The influence of hunger on shoal size choice by three‐spined sticklebacks, Gasterosteus aculeatus

Single sticklebacks (Gasterosteus aculeatus) were presented with a choice between (a) a shoal and an empty compartment, and (b) two different sized shoals of conspecifics. The choice of hungry test fish (food‐deprived for 24 h and 72 h, respectively) was compared to that of fish which were fed to satiation once a day. It was hypothesized that due to the increased level of competition for food in large shoals, hungry fish would spend less time with the larger of two shoals than their well‐fed conspecifics. The results showed that there was indeed a significant trend for test fish to spend a decreasing amount of time near the compartment with the larger number of fish with increasing duration of food deprivation.