Returning to Their Natal Estuaries to Spawn Scientists analyzed the chemical composition of otoliths of adult (spawning age) weakfish caught in five estuaries, to determine the estuary where they hatched. The pop-up graphs show the percentage of fish caught in each estuary that hatched in each of the five estuaries. The results indicate that most fish returned to their natal estuaries to spawn. (Illustration by Jayne Doucette, WHOI Graphic Services)