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Age validation is the first step to determine shellfish species age determination. This information is vital for different inferential models used in marine ecosystem management activities. In spite that various validation techniques are used for marking carbon calcium structures, the calcein marking technique for oysters had never been used for age validation in Pinctada mazatlanica. Thus the objectives of this study included: the evaluation of calcein to mark a shell growing-edge, and the efficacy of Coomassie Blue staining on posterior shell growth, to produce visible micro growth-bands that would enable age validation of juvenile mother-of-pearl oysters. Oysters were collected and cultivated at The Perlas del Cortez S. de R. L. MI. pearl-farming operation, in Pichilingue, La Paz Bay, Baja California Sur, Mexico; a total of 36 oysters (shell height 11.5-36.4mm) were injected with calcein (0.125g/L), and another 50 oysters (shell height 14.8-42.7mm) were submersed in calcein (0.4 and 0.7g/L). Shell slices of calcein-marked oysters were posteriourly stained with Coomassie Blue R-25 for micro growth-band recognition. Our results showed that Calcein marking only worked by submersion and produced a concise bright lime-green florescent band along the growing-edge with clear boundaries for both concentrations. However, marks resulted better at the lower calcein concentration (0.4g/L) with more "perfect" and "good" marks on the growing-edge (p=0.0012). Commassie Blue staining technique was successful, and allowed to conclude that one micro growth-band was laid down per day, similar to other oyster species. Mean 15-d increment of shell growth height was slightly greater at the lower calcein concentration (=0.735mm) than at the higher one (=0.577mm) (not significant difference, p=0.198). Calcein marking of shell growing-edges and Commassie Blue staining of posterior shell growth, as a method for age validation is recommended for shellfish shell growth-band counts. This will allow back-dating for estimation of very precise colonization dates, both spatially and temporally in future work. La validación de la edad es el primer paso para determinar las edades de las especies de moluscos, esta información es de vital importancia para los diferentes modelos de inferencia utilizados en actividades de gestión de los ecosistemas marinos. Diversas técnicas de validación se utilizan para marcar estructuras de carbonato de calcio, aunque la técnica de marcado de calceína en ostras nunca se había utilizado para la validación de la edad de P. mazatlanica. Los objetivos de este estudio fueron: evaluar la calceína como marcador interno de la concha y la eficiencia del azul de Coomassie en la tinción de la matriz proteica de la concha, para facilitar la observación y conteo de micro bandas de crecimiento que permiten validar la edad de las ostras juveniles de madre perla. Las ostras fueron recolectadas en la costa de la empresa Perlas del Cortez S. de RL MI., en Pichilingue en Bahía de La Paz, Baja California Sur, México. Se inyectaron 36 ostras (altura de concha 11.5-36.4mm) (0.125g/L de calceína) y otras 50 ostras (altura de la concha 14.8-42.7mm) se sumergieron (0.4 y 0.7g/L de calceína). Secciones de la concha marcadas con calceína fueron teñidos con azul de Coomassie R-25 para el reconocimiento de las micro bandas de crecimiento. El marcado con calceína fue exitoso por inmersión y produjo una banda fluorescente de color verde lima brillante concisa a lo largo del crecimiento interno de la concha. Sin embargo, las marcas fueron mejores a una concentración de calceína inferior (0.4g/L), con mayor cantidad de marcas "buenas" y "perfectas" (p=0.0012). La técnica de tinción con azul de Commassie también fue exitosa. Se detectó un crecimiento diario por micro banda, similar a lo encontrado en otras especies de ostras. La diferencia del crecimiento medio en relación a la altura de la concha en un lapso de 15 días, fue ligeramente mayor con una concentración de calceína inferior (=0.735mm) que con la de mayor concentración (=0.577mm), pero no significativamente (p=0.198). El marcado de conchas con calceína y tinción de matrices proteicas con azul de Coomassie posterior a su crecimiento, es recomendando como un método para la validación de la edad facilitando el conteo de micro bandas de crecimiento internas de la concha. Además, permitirá estimar edades con el fin de predecir fechas de colonización y ubicación de bancos naturales.

Determining age is an important step when assessing growth, mortality, and yield of cultivated and wild populations, but studies linking shell growth marks in the pearl oyster Pteria sterna with the age of individuals are lacking. Thirty juveniles (20.0 ± 1.2 mm shell height), collected from a winter spat fall, were marked with the fluorochrome calcein and kept in the field in culture containers. After day 16, the juveniles were cleaned and their shells cut along the sagittal axis to determine periodicity of micro growth bands formed in the inner shell layers and to estimate age. During this trial, fluorescent calcein marking succeeded in individuals larger than 20 mm shell height; these formed an average of 15 micro growth bands over the 16 days, representing 1 band per day. The marker created a wide fluorescent band containing three micro growth marks, suggesting that calcein was incorporated into the shell over the first three days. The use of calcein was found to be an accurate method for validating the micro growth band frequency of formation in P. sterna juveniles, which in turn can help to estimate age.

This thesis is composed of two separate spatially-explicit state-space dynamic models developed with the general objective of contributing to the understanding of migratory behavior in fish. The first model focuses on the behavior of mature adults during their reproductive migration, while the second focuses on the migratory tactics of fish during their migration cycle. Both models were applied to the marine migration of sockeye salmon (Oncorhynchus nerka) from the Fraser River. The first model is based on the hypothesis that the migratory behavior of returning individuals arises as an adaptive response to minimize a measure of the total costs of migration, given an expectation of the state of the environment during the migration (defined in terms of currents, temperature, and risk of predation). The model predicts that the higher swimming speed observed when sockeye salmon reaches the coast, and the use of the Juan de Fuca as the primary route to reach the Fraser River, are likely a response to a higher risk of mortality in the coast. The model also indicates that given the short arrival time of individuals from the same race, they either start their migration from a short longitudinal range, or are distributed across a wider range and start their migration at different times, with individuals further away from the Fraser River starting earlier. Predicted swimming speed and orientation resulted very sensitive to the spatial distribution and value of predation risk. This model could not predict the oceanic migration route and the latitude of landfall of Fraser River sockeye. I concluded that the spatial distribution of mortality was not properly represented, or that the tradeoff used to define the model was not adequate. The second model is based on the hypothesis that juvenile fish have a tradeoff between foraging activity and migration activity. The model was able to predict the following characteristics for sockeye salmon from the Fraser River: 1) Juveniles migrate along the coast and then move into the Alaska Gyre where they stay the rest of their oceanic residence. Model predictions do not support the commonly held hypothesis of an annual circuit around the Alaska Gyre. 2) The juvenile migration arises as a response to high zooplankton density in the coast at the time of the migration, although the high risk of mortality there creates a bottleneck in their life cycle. 3) The model predicts a seasonal growth pattern as a response to the seasonality of zooplankton density. 4) Juvenile fish display higher swimming migration activity than adults. 5) Individuals behaving optimally distribute below the observed thermal limits, however their distribution follows that of prey density. 6) The size-dependency of mortality observed during the smolt-to-adult phase likely arises from smaller individuals taking longer to swim through the coast.