Cherisse Du Preez, a University of Victoria PhD student, studying with Verena Tunnicliffe, project director of the Victoria Experimental Network Under the Sea (VENUS), used a remotely operated vehicle to take an in-depth look at Learmonth Bank, near Dixon Entrance. She was speaking at the recent International Marine Conservation Congress in Victoria. She said that it is a trawling hotspot and so they were looking for answers about whether the sponges and corals [on the ocean floor] are important to commercial fish.
According to Du Preez the research can help define the thin line between protection and economic needs. The Learmonth Bank ranges from 50 to 500 metres in depth and has smooth-bottomed trawled areas and rough-bottomed untrawled areas. Du Preez and Tunnicliffe looked at populations of rockfish and shortspine thornyheads, both species caught by trawlers, and hope their findings may influence future fishing plans and protect the area’s deep sea sponges and coral gardens.
The study found that the rough bottom area around the edge, populated with corals and sponges, is home to hordes of long-lived rockfish, which appear to rely on sponges for habitat. In the trawled area in the middle of the study area, the flattened ocean bottom had 13 times less coral and attracted few rockfish, but was popular with the thorny heads.
Du Preez said that people are destroying a non-renewable resource of incredible sponges and corals. What makes the area fascinating for researchers is that it offers a nearby comparison of an unfished ecosystem because of a border dispute between Canada and the U.S.
