In recent years, purple sea urchin populations have greatly increased along the northern California coast and have made the main foods for abalone (kelp and other seaweeds) so scarce that many abalone have starved to death. The increased number of shells washing ashore indicates the extent to which abalone populations are being impacted by lack of food. It has also been common to find abalone which have very shrunken bodies due to lack of food rather than a disease. The shrunken abalone are weaker than healthy abalone and are more likely to be dislodged and killed by large waves.