Methods of Age Determination of Band-Finned Flounder Liopsetta pinnifasciata (Pleuronectidae)

Abstract—Techniques involving chemical treatment are suggested for discrimination of annual and seasonal rings in the otoliths of band-finned flounder Liopsetta pinnifasciata. In the first annual zone, three seasonal rings are discerned, and four seasonal rings are discerned in subsequent zones. It is supposed that these rings correspond to biological seasons. The annual rings on otoliths and scales are formed synchronously: the first ring in December–March, and the subsequent ones in December–February. The time of formation of the first annual zone is less than a year; accordingly, the age of Liopsetta pinnifasciata determined by registering structures is less than its calendar age. According to calculations, metamorphosis of Liopsetta pinnifasciata ends at the length approximately 20 mm.