Division 5.1

Impacts of bottom towed gear activity on bedrock reef:

1. 5.1.1.

   The available evidence^f1 consisting of empirical studies quantifying the impact of fisheries to hard bottom habitats is limited. However, it is known that towing trawls across rocky substrates will cause damage or death to a significant proportion of large, upright attached species such as sponges and corals (Løkkeborg 2005). 67 % of sponges were damaged during to a single trawl pass, in the Gulf of Alaska (Freese et al 1999). Other species such as hydroids, anenomes, bryozoans, tunicates and echinoderms are vulnerable to mobile fishing gear (McConnaughey et al 2000, Sewell and Hiscock 2005). Trawling may also reduce habitat complexity as boulders and cobbles associated with the hard substrate are moved around (Engel and Kvitek 2008, Freese et al 1999). Resistance to damage at a physical level is variable with substrate type, with mudstone reefs particularly vulnerable to structural damage (Attrill et al 2011). It is considered that the risk of significant impact is sufficient to require a categorisation of red risk and therefore management measures implemented this year.