Wildlife Population Dynamics
River Otter Landscape Ecology
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Like much of the rest of North America, river otter (Lutra canadensis) were abundant in Iowa during European settlement, but unregulated trapping and hunting, and loss of habitat caused them to be essentially extirpated in the state. Wildlife managers began reintroduction efforts in the 1970’s that have helped make otters widespread in North America. Iowa’s river otter reintroduction was initiated in 1985 at Red Rock Reservoir. Sixteen otters from Louisiana were released, initiating a pilot project to determine the suitability of Iowa’s aquatic resource for otters. These otters survived normally and subsequent releases were continued until 2003. In total 345 otter were released in Iowa between 1985 and 2005. This reintroduction coupled with wetland restoration and conservation contributed to the growth and widespread distribution of otters in Iowa.
Students and I have done research in the past on the age structure and reprodcutive effort of river otters in Iowa, in coopteration with the Iowa Department of Natural Resources. This research is helping to monitor restoration success and guide management efforts of river otters. You can read the publication on river otter populations in Iowa, or a report on the status of river otters in Iowa.
Frequently Asked Questions About River Otters in Iowa
Q: How many river otters are in Iowa?
A: In the proposed open area, approximately 4500; statewide approximately 6000-8000.
Q: Where are river otters found in Iowa?
A: River otters can be found along rivers, streams and lakes throughout Iowa. River otter successful reproduction has been documented in all 99 counties in Iowa. They are most abundant in the proposed open area for harvesting, however some watersheds in the closed area sustain healthy populations of river otters.
Q: How many river otters are incidentally harvested each year?
A: Nearly 100 river otters are turned into the DNR each year.
Q: Would opening a river otter season result in a substantial increase in the number of otters harvested each year?
A: It is unlikely that there would be an increased in the number of otters harvested due to the difficulty of targeting the species. Trappers capturing river otters now are likely to be the same people capturing them during an open season. A small increase may come from hunters who would be able to legally harvest an otter.
Q: Will population dynamics of river otters in Iowa change if there is a trapping season?
A: With a 300 harvest season quota in the open area, and with the current population increase of 7% annually, the river otter population in the state will continue to increase.
Q: Why have river otter populations increased in Iowa recently?
A: In 1985 restoration of the river otter was initiated. Through the early 1990’s, over 325 river otters were released at 25 different sites throughout the state. Since then, populations have established, continue to reproduce and spread throughout the state.
Q: Does the DNR receive complaints concerning river otters?
A: The number of complaints about fish depredation in ponds due to river otters has increased. There are also concerns about fisheries for smallmouth bass, northern pike, and catfish in river corridors throughout Iowa.