Spatial pattern of natal signatures in the otoliths of juvenile kelp rockfish along the Californian coast

Abstract

The natal origin of a post-dispersal marine fish may be determined by examining the trace elemental signatures present in the core (i.e. the pre-dispersal region) of the otolith. We found distinct spatial differences in the natal elemental signatures in the core region of the otoliths of post- dispersal juvenile kelp rockfish Sebastes atrovirens collected along the coast of California, USA. Laser ablation inductively coupled plasma mass spectrometry of individual otolith cores revealed detectable levels of Mn, Mg, Ba, and Sr. Using a Bayesian classification model, 2 unique elemental signature types were identified in both 2001 and 2002, and the signatures were chemically similar across years. In both years, locations received a mixture of natal types ('A' and 'B'), indicating the con- tribution of at least 2 chemically distinct sources to recruitment. The spatial pattern of the natal types varied among sites for both years. In 2001, Type A was nearly absent from the northernmost location, suggesting a southern origin and a limitation in the dispersal and contribution of this chemically iden- tified natal type. In 2002, most locations had a mix of Types A and B, but Type A was most abundant in the south and least abundant in the central part of the spatial domain. However, it was not possible to specify the full extent of dispersal of either natal type. We demonstrated use of elemental signa- tures in the otolith core of post-dispersal individuals to evaluate larval dispersal patterns which may document the extent to which kelp rockfish populations along the California coast receive recruits from different chemically distinct sources.