Semimytilus algosus (Gould) 1850, constitutes a potencial resource for cultivation in Chile. The geographic distribution extenas from Manta, Ecuador to the Gulf of Arauco in Chile (Osario & Bahamonde, 1968). Juveniles with a 7 mm mode were collected from the mouth of the Bio-Bio River (36º 48'S, 73º10'W), and were encorded using the Spanish and French systems. These cords, 3 m long, were suspended from an experimental raft (4x4 m) in the western part of Concepción Bay (36º 42'S, 72º 02'W). After 11 months of suspension the mussels had attained a modal lenght of 52 mm, and absolute increase of 45 mm. The maximun length measured was 67 mm. A parallel study of the natural population revealed a slow growth rate, with much smaller maxima than those obtained with the raft. The experimental population seemed to exhibit a short life cycle, as demostrated in part by the rapid growth rate and a high natural death rate before completing a year of suspension. A histological analysis showed S.algosus to be hermafroditic, with mature gametes during the entire year. The gametes varied only slightly in shape and size from the gametes described for other mussel species. Canning tests were made in the local industries. Individuals with a modal length of 36-38 mm yielded 30%, while those of 30 mm individuais used in this experiment, S. algosus demonstrated a yield that compared favorably with that of other comercially important mussels, and would seem to present a great potential for a future induslrial resource.
