Patterns and schedules in hindcasted environments and fish life cycles

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Biophysical NPZD (nutrient, phytoplankton, zooplankton, detritus) models are now available to generate long-term hindcasts of climate-forced variability in the physical and lower trophic environment of fish populations. The paper presents a method to evaluate the seasonal and inter-annual variability in the hindcast outputs of NPZD models. First, Empirical Orthogonal Functions (EOF) are used to extract the major patterns in space and their variability in time for a list of variables that are output of a long-term hindcast run. Then Multi-Factor analysis (MFA) is applied on the amplitudes of the EOFs to characterize the seasonal pattern in all the variables and the variability across years around that pattern. Correlation of the amplitudes to the principal components of the MFA help identify the drivers of the variability. life cycle scheduling of various species is matched with the MFA results to identify the type and magnitude of environmental variability that each life stage is expected to experience and hence identify potential critical periods in the life history. Applications of the procedure are performed in the North Sea and the Bay of Biscay for sprat (Sprattus sprattus), European anchovy (Engraulis encrasicolus) and sole (Solea solea), resident species in both areas. This generic procedure was also applied to North Sea herring (Clupea harengus).