IMPACT OF ABRUPT HOLOCENE CLIMATES CHANGES AND SOLAR CYCLICITY ON FISH POPULATION DYNAMICS IN THE NE PACIFIC

Based on temperature and rainfall records collected over the past century it is known that the climate in the NE Pacific Ocean is significantly influenced by interdependent cycles of the Aleutian Low, the Jet Stream, and El Nino/ La Nina. Less well-understood are climatic events that occur at the decadal, centennial and millennial cycles, and how these climate changes influenced fluctuations in the assemblages and biomass of fish populations through the Holocene. We examined annually deposited, finely laminated sediments that were deposited under primarily anoxic conditions from Effingham Inlet, SW coast of Vancouver Island, Pacific Canada from ~2,000 and 5,000 years BP. Wavelet transform, spectral and cross-spectral analysis were performed on grey-value time-series derived from high-resolution digitized sediment core X-ray images (sub-annual resolution) and fish scale remain density (=35 year resolution) of the Pacific herring (cold water species) and northern anchovy (warm water species). We detected in the time-series data well-preserved and stationary ~11 year Schwabe sunspot cycles, ~70-100 year Gleissberg cycles with an underlying sedimentation rate that consistently varied around 0.3+/- 0.1 cm per year through the entire interval. Several observed cycles changed frequency following the transition of regional climate to a higher rainfall phase that impacted coastal upwelling ~3,300 years BP. These less-stationary cycles had wavelengths of ~3.5-5, ~40 (interdecadal cycle -- Aleutian Low?), ~140, ~200 (Suess Cycles), ~330, ~500, and ~1,000 -1,300 (Bond cycles) years. We consider the ~88 year Gleissberg solar cycle to be a significant forcing mechanisms for pelagic fish populations as abundance peaks in anchovy and herring productivity, although negatively correlated with each other, are strongly correlated to this cycle through the entire interval of deposition.