for thousands of years, clams have been dug up along the beaches of california for food, first by native americans, and these days by tourists. today, the clam population is at an all-time low, and many scientists agree that several species of clams will inevitably become extinct in california. dr. clay, a marine biologists, believes that ddt (a pesticide) dumped into the ocean during the 1950’s and 60’s could be another factor in the dramatic decrease in the clam population.