DEstd: Derived Effort Based Standardization (DEstd)

In FESta: Fishing Effort Standardization

Derived Effort Based Standardization (DEstd)

Description

The derived effort approach (Sparre, 1998) assumes effort is a good measure when it relates linearly to catch rate. Since different gears use incompatible effort units, each is converted to CPUE and then to a relative CPUE so they can be combined. Dividing total yield by the yield-weighted sum of these relative CPUEs gives a standardized effort series that reflects relative abundance.

The catch per unit effort for gear i in year y is:

CPUE_i(y)=\frac{Y_i(y)}{f_i(y)}

where Y_i(y) is the catch and f_i(y) is the corresponding effort.

Relative CPUE is computed as:

R_i(y)=\frac{CPUE_i(y)} {\mathrm{Mean}[CPUE_i]}

where \mathrm{Mean}[CPUE_i] is the average CPUE of gear i across all years.

Annual relative effort is estimated as:

R(y)=\sum_{i=1}^{k} \left[ R_i(y)\times\frac{Y_i(y)}{Y_E(y)} \right]

where Y_E(y) is the total catch from gears for which effort information is available.

The Standardized CPUE is then calculated as:

E(y)= \frac{Y_T(y)/R(y)} {\mathrm{Mean}[Y_T/R]}

where Y_T(y) is the total annual catch (including gears for which effort is not known).

Usage

DEstd(data, year_col, gear_col, catch_col, effort_col, total_catch_col)

Arguments

data	A data frame containing the columns of year, gear, catch, effort and total annual catch. See the example dataset DEstd_dataset.
year_col	Specify the year column name (eg. "Year").
gear_col	Specify the gear types column name (eg. "Gears").
catch_col	Specify the catch column name (eg. "Catch").
effort_col	Specify the effort column name (eg. "Effort").
total_catch_col	Specify the total annual catch column name (eg. "Annual Catch").

Value

The output includes a summary table containing Year, Total Catch, Nominal CPUE, and Standardized CPUE. In addition, two plots are produced: Nominal CPUE versus Total Catch and Standardized CPUE versus Total Catch.

Note

The unit of the standardized CPUE will be based on the units of Catch and Effort.

If effort column has zero values then the rows corresponding to them are removed to calculate CPUE.

References

Sparre, P., and Venema, S.C. (1992). Introduction to Tropical Fish Stock Assessment. FAO Fisheries Technical Paper No. 306/1, 376 pp.

Acknowledgements: The authors sincerely thank the Director, ICAR–Central Marine Fisheries Research Institute (ICAR-CMFRI), Kochi, for providing the necessary facilities and institutional support. The authors also gratefully acknowledge the support provided by the Indian Council of Agricultural Research (ICAR), Department of Agricultural Research and Education (DARE), Government of India, through the ICAR-National Fellow Project.

Examples

## Not run: 

library(FESta)
data("DEstd_dataset")
result<-DEstd(data=DEstd_dataset,year_col = "Year",gear_col = "Gear",
catch_col = "Catch",total_catch_col="Total_Catch", effort_col = "Effort")
print(result)

## End(Not run)

FESta documentation built on Aug. 20, 2026, 5:10 p.m.