Investigating Petrale Sole Recruitment Mechanisms via Larval Transport: Insights into Population Connectivity

Enrique Curchitser Rutgers, The State University of New Jersey

Abstract:

This study will build an IBM of larval drift (e.g. Parada et al. 2010, Parada et al. 2014, Hinckley et al. 2015) for CC petrale sole, allowing for the determination of the direction of larval drift from discrete spawning grounds off the U.S. west coast for the years 1990-2009, as well as record larval oceanographic histories. The IBM will enable the theoretical determination of which spawning grounds most greatly contribute to recruitment success via on-shelf transport as well as the variability of recruitment success through time. The center of spawning success will be evaluated to identify potential changes in phenology during the study time period. The years 1990-2009 encompass years with both high and low recruitments that are well estimated in the stock assessment as well as a range of environmental conditions, including both El Niño and La Niña years and both positive and negative phases of the PDO and North Pacific Gyre Oscillation (NPGO). The IBM is forced by annually varying ROMS hydrodynamic model with output for the CC (Curchitser et al. 2005, Hermann et al. 2009, Danielson et al. 2011). A time series (1950-2009) of ROMS model output on both ~10 km and 2 km grids (NEP) are currently available. Oceanographic outputs from the ROMS model will be validated with physical oceanographic data collected during the NWFSC Pacific hake acoustic survey, including temperature, salinity, currents, as these data are not used in the ROMs model. With a few exceptions, due to equipment failure or survey conflicts, data are available for survey years during 1992 to 2015. The coupled IBM-ROMS model will inform the transport dynamics of petrale sole during their pelagic life stages, allowing for the impacts of variability in cross- shelf and alongshore transport in the CC to be quantified (e.g. Combes et al. 2013). Combes et al. (2013) found that 10 km ROMS models were able to capture both the mean large-scale features of the mesoscale activity, which influences cross-shelf transport, and the subsurface poleward flow in the CC which is likely to be important for petrale sole pelagic transport.