Sang-Duk Choi

Effect of light intensity on first feeding of the chub mackerel Scomber japonicus larvae

Abstract This study investigated the effect of different light intensities on first feeding of chub mackerel Scomber japonicus larvae. Fertilized eggs, obtained from LHRHa-induced spawning of captive broodstock, were stocked (60 larvae/l) into twelve 30-l aquaria under light intensities of 0, 100, 200, 500 and 1000 lx, with three replicate aquaria per treatment. Temperature was maintained at 20°C and salinity was 35 psu. Larvae were fed the rotifer Brachionus rotundiformis at a density of five rotifers/ml. Feeding incidence was measured as the percentage of larvae with prey in the digestive tract. Feeding intensity was evaluated as the number of prey in the digestive tract of the larvae. Larvae fed in darkness (0 lx) had significantly lower (P<0.05) feeding incidence (13±0.05% larvae with prey) and feeding intensity (1.00±0.05 rotifers per larva) than those larvae fed at 100 (30±0.07%, 1.17±0.09 rotifers per larva), 200 (43±0.08%, 1.24±0.11 rotifers larvae−1), 500 (53±0.08%, 1.48±0.14 rotifers per larva) and 1000 lx (60±0.08%, 1.38±0.13 rotifers per larva). The feeding incidence of S. japonicus larvae increased with light intensity while feeding intensity showed no significant difference (P>0.05) between light treatments.

Comparative stomach contents and growth of the juvenile black rockfish Sebastes inermis reared in illuminated and unilluminated cages

The principal objective of the present study was to determine the positive effects of artificial illumination on the juvenile black rockfish Sebastes inermis by comparing stomach contents and growth between juveniles exposed to light and those maintained in the absence of light. The major prey items of juvenile black rockfish in illuminated cages were: copepods (%IRI=62.6); amphipods (%IRI=36.7); and polychaetes (%IRI=0.3), whereas those, in unilluminated cages were: copepods (%IRI=93.3); amphipods (%IRI=6.1); and polychaetes (%IRI=0.4). The specific growth rates of the juveniles reared in illuminated cages (0.67%) were significantly higher than those juveniles maintained in the unilluminated cages (0.27%).

Morphological and Molecular Classifications of Genus Pholis

Abstract Morphological and molecular classifications were attempted in an effort to establish species‐specific classifications of three species of the genus Pholis in Korea; these species were subjected to morphological and molecular methodologies using body measurements, RFLP, RAPD, and phylogenetic trees using the nucleotide sequences of mitochondrial 16S and 12S ribosomal DNAs, cytochrome c oxidase I, and cytochrome b. The data demonstrated that the three species of genus Pholis are distinct from each other, both morphologically and genetically.