The ground gears were then alternated, so that we com-pleted one paired comparison of all four configurations on each day (i.e. six deployments). The trawls were also swapped from side-to-side after the first three deployments, while the pairs of load cells were rotated from side-to-side each day. Over eight days fishing we completed 24 replicate deployments of each ground gear.
The technical data collected during each deployment included the: (i) warp tension (kgf) for each configuration (recorded at 30-second intervals from the above-water load cells—to estimate total system drag); (ii) ground-gear tension (recorded at 30-second intervals from the underwater load cells); (iii) the total distance(m) trawled (sleds on and off the bottom–obtained from the GPS);and (iv) speed over the ground (SOG) and through the water (STW;both in ms−1). Biological data collected at the end of each deploy-ment included the: total weights of school prawns, Metapenaeus macleayi and bycatch; numbers of each by catch species; and total lengths (TL in mm) of the most abundant teleosts. Random sam-ples of ∼500 g of school prawns were placed into plastic bags and transferred to the laboratory, where they were measured (cara-pace length–CL in mm), weighed and counted. These latter data were used to estimate the total numbers and the mean CLs caught during each deployment.