TM 181 Table 5.5

Table 5.5. Effects of otter trawls on sand substrate habitat: summary of published studies. (S = statistically significant; citations in bold print are peer-reviewed publications.)

No.	Reference	Location	Depth	Sediment	Effects	Recovery	Approach
1	Ball et al. 2000	Irish Sea	35 m	Muddy sand	Lower number of infaunal and epifaunal species and individuals, and lower species diversity and richness, compared to wreck site.		Experimental trawling in a heavily fished fishing ground; unfished area near a shipwreck used as control.
2	Bergman and van Santbrink 2000	Southern North Sea (Dutch coast)	<30-50 m	Silty sand and sand	High (20-50%) mortalities for six sedentary and/or immobile megafaunal (>1 cm) species, <20% for 10 others, from a single pass of the trawl; S effects on 11 of 54 occasions.		Experimental trawling (one- and-a-half tows per unit of area) in commercially trawled area; effects assessed after 24-48 hr.
3	*DeAlteris et al.1999*	Narragansett Bay, Rhode Island, USA	7 m	Sand	No tracks found.	Hand dug trenches not visible after 1-4 days.	Diver observations.
4	*Drabsch et al.* 2001**	Gulf of St. Vincent, South Australia	20 m	Coarse sand with shells	Trawl door tracks; smoothing of topographic features; removal of, and damage to epifauna; no S effects on total infaunal abundance; S reduction in density for one order of crustaceans 1 wk of trawling.		Experimental trawling (two tows per unit area) in area with no trawling for 15 yr; effects assessed after 1 wk (site one) and 3 mo (site two).
5	*Frid et al.* 1999**	Northeast England (North Sea)	55 m	Sand	Total abundance of benthic macrofauna increased as phytoplankton abundance increased; no correlation with fishing effort.		Related changes in benthic fauna in a lightly trawled location to low, high, and moderate fishing activity, and to changes in phytoplankton production over 27 yr.
6	*Gibbs et al.* 1980**	Botany Bay, New South Wales, Australia	Shallow estuary	Sand with 0- 30% silt-clay	Sediment plume; no consistent effects on benthic community diversity; very little disturbance of seafloor.		Sampling before, immediately after, and 6 mo after 1 wk of experimental trawling in a fished location; control area located 200 km away.
7	*Gilkinson et al.* 1998**	Test tank to simulate Grand Banks of Newfoundland		Sand	Trawl door created 5.5-cm berm adjacent to 2-cm furrow; bivalves displaced, but little damage.		Observed effects of commercial otter door model in test tank.
8	*Hall et al.* 1993**	North Sea	80 m	Coarse sand	Abundance of infauna related to changes in sediment type and organic content, not distance from shipwreck.		Sampled infauna at increasing distance from a shipwreck (proxy for increasing fishing effort).
9	McConnaughey et al. 2000	Eastern Bering Sea, Alaska	44-52 m	Sand with ripples	Reduced abundance (S for sponges and anemones); more patchy distribution; S decrease in species diversity of sedentary epifauna; mixed responses of motile taxa and bivalves.		Compared abundance of epifauna caught in small-mesh trawl inside and outside an area closed to trawling for almost 40 yr.
10	Moran and Stephenson 2000	Northwest Australia	50-55 m	Not given, presumed to be sand	Single tow reduced density of macrobenthos (>20 cm) by 15%, 4 tows by 50%.		Video surveys before and after four experimental trawling events (one tow per unit area) at 2-day intervals in unexploited area.
11	Sainsbury et al. 1997	Northwest Australia	<200 m	Calcareous sands	Decreased abundance of benthic organisms and fish associated with large epifauna; removal of attached epifauna (single tow removed 89% of sponges >15 cm).	Increased catch rates of fish associated with large epifauna and small (<25 cm) benthos within 5 yr; recovery of large epifauna takes >5 yr.	Compared historical survey data (before and after fishing started) to data collected in area that remained open to commercial trawlers and to area closed for 5 yr.
12	*Kenchington et al.* 2001**	Grand Banks, Newfoundland	120-146 m	Fine to medium grain sand	S short-term reductions in total abundance and abundance of 15 infaunal and epifaunal taxa (mostly polychaetes) in only 1 of 3 yr; no short-term effects on biomass or taxonomic diversity; no long-term effects.	Benthic organisms that were reduced in abundance in 1994 had recovered a yr later.	Experimental trawling (3-6 tows per unit of area) in closed area 1, 2, and 3 yrs after closure; lightly exploited for >10 yrs; effects evaluated within several hours or days after trawling and after 1 yr.
13	Prena et al. 1999	Grand Banks, Newfoundland	120-146 m	Fine to medium grain sand	24% average decrease in epibenthic biomass; S reductions in total and mean individual epifaunal biomass, and biomass of five of nine dominant species; damage to echinoderms.		Experimental trawling (3-6 tows per unit of area) in closed area 1, 2 and 3 yr after closure, lightly exploited for >10 yr.
14	Schwinghamer et al. 1998	Grand Banks, Newfoundland	120-146 m	Fine and medium grain sand	Tracks in sediment; increased bottom roughness; sediment resuspension and dispersal; smoothing of seafloor and removal of flocculated organic material; organisms and shells organized into linear features.	Tracks last up to 1 yr; recovery of seafloor topography within 1 yr.	Experimental trawling (3-6 tows per unit area) in closed area 1, 2 and 3 yr after closure, lightly exploited for >10 yr.

www.nefsc.noaa.gov

Link Disclaimer

(Modified Jun. 13 2008)