An end-to-end ecosystem model framework to study environmental controls on population dynamics and habitat utilization of forage fish and apex predators in the California Current.
Fiechter J1, Huckstadt L1, Costa D1, Rose K2, Curchitser3, Hedstrom K4, Edwards C1 Moore A1,
1 University of California at Santa Cruz, USA
2 Louisiana State University, USA
3 Rutgers University, USA
4 University of Alaska, Fairbanks, USA
We present results from a fully coupled end-to-end ecosystem model for the California Current Large Marine Ecosystem (CCLME), with the aim of quantifying the impact of environmental variability on trophic interactions, habitat utilization, and foraging patterns/success of mid- and higher trophic level species. The ecosystem modeling framework consists of a lower trophic level ecosystem model (NEMURO) embedded in a regional ocean circulation model (ROMS), and both coupled with a multi-species individual-based model (IBM) for forage fish (sardine and anchovy) and an apex predator (California sea lion). For sardines and anchovies, population dynamics is based on growth, reproduction, and mortality (natural, predation, and fishing). For sea lions, bioenergetics and behavioral attributes are specified using available TOPP (Tagging Of Pacific Predators) data on their foraging patterns and diet in the CCLME. Output from a 50-year run (1959-2008) of the model shows how different environmental processes (e.g., temperature, prey availability) control sardine and anchovy population dynamics on interannual and decadal timescales, and lead to clear low frequency out-of- phase responses between the two species. We also illustrate how the variability in forage fish distribution and abundance translates to shifts in foraging patterns and success for California sea lions. While specifically focusing on trophic interactions affecting habitat utilization of sea lions in the CCLME, an overarching goal of our end-to-end modeling approach is to better understand and characterize biological “hotspots” (i.e., the aggregation of multiple marine organisms over multiple trophic levels) off the U.S. west coast, and in other regions where similar fully-coupled end-to-end ecosystem models may be implemented.