A pulse feeding strategy for rearing larval fish: an experiment with yellowtail flounder

Providing a good foraging environment for the larviculture of marine fish m ust take into account a number of factors including water temperature, ligh t intensity, prey type, prey density, and frequency of feeding. We designed an experiment to determine if larvae require continuous exposure to live p rey, or if feeding in "pulses" is adequate to promote good growth and survi val. Larvae of yellowtail flounder (Pleuronectes ferrugineus) were fed once (1 x, at 10 AM), twice (2 x, at 10 AM and 10 PM), four times (4 x, at 10 A M, 4 PM, 10 PM and 4 AM), or continuously (by automatic feeder) at 8000 pre y per liter (p/1). Larval growth, survival, and foraging behavior were moni tored during weeks 1-7 post-hatch. Larval growth rate was significantly red uced in the 1 x treatment. The growth rate of larvae was similar in other t reatments. Larval survival was lowest in the 1 x treatment, but was not sig nificantly affected by feeding frequency. The consumption rate of larvae in the 1 x and 2 x treatments was significantly higher than that of larvae in the continuous treatment. This behavioral response to hunger probably enab led larvae in the 2 x treatment to grow as rapidly as larvae in the continu ous prey treatment. It is concluded that yellowtail flounder larvae do not require continuous exposure to high prey densities and there may be potenti al to reduce the cost of live food and labor in the culture of this and pos sibly other species. (C) 2000 Elsevier Science B.V. All rights reserved.