Stomach capacity as a directing factor in prey size selection of three-spined stickleback

A basic ecological tenet is that a predator chooses the prey that it consumes according tothe energetic gain available in relation to the time cost of dealing with each prey. For afish predator, the energetic content of prey increases with size whilst there is an associatedincrease in handling time (Werner, 1974; Kislalioglu & Gibson, 1976; Hoyle & Keast,1986; Gill & Hart, 1994). Prey choice can be based on the profitability of each size ofprey where the greatest profitability is defined as the prey size giving the maximum energygain per unit handling time (Stephens & Krebs, 1986). For a 45-mm