Rules of Engagement

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Published on: Dec. 2, 2003

Last revision: Nov. 16, 2010

animals have been entering and exiting the water. You also find fish heads scattered around the pond and an occasional fish just partially eaten. What kind of animal would do this? Otters. Yes, river otters are responsible for damage in this situation.

Otters eat an average of 2.5 pounds of meat daily. Fish and crayfish are their favorite food items. They also eat frogs, salamanders, snakes, turtles, and muskrats. Otters eat crayfish more frequently throughout the spring, summer, and fall. However, as water temperatures cool in late fall, crayfish burrow into the mud and are less available, forcing otters to eat more fish. An analysis of 443 otters during the 1997-99 trapping seasons revealed the following occurrences of food in their stomachs:

Food type Percent
Crayfish 61
Fish 51
Frogs 17
Muskrats 3
Ducks 1
Empty stomachs 4

The proportions are similar wherever otters are found. The river otter's keen senses and predatory skills make catching their food "child's play." When otters enter a pond or lake, they tend to stay only a short time, from a day to a couple of weeks. If they find abundant fish or crayfish, they remember the location and will eventually come back for more.

Their nomadic behavior increases their odds of survival because it increases their sources of food and decreases your odds of catching them in the act. Knowing this, what can you do if you suspect otters are seriously reducing the number of fish in your pond?

Avoid engagement--This is harder to do as the otter population has increased. Ponds larger than 1 or 2 acres, especially those with underwater brush piles or other good escape cover, suffer less severe damage than smaller impoundments. Small, shallow ponds stocked with "fed" catfish and without any escape cover literally provide "fish in a barrel" for otters.

Good fences make good critters--Well-maintained electric, chain link, small-mesh welded wire, or combination electric and permanent fencing can protect catfish in small, shallow ponds.

Identify the perpetrator--Don't assume every furry animal in your pond is an otter. Beaver and muskrat also frequent ponds and are not a threat to fish. If your pond or lake is large enough, there is no cause for alarm, even if the furry animal is an otter. In some cases, otters may even help populations of desirable fish by eating some species

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