Abstract

In Chile, various species of keyhole limpet of the Fissurella genus constitute a multispecific fisheries activity. Nevertheless, management of these species is limited because of insufficient understanding of their reproductive biology. Fissurella nigra Lesson, 1831, is one of the species currently extracted by local fishermen in southern Chile. The breeding cycle of F. nigra was studied through changes in the stages of gonad maturity using histological techniques, as well as monitoring the temporal variations in the gonadosomatic index (G.S.I.). Minimum maturity size, spawning induction, artificial fertilization and early larval development were also studied to obtain data on the biological background of this species that will facilitate management and enhance culture feasibility. Fissurella nigra is characterized by a unimodal reproductive cycle with one breeding season between October and December, coinciding with the period when gametes are spawned. Fertilization is external and mainly nocturnal spontaneous spawning occurred between August and November (most abundant in October and November) in adult organisms kept under laboratory conditions. Spawning was induced in October by combining thermal shock with desiccation. This method proved successful, provoking massive spawning. The gonad became visible in 50% of organisms within a size range of 26.0-35.9 mm. Early development occurs within the egg membrane and the veliger larval stage is reached approximately three days after fertilization.