Pattern of feed intake in four species of fish under commercial farming conditions: implications for feeding management

Meal duration and feed ingestion rate were measured in sea cage-reared Atla ntic salmon Salmo salar, rainbow trout Oncorhynchus mykiss, yellowtail Seri ola quinqueradiata and red sea bream Pagrus major fed dry extruded feed in discrete meals. At the population level, satiation times in yellowtail, sal mon and trout were typically about 15-25 min, but time to satiation was lon ger (60-90 min) in red sea bream. In all species. feed ingestion rate decli ned progressively during the course of the meal as the fish became satiated , Initial feed ingestion rates in salmon were approximate to 0.3-0.5 kg fee d tonne fish(-1) min(-1) and in trout 0.5-0.9 kg feed tonne fish(-1) min(-1 ) although the capacity to deliver feed may have restricted ingestion. Wate r temperature had little effect on ingestion rates, possibly because the nu mber of meals per day (1-3) was varied with water temperature, and this may have standardized hunger level at the start of meals, Yellowtail ingested feed at approximate to 3.5 kg feed tonne fish(-1) min(-1) at water temperat ures of 18 degrees C and 28 degrees C, whereas red sea bream ingested feed at initial rates of 0.6 and 1.4 kg feed tonne fish(-1) min(-1) at 26.5 degr ees C and 18 degrees C respectively. The findings are discussed in relation to feeding strategies to minimize interfish competition for feed and to im prove the ability of fish farmers to detect the point at which fish are sat iated.