Skip to contents

Calculate Catch Weight from Length-Weight Relationships or Bucket Measurements

calculate_catch.Rd

Calculates total catch weight using either length-weight relationships or bucket measurements. The function prioritizes length-based calculations when available, falling back to bucket-based measurements when length data is missing. For Octopus (OCZ), the function converts total length (TL) to mantle length (ML) by dividing TL by 5.5 before applying the length-weight formula. This accounts for species-specific differences in body morphology.

Usage

calculate_catch(catch_data = NULL, lwcoeffs = NULL)

Arguments

catch_data

A data frame containing catch information with columns:

  • submission_id - Unique identifier for the catch

  • n_catch - Number of catch events

  • catch_taxon - FAO 3-alpha code

  • individuals - Number of individuals (for length-based calculations)

  • length - Length measurement in cm

  • n_buckets - Number of buckets

  • weight_bucket - Weight per bucket in kg

lwcoeffs

A data frame containing length-weight coefficients with columns:

  • catch_taxon - FAO 3-alpha code

  • a_6 - 60th percentile of parameter 'a'

  • b_6 - 60th percentile of parameter 'b'

Value

A tibble with the following columns:

  • submission_id - Unique identifier for the catch

  • n_catch - Number of catch events

  • catch_taxon - FAO 3-alpha code

  • individuals - Number of individuals

  • length - Length measurement in cm

  • n_buckets - Number of buckets

  • weight_bucket - Weight per bucket in kg

  • catch_kg - Total catch weight in kg

Details

The function calculates catch weight using two methods:

  1. Length-based calculation: W = a * L^b * N / 1000 Where:

    • W is total weight in kg

    • a and b are length-weight relationship coefficients (75th percentile)

    • L is length in cm

    • N is number of individuals

  2. Bucket-based calculation: W = n_buckets * weight_bucket Where:

    • W is total weight in kg

    • n_buckets is number of buckets

    • weight_bucket is weight per bucket in kg

The final catch_kg uses length-based calculation when available, falling back to bucket-based calculation when length data is missing.

Note

  • Length-based calculations use 75th percentile of length-weight coefficients

  • All weights are returned in kilograms

  • NA values are returned when neither calculation method is possible

Examples

if (FALSE) { # \dontrun{
# Calculate catch weights
catch_weights <- calculate_catch(
  catch_data = catch_data,
  lwcoeffs = length_weight_coeffs
)
} # }