Manuel García-Ulloa Gómez

Growth of fresh-water prawn Macrobrachium tenellum (Smith, 1871) juveniles fed isoproteic diets substituting fish meal by soya bean meal

Growth parameters (standard length, weight, specific growth rate and daily we ight gain) of prawn Macrobrachium tenellum juveniles fed 40% crude protein isoproteic diets substituting fish m eal with soya bean meal at various levels (20, 40, 60, 80 and 100%) were evaluated for 45 days under laboratory conditions. Experimental diets were compared with a 100% fish meal based di et. Total survival was recorded for all the treatments at the end of the experiment. There were no significant differences (p � 0.05) for all the growth parameters among the dietary treatments. The initial mean weight (0.36 ± 0.10 g) increased almost three times (1.00 ± 0.13 g) after 45 days. The final specif ic growth fluctuated from 1.82% BW/d for the 60% soya bean meal inclusion diet, to 2.62% for the 100% fish meal diet. The mean final survival was 91.66%. Growth performance of M. tenellum juveniles was not affected by the dietary soya bean meal levels tested.

A response-surface analysis of the relative importance of the temperature, salinity and body weight on the respiratory metabolism of the white shrimp Litopenaeus vannamei (Boone, 1931)

We used a response-surface analysis to determine the importance of different factors affecting the resting routine metabolic rate (QO2) of the white shrimp Litopenaeus vannamei. The oxygen consumption rates were estimated using a multi-factorial design with 28 combinations of different salinities (15, 20, 25, 30, 35, 40 and 45 psu) and temperature (20, 25, 30 and 35 °C) values. The response-surface analysis produced a quadratic function showing that temperature more profoundly affects the oxygen consumption rate. Response-surface curves were generated to predict the optimal conditions resulting in oxygen consumption to better understand the successful growth of this species.

Effect of constant temperature on growth of the arched swimming crab Callinectes arcuatus Ordway (1863) over a 360-day period

The effect of five constant temperatures (20°C, 23°C, 26°C, 29°C and 32°C) on the growth of juvenile arched swimming crabs, Callinectes arcuatus, was evaluated over a 360-day experimental period. The crabs were reared in a recirculating system. The growth rate was significantly greater (p < 0.05) at 29°C, which was close to the species-preferred temperature of 26°C. The lowest growth rate occurred at 20°C. Blue crabs grown for 360 days at 29°C were twice as large as those grown at 23°C. The findings of this study could be applied to optimise the culture conditions for this tropical crab.