Rates (IRATE) model is used to analyze tagging data. It is based on
the Hoenig et al. (1998) alternate formulation of the Brownie et al.
(1985) band recovery models that allow fishing and natural mortality to be
derived from the exploitation rate and survival rate estimates of a Type
II (continuous) fishery. IRATE allows both age-independent and
age-dependent instantaneous rates models (Hoenig et al., 1998; Jiang et
al., 2007) to be fitted to multi-year fish tag return data.
IRATE allows model development with either
age-dependent harvest-only or harvest and catch-release tag returns or
similar age independent models. The
software, developed by Dr. Gary Nelson of the Massachusetts Division of
Marine Fisheries, also allows estimation of harvest reporting rates, catch
and release reporting rates, and tag retention of harvested and/or
released fish.However, not
all parameters in the model can be estimated simultaneously with tag data
alone. Some parameters must be fixed and assumed known (usually reporting
rate and tag loss) to obtain good estimates of remaining parameters.Additionally, the model can
account for non-mixing of the tagged fish in the first release year and
adjust for harvest and M selectivity in the age-based models.The negative log
likelihood is used as the objective function to obtain maximum likelihood
estimates of parameters. Several
fit statistics are provided that can be used to select the best model
formulation; these include the Akaike Information Criterion (AIC), c-hat
(a measure of overdispersion) and standard residuals.
The calculation engine is written in AD Model Builder.
H.H., K.H. Pollock, C. Brownie, J.M. Hoenig, R.J. Latour, B.K. Wells, and
J.E. Hightower. 2007. Tag return models allowing for harvest and catch and
release: evidence of environmental and management impacts on striped bass
fishing and natural mortality rates. N. Amer. J. Fish. Man. 27: 387-396.