fishing methods such as trawling, long lining and trapping.
Diving naturalists studying the Knight Inlet Primnoa population over the past several years have recommended that Canada’s Department of Fisheries and Oceans protect this remarkable and precious site. To date DFO has taken no decisive action.
Photograph taken in Knight Inlet, British Columbia, using a Nikon D-50 with a Nikon 12-24mm lens set at 12mm in a Sea & Sea housing fitted with a dome port and twin Sea & Sea YS-D1 strobes. Exposure ISO 400, f4 at 1/50 second shutter speed.
For further information about these fascinating corals at Knight Inlet and why they need protection now, visit: www.NeilMcDaniel.com
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