Developmental changes in diel feeding activity and estimation of daily food consumption in hatchery-reared larval and juvenile marbled sole Pleuronectes yokohamae
2005
Yamamoto, S.(Okayama-ken. Fisheries Experiment Station, Ushimado(Japan)) | Sugino, H. | Cyuuriki, K. | Masunari, N. | Kondou, M.
Diel changes in feeding activity and daily food consumption were investigated in hatchery-reared larval and juvenile marbled sole Pleuronectes yokohamae ranging from 4.4 to 44.7 mm in total length (TL). Feeding activity was examined by counting number of food organisms in the gut, and the daily food consumption was estimated using the method developed by Elliott and Persson (1978). During the larval and juvenile stages, the number of food organisms in the gut increased graduany after dawn and reached their peak at dusk. Larvae in the swimming period (TL 4.4 - 7.5 mm) ingested food organisms only during daylight hours. Just after settlement (TL 7.9 mm), they were able to feed on a few food organisms in the dark after sunset, and the juveniles of bottom dwellers fed continuously throughout both the day and night. It was confirmed, for the first time in this species, that the larvae were able to feed in the dark of night. Although daily food consumption increased exponentially, the rate of daily food consumption (dry daily food consumption/dry body weight x 100%) decreased from over 100% to under 30% with growth. The range of these rates was nearly equal to the ranges of the other species which pass their larval stage during the warm season in spring. It was speculated that the feeding environment would be very severe for this species that grows in the wild during the cold winter season, when the water temperatures are very low, and plankton, as food organism, is scarce.
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