Incorporating Sea Surface Temperature into the Stock-Recruitment Relationship: Applications to Jack Mackerel (trachurus Murphyi) off Chile

espanolSe modelo la tasa de reclutamiento en relacion a la biomasa desovante y la temperatura superficial del mar (TSM) para la poblacion de jurel (Trachurus murphyi) afuera de las costas de Chile usando el modelo de Ricker. Los datos respecto al reclutamiento y la biomasa desovante fueron proporcionados por los modelos de evaluacion de stock desde 1975 al 2001, mientras que la serie temporal anual de TSM fue tomada de las estaciones meteorologicas localizadas a lo largo de la costa de Chile por el Centro Nacional de Datos Hidrograficos y Oceanograficos de Chile (CENDHOC). El modelo estandar de Ricker fue modificado de la siguiente manera: (1) incluyendo la serie temporal de TSM como un predictor lineal, (2) modelando la serie temporal de TSM con funciones de suavizacion y (3) modelando ambas, la biomasa desovante y la serie temporal de TSM con funciones de suavizacion. Los modelos resultantes fueron comparados con el modelo estandar de Ricker sin TSM. La seleccion del modelo se realizo segun los criterios de informacion automatica. La inclusion de la TSM mejora el ajuste de esos modelos, a pesar de la penalizacion de un termino adicional y una posible fuente de variabilidad adicional. El mejor modelo resultante incorpora la serie temporal de TSM con funciones de suavizacion y la biomasa desovante mediante funciones parametricas, con una bondad de ajuste del 90%. La incorporacion de una variable ambiental en la relacion stock-reclutamiento puede ser un metodo promisorio para considerar los efectos de la pesca y el ambiente simultaneamente, y es particularmente relevante para el manejo pesquero a la luz del cambio climatico. EnglishThe recruitment rate was modeled in relation to spawning biomass and to sea surface temperature (SST) for the jack mackerel (Trachurus murphyi) population off the Chilean coast using the Ricker model. Data regarding recruitment and spawning biomass were obtained from indirect stock assessment models from 1975 to 2001, while annual time series of SST were collected from the meteorological stations placed along the Chilean coast by the National Center of Hydrographic and Oceanographic Data (CENDHOC). The standard Ricker model was thus modified as follows: (1) the SST temporal series was included as a linear predictor; (2) the SST temporal series was modeled through smoothing functions; and (3) spawning biomass and SST temporal series were both modeled using smoothing functions. The resulting models were compared with the standard Ricker model without SST. Model selection was carried out using automatic information criteria (AIC). Including SST improved the fit of the recruitment model, despite the penalty of an additional term and a possible additional source of variability. The best model resulting includes the SST temporal series with smoothing functions and the spawning biomass with parametric functions, with a goodness-of-fit of 90%. Incorporating an environmental variable into stock-recruitment relationships may be a promising method for simultaneously considering effects from fishing and the environment, and is particularly relevant for managing fisheries in light of climate change.