Target strength of a nylon monofilament and an acoustically enhanced gillnet: predictions of biosonar detection ranges

Metal oxide nets made from barium sulphate increased the detectability of gillnets by marine mammals when compared to nylon nets when approached at angles of incidence greater than normal incidence but less than 40 degrees. Hypothesized detection ranges indicate bottlenose dolphins (Tursiops truncatus) should be able to detect metal oxide nets in time to avoid entanglement, but harbor porpoise (Phocoena phocoena) may not be able to detect either net in time to avoid contact.
Field Studies:

Location	Fishing gear	Reduction technique	Bycatch species	Effect on bycatch species	Catch	Effect on target catch	Type
Captivity	Gillnets	Metal oxide/barium sulfate nets	Small Cetaceans (maximum length < 7.5 meters)	Increased detectability	Trout		In the wild