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In a four week trial, growth performance and survival of just-released juvenile Cherax quadricarinatus (0.05 ± 0.02 g) reared in a recirculation system at three densities (134, 178, 223 juv/m²) were evaluated. Final weights ranging from 0.62 to 0.64 g with final total lengths from 30.59 to 31.11 mm and final mean survival of 68% were obtained, without significant differences between growth parameters at the different densities (p> 0.05). Results suggest the possibility to achieve good production yields in a recirculation system during the first month at densities as high as 223 org/m². [ABSTRACT FROM AUTHOR]

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Previous studies demonstrated that it is possible to optimize Oreochromis mossambicus fry production in a recirculating system by means of supplemented diets with Artemia's cysts. In the present work, productive yields of Oreochromis niloticus, species kind highly cultured in México and worldwide, and O. mossambicus fry are reported in order to know the possible differences on growth and survival. Tilapia fry with a mean wet weight of 0.011 ± 0.002 and 0.017 ± 0.005 g(O. niloticus and O. mossambicus, respectively), were fed with a dietary inclusion of 10% of decapsulated Artemia cysts (QDS) in a starter commercial diet, during the first month of exogenous feeding after yolk absorption. Fry were reared in a recirculating system at a stocking density of 5 org/l (5000 org/m3). Diet was given at a daily feeding rate of 25% of body biomass, four times a day. Final mean weight and survival for O. niloticus and O. mossambicus were 1.31 ± 0.15 and 1.60 ± 0.22 g, and 90 % y 97.5 %, respectively. There were no significant differences (p > 0.05) in final yields (mean weight, length, biomass/l, daily weight gain, specific growth, feed conversion and survival) between species. The results suggests that an inclusion of 10% of QDS in the hatchery diet may improve growth performance of both Oreochomis species under similar management conditions. Technical and economic considerations should be carefully reviewed before using QDS at commercial level. [ABSTRACT FROM AUTHOR]

Several studies on the culture of the Pacific oyster Crassostrea gigas have been carried out since 1997 in the lagoon of Barra de Navidad (Jalisco, México). The presence of mud blisters in the oyster inner valves caused by shell-boring polychaetes has represented one of the main culture problems. Boccardia sp. (Polychaete: Spionidae) was identified from the mud blisters of 60 oysters. Despite the commercial significance of this organism to the oyster culture, there is a lack of information about its impact over the Mexican shellfish industry. This paper represents the first report on the presence of this worm in an oyster culture facility located at the mid coast of the Mexican Pacific. [ABSTRACT FROM AUTHOR]