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Add swept-area estimates following the FishGlob workflow

Source: R/fishglob.R
add_swept_area_fishglob.Rd

Compute haul-level swept-area estimates for a datras_raw / DATRASraw object using the FishGlob methodology.

Usage

add_swept_area_fishglob(x)

Arguments

x

A datras_raw object containing haul-level data in HH.

Value

A datras_raw object with two additional columns in HH:

  • SweptArea: swept area in \(km^2\),

  • DoorsArea: door-swept area in \(km^2\).

Details

The function adds haul-level swept area (SweptArea) and door-swept area (DoorsArea) to the HH table. Missing WingSpread, DoorSpread, and Distance values are reconstructed using survey-specific prediction models and hierarchical fallback rules.

The implementation follows the methodology used in the FishGlob workflow. Missing WingSpread and DoorSpread values are predicted from internally stored survey-specific models. When observed values are missing or judged implausible, the function applies survey-specific corrections and fallback prediction rules.

Missing towing distance is reconstructed from GroundSpeed and HaulDur. Missing GroundSpeed values are imputed hierarchically using averages at the following levels:

  • survey-year-ship,

  • survey-year-country,

  • survey-country,

  • global mean.

Swept area is then computed as: $$ SweptArea = Distance \times WingSpread \times 10^{-6} $$

Door-swept area is computed analogously as: $$ DoorsArea = Distance \times DoorSpread \times 10^{-6} $$

Both quantities are returned in \(km^2\), assuming Distance, WingSpread, and DoorSpread are recorded in metres.

Some survey- and gear-specific filtering and manual corrections are applied to match the FishGlob workflow.

The original spread-estimation logic was developed by Aurore Maureaud and P. Daniël van Denderen and is available from the FishGlob code repository.

References

FishGlob workflow code: https://github.com/fishglob/FishGlob_data/blob/main/cleaning_codes/source_DATRAS_wing_doorspread.R

See also

add_swept_area_simple(), clean_fishglob()

Examples

if (FALSE) { # \dontrun{
x <- add_swept_area_fishglob(x)
} # }