• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.6
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• pp.699-707
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• 1995

Eurasian yellow perch (Perca fluviatilis) and American yellow perch (Perca flavescens) are known to be endemic species in Eurasia and North America, respectively. The presence of endemic species on each continent suggests their independent evolutionary history. However, because of the morphological similarity, distribution pattern, and only recent fossil record, their divergence time and speciation of the two Perca species has long been controversial. Here, from the comparison of the entire nucleotide sequences of cytochrome b gene, large genetic divergence between the two Perca species is observed although they are morphologically similar each other. Among 1,140 base pairs, interspecific nucleotide differences are found at 130 sites $(11.4\%)$. The differences varies with codon position, showing 22 sites in the first, 5 sites in the second, and 103 sites in the third codon position. Considering the types of nucleotide changes, transitional differences are much more than transversional differences and its ratio turned out to be 5.19. The estimated divergence time of the two Perca species indicates that they were separated each other approximately in the late Miocene period, which implies the long history of speciation. With comparison of the inferred amino acid sequences, strong structural and functional constraints which seem to be maintained by the highly conservative amino acid residues or protein regions, as found in other taxonomic groups of organisms, are also recognized in the cytochrome b of the fishes examined.

• Journal of Aquaculture
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• v.3 no.1
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• pp.39-48
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• 1990

The growth response of the yellow perch, a highly proteinaceous food feeder in nature, to different protein levels (50, 40 and $27\%$) in formulated diets was determined over a 20-week period. Approximately $23\%$ of dietary protein could be spared by substituting less expensive carbohydrate and lipid materials without any noticeable ill-effects or reduction in weight gains. In turn, there was no statistically significant difference between total weight gains of fish fed at three different levels of protein diets, although fish on the 50 and $40\%$ protein diets grew better in the first few weeks. A shift in the protein requirements occur-red after about 10 weeks of rearing. Growth efficiencies(growth/food intake) became nearly the same at all levels of protein and decreased consistently throughout the remainder of the study period. The results indicate that young yellow perch(6g initial weight) can grow normally with the $27\%$ protein diet after about 10 weeks of initial feeding with higher protein diets(or regular commercial diets).