Distribution and reproduction of the planktonic copepod, Calanus pacificus, off southern California during winter-spring of 1992, relative to 1989–91

Abundance and production of eggs by female Calanus pacificus off southern California were assessed in February and April, 1992, together with biomass of chlorophyll and abundance of larval anchovy. Because 1992 was an anomalous year as a result of a Californian El Nino, the patterns were compared with analogous data for 1989-91. Female Calanus were much less abundant in both February and April of 1992 than in the earlier years, and the anomalies were negatively related to temperature anomalies, but the biomass of chlorophyll and per capita egg production were anomalously low only in February. The horizontal distribution of female Caianus was similar to that of chlorophyll in winter, but was more efficient (in the sense of permitting more complete utilization of the available chlorophyll) in April, 1992, than in the earlier springs. The abundances of larval anchovy were positively correlated with the reproduction of the Calanus population in 1992 and in the earlier years, but the larvae were poorly distributed with respect to Calanus spawning, in both 1992 and the earlier years, to take best advantage of the resulting nauplii as food.