This study evaluated the effect of the density at harvest on the performance and profitability of hatchery‐reared spotted rose snapper cultured in cages. The fish were stocked at harvest densities of 15, 20, and 22 kg/m3 in cages of 222 and 286 m3. More than 39,000 snapper fingerlings with an initial weight of 14 g were stocked. The fish were fed an extruded diet and cultured over a 360 d period. The thermal growth coefficient ranged from 0.04 to 0.05 and survival was 95% for all treatments, with the highest final weight (436.8 g) observed for fish reared at a density of 20 kg/m3. The allometric value b indicated that hatchery‐raised, cage‐cultured snapper were heavier than their wild counterparts. The major costs were feed (ranging from 44.7–45.9%), labor (22.4–32.6%), and seed costs (20.2–26.1%). The total production cost ranged from US$ 6.5 to US$ 7.5/kg. The baseline scenario was not economically feasible. However, a 10% increase in the sales price resulted in increases in the internal rate of return (183%) and net present value (US$ 97,628.9). These results suggest that L. guttatus has the potential for commercial production in cages.

Length-frequency data of juveniles and sub-adults of Penaeus californiensis were analyzed, collected from January 2002 to January 2003 in the Agiabampo lagoon system and adjacent marine coastal zone. Six models were parameterized with four criteria, in addition to a mixed criterion (fat-tail and depensatory), to estimate the parameters that best fit the growth curve. The model that best fit was the Johnson model with the mixed criterion in females and males: k = 6.02 (5.93-6.12); L∞ = 188.8 (186.3-191.8); t0 = 0.0221 (0.0207-0.0234); and: k = 8.98 (8.85-9.12); L∞ =153.3 (151.7-155.0); t0 = 0.0386 (0.0378-0.0394), respectively. The conclusion is that: 1) the mixture approach found in this study as best leads to the application of a very high-performance objective function to analyze individual length-at-age variability, 2) shows that the best model to describe the growth trajectory of P. californiensis in marine and estuarine environments is a sigmoid curve with an inflection point near to cero age (Johnson model).

ABSTRACT. This study describes the growth parameters of males of the blue crab Callinectes arcuatus based on samples from a coastal lagoon in the southern Gulf of California and from individuals raised under controlled conditions. The models assessed were the four variants of the Schnute growth model and a special case of the von Bertalanffy model (VBGM). The Akaike information criterion was used to select the best model. The models with the best fit were Case 3 of the Schnute model for the separated wild and captive-reared data sets, but the combined data set fit better to the VBGM function, indicating linear growth, and Case 5 suggesting asymptotic growth of the C. arcuatus. Our results depend on the assumption that reared and fished individuals were covering the entire benthic growth period. It is concluded that 1) modeling growth by treating cohorts as individuals yields accurate estimations of k and the L∞ equivalent that can be used directly in stock assessment models, and (2) the ranges of validity of the best growth models for C. arcuatus growing in wild and cultured environments overlapped in the size range of 62 to 85 mm of carapace/width, but they have a continuity that represents blue crab growth throughout their benthic life. Keywords: Callinectes arcuatus, growth, multi-model, wild population, controlled conditions, Gulf of California. Estimación de los parámetros de crecimiento de los machos de la jaiba azulCallinectes arcuatus (Brachyura: Portunidae) del Golfo de California, utilizando el modelo de Schnute RESUMEN. Se describen los parámetros de crecimiento de machos de la jaiba azul Callinectes arcuatus, de una laguna costera del sureste del Golfo de California y de ejemplares mantenidos en condiciones controladas. Los modelos evaluados fueron las cuatro variantes de Schnute y el de von Bertalanffy (VBGM). El criterio utilizado para seleccionar el mejor modelo fue el de Akaike. Los modelos que presentaron un mejor ajuste fueron el Caso 3 de Schnute para datos separados, del medio natural o en condiciones controladas, indicando una relación lineal; y el Caso 5 de VBGM para los datos combinados, lo que sugiere un crecimiento asintótico para C. arcuatus. Estos resultados corresponden al análisis de los datos conjuntos de los organismos obtenidos del medio natural y de los estanques en condiciones controladas. Se concluye que 1) el modelo de crecimiento obtenido a través del análisis de las cohortes individuales presenta estimaciones adecuadas de k y L∞, que se puede considerar equivalente al utilizado en modelos evaluación de stocks, y 2) los rangos de validez de los mejores modelos de crecimiento para la jaiba azul C. arcuatus en el medio natural y en condiciones de cultivo coinciden en el rango de tamaño de 62 a 85 mm de ancho de cefalotórax, teniendo una continuidad que ajusta adecuadamente su crecimiento durante su etapa de vida bentónica.

The species composition and variation in density (postlarvae m-3 ) of penaeid shrimp postlarvae were surveyed every 14 days in two zones of the Mexican Pacific coast; in the north (Mazatlân, 23°N 106°W) and south (Gulf of Tehuantepec, 15°N 95°W). Sampling coincided with full moon and new moon, and they were carried out with plankton net (0.3 m mouth diameter and 450 p,m mesh size). Average sea surface temperature (SST) for 1985-1995 increased from Mazatlân (26.2 ± 0.2°C) to Tehuantepec (28.3 ± 0.5°C). The difference in SST between the coldest and warmest month was 7.8°C in Mazatlân and 3.3°C in Tehuantepec. Four species of penaeid shrimp postlarvae were identified; Litopenaeus vannamei (Boone, 1931), L. stylirostris (Stimpson, 1874), Farfantepenaeus californiensis (Holmes, 1900) and F. brevirostris (Kingsley, 1878). There was a regional variation in the species composition. L. vannamei was abundant at both coasts with 40% and F. californiensis varied from south to north from 45 to 36%; the less representative species were L. stylirostris and F. brevirostris, which varied from south to north from 15 to 24%. The occurrence period near Mazatlân is seven months, and it is year-round in Tehuantepec. This study suggests that warm water and low seasonal SST variability facilitate the presence of the shrimp larvae over a longer period. RESUMENLa composition de especies y la variation de la densidad (postlarvas m-3 ) fueron evaluadas catorcenalmente en dos zonas costeras del Paclfico mexicano; una al norte (Mazatlân, 23 °N 106°W) 5)

In the present study we explored the effect of the tidal hour on the postlarvae abundance of the penaeid white-leg shrimp (Litopenaeus vannamei (Boone, 1931)) in three Mexican Pacific coastal lagoons. Correlation analysis of tidal hour against the hourly variation of the abundance of postlarvae was conducted in three regions of the Mexican Pacific; the system lagoon Huizache-Caimanero LHC, the region of the “Grandes Lagunas” SGL and the “Mar Muerto” Lagoon LMM. Two peaks were found in L. vannamei abundance in the three locations, at 04:00 and 16:00 of tidal hour in LHC and SGL, and 06:00 and 12:00 of tidal hour in LMM. Significant correlations between postlarvae and the tidal hour for the three regions were found. The tidal hour standardizes the time of ebb and flow. It is concluded that tidal hour can be used as cue for shrimp postlarvae immigration to nurseries.