Use weakened fishing gear
Overall effectiveness category No evidence found (no assessment)
Number of studies: 0
Background information and definitions
Using weakened fishing gear may allow entangled or hooked marine and freshwater mammals to release themselves more easily. This may involve using nets and ropes with a reduced breaking strength (e.g. Knowlton et al. 2016), or weak links between fishing lines, buoys, or net panels. The bending strength of hooks may be decreased to a level that retains the target catch but allows caught mammals to release themselves by straightening the hook (sometimes referred to as ‘weak hooks’; Bayse & Kerstetter 2010, Bigelow et al. 2012). However, mammals may still be injured by weakened gear, and it is important to assess the survival of released animals (McLellan et al. 2014). This intervention may also increase the amount of debris and derelict fishing gear in marine and freshwater environments.
Bayse S.M. & Kerstetter D.W. (2010) Assessing bycatch reduction potential of variable strength hooks for pilot whales in a western North Atlantic pelagic longline fishery. Journal of the North Carolina Academy of Science, 126, 6–14.
Bigelow K.A., Kerstetter D.W., Dancho M.G. & Marchetti J.A. (2012) Catch rates with variable strength circle hooks in the Hawaii-based tuna longline fishery. Bulletin of Marine Science, 88, 425–447.
Knowlton A.R., Robbins J., Landry S., McKenna H.A., Kraus S.D. & Werner T.B. (2016) Effects of fishing rope strength on the severity of large whale entanglements. Conservation Biology, 30, 318–328.
McLellan W.A., Arthur L.H., Mallette S.D., Thornton S.W., McAlarney R.J., Read A.J. & Pabst D.A. (2014) Longline hook testing in the mouths of pelagic odontocetes. ICES Journal of Marine Science, 72, 1706–1713.