Damage Prevention and Control Methods

Because river otter damage has been minor compared to that of other species, and because of its legal status under the CITES Agreement, little control research and experimentation has been done. Registration of repellents, toxicants, or fumigants for river otter control has not been sought. Alternate aquacultural practices and species, predator avoidance behavior, and use of protective habitat have not been fully explored. Careful assessment should be made of reported damage to determine if nonlethal preventative measures can be employed, and to ensure that if any lethal corrective measures are employed, they do not violate state or federal laws. Damage problems should then be approached on an individual basis. Cultural methods and habitat modification are normally not applicable. Opportunities to use repellents, toxicants, fumigants, and frightening devices are infrequent, yet the development of any of these or other effective nonlethal approaches would be preferable to lethal control measures.

Trapping

Traps that have been used effectively for river otters include the Conibear^® (sizes 220 and 330) or other similar body-gripping traps and leghold traps (modified No. 1 1/2 soft-catch and No. 11 double longspring). The latter two are usually employed to capture river otters for restocking purposes. In water, body-gripping traps are usually placed beneath the water surface or partially submerged where runs become narrow or restricted . They are effective when partially submerged at dam crossings, the main runs in beaver ponds, or other locations where otters frequently leave the water. Body-gripping traps are also effective in otter trails that connect pools of water or that cross small peninsulas. In these sets, the trap should be placed at a height to blend with the surrounding vegetation to catch an otter that is running or sliding. After ice forms on the surface of streams and lakes, some trappers bait the triggers of body-gripping traps with whole fish. River otter trapping is prohibited in 21 states and one Canadian province. Check local regulations before trapping.

Most of the wild otters used for restocking in recent years were caught with No. 11 longspring traps in coastal Louisiana. These animals were usually caught in sets for nutria, in traps that were set in narrow trails and pullouts where shallow water necessitated that otters walk rather than swim. Leghold traps are also effective when placed in shallow edges of trails leading to otter toilets or other areas they frequent. Leghold traps set in out-of-water trails and peninsula crossings should be covered with damp leaves or other suitable covering.

With the depression of fur prices, nuisance beaver problems and efforts to control them have increased substantially throughout the United States. The killing of otters during beaver control trapping can be minimized by using snares, but they do occasionally sustain moderate injuries. In most situations, snared river otters can be released unharmed. Accordingly, snares are neither the most effective, nor the most convenient devices for capturing river otters or removing them from an area, and therefore are not recommended for either.