Preliminary Assessment of Techniques for Catching and Radio-Tagging Harbor Porpoises

摘要

Data collected from 1983 to 1987 indicate that an estimated 200-300 harbor porpoises (Phocoena phocoena) were killed annually in north-central California in set net fisheries for halibut and other finfish. It is not known if the incidental porpoise take represents a significant impact to one panmictic or several regional populations. Effective management of these porpoise/fishery interactions requires data on the relative discreteness of local populations. In addition, information is needed on the seasonal distribution and movements of various age and sex classes of harbor porpoises in and near the area affected by the fishery. A radio tracking program was planned to address these needs, and a preliminary study was undertaken to assess the feasibility of such a project. The report discusses the site and net system that was designed to capture porpoises and the procedures that were planned for attachment of the transmitter package and subsequent tracking of the porpoises. Our experiences have suggested that modifications to our capture system that may prove more effective in future attempts.