Age Determination and Growth from Otolith Daily Growth Increments of Hypoptychus dybowskii (Gasterosteiformes)

Abstract

Age and daily growth of Hypoptychus dybowskii collected periodically off Usujiri, southern Hokkaido, June 1993 to June 1994, were investigated using otolith-increment counts. Daily increment formation was verified by comparing the number of increments formed after alizarin complexone marking with the number of days after treatment. Most growth occurs during the first 6 months from hatching. The relationship between standard length and the number of daily growth increments was best fitted to a Logistic curve for male, and a Gompertz curve for females: (males) Lt = 56.25/(1 + exp-0.034(t - 68.00)) and (females) Lt = 63.16 exp-exp-0.018(t - 54.98) No specimen had more than 365 increments in its sagittae, suggesting this species has a life span of one year.