The Chumash people and Tongva people used sewen plank canoes (Tomols) to travel across and fish in the seas between the Southwest California Coast and the Channel Islands of California. Some of their chief catches were sardines (pilchards) who were mentioned several times by the early Spanish explorers. Sardines are small epipelagic fish (surface water fish to 200m) which then migrated along the California coast in large schools at certain times of the year. They are an important forage fish for larger forms of marine life and a major fishery in the California waters till the sardine schools greatly diminished due to ocean current temperature changes and over fishing. The sardines were caught by the California Indians primarily with some kind of net.