Zhixian Sun

Otolith is a calcified structure in the bony fishes’ inner ear. Each fish has three pairs of otoliths in their semicircular ear canals. The otolith can grow through the whole life period without resorption, that means it documents the fish’s whole life, and it is a very powerful method to study the natural history of the fish.

Many marine fishes have their planktonic early life period which uses ocean current to disperse their offspring over vast distances. The Meso-American Barrier Reef, lines the coast of Belize, may be the significant biogeographic barrier in such a process, which causes isolation. The species in this semi-enclosed system may involve unique early life history, causing endemism. Among the approximately five hundred native marine fishes found in Belize, twenty fish species were found endemic to Belize Meso-American Barrier Reef and twelve of them can only be discovered inside the lagoonal region. Halichoeres socialis Randall & Lobel, 2003 (Labriformes: Labridae) is a kind of small schooling wrasses which is endemic to the lagoonal area of Pelican Cay, Belize. To answer the question of its endemism, the early life history was studied by doing otolith analysis. By examining the increments (daily rings) on the otolith, we can know the age (day) of the larval individuals, and the pelagic duration after they hatched.