Abstract

Objective: To investigate the scales of barfin plaice (Liopsetta pinnifasciata), which depends on the size and sex of the fish. Methods: The samples were collected in Peter the Great Bay (Sea of Japan) during 2011–2014 aboard research vessels and at observation posts of Pacific Scientific Research Fisheries Center. In total, 155 specimens of barfin plaice were analyzed and 2 110 scales were investigated using MBS-10 binocular microscope. Results: Temporal differentiations of scale forming is revealed for barfin plaice. The eye side of its juveniles is covered mostly with cycloid scales. Ctenoid scales are observed in elder fish with the minimum size of 11.4 cm and 13.5 cm for males and females, respectively. Sexual dimorphism of the scale structure is usual for mature fish. Ctenoid scales dominate 92.8% of the males but cycloid scales dominate 85.4% of the females. Besides, 74% of the males have ctenoid scales only, 42% of the females have cycloid scales only, and both types of scales are presented for 38.3% of the males and 38.4% of the females on average. Conclusions: Juveniles of barfin plaice have cycloid scales only, the young immature fish, both males and females, have a small number of ctenoid scales, but ctenoid scales prevail in the adult males, while cycloid scales are still dominant for the adult females. However, many adults of both sexes have two types of scale simultaneously. The relative radius of the scales decreases with the increase of the body size.

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