Trapping: River Otters
Trapping is the most effective removal method; once set, a well-placed trap does the work for you. In other words, you can catch an otter without having to physically be there. However, traps do not discriminate between what they catch, the location must be chosen strategically in order to reduce bycatch (non-target animals). Common bycatch that occurs when trying to catch otters are beavers and raccoons. Beavers, raccoons, and otters often frequent the same trails and travel corridors where traps are likely to be placed. Additionally, otters and beavers often use the same slides and trails to access water. Proper placement of traps is important to help limit bycatch, particularly when domestic animals and people are in the area.
Otters can be trapped in a variety of traps, including cage traps, footholds, and body-grip traps. Correctly choosing a trap will depend on your objectives and trap location. When trapping, make sure that all traps are anchored securely, so that captured animals cannot break free with the trap. Footholds are best anchored with cable stakes; body-grip traps with cable in conjunction with metal stakes. Reference material is available online and in trapping manuals on how to set traps for the highest chance of success.
Cage traps for otters can be expensive and are often less efficient than other trapping methods; however, they offer the best method for live trapping otters and reducing harm to non-target animals. Cage traps come in a variety of forms and can be used baited or un-baited depending on the situation. Comstock traps are a fast-closing, versatile, and heavy-duty type of cage trap often used to trap beaver and otter. These can be placed along slides and trails in a variety of positions. Un-baited traps include runway traps and colony traps. (Colony traps are typically set underwater to drown otters). Baited cage traps can be set next to trails or in shallow water to live trap otters.
Foothold traps for otters can be effective choice, but may require a little more experience and trapping skill. These are often rigged so otters drown when captured; however, if the otter is not drowned caution should be used when dispatching the otter in order to prevent personal injury. Foothold traps can also offer a way to release non-target animals when drowning rigs are not used. Foothold traps can be set in or out of water, but there is a size limit on trap jaw spread for land traps in Kentucky (≤6 inches). (NOTE: Once again check the most up-to-date state trapping regulations for the specific size).
Foothold traps are sized using numbers, with smaller numbers indicating a smaller trap; however, state trapping regulations go by the size of the jaw spread when the trap is set due to variation in trap sizing by different manufacturers. Therefore, jaw spread size is what you need to be concerned about when selecting a trap for land use. When trapping otters with foothold traps, use traps that have a jaw spread of 6 inches or larger. (NOTE: As of writing, in Kentucky any trap with a jaw spread of greater than 6 inches must be placed in water). Foothold traps can be placed in trails or at the bottom of slides, and are often used with bait or scent lures. Drowning sets are foothold traps that are placed near water and attached with a one-way slide to a cable that is anchored to both the bank and in at least 4 feet of water. When caught, the otter will swim down the cable and will not be able to return to the surface for air due to the one-way slide.
A body grip trap is effectively a kill trap; however, to ensure a quick death, proper size and placement of the trap is important. Body grip traps are set in trails, slides, or channels that otters travel. Several sizes of body-grip traps can be used for otters, but the 220 (7in x 7in), 280 (8in x 8in) and 330 (10in x10in) in) are the most common and effective. In Kentucky, 280s and 330s can only be set in water. If you want to set a body-grip trap on land for an otter, use the 220-sized trap. Use 280s and 330s at the bottom of slides and in swimming channels in the water. With body-grip traps, it is impossible to release bycatch, so make sure to place body-grip traps on known otter travel ways to reduce the chance of harming other species, pets, and potentially humans.
NOTE: Body grip traps can be dangerous if they are not handled or set properly. Using a set tool and a safety latch system can help ensure that setting and placing traps is as safe as possible. Additionally, steel traps are indiscriminant and some sets are lethal. When placing traps around populated areas, make sure to take precautions to avoid catching domestic animals (i.e., dogs and cats). This may mean using un-baited traps, or only setting traps in water for otters.