SGER: Quantifying the effect of upwelling and relaxation on otolith chemistry and fish growth

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The role of upwelling and relaxation events on recruitment of fishes to central California has been documented in a general sense. However, there is a lack of understanding about the actual transport mechanism, timing of transport and water mass residence, benefits or costs associated with entrapment in upwelled waters, along fronts, or within eddies, and the ultimate effects on survival within the pelagic environment and after settlement. In the proposed study the investigators will attempt to retrospectively determine water mass exposure and quantify the influence of these various oceanographic features (with an emphasis on upwelling and relaxation) on growth and condition of pelagic juvenile shortbelly rockfish during and after exposure by using otolith microstructure and chemistry and RNA:DNA analysis. The results will be used to evaluate otolith microstructure and chemistry as tools for understanding the factors that contribute to recruitment variability and year-class strength of rockfishes along the California coast. The proposed project will be extremely beneficial for quantifying the mechanism underlying the year-class strength is considered the most challenging issue in fisheries. The broader impacts of the results include use in modeling dispersal and recruitment mechanisms, tune the gross estimates of year-class strength that come from pelagic surveys, and aide in the proper design on protected areas. A graduate student will also be trained during the project.