Fishing

Deep-sea bottom trawling which uses a towed net held open by heavy doors to fish along the sea floor, is considered one of the greatest threats to the persistence of cold-water reefs (Freiwald et al., 2004). Fishing practices of deep-water trawling and long-lining cause significant disturbance (Hall-Spencer et al., 2002), with 50% damage to L.pertusa reefs in Norway prior to area closures (Fosså et al., 2002). The highly destructive nature of this fishing practice was brought to the public’s attention by the media in the 1990’s, when video evidence was captured for cold-water reefs off the coast of Norway for the first time (Fosså et al., 2002; Armstrong and Van den Hove, 2008). The pictures  demonstrated the scarring caused by the nets being towed, dumped fishing lines, ghost fishing and mounds of coral rubble that was once beautifully diverse reefs (Fig.9a and b). The extent of this kind of damage is exacerbated by the slow growth and reproductive rates of cold-water corals and there is limited evidence for a degree of resilience to disturbances of these magnitudes (Armstrong and Van den Hove, 2008). The same is true of the species fished from the reefs which also show extended longevity and slow growth rates e.g. rockfish living to 200 years (Cailliet, 2001). The removal of these species, often ending up as wasteful by-catch, could be detrimental for the community interactions within the reefs (Roberts, 2002).

Fig.9a. Coral rubble created by the destruction of corals by bottom trawlers. Adapted from Fosså et al., (2002)

Fig.9b. Gill net ropes causing damage and evidence of fishing activities. Adapted from Fosså et al., (2002).

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