Coral bank obstructions to trawling in the middle to outer continental shelf east and west of Lagos.

The continental shelf east and west of Lagos [long.2o.04.00E to long.4o 00’.00”E] is narrow shelf ranging in width between 25 to 30 kilometers. Echograms from several NIOMR’s cruises reveal the presence of some isolated and in some cases continuous bands of dead Holocene coral banks, within the middle to outer continental shelf [40-120m depth]. The most prominent of these structures are ones occurring between 75-100m of water and running almost parallel to the coastline. The dead coral structures are non-reef forms. They are found either as continuous Bands of rough bottom with width ranging between, 100 to 3,500m or in isolated pinnacled shapes. The pinnacled forms reach heights of over 7 meters in some cases. These coral structures pose obstructions to trawling within this part of the continental shelf which has been documented as fishing ground for fish species including Squatina oculata, Ariomma bondi, and Dentex angoleensis. Reports from fishing expeditions have shown that many expensive fishing nets have been torn and destroyed by these coralline structures during trawling exercise. There is urgent need therefore to map these obstructions in other to minimize the loss of trawl nets and maximize the exploitation of the fisheries resources within this part of the shelf. The continental shelf east and west of Lagos [long.2o.04.00E to long.4o 00’.00”E] is narrow shelf ranging in width between 25 to 30 kilometers. Echograms from several NIOMR’s cruises reveal the presence of some isolated and in some cases continuous bands of dead Holocene coral banks, within the middle to outer continental shelf [40-120m depth]. The most prominent of these structures are ones occurring between 75-100m of water and running almost parallel to the coastline. The dead coral structures are non-reef forms. They are found either as continuous Bands of rough bottom with width ranging between, 100 to 3,500m or in isolated pinnacled shapes. The pinnacled forms reach heights of over 7 meters in some cases. These coral structures pose obstructions to trawling within this part of the continental shelf which has been documented as fishing ground for fish species including Squatina oculata, Ariomma bondi, and Dentex angoleensis. Reports from fishing expeditions have shown that many expensive fishing nets have been torn and destroyed by these coralline structures during trawling exercise. There is urgent need therefore to map these obstructions in other to minimize the loss of trawl nets and maximize the exploitation of the fisheries resources within this part of the shelf.

NIOMR

Published