Damage to Structures
Otters damage boats by tearing covers and contaminate areas through defecation.
Damage to Livestock and Pets
The presence of river otters in or around a fish hatchery, aquaculture, or facility for fish culturing is a good indication that a problem is imminent. Slow-moving channel catfish are more vulnerable to predation by otters than other fish.
Scats or toilets of otters that contain scales, exoskeletons, and other parts of the species being farmed are evidence that damage is ongoing. Parts of fish found in shallow water and along the shore are evidence that fish are being taken. Otters occasionally cause damage to populations of fish in marine aquaculture facilities.
Otters can represent a threat to pets in parks when they occupy ponds that have been stocked in urban locations. Otters can kill small domestic dogs.
Damage to Landscapes
Otters infrequently damage gardens and landscapes.
Health and Safety Concerns
River otters are susceptible to canine distemper and can contract parasites such as the giant kidney worm and Toxoplasma gondii. A study in California showed that 17% of otters tested positive for T. gondii.