1Hachinohe Laboratory, Tohoku National Fisheries Research Institute, Fisheries Research Agency, Hachinohe, Aomori 031-0841, 2Miyagi Prefecture Fisheries Technology Institute, Ishinomaki, Miyagi 986-2135, Japan
We examined the age and growth of roughscale sole Clidoderma asperrimum caught off the Pacific coast of northern Honshu, Japan, using the otolith sectioning method. A theoretical growth equation for this sole was fitted by the von Bertalanffy growth equation for both sexes, indicating that males approach the maximum length (l∞) faster than females; total length (TL, cm)=39.5(1−e-0.474(t+0.172)) for males and TL=52.6(1−e-0.366(t-0.003)) for females. The maximum ages observed for 303 samples were 15 and 22 years for males and females, respectively, and it was considered that this sole is one of the most long-lived fish among pleuronectids. A bimodal length-frequency distribution with peaks at 39 and 49 cm TL was estimated from the catch data at Ishinomaki (main fishing port for roughscale sole) in 2008-2009. The age composition divided by the age-length key showed that the smaller and larger peaks were mainly composed of males of 6-10 years and females of 6-16 years, respectively. These results suggest that older fish were mainly caught by offshore bottom trawl fisheries in this area. Furthermore, differences between the otolith sectioning and surface methods for this sole were discussed, and underestimation of ages using the surface method was confirmed in 7+year-old fish.