Tag Returns from Dead Animals

Abstract

This scenario arises when tagged animals die through natural mortality and possibly exploitation (e.g., hunting and fisheries), and their tags are recovered. A wide variety of models for both exploited and unexploited populations are considered depending on what underlying population assumptions are made, the first being time dependence for both the survival and tag–recovery probabilities. In the exploited case, reward and solicited tags are introduced with commercial fisheries having a special mention. Instantaneous models are included based on Poisson processes and, later, catch-age data. Departures from the underlying assumptions are considered. In endeavoring to separate estimates of natural and exploitation mortality, three types of hypotheses are considered, one, for example, being the additive hypothesis. Other special cases are Ricker’s two-release method, a model with constant survival and time-dependent recovery probabilities, and various age-specific and other models. Departures from the assumptions such as heterogeneity lead to the methods of mixtures and random effects.