Erratum to: Egg collection from hatchery-reared broodstock of spotted halibut Verasper variegatus treated with LHRH analog

Abstract

The objective of this study is to establish a method for acquiring large quantities of high-quality eggs for artificial fertilization from hatchery-reared broodstock of spotted halibut Verasper variegatus. We estimated the optimum conditions for implantation of luteinizing hormone-releasing hormone analog (LHRHa) cholesterol pellet (LHRHa-CP) to induce ovulation from two experiments which focused on the dose and the timing combined with monitoring of oocyte development by ovarian cannulation. From the results of cannulation, vitellogenesis of hatchery-reared broodstock was suggested to occur normally, although final oocyte maturation was not initiated in the first clutch of oocytes. In late December, oocytes in the most advanced clutch still underwent vitellogenesis, having diameter of about 0.82 mm. LHRHa-CP implantation during this period had no remarkable effects, except for administration at high dose (100 μg/kg). In contrast, in mid January, when oocyte diameter reached about 0.95 mm, ovulation occurred in most individuals, even at low dose (20 μg/kg). In mid February atretic oocytes became remarkable and LHRHa-CP implantation showed much lower performance in terms of egg quality. The diameter of growing oocytes converged to about 0.95 mm, which was that of fully grown postvitellogenic oocytes. Thus, oocyte diameter is suggested to be an effective indicator to estimate the timing of LHRHa-CP implantation.