Otolith microchemistry provides information complementary to microsatellite DNA for a migratory fish

We investigated the ability of otolith microchemistry to discriminate natal habitats of the splittail Pogonichthys macrolepidotus, a migratory cyprinid endemic to the San Francisco Estuary, California. Splittails are broadly distributed in the brackish and freshwater portions of the lower estuary and make long-distance upstream migrations during winter to rivers and floodplains for spawning. We found that the ratios of Sr : Ca and Sr-87 : Sr-86 in the otoliths (ascertained by laser ablation inductively coupled mass spectrometry) of age-0 fish collected from natal habitats significantly varied among four primary spawning rivers. Based on these two constituents, quadratic discriminant function analysis correctly classified 71 % of the fish to their natal rivers. Recent work with rnicrosatellite DNA indicates that splittails from these same rivers represent two genetically distinct populations.