Estimate population size from single release tag data
single_release(tags, catch, recaps, mean_wt = 0, prior_recaps = 0, method, unit, type, tag_mort = 0, reporting = 1, nat_mort = 0, chronic_shed = 0, chronic_mort = 0)
| tags | number of marked animals released (note these must be whole numbers for the bootstrap to work) |
|---|---|
| catch | vector of the number or weight of animals captured and checked for tags by haul on the second survey |
| recaps | vector of number of marked animals recaptured by haul |
| mean_wt | mean weight of a single fish (optional argument for Chapman weight method) |
| prior_recaps | vector of subsequent recaptures (first year this represents within season recaptures) |
| method | method |
| unit | measurement unit (numbers, kg, tonnes) |
| type | do we assume fishing occurs over a short period (Ricker type 1) or is extended over the year and competes with natural mortality and tag sheddding (Ricker type 2) |
| tag_mort | initial tag-induced mortality |
| reporting | vector of tag reporting rate |
| nat_mort | vector of natural mortality (instantaneous) |
| chronic_shed | vector of chronic (ongoing) tag shedding |
| chronic_mort | vector of chronic (ongoing) tag-induced mortality |
For a Type 1 fishery the adjusted releases are calculate as follows
1) Initial tag-induced mortality is applied
2) Within season recaptures divided by the tag reporting rate are removed
3) Natural mortality and chronic tag loss and tag-induced mortality is applied.
For a fishery that operates throughout the year (Ricker Type 2) fishing and natural mortality competed to deplete the tagged population. The adjusted releases are calculated as follows
1) Initial tag-induced mortality is applied
2) Half of the within season recaptures divided by the tag reporting rate are removed
3) Half of the natural mortality and chronic tag loss and tag-induced mortality is applied
4) The remaining within season recaptures divided by the tag reporting rate are removed
5) The remaining natural mortality and chronic tag loss and tag-induced mortality is applied.
## Chapman estimates of population numbers single_release(tags=100, catch=200, recaps=5, method="Chapman", type=1, unit="numbers")#> Chapman estimate of population numbers #> N_hat var_N #> 3382.5 1492365.2single_release(tags=100, catch=200, recaps=5, method="Chapman", type=1, unit="numbers", tag_mort=0.1)#> Chapman estimate of population numbers #> N_hat var_N #> 3063.705 1216347.233single_release(tags=100, catch=200, recaps=5, method="Chapman", type=1, unit="numbers", tag_mort=0.1, reporting=0.8)#> Chapman estimate of population numbers #> N_hat var_N #> 2535.308 692050.552