A cautionary tale: surrogates for radio-tagging practice do not always simulate the responses of closely related species

Telemetry is useful for monitoring rare and threatened species if they can be effectively tagged. Relatively abundant, closely related species are sometimes used as surrogates in refining tagging methods or testing the suitability of methods before transfer to rare and threatened species. A decision framework for developing a radio-tagging method of an endangered fish (Macquaria australasica; Percichthyidae) is presented based on experiences with tagging a closely related, surrogate species (Macquaria ambigua). Aquaria and field-based trials demonstrated the suitability of internally implanting a radio-tag with an externally exited antenna on the surrogate species. However, transferring this method to the endangered species under field conditions was unsuccessful in terms of mortality and/or radio-tag rejection. In this case, a surrogate species served to refine radio-tagging methods, but did not successfully indicate the suitability of these methods for a closely related species. This cautionary tale illustrates that surrogate species are not always effective and extrapolation of methods, even across closely related species, may be perilous.