Tag Reporting Rate Estimation: 2. Use of High‐Reward Tagging and Observers in Multiple‐Component Fisheries

Tag return models can be used to estimate survival and tag recovery rates. The additional knowledge of an estimated tag reporting rate allows separation of the total mortality rate into fishing and natural mortality components. We briefly review two methods for estimating tag reporting rates: high‐reward tags with a 100% reporting rate, and catch from multiple‐component fisheries with a 100% reporting rate in one component (e.g., due to the presence of observers in a boat‐based commercial fishery). The assumptions of each method are presented and discussed. We simulated the effects of combining the two methods to obtain more robust estimates of the tag reporting rate and other important parameters, such as the exploitation rate. When high‐reward tags did not produce a 100% reporting rate or when the observer component in a multiple‐component fishery did not have a 100% reporting rate, the combination of methods provided better estimates. It is still necessary to assume that the high‐reward tags in the observer component of the fishery have 100% reporting rate. However, this is a much weaker reporting rate assumption than those used for each method alone and is much more likely to be satisfied in real fisheries applications. Therefore, the combined method should tend to give less biased estimates in practice than either method used separately.