Going from zero to 60 in less than 5 seconds is fast. So is going from 50 to more than 15,000 in about 20 years. Maybe it’s too fast.
We may have broken the speed limit in Missouri with our river otter restoration program. In 1980, we estimated that only 35 to 70 otters survived in the few remnant swamps and wetlands in Missouri’s Bootheel region. Their numbers had not changed in more than 50 years. Since we began stocking the animals, their population has peaked at more than 15,000.
The first batch came from Louisiana in 1982. We fitted them with radio-implants, so we could track them, and set them loose in some of Missouri’s finest wetlands in and around Chariton County in north-central Missouri. Knowing the quality of the wetlands, we weren’t completely surprised when, in a few short generations, they made hundreds of new otters that spread out into the adjacent duck clubs and borrow ditches.
Missouri has few such wetlands, so the real test was to see if otters could once again exist in other habitats. We wanted to establish otter populations along Missouri’s rivers and streams.
Or, so we thought.
During an 11-year program, we released 845 otters, setting them free in 43 streams in 35 counties. We traded some of our wild turkeys for wild-caught Cajun otters—the same subspecies that once existed here.
The rest, as they say, is history. The otters not only survived, they flourished. Otters now exist in every county in the state and in most watersheds, even those miles from the original release sites. And, they made their way into places we never would have believed they could, and where they were really not wanted.
Fishing is important to Missourians. The state’s numerous farm ponds, most of which contain a combination of largemouth bass, bluegill and channel catfish, provide lots of recreational angling for kids and adults.
In our vision for otters living in Missouri, we sure didn’t see these ponds as providing good habitat for otters, nor did we see the impending train wreck that otter depredation of the fish in these ponds would cause.
There is no predator of fish more efficient than river otters. Traveling in groups of two to eight animals, they can hammer fish in a small pond before anyone even knows they are there. Sometimes they travel four or more miles from streams to hit these fast-food opportunities.
Otters eat fish in the winter when they are most vulnerable. They especially target hand-fed catfish. They might eat 2 to 3 pounds of fish per day. At times, fish are so easy to catch that otters kill many more than they eat, leaving the evidence of the massacre on the banks for the owners to discover.
As otters multiplied and spread out from the release points, calls began to pour in about farm ponds being ravaged. Anglers became angry, demanding some kind of relief. We now recommend that pond owners who are at all worried about their fish shoot otters when they show up. All we ask is that they contact us if they do so.
Otter damage wasn’t limited to farm ponds. Otters also found fishing easy in shallow pools of small headwater streams and tributaries in the central Ozarks. Conservation agents in that region handled more than 500 otter complaints in one year alone. As one local angler put it, “There’s not enough room for otters and fishermen in the Ozarks.”
Local politicians became involved, and the otter topic became a hot-rock in the state capitol. The news media fed on the issue with newspaper headlines like, “Otters at Center of Controversy,” “The fur flies over Missouri’s cute but greedy river otters,” and “Ozark Otter Disaster.”
Almost overnight, the Conservation Department had gone from hero to goat for its “successful” otter restoration program.
We initiated our first regulated trapping season in 1996 to help bring balance back to the state’s rivers and ponds. Despite two court cases forced by two national animal rights groups, we have had annual trapping seasons ever since. Missouri trappers are the backbone of our management efforts to restore some balance to the otter population.
By 1998, however, we realized that the two-month-long trapping season wasn’t enough, so we formed a citizen advisory committee to help find a solution. The committee, composed of otter enthusiasts, anglers, county commissioners, an animal rights activist, fisheries and wildlife biologists, stream ecologists, crayfish experts, university professors, graduate students, a trapper and a few local business owners, worked together to tackle the problem.
After two long years of looking at data, taking field trips to farm ponds, wading along streams searching for otter latrines and fish parts, and wrangling over their varied interests, the team agreed on a compromise.
Otter management zones now protect otters in low-density areas with a limited otter harvest, and they provide much-needed relief in the Ozarks by adding a full month to the trapping season with no limit. This helps us to direct the most intensive trapping pressure where it is most needed, and it allows a sustainable harvest of otters in other areas where we want otter populations to remain stable.
Our management goal is to use regulated trapping to maintain healthy otter populations within the tolerance levels of both habitats and people.
In the Ozark streams where the problems are the most severe, our goal is to reduce otter populations to the level where we can improve quality sport fish populations.
Thanks to the current high market prices ($40 to $120) for otter pelts, trappers have been very helpful. In the 2005–06 trapping season, Missouri trappers took more than 3,000 otters. In areas where we want fewer otters, trappers have taken as many as 50 percent of the otters each year. Annual survival rates are averaging about 75 percent in areas where our goal is to allow populations to remain stable or continue to increase slowly.
Missouri’s otter population probably peaked at somewhere between 15,000 and 18,000 animals. We documented as many as three otters per mile in some small streams, and their fish populations did decline. Anglers report better fishing recently, however, and complaints about otters have gone down, although we still have a way to go in some areas.
The statewide otter population is now closer to our goal of 10,000. In most streams, densities are about one otter per mile, and our fisheries managers report that fish populations look good.
Reducing their numbers has made otters nicer neighbors. People tolerate them better, and even many anglers admit they don’t mind sharing a few fish with them.
We have studied otter diets since we began stocking the animals and have found that their most important food is crayfish, which they eat almost exclusively from April until October. Crayfish populations in Ozark streams are among the highest recorded anywhere.
In winter, otters primarily eat fish. They mostly consume long-eared sunfish (35 percent), but also a significant amount of smallmouth bass (12 percent). Goggle-eye and suckers each account for about 10 percent.
Each year we collect otter carcasses from trappers and, among other tests, we determine their age from their teeth. Otters in Missouri are breeding at earlier ages and having more pups in each litter than previously documented. Many female otters are breeding as yearlings, giving birth to first litters near their second year of life. This cuts the generation time in half, and greatly increases the population growth rate.
Six years ago we enlisted two husband-and-wife trapper teams to live-trap otters and implant small radio transmitters in them. This allows us to determine where otters go, how long they live and how they die.
Of the more than 300 otter captures so far, we have documented 97 mortalities. Of these, 78 were trapped, six were shot, two died from bacterial infections, one was struck by a car and another was struck by a train. We couldn’t determine a cause of death for nine of the otters.
What this tracking study suggests is that when food is abundant, there is no other way than trapping to control otters. Without trapping, otter survival rates would contribute to rapid population growth and many more otter problems.
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