FOOD-CONSUMPTION IN 24 HOURS BY ATLANTIC SALMON (SALMO-SALAR L) IN A SEA CAGE

One-year-old 500-g Atlantic salmon in a sea cage, fed a standard commercial diet labelled with X-ray-opaque glass balls, consumed 1.45% of their fresh body weight per 24-h period in mid-October. Approximately 67% of their intake was from hand-feeding, and 33% from an automatic feeder. Wastage from these sources was 1.4% and 40.5%, respectively (19.0% overall). The quantities of handfed food consumed by the fish were normally distributed, suggesting relatively uniform opportunity for feeding within the population. By contrast, 40% of food from the feeder was eaten by 18% of the fish sampled. The lower efficacy of the automatic feeder was probably due to its sharply localised delivery, and to consequent severity of competition for its output. © 1990.