Comparisons within and between years resulting in contrasting recruitment of Pacific hake (Merluccius productus) in the California Current System

In a search for correlates and possible causes of the difference in recruit ment success of Pacific hake (Merluccius productus) of the 1981 and 1984 ye ar-classes, we analyzed (by optical plankton counter) the distribution into sizes of preserved zooplankton samples from stations with and without larv al hake in winter and spring of these two years. We also assessed the onsho re/offshore distributions of larvae, potential for geostrophic and Ekman tr ansport, and their overall survival rates. Cluster analyses of biovolume sp ectra led to the development of a simple ratio of "medium" to "small + larg e" zooplankton that statistically separated stations within a year where la rval hake were likely to be found from those where they were unlikely to be found. This biovolume ratio was independent of temperature, and the same r atio statistically distinguished stations where larval hake tended to occur in spring 1998. However, we found no property or process that might explai n why the 1984 year-class was spectacularly successful.