By May, the upwelling of nutrient-rich water, the greening of the sea, the surge of new life that began in March and accelerated in April nears its annual climax, at least in nearshore waters.
May sees a nearly continuous sequence of diatom blooms along the Central Coast. These blooms provide food for an explosion of copepods, juvenile krill, and small schooling fish, such as anchovies. These animals, along with small predators such as market squid and juvenile rockfish, in turn provide essential food for larger animals such as seabirds and marine mammals.
Taking advantage of this plentiful supply of food, millions of schooling fish and tens of thousands of seabirds and marine mammals migrate to the Central Coast in May. Along the coast, seabirds and many other animals give birth at this time of year, when both adults and young are most likely to find ample food.