Fig 1.
The red square represents the area of coverage of the hydrodynamic OFES model subset. The maps in the left represent the characteristics that were considered for the division of the polygons: The geographic structure of the ridge (Islands and seamounts); Management area (Marine parks and Marine protected areas with multiple uses; MPA-MU); and areas of influence of fishing activity (Industrial and artisanal fleets).
Table 1.
Biological functional groups in the JFRE model and their main configuration.
The initial biomass in metrics tonnes, the classification (A) under fisheries means active fishery, (S) means secondary fishery or bait fishery, (C) represents currently closed fisheries and (B) was used for species that are bycatch of other fisheries (J.F. abbreviation stand for Juan Fernández). More detailed descriptions of the functional groups can be found in the supplementary material.
Fig 2.
The left side includes the main components (biological, physical and economic) and forcings that were considered for the JFRE model.
The flowchart shows that the model runs for 35 years if after this period the model is dynamically stable it creates a new initial condition at equilibrium. When the model is already dynamically stable, the calibration process is performed to represent the conditions observed in the ecosystem.
Table 2.
Scenarios used to evaluate the effects of historical fishing activity in the JFRE.
Table 3.
Scenarios used to evaluate the effects of future fishing activity in the JFRE.
C stands for current level of fishing pressure, I is the increase in fishing pressure and I+ is the cumulative increase of fishing pressure for both types of artisanal fisheries.
Fig 3.
In the left column are presented the time series of the biomass relative to the initial biomass of an unfished (blue line) and fished (yellow line) ecosystem.
The first three rows of the right column represents the time series of simulated catches in Atlantis (red line) and observed (gray dots). For the Fur seal, the dots represented the observed abundance and the red line is the estimated abundance from Atlantis.
Table 4.
Metrics used to determine the skill in model assessment.
p-values are provided in brackets.
Fig 4.
Food web of the Juan Fernández Ridge ecosystem.
The code representing the functional groups can be found in Table 1.
Fig 5.
Relative change in biomass (A) and abundance (B) for the scenarios with only artisanal, industrial and the historical fisheries (industrial + artisanal). An unfished ecosystem is the base case for comparisons. Note that the y-axes is the ratio of change against the starting conditions—so a -0.5 result indicates a 50% decrease and a 0.5 result indicates a 50% increase -.
Fig 6.
Summary of the catch distribution for the total bait caught from artisanal fisheries (A)), the total artisanal bycatch (B)) and the industrial bycatch (C)). The upper and lower limits of boxes represent the 25th and the 75th percentile and the middle line the 50th percentile of the data distribution. The whiskers represent the range of the catches.
Fig 7.
Relative change in biomass (A) and abundance (B) for the business as usual (BAU), a 50% increase in fishing effort of crustaceans (ICRUS50%), 50% increase in fishing effort for crustaceans and finfish (IBoth50%) and 100% increase in fishing effort for finfish (IFish100%). An unfished ecosystem is the base case for comparisons. Note that the y-axes is the ratio of change against the starting conditions—so a -0.5 result indicates a 50% decrease and a 0.5 result indicates a 50% increase -.
Fig 8.
Relative change in catch for the last 20 years of projection for 50% increase in fishing effort of crustaceans (ICRUS50%), a 50% increase in fishing effort for crustaceans and finfish (IBoth50%) and 100% increase in fishing effort for finfish (IFish100%).
The catches from a business as usual scenario is the base case for comparisons. Note that the y-axes is the ratio of change against the starting conditions—so a -0.5 result indicates a 50% decrease and a 0.5 result indicates a 50% increase -.
Table 5.
Information and model components that are needed for a future update or to use the model with data assimilation.
These components are divided by: Priority, that means how urgent they are; Type, which include new model components to configure in the Atlantis framework (socio-economic components) and data which can be composed of single data or time series; Periodicity, correspond the ideal maximum time lag needed for the information; and Spatial if the information that is needed should be at the spatial level. Note that information at the level of the species should primary include key species from the ecosystem such as Spiny lobster, J.F. morwong, sea urchins.