REARING THE PENAEID SHRIMP Artemesia longinaris FROM EGG TO JUVENILE IN THE LABORATORY

Abstract

ABSTRACTThe brown shrimp (Artemesia longinaris) has been reared in laboratory conditions from eggs to juveniles of 60 mm in total length.The ripe females are obtained from the coastal fishing grounds off Mar del Plata City (latitude of 38°S) in the spring from September to December. The depth in this zone is between 3 and 10 m. The shrimps are caught with a beam trawl commonly used by the small boats in this region. The size of the adult females reaches about 145 mm of the total length.The ripe females brought to the laboratory are put in special spawning aquaria. The spawning generally occurs within 24–48 hours. In some cases some females spawn after 4–5 days. Generally if the spawning does not take place immediately the ovary is reabsorbed.At the temperature of 17–20 C the hatching of the naupli takes place after 24–36 hours. This species has six stages of nauplius which are accomplished after 4–5 days. Afterwards the nauplius is transformed in a protozoea with its three characteristic substages. These stages last during 11–12 days. These larvae were fed on the Alga Skeletonema costatum, especially reared for this purpose. Its concentration in the aquarium with shrimp larvae was of 25,000 and 60,000 cells/ml of Skeletonema.After the stage of protozoea appears the stage of Mysis with its typical four substages appear. This stage lasts during 12–14 days. The mysis were fed on the just hatched naupli of Artemia. After the moult the mysis are transformed in postlarvae of 5.0 – 5.7 mm in length.The growth of postlarvae is relatively fast if one considers that Artemesia longinaris belongs to the species of temperate waters. According to the results obtained in the summer 1972–73 and at the end of 1973 the average growth rate was 0.3–1.0 mm/day. The shrimps reared in aquaria during 90 days from the first postlarvae reached the size of 40–60 mm total length. These animals were fed first on Artemia naupli and afterwards on minced meat of shrimp and special diet with vitamins, proteins, vegetables, etc.