A time series of daily larval production at hatching /10m2 of Pacific hake (Merluccius productus), also called Pacific whiting, from 1951-2005 was constructed based on data collected from CalCOFI surveys off the coast from San Diego to San Francisco in January – April, the peak spawning time of Pacific hake. This area has been covered by CalCOFI January cruises since 2003, and by CalCOFI surveys prior to 1985. For some years between 1980-2003, the CalCOFI survey area reached only to the north of Morro Bay. For those years, the larval production at hatching was estimated based on a conversion factor to scale to the entire area. The time series of hake larval production indicated that the density of daily Pacific hake larval production fluctuated with peaks in 1987 and 1986. Minor peaks were in 1952, '58, '66, and '72. The density of daily larval production has been decreasing since 1987. The decrease of Pacific hake larval production coincided with the increase of sea temperature since 1980’s. The larval production was particularly low in 2003-2005. This time series can be considered as an index of spawning biomass of hake to tune the biomass estimates in the stock assessment.
The general pattern of Pacific hake migratory behavior (Dorn 1995).