Modern Snares for Capturing Mammals: - Association of Fish and ...

Most snare locks currently available would be considered positive locks, though many locks canbe converted to power-assisted locks by the addition of a spring or other powering device. Threeexamples of power-assisted locks are shown below.Breakaway DevicesBreakaway devices are used to improve the selectivity of a snare, and can be designed in manyways. They can be incorporated into the snare lock (as a component or as the structural materialitself), or as an attachment to the snare lock or cable. Breakaway devices are typically ratedbased on the amount of force necessary to cause the loop to ‘break’ or release (e.g., a 285 lb. S-hook). The desired rating is based on both the minimum rating necessary to hold the desiredanimal, and the maximum rating allowable for release of other animals. As such, the need forbreakaway devices, and the desired rating if used, will vary in different areas of the country, andmay involve trade-offs between achieving desired selectivity and maintaining acceptableefficiency for the intended species.We illustrate breakaway devices with several examples below, but discuss applications andissues later (see pp. 21-22). Importantly, presence of some breakaways cannot be determinedvisually (e.g., slide-off ferrules or some shear pins).Breakaway Device – any device incorporated into a snare or snare component that allows theloop to break open, and an animal to escape completely free of the snare, when a specifiedamount of force is applied.Shear PinJ-hookS-hookShear Pin Ferrule that slides off Lock material that shears10Ver. 1.0