Growth and length-weight parameters of Pacific mackerel (Scomber japonicus) in the Gulf of Guayaquil, Ecuador

The seasonally oscillating growth parameters and length-weight relationships for Scomber japonicus caught in the Gulf of Guayaquil, Ecuador, were determined based on length-frequency data from 1989 to 1996, using the FiSAT software package of Gayanilo et al. (1996). Estimates of growth parameters are in general agreement with previous studies on the same species. Results also imply that the growth of Scomber japonicus slows down during the cold season by approximately 50% with respect to the average growth. The mean value of the power b is significantly larger than 3, indicating that the model of allometric growth should be used for the length-weight relationship and calculation of the condition factor.

Estimates of growth and comparisons of growth rates determined from length- and age-based models for populations of purple wrasse (Notolabrus fucicola)

Growth of a temperate reefa-ssociated fish, the purple wrasse (Notolabrus fucicola), was examined from two sites on the east coast of Tasmania by using age- and length-based models. Models based on the von Bertalanffy growth function, in the standard and a reparameterized form, were constructed by using otolith-derived age estimates. Growth trajectories from tag-recaptures were used to construct length-based growth models derived from the GROTAG model, in turn a reparameterization of the Fabens model. Likelihood ratio tests (LRTs) determined the optimal parameterization of the GROTAG model, including estimators of individual growth variability, seasonal growth, measurement error, and outliers for each data set. Growth models and parameter estimates were compared by bootstrap confidence intervals, LRTs, and randomization tests and plots of bootstrap parameter estimates. The relative merit of these methods for comparing models and parameters was evaluated; LRTs combined with bootstrapping and randomization tests provided the most insight into the relationships between parameter estimates. Significant differences in growth of purple wrasse were found between sites in both length- and age-based models. A significant difference in the peak growth season was found between sites, and a large difference in growth rate between sexes was found at one site with the use of length-based models.

Ovarian growth and ovulation in the mature blue crab, Callinectes sapidus Rathbun

Introduction. Observations: structure of the ovary during the periods of growth and ovulation in the mature crab (stages 1-5). Discussion and conclusions.