Median (solid line), mean (white square), inner quartile and range (box and whiskers) and any outliers to the range (bold filled circles) showing all raw data for flat oyster dredge efficiency by oyster density and distribution on the bed for April and September data combined. Density of 1.2 oysters m² only occurred in September. Significant declines in dredge efficiency occur as density increases and is similar between the two different distribution types. While more density treatments would be valuable this suggests that Catch efficiency changes with density. If this relationship is robust to further work it would suggest that efficiency values are high when oyster densities are low – e.g. 20% as density approaches 0.5 m².