Age and growth of alfonsino Beryx splendens from the Kanto District, central Japan, based on growth increments on otoliths

Abstract

Age and growth of alfonsino Beryx splendens (Lowe) were studied using counts of presumed daily incremental growth rings on the transverse section of otoliths of fish collected from the Kanto District, central Japan. Microstructural growth increments were observed from the core to the outermost margin of the broadest of approximately 50 branches formed on the surface of an otolith. Of 98 otoliths examined, 46 were readable. The number of increments and fish lengths ranged from 448 (218 mm fork length [FL]) to 3701 (411 mm FL). The ages of these fish were estimated to be 1 year, 2 months and 10 years, 2 months, respectively, assuming that an increment was formed daily. The von Bertalanffy growth equation combined for males and females was expressed as follows: L_t=542{1-exp[-0.133(t+2.00)]}, where L_t is fork length (mm) at yearly age t. The results of the present study were compared with those of other researchers who had studied alfonsino from central Japan.