Using a climate-to-fishery model to simulate the influence of the 1976-1977 regime shift on anchovy and sardine in the California Current System
Authored by Haruka Nishikawa, Enrique N Curchitser, Jerome Fiechter, Kenneth A Rose, Kate Hedstrom
Date Published: 2019
DOI: 10.1186/s40645-019-0257-2
Sponsors:
Japanese Society for the Promotion of Science (JSPS)
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
Model code not found
Abstract
The influence of the well-known 1976-1977 regime shift on the Northern
anchovy (Engraulis mordax) and the Pacific sardine (Sardinops caeruleus)
populations in the California Current System (CCS) is investigated using
a climate-to-fishery model. This model consists of four coupled
submodels (regional ocean circulation model; Eulerian
nutrient-phytoplankton-zooplankton-detritus model; individual-based full
life cycle anchovy and sardine model; agent-based fishery model).
Analysis of a historical simulation (1958-1990) showed that survival
fraction of age-0 anchovy was lower just after 1977, while survival
fraction of age-0 sardine was relatively unaffected by the regime shift.
The age-0 survival of both species was influenced by the growth in the
larval stage. Simulated zooplankton densities in the historical
simulation shifted from high to low in 1976-1977 in the CCS, with the
shift being most drastic in winter in the coastal area. The model also
shows that anchovy larvae feed extensively from winter to early spring
in the coastal area, while sardine larvae were mainly distributed in the
offshore area. The differential seasonal and spatial responses of
zooplankton in the simulation caused anchovy survival to be more
sensitive than sardine to the 1976-1977 regime shift. The
model-generated zooplankton shift was a result of reduced phytoplankton
production due to lowered nutrient concentrations after 1977 due to the
weakening of both the coastal upwelling and mixed layer shoaling, which
reduced the vertical nutrient flux from the bottom layer to the surface
layer.
Tags
Individual-based model
movement
Ecosystem
Fluctuations
Populations
Variability
Trends
California current system
North pacific
Sea
Sardine
Surface
Anchovy
Climate-to-fishery model
Regime shift
Flux