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The heterogeneous and homogeneous growth (HmG) assumptions in an intensive tilapia Oreochromis niloticus pre-grow-out production were evaluated under the different stocking scenarios. Four growth models (von Bertalanffy, Logistic, Pütter, and Gompertz) were tested and modified to include the effect of stocking density and growth difference. Models with homogeneous growth were fitted using a nonlinear regression, while heterogeneous growth (HtG) models were parameterized using quantile (0.05, 0.15, 0.25, 0.50, 0.75, 0.85, and 0.95) regression. According to goodness of fit and validation, the models that best fit homogeneous and HtG were Logistic and von Bertalanffy, respectively, which confirm the existence of the dense dependency effect on growth performance. Density and growth have an inversely proportional relationship. Quantile regression provided greater efficiency in predicting growth of the different groups of individuals in the population. The results obtained can be used by the aquaculture farmer to select stocking management strategies and optimal transfer time for tilapia juveniles. [ABSTRACT FROM AUTHOR]

The feasibility of obtaining a similar growth response from juvenile pink abalone Haliotis corrugata at a research laboratory and a hatchery, when using natural feeds was evaluated. Four macroalgae, Egregia menziesii, Eisenia arborea, Macrocystis pyrifera, Gracilaria sp., and the surfgrass Phyllospadix torreyi were used as feeds. Response patterns of abalone were very similar at both facilities in terms of final length, weight, and survival, varying from 13.0 to 15.50 mm, 0.31 to 0.52 g, and 60.0% to 78.6%, respectively. Better growth was obtained when E. menziesii, M. pyrifera, and Gracilaria sp. were offered. Poor results were obtained with surfgrass. The feed conversion ratio was determined at the laboratory and did not vary significantly, ranging from 42.3 to 199.0; although a significant inverse correlation was observed with growth rate. Growth in length and weight and survival rates varied within 1.6–20.2 μm day−1, 0.123–1.664 mgday−1, 0.4–0.64%day−1, respectively. Mean growth rate in length (14.7μm day−1) and weight (1.18 mg day−1) at the hatchery were significantly higher than that obtained at the laboratory (9.4 μm day−1 and 0.77 mg day−1), which is most likely a consequence of more suitable water temperature at the hatchery. Mean survival rate was significantly higher at the laboratory (53.1%day−1) than at the hatchery (46.1%day−1). [ABSTRACT FROM AUTHOR]

Two abalone species: green Haliotis fulgens and yellow Halioti corrugata represent nearly 97% of the total production in the Mexican abalone fishery. It has been assumed that abalone feed on the kelp algae Macrocystis pyrifera. Regional hatcheries use this species as a main source of natural food. M. pyrifera does not occur at the southern limit of the distribution of abalone species along the Baja California Peninsula. In this study, growth rates of juveniles H. fulgens, 17.3 ± 2.2 mm shell length and 0.4 ± 0.2 g body weight, were evaluated. Juveniles were fed with common species in the benthic environments inhabited by abalone along the western coast of Baja California during 191 days. Three diets were based on algae: palm kelp, Eisenia arborea, giant kelp, M. pyrifera and Gelidium robustum, and one on seagrass, Phyllospadix torreyi. Shell length and body growth rates varied between 21.5 μm day−1 and 2.2 mg day−1 for E. arborea and between 45.9 μm day−1 and 6.7 mg day−1 for M. pyrifera. Higher specific growth rates (SGR) in length and weight were determined for M. pyrifera: 0.2% and 0.7% day−1. Significant differences between values of juveniles fed M. pyrifera with the rest of the diets were found. The highest mortality (21%) was in juveniles fed the red algae G. robustum. [ABSTRACT FROM AUTHOR]

The influence of the lunar phases on the catch-per-unit effort (CPUE) of the striped marlin (Tetrapturus audax) captured by the Cabo San Lucas, Baja California Sur, Mexico sport-fishing fleet from October 1987 to June 1989 was analyzed. The information is from 3,377 fishing trips by 13 vessels that represent about 10% of the fleet. The analysis of the CPUE showed a maximum in January 1988 and a minimum in February 1989. Taking into account the knowledge of the factors that had influence on the fishing success is important in the resource management. No significant difference during the full moon compared with results during other lunar phases was found.