To investigate the possibility of climatic influence on the marine biosphere, we analyzed the decadal time series of zooplankton biomass and sea surface temperature (SST) measured at stationP, Gulf of Alaska, during the period 1957--1980. A relationship between the two series is not apparent in the raw data. However, Fourier analysis revealed peaks at 28.8 months in both zooplankton and SST spectra. This period belongs to the range of the quasi biennial oscillation (QBO). Such a signal has been found originally in atmospheric and later in physical oceanographic variables. However, it has not been reported previously in biological variables. Cross-spectral and band-pass filter analyses indicate that temperature and zooplankton variations at this frequency may be related. Possible mechanisms are discussed. These results are important because they indicate that a climatic signal, the QBO, is present in the oceanic biota.¿ 1997 American Geophysical Union