We propose to use trace element analysis of otoliths from adult and juvenile rockfish in the Georgia Basin/Puget Sound (GB/PS) region to determine the sources from which larvae originate and the oceanographic regions they occupy during the pelagic larval phase. The elemental composition of fish otoliths has been used successfully to identify stock structure, recruitment patterns, and dispersal pathways for a number of fish species from tropical and temperate regions. The technique is highly appropriate for use in the GB/PS region because of the strong fluvial and oceanic signals provided by inputs from the Fraser River and Strait of Juan de Fuca, respectively. The technique has been successfully used in the GB/PS region to characterize migration patterns of anadromous fish.

We will use two species of rockfish as model systems. Copper (Sebastes caurinus) and quillback (Sebastes maliger) rockfish both are species of local importance. Populations of both species have declined sharply over the past few decades, and both now are regional conservation targets. The research we propose is highly relevant to problems of bottomfish recovery, marine conservation and management, and marine protected area network design. The results of our research will indicate whether populations of these rockfish species constitute open populations characterized by substantial long-distance dispersal, or whether these are closed populations in which larval dispersal is spatially limited. Our results will help guide the design and implementation of marine protected area networks in the GB/PS region and throughout Washington State.

Here we request a second year of support for a project currently underway and funded by the SeaDoc Society. We originally designed and proposed this as a 2-year project. Because our work in Year 1 necessarily included exploration of analytical techniques, the most meaningful results will be realized only after a second year of work