Melissa Haltuch1 Teresa A’mar2 Juan Valero3 Owen Hamel1 Nicholas Bond4
1NWFSC
2Fred Hutchinson Cancer Research Center
3CAPAM
4JISAO
March 06, 2018 9:00 (PST): FSH 203
“Progress and Challenges in Implementing Ecosystem Drivers of Recruitment in West Coast Sablefish Stock Assessments” and “Assessing the effects of climate change on U.S. West Coast sablefish productivity and on the performance of alternative management strategies”
U.S. West Coast sablefish is one of the most commercially valuable species targeted by the groundfish fishery. Research on ecosystem drivers of sablefish recruitment has a long history, the results of which have been a topic of ongoing debates during the scientific review of stock assessment products for management. This review extends from the published peer review literature on the topic to the most recent implementation of the sablefish stock assessment accepted for management by the Pacific Fishery Management Council. We discuss technical and implementation challenges, as well as lessons learned along the way.
AND
U.S. west coast sablefish are commercially valuable, making assessing and understanding the impact of climate change on the California Current (CC) stock a priority for (1) forecasting future stock productivity, and (2) testing the robustness of management strategies to climate variability and change. The horizontal-advection bottom-up forcing paradigm describes large-scale climate forcing that drives regional changes in alongshore and cross-shelf ocean transport and directly impacts the transport of water masses, nutrients, and organisms. This concept describes a mechanistic framework through which climate variability and change alter sea level (SL), zooplankton community structure, and sablefish recruitment, all of which have been shown to be regionally correlated. This study forecasts potential future trends in sablefish productivity using SL from Global Climate Models (GCMs) as well as explores the robustness of harvest control rules (HCRs) to climate driven changes in recruitment by conducting a management strategy evaluation (MSE) of the currently implemented 40-10 HCR as well as an alternative Dynamic Unfished Biomass 40-10 HCR. A majority of the GCMs suggest that after about 2040 there will be a slight trend towards generally lower SLs relative to the global mean, with an increasing frequency of low SLs outside of the range of the historical observations, suggesting favorable conditions for sablefish in the northern CC by 2060. Projected SLs from the GCMs suggest that future sablefish recruitment is likely to fall within the range of past observations but may be less variable and is likely to exhibit decadal trends that result in recruitments that persist at lower levels (through about 2040) followed by somewhat higher levels (from about 2040 through 2060). Although this MSE suggests that spawning biomass and catches will decline, and then stabilize, into the future under both HCRs, the sablefish stock is not projected to fall below the stock size that would lead to a fishery closure during the period analyzed (through 2060). However, the 40-10 HCR triggers stock rebuilding plans more frequently than the alternative Dynamic Unfished Biomass 40-10 HCR (based on the concept of a dynamic, rather than static, baseline stock size), suggesting that the alternative HCR is more robust to potential future climate driven changes in sablefish productivity.