Stealth fishing gear

Stealth fishing gear refers to fishing gear and bait that have been camouflaged to deceive predatory species. For bycatch species such as marine turtles and seabirds, the aim is to reduce the detection of bait. For target species, such as swordfish and tunas, the aim is to reduce the detection of the fishing gear and thus increase catch rates.
For example, an experiment to reduce the visibility of longline gear to sea turtles in the Hawaii-based pelagic longline fishery used the following equipment:
  • dark blue-gray monofilament for main lines, float lines and branch lines;
  • dulled hardware (stainless-steel branch line and float line snaps painted dull blue to remove the metallic shine);
  • counter-shaded floats (blue on the bottom half, orange on the top half);
  • lightsticks shaded on the upper half ('downwelling');
  • lightsticks with narrow light frequency (yellow electronic light-emitting diode lightsticks); and
  • blue-dyed squid bait.
Results showed that the stealth fishing gear was less economically viable than normal gear but still held promise for reducing turtle bycatch. See Light Cues for more detail about research into chemical and LED light sticks.
Stealth gear may also describe bait that has been dyed blue to disguise it from seabirds. The success of this strategy has been inconsistent across studies. Recent research suggests dyeing is only effective with squid bait. See Dyed bait for further information.
  1. ACAP. 2011. AC5 Annex 6: Review of seabird bycatch mitigation measures for pelagic longline fisheries. Seabird Bycatch Working Group. Fourth Meeting of the Seabird Bycatch Working Group, Guayaquil, Ecuador. Doc 11.
  2. Cocking, L.J., Double, M.C., Milburn, P.J. and Brando, V. 2008. Seabird bycatch mitigation and blue-dyed bait: A spectral and experimental assessment. Biological Conservation 141(5): 1354-1364.
  3. FAO. 2009. Guidelines to reduce sea turtle mortality in fishing operations. FAO Fisheries Department, Rome.
  4. Long, K. J. and Schroeder, B.A. (eds). 2004. Proceedings of the International Technical Expert Workshop on Marine Turtle Bycatch in Longline Fisheries. NOAA Technical Memorandum NMFS-F/OPR-26.