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The deep-water coral Lophelia pertusa in Norwegian waters: distribution and fishery impacts - page 4 / 12





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Figure 2. Lophelia pertusa colonies at 40 m depth on the Tautra ridge in Trondheimsfjorden, Norway. This reef is protected by the 8 June 2000 statute with status as a marine nature reserve on an interim basis. Photo by Erling Svensen.

probably be much larger than the chosen 200 and 500 m, and in some cases exceed 500 m. We believe that our size estimates are thus conservative. Lastly, a coral area is a section of the bottom defined by sev- eral co-ordinates. However, an area is rarely entirely covered by corals or reefs, but they are scattered on elevations, ridges and iceberg plough marks.


Occurrence of corals

In total we present 407 records of corals determined by 583 geographical points of colonial scleractinians. Records of Lophelia pertusa from the literature (n = 95), Statoil (n = 70), NDF (n = 29) and IMR (n = 55) are considered as verified information, while records from fishermen (n = 158) at sites not checked by us as non-verified (Table 1, Fig. 1).

The presence of corals mentioned in the literat- ure are restricted to the fjords and near coastal waters because earlier research had limited access to sea go- ing vessels. Dons (1944) had only two records from the shelf break in mid-Norway (between 63and 68N) and four from Northern Norway on the basis of information from fishermen. The records from the continental break derived mainly from fishery-related activities, NDF and IMR. Statoil provided informa- tion for the shelf Southwest of Haltenbanken (Hovland et al., 1997; Mortensen et al., 2001.) IMR provided information from trawling activities scattered on the shelf and continental break.

Corals are most abundant on the continental shelf in mid-Norway at 200-400 m depth (Fig. 1). The largest densities occur along the continental break and on edges of shelf-crossing trenches. A photo of a well- developed reef from Trondheimsfjorden is given in Figure 2.

Inspected localities

Many reports on coral occurrences as well as damage originate from Storegga, a steep part of the continental break between 6230N and 6350N (Fig. 1). Three localities on Storegga were inspected between 1998 and 1999: Aktivneset, Korallneset and Sørmannsne- set. During 1999 two localities were inspected on the shelf: Maurdjupet and Iverryggen (Table 2, Fig. 1). All these localities and surrounding areas are subject to extensive bottom trawling.


Fishermen reported areas with severely damaged cor- als, especially at the shallowest depth (200 m) (Fig. 3). There are also claims of increased bottom depth in a number of areas, (detected in the echograms) as a consequence of reefs being ‘trawled away’. Some refer to specific locations with abundant coral reefs that have disappeared by now, others state that corals were present until 1992–93. Sørmannsneset had been considered a good fishing place for tusk and ling with passive gear 10–12 years ago. Thus, the general im- pression is that coral reefs have decreased significantly in this area. We performed two inspections with ROV in 1998 at Sørmannsneset covering a vertical range from 370 to 225 m and distances between 2.5 and 2.9 km (Fig. 3, Table 2). The observations confirmed that the most severe damage occurred at shallowest depths (200 m) as crushed remains of Lophelia skel- eton were spread over the area while living corals were

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