Within the scope of the EC Study Project "The environmental impact of demersal fishing gears on the marine environment", a commercial fishing ground on the north coast of Crete, Greece, was studied for otter-trawling impacts. The trawling season is limited to eight months between October and May. The major trawling lane, at 200 m depth off the port of Heraklion, is narrow because of bottom contouring. Four sampling stations were chosen in the vicinity, two in the lane and one on either side. Sediment chemistry and macrofaunal community structure were studied over 11 months, starting before the trawling season and ending well after. During each sampling trip a towed video survey was completed to check seabed conditions. In addition, beam-trawl samples were taken at the beginning and at the end. Video observations revealed the extent of trawling activities and showed higher numbers of epifaunal species outside the lane (particularly the echinoderms Leptometra phalangiuin, Stichopus regalis, and Ophiura texturata). The epifauna in the beam-trawl samples also showed lower numbers in the lane. Sediments were predominantly clay. Sedimentary organic carbon, chlorophyll, and phaeopigments all exhibited significant differences between stations during the trawling season. Species number, abundance, and biomass were all generally significantly lower in the lane during the trawling season, noticeable particularly in the phyla Echinodermata, Sipuncula, and to a lesser extent the Polychaeta. The closed season did not seem to allow recovery to pre-season levels. Impacts on the less mobile fauna were more pronounced, but degree of robustness also seems to play a major role. (C) 2000 International Council for the Exploration of the Sea.
