swept_area: Calculate the estimate of total biomass and abundance

In andybeet/survdat: Tools for working with NEFSC survey data

Calculate the estimate of total biomass and abundance

Description

Calculates the estimate of total biomass and abundance using the swept area. Variance of the estimate is also calculated. Requires the outputs from both the stratprep and stratmean functions.

Usage

swept_area(
  prepData,
  stratmeanData,
  q = NULL,
  a = 0.0384,
  areaDescription,
  groupDescription = "SVSPP"
)

Arguments

q	Table of survey catchability with a column of group names and a column of catchabilities. If not provided, assumes a q of 1 for each group (Minimum swept area estimates).
a	The average swept area of the trawl. Default value is the swept area of a standard NOAA Ship Albatross IV tow.
areaDescription	Column of survdat containing strata designations.
groupDescription	Column of survdat upon which the totals are based (i.e. SVSPP).
survdat	NEFSC survey data generated by Survdat.R and modified by stratprep().
stratmean	Output from strat_mean().

Value

Returns a table with the estimates of total biomass and abundance as well as the stratified mean biomass and abundance for each group indicated by the groupDescription parameter. In addition, the variance of the totals and variance and standard error for both means are provided.

See Also

Other survdat: calc_stratified_mean(), calc_swept_area(), get_area(), get_length_weight(), get_survdat_clam_data(), get_survdat_data(), get_survdat_scallop_data(), post_strat(), strat_mean()

Examples

## Not run: 
# Called internally

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andybeet/survdat documentation built on Nov. 9, 2023, 10:11 a.m.