The deep-water coral Lophelia pertusa in Norwegian waters: distribution and fishery impacts

Abstract

The paper presents documentation on the distribution of, and damages to, deep-water reefs of the coral Lophelia pertusa in Norwegian waters. The reef areas have traditionally been rich fishing grounds for long-line and gillnet fisheries, and the coral habitat is known to support a high diversity of benthic species. Anecdotal reports claim that trawlers often use the gear, wires, chains and trawl doors to crush the corals and clear the area before fishing starts. To get an overview of the situation, information about the distribution and damage were collected from the literature, fishermen, and our own investigations. The results show that the corals are abundant particularly on the mid Norwegian continental shelf between 200 and 400 m depth. In general it seems that the largest densities are distributed along the continental break and at ridges of morainic origin. The reports from fishermen suggested severe damage to the corals and in situ observations using ROV confirmed the presence of mechanically damaged corals located on trawling grounds. A first estimate of the fishery impact indicates that between 30 and 50% of the reef areas are damaged or impacted. Fishermen claim that catches are significantly lowered in areas where the reefs are damaged. Potential ecological consequences of the destruction are discussed.