An Investigation of Northeast Pacific Groundfish Recruitment Variability Driven by Physical and Biological Factors

Marine ecosystems respond in a variety of ways to physical and biotic forces in the ocean environment through direct and/or indirect pathways, causing the abundance and productivity of marine species to vary over a broad spectrum of time scales. We used spectral analysis of recruitment rate and total biomass time series to evaluate the dominant time scales of variability in the population dynamics of commercially harvested groundfish stocks from the Gulf of Alaska and Bering Sea. We then developed conceptual models for biotic and abiotic processes in these ecosystems that may impact the recruitment rates of identified groups, with particular attention paid to the dynamics of past ecosystem regime shifts. Our conceptual models were used to provide a framework for identifying physical and biological time series that influence variability in recruitment rates for selected stocks and we use this as an initial step in the development of statistical models for explaining and potentially predicting variability in groundfish recruitment rates with observations of physical and biotic variables.