Estimate total harvest from a mark-recapture population estimate

Computes a total harvest estimate and its uncertainty using the delta method, given a closed-population angler population estimate from estimate_angler_n and a known harvest rate.

The point estimate is \(\hat{H} = \hat{N} \times r\) where \(r\) is the harvest rate (proportion of anglers that harvested fish). The delta-method standard error is \(SE(\hat{H}) = r \times SE(\hat{N})\), propagating only the uncertainty in \(\hat{N}\) (harvest-rate uncertainty is not propagated in this release).

Usage

estimate_mr_harvest(angler_n, harvest_rate, conf_level = 0.95)

Arguments

angler_n: A creel_estimates object returned by estimate_angler_n.
harvest_rate: numeric scalar. Proportion of anglers that harvested fish. Must be in \((0, 1]\). Uncertainty in the harvest rate is not propagated (see Details).
conf_level: numeric. Confidence level for the CI. Default 0.95.

Value

A creel_estimates S3 object with method = "mark-recapture-harvest" and an estimates tibble with columns: parameter, estimate, se, ci_lower, ci_upper.

Details

The harvest rate is treated as a known constant in this implementation (Hansen & Van Kirk 2018, D-04). Propagation of harvest-rate uncertainty via a two-source delta method is a planned future extension.

References

Hansen, M. J., & Van Kirk, R. W. (2018). A mark-recapture-based approach for estimating angler harvest. North American Journal of Fisheries Management, 38(2), 400–410. doi:10.1002/nafm.10038

Examples

# Step 1: estimate angler population
result <- estimate_angler_n(M = 200L, n = 50L, m = 10L)

# Step 2: compute total harvest
harvest <- estimate_mr_harvest(angler_n = result, harvest_rate = 0.35)
print(harvest)
#> 
#> ── Creel Survey Estimates ──────────────────────────────────────────────────────
#> Method: mark-recapture-harvest
#> Variance: delta
#> Confidence level: 95%
#> 
#> # A tibble: 1 × 5
#>   parameter     estimate    se ci_lower ci_upper
#>   <chr>            <dbl> <dbl>    <dbl>    <dbl>
#> 1 total_harvest     326.  81.1     167.     485.