The researchers studied the food and growth of anchovy, sardine, and horse mackerel larvae in the Bay of Biscay. They looked at the nutrients in the water and the protein, fat, and other contents in the larvae. They found that the larvae had enough food to grow well in the spring and early summer. The RNA/DNA ratio in the larvae increased as they grew, reaching an optimal level. This ratio can show how healthy the larvae are compared to starving ones.