create.ETdiagnosis: ET Diagnosis

Description

ET-Transpose allows to obtain a picture of an ecosystem under a given fishing mortality. ET-Diagnosis is a routine that can simulate how this baseline ecosystem would be impacted by increasing or decreasing fishing effort. Ecosystem-wide effects of altering fishing effort include potential changes of biomass, accessible biomass, production, kinetics and catch trophic spectra as well as impacts on the mean trophic level of the catch and biomass. Additionally, ET-Diagnosis can be a useful exploratory tool for ecosystem-based management by simulating how reducing or increasing fishing effort and/or preferentially targeting different trophic levels could improve yield at the ecosystem scale. Lastly, ET-Diagnosis allows to view how different assumptions about ecosystem functioning (extent recycling, top-down effect) can have effects on both trophic level specific and ecosystem-wide properties in relation to fishing.

Usage

create.ETdiagnosis(ET_Main, Mul_eff = NULL, Beta = NULL, 
TopD = NULL, FormD = NULL, TLpred = NULL)

Arguments

ET_Main

is the ET_Main table returned by the create_ET_Main function in its list of table.

Mul_eff

is a vector of the different effort multiplier you want to test.

Beta

is a coefficient expressing the extent of biomass input-control. Beta=0 refers to an ecosystem where all secondary production originate from grazing on primary producers and Beta=1 to an ecosystem where detritus and/or recruitment contribute a major part

TopD

is a coefficient expressing the top-down control, the fraction of the natural mortality which depends on predator abundance. It may vary between 0 and 1.

FormD

is a shape parameter, varying between 0 and 1, which defines the functional relationship between prey and predators. The value 1 relates to a situation where predators abundance has a linear effect on the speed of the flow of their preys.

TLpred

TLpred, is the trophic level at which you consider the predator trophic classes start. The default value is 3.5.

Value

The function provides two types of results for each different fishing effort simulated: summary statistics for the whole ecosystem, including absolute and relative values compared to the baseline scenario; catches, total and accessible biomass and production, kinetics for all trophic levels.

References

Gascuel et al. (2009) EcoTroph (ET): a trophic level based software for assessing the impacts of fishing on aquatic ecosystems.

Examples

Run this code

data(ecopath_guinee)
create.ETdiagnosis(create.ETmain(ecopath_guinee)$ET_Main)
create.ETdiagnosis(create.ETmain(ecopath_guinee)$ET_Main,TopD=0.6)