Pingers have been shown to be effective in reducing bycatch, at least for some marine mammal species in
some settings (Kraus et al. 1997; Culik et al. 2001; Bordino et al. 2002). A trial of pinger use in the
California drift gillnet fishery for swordfish and sharks showed that for both cetaceans and pinnipeds, the
entanglement rate in nets with pingers was only one third of what it was in nets without these devices
(Barlow and Cameron 2003). Likewise, a large-scale trial of pingers in Danish gillnet fisheries showed a
reduction in bycatch of harbor porpoises (Larsen 1997; Vinther 1999)