Subject: abstract - pingers (fwd)

Mike Williamson (
Fri, 15 May 1998 18:56:49 -0400 (EDT)


---------- Forwarded message ----------
Date: Tue, 12 May 1998 09:39:24 -0400
From: Dagmar Fertl <>
Reply-To: Marine Mammals Research and Conservation Discussion
Subject: abstract - pingers

     The following might be of interest to readers.  Please do not hit the
     reply key to get a copy of the're on your own for that.
     I'm not responsible for accuracy of the abstract, since I pulled it
     off a service, and they managed to have used "fingers" instead of
     pingers in the title itself.
     Dawson, SM; Read, A; Slooten, E.  1998.  Pingers, porpoises and power:
     Uncertainties with using pingers to reduce bycatch of small cetaceans
      BIOLOGICAL CONSERVATION v84 i2 pp. 141-146.

     Incidental mortality in gillnets is probably the most serious global
     threat to dolphin and porpoise populations. In 1994, a well-designed
     study demonstrated a 92% reduction in bycatch of harbour porpoises in
     sink gillnets equipped with acoustic pingers. This result has not yet
     been fully replicated; in the New Hampshire area where the experiment
     was conducted or elsewhere. Statistical power analyses indicate that
     such studies are feasible only in areas of high entanglement rate.
     Currently unanswered research questions include whether the 1994
     results can be replicated, whether habituation might decrease
     effectiveness over time, and what the mechanism of deterrence is.
     Practical constraints include the size, cost and battery life of
     current pingers, and whether their rue could be monitored
     cost-effectively. Front a management perspective, even if the
     effectiveness of pingers is confirmed, widespread incorporation of
     them into gillnets may not alone be sufficient to meet the
     requirements of the US Marine Mammal Protection Act. For this reason
     scientists, managers and fishers must continue to explore other
     options, including time/area closures and encouragement of more
     selective fishing methods.

                            Dawson, SM
                            UNIV OTAGO
                            DEPT MARINE SCI, POB 56
                            NEW ZEALAND