Field and laboratory pilot rearing experiments with early ontogenic stages of Concholepas concholepas (Gastropoda: Muricidae)

Abstract

The carnivorous gastropod Concholepas concholepas, known in Chile as “loco”, is a species present only along the Chilean coast line and in central-southern Perú showing high economic and ecological importance. Its fishery, which in the past decades has ranged between 828 (2001) and 24,828 (1980) metric tons per year [SERNAP, 2005. Servicio Nacional de Pesca: Anuarios estadísticos. ( http://www.sernap.cl/paginas/publicaciones/anuarios/index_anuario.php)], is based exclusively on the exploitation of wild stocks. So far, there has been limited interest in tackling the biological and technical feasibility of cultivation of C. concholepas. Hence, the knowledge about its early ontogenetic stages (i.e., larval, early postmetamorphic and small juvenile) cultivation is still deficient. In this study we investigated, under laboratory and field conditions, C. concholepas survivorship, growth rates, feeding rates and the onset of sexual reproduction. Competent loco's larvae were collected in the field and metamorphosed in the laboratory to assess growth rates and survivorship during the first six months of postmetamorphic life. Moreover, using small juvenile C. concholepas of ca. 20 mm of peristomal length, collected in the field, we monitored for the body size and live weight traits in laboratory and field rearing conditions. The feeding of the early postmetamorphics and small juveniles was exclusively based in mono diets of the mussel Semimytilus algosus. The rearing of small juveniles was conducted in two consecutive phases, using two specially designed rearing apparatus. The biochemical content of our laboratory cultivated specimens was compared with values obtained from specimens collected in natural habitats. Their rapid growth and good survivorship makes this species suitable for rearing of cocktail-size specimens (50–60 mm) in less than a year. According to the growing rates reported in this study the legal commercial size of C. concholepas: 100 mm of PL would be reached under field and laboratory conditions in 1.65 and 2.64 years respectively. Moreover, it was found that in our rearing conditions C. concholepas reach sexual maturity in less than a year of benthic life. In summary, considering the findings about C. concholepas high growth rates, and low mortalities, we suggest that our rearing methodologies may be scaled up and implemented for the commercial aquaculture of this unique and valuable muricid.