Direct Estimation of Disturbance Rates of Benthic Macroinvertebrates from Contact with Standard and Modified Ocean Shrimp (Pandalus jordani) Trawl Footropes

Abstract

ABSTRACT We used a video camera mounted on the footrope of an ocean shrimp (Pandalus jordani) trawl to measure macroinvertebrate contact and disturbance rates directly from 4 different trawl footrope configurations. One footrope without a central groundline and 2 experimental footropes with groundlines that were modified to reduce macroinvertebrate impact were compared with the most common footrope style used in the fishery: a disk-covered groundline (mud gear). Relative to mud gear, the footrope without a central groundline reduced macroinvertebrate disturbance rates 99% for sea whips (Halipterus spp., P < 0.01), 100% for sea stars (Asteroidea) and anemones (P < 0.05), and 96% for Dungeness crabs (Cancer magister, P < 0.001). The experimental footrope incorporating a PVC pipe-covered groundline reduced disturbance rates for sea whips and Dungeness crabs by 63% and 55%, respectively (P < 0.001), but not for sea stars or anemones. The experimental footrope incorporating elevated sections of groundline redu...