Both predators had longer bout lengths when prey was shallow, until an optimum of 15m depth. The effect of aggregations alone was weak, both prey depth and aggregations were non-significant in A. torda (Fig 3H). However, due to the substantial interaction between prey aggregation and depth, A. torda increased bout length if there were many aggregations and shallow depth distributions, but also deep depth distributions with few aggregations (pd=0.38, Fig.A11G). Meanwhile, U. aalge had long bouts when aggregations were high except when prey was at its deepest (pd=0.37, Fig A11H).