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Otters
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Andy's Tracks & Trails
River Otters

After securing permission to trap a property with beaver, muskrat, mink & coon in abundance, the owner asked that I not trap the cute and friendly otters.  Of all the animals I regularly trap, no other furbearer is so often mischaracterized by people, media and television wildlife shows as the river otter.  Ask any veteran trapper about releasing animals from traps, and almost all will have an exciting otter story or two at the top of their list!
Photo #1 Large male otter

Otters are intelligent, aggressive predators.  Streamlined and heavily muscled, their movements can be deceptively fast.  Like a large northern pike or musky in a body of water, the otter is at the top of the food chain in the waters it inhabits and is always hungry.  With strong jaws and a healthy set of teeth, otters make short work of anything they decide they want to eat!

Photo #2 Adult otter whiskers

Adult River Otters grow from 4 to 5 ½ feet in length including a 20-inch tail, and males, which tend to be somewhat larger than females, can exceed 30 pounds.  The average weight is probably in the 15 to 25-pound range for adults.  Feet have strong, sharp claws, are webbed with rubbery foot pads which aid in moving on the ice.  Fur is short, dense and multi-colored, usually a light brown to dark brown color, with gray or grizzled appearance on throat and muzzle.  Long stiff sensitive whiskers cover the otter’s snout, which aid it in capturing prey in murky water.

Color variations range from coal black to albino.  Otters have ear and nose canals that close when diving, and nearsighted vision allow otters to see well under water.  Otters have lived more than 20 years in captivity, but in the wild they usually live less than half that.

Family groups consist of an adult female otter, with young of the year.  The young tend to stay with the female over the winter and learn locations for reliable food, areas to access water through the ice, and abandoned beaver lodges and bank runs to lay up in.   Males tend to be solitary, or travel in smaller bachelor groups.
Photo #3 Various pelt colors – brown to black

Females give birth in the spring to a litter of 4 – 6 pups and will mate again almost immediately after giving birth.  Delayed implantation prevents the development of the young until the female has made it through the worst of winter conditions.  Summers consist of pups learning to swim, dive, and hunt.  People watching “playful” otters are usually seeing behavior that helps otters in capturing or killing their prey.  Wrestling, carrying objects, chasing ducks and geese, fish, frogs and turtles.

During the past 10 years in north central Minnesota, several instances of a lone otter or family otter groups have approached and/or bitten people swimming in area lakes (Star Tribune – Island Lake, August 2012).  Most likely a female otter concerned about people getting too near her pups.  Not a good idea.
Photo #4 Belly slides of family group of 5 otters on creek ice

My experience with watching otters feed is that they will key on animals that they find in abundance.  Frogs grouping up for hibernation in the muck of a pond bottom, crayfish congregating in a pool below a stream culvert, marshes with areas of open ice and numerous muskrat huts, spring sucker runs, etc.  A few years ago, I watched an adult otter feed from a hole in the ice for more than 15 minutes.  It dove every ten seconds or so under the ice, and re-emerged with a fish, frog or crayfish every single time.  Whatever was caught was chewed until gone, at which time the otter dove again.  The cold-water environment otters live in make it have a high metabolism.  They are always hungry during trapping season!

Photo #5 Carp on river bank from otter

A lot of trappers have otters on their traplines, but aren’t aware of it or don’t know what sign to look for.  In summertime, look for tracks, scat or otter toilets, belly slides down river banks, crossovers from one body of water to another, grass twisted up on shorelines (otter rolling) turtle shells in piles in bogs and weedy bays, fish carcasses, trails through grass at roadside culverts.  Some of the sign will not last as long due to humidity and temperature, insects, etc.

Photo #6 Belly slides down dry river bank

In winter, look for tracks and belly slides in snow, or if before snow, in the frost on lake or pond ice.  My favorite time to scout for otter populations is after the season is closed.  During late February or March, conditions are usually good for visual checks while driving by a location.  Check your lakes, streams and rivers for otter sign in the snow, belly slides, crossovers, toilet areas, and otter holes gaining access to under ice food sources.  Most likely, if present in late winter/spring, otters will be present the following winter during trapping season.  Keep some notes about which watersheds show the most sign, or at what intervals otters are coming through at that location.
Photo #7 Crossover from Lake to River with catch

Otter droppings and vomit (fish bones/scales) are often deposited in the same locations over and over.  Usually made up of small fish scales and bones, shells and crayfish claws, these otter “toilets” can get quite large, and are always hot spots for catches.
Photo #8 Belly slides on marsh

Otter holes can be found in snow drifts, muskrat huts and beaver lodges, lake and river ice, and very often, near beaver dams.  Trappers will note where otters came out from under the ice, rolled in the snow to dry and clean their fur, then return under the ice for hunting or travel.

Once you’ve found otter sign on your trapline, how best to catch them?  Narrow your search to natural funnels, pinch points, cross overs, spots that don’t freeze, and moving water.  I used to spend way too much time looking for that “perfect” otter catch spot.  What I’ve learned is that if otters are traveling through, make your own “perfect” spot.  Narrow the stream or creek with brush, branches or a dive under log.  Dig a false beaver run, every passing otter will check it out.  Baited pocket sets with strong foot traps on drowning wires are critical.  Don’t under stake a set as otters will match the biggest coon for power when fighting a trap and don’t succumb to hypothermia as easily as raccoons do.

Photo #9 Close up of otter scat with fish scales

On lakes and marshes, water coming in and going out are your “hot spots”.  Look for your natural funnels here, and create your own if none are found.  One thing I don’t understand is many times I’ve found a clean half water-filled culvert running under a road, and every single otter traveling through will go up and over the road, avoiding the culvert.  Other times I’ve found heavily cluttered and partially plugged road cuvlerts, yet every passing otter travels its way through and avoids crossing over the road.

Trappers need to be flexible and adjust to the conditions they find along the trapline.  Once the otter hot spot has been found, how do I set it up?
For successful otter trapping, trappers need to think of the three “zones” for the trap they intend to use and the forecasted weather conditions.  If mild with warm temps, all three zones are easily used.  Fully submerged trap, partially submerged trap, or out of water trap.  Many times, I’ve messed up with a great location at a hot spot, finding my partially submerged body grip frozen in and inoperable when otters passed by.  Right at freeze up, the three zones thinking becomes most critical, and often trappers are limited to two zones, fully submerged, or out of the water.



Photo #10 Hole in ice with large otter toilet

With blocking and fencing, it does help if a location can be made or adjusted prior to the trapping season.  If the stream is too wide, don’t try to narrow it down to a spot in the middle, for your set.  Put an obstruction in the middle of the stream, and set up body grips to each side of the obstruction.  Remember otters traveling in family groups?  Often a double catch will be waiting.  I notice more refusals when a stream is blocked too much, or doesn’t look natural.  Far less avoidance with a two-trap set up.

Another consideration often overlooked by trappers is the water conditions at the set location.  Cloudy or clear?  Otters see very well under water and a bright shiny body grip trap, or one dipped too dark in a bright sandy river bottom with clear water will be noticed and avoided.  I’ve set up different body grip traps for otter trapping in different waters.  Bogs will get body grip traps painted dark or dipped; clear water gets green or tan painted with a camo pattern to be less visible.  Blending with natural materials always helps the set location.  One fully submerged trap near a beaver dam break sat for two weeks without success, even though several otter tracks had come and gone from the pond.  I changed to a darker trap, and wedged abundant cat tails from the pond near the trap to blend, and two otters in a row was the result!

As far as trap triggers go, I generally set my body grip triggers to the top if the set is designed as a swim through set.  A slide through set will usually get the trigger set on the bottom, depending on weather conditions.  I have not tested circular triggers much to see how they work differently, but plan to run some this winter.  Regardless of trigger set up, make sure triggers are fine-tuned, with as little travel as possible before firing.
For both body grip and foot traps for otters, the more swivels, the better.  Once caught, otters will spin repeatedly, locking up a trap chain very quickly with grass, sticks and mud, especially if the swivels are in poor condition or rusted.  If checking a location for a foot trap set on drowning wire, make sure that logs, sticks and underwater obstructions are completely removed so the trap chain will not entangle on its way down into deep water.  I always carry a folding pruning saw to cut roots and sticks away from the pond bottom.  Works great.

Photo #11 District 6 Trapper Mike Herschman with otter caught in 160 body grip in snow hole set. Trap was concealed in dry grass placed in snow drift hole.

In my area of East Central Minnesota, otters seem to be drawn to beaver colonies and beaver habitat.  Consistently, one of my best spots to catch otters is at an abandoned beaver lodge, or beaver run.  I will consistently mark abandoned beaver bank runs where beavers have been removed, or have moved on to other locations, prior to trapping otters.  Once I get good walking ice, I will revisit these locations and set up my body grip traps at entrances to the old beaver runs.  I often do this while hut trapping muskrats in December.  Coming and going every day to check rat huts allows me to look for fresh otter sign on a daily basis.  Many times, I’ve been there 4 days or more and never seen otter sign above ice, yet will catch an iced in otter, living in the marsh under the ice and using the beaver runs.  Otters can and do significantly impact muskrat populations in many areas I have trapped.  Part of the answer to where have all the muskrats gone?  There were a lot less otters in my areas 40 years or more ago.  Yet muskrats were extremely plentiful then.

Photo #12 Large male otter from old beaver run

I have not personally seen evidence of otters preying on beaver populations, but have read that in the far north, it is not unheard of.  In my area of the State, otters and beavers seem to co-exist rather well, and having both in a lake or marsh leaving bubble trails all over under the ice allows muskrats to move about much farther than without them being present.   

Other hot spots for otter include small feeder creeks into larger rivers, crossovers on river bends, points on large lakes and islands, especially with grassy banks, and after freeze-up, anywhere with open water.

Photo #13 Double on otters in body grips

My memory tells me that the majority of my otter catches coincide with a change in the weather.  Specifically fall and winter storms.  Open water, hard freeze, in between, it doesn’t seem to matter.  If we have several days of calm consistent weather, and then the weather reports show a low-pressure system approaching with wind, rain and/or snow accumulation, I want my otter sets to be ready.  Otters seem to really move in such weather.  I also see a trend towards otter moving from smaller water to bigger water, smaller creeks to bigger rivers.  Maybe they don’t want to get locked in to a less than ideal location when the really cold weather hits.

Take some time this winter to put some quality sets out, be patient, and hopefully you’ll catch some prime Minnesota Water Wolves!


©️ Copyright 2021 MN Trappers Assn. All rights reserved.
©️ Copyright 2019 MN Trappers Assn. All rights reserved.
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