Indiana River Otters: From Recovery to Control

otter_pair_maxwell“The [Indiana] Department of Natural Resources is considering allowing a trapping season for river otters less than two decades after being reintroduced to the Hoosier landscape,” wrote John Martino, outdoors columnist for the Kokomo Tribune last week. In the article, Martino says the river otters were official declared extirpated from Indiana in 1942.

The state’s reintroduction program began in 1995 and included 303 river otters trapped in Louisiana and released in Indiana, the article says. Ten years later river otters were taken off the state endangered species list.

In 2013 the IDNR received more than 64 formal complaints about river otters eating fish from private ponds, Martino reports. The department issued 11 nuisance animal control permits in 2012, he adds. Now, he reports, the department is considering controlling the river otter population by opening a trapping season for river otter in the counties where it is most abundant.

Read the article in the Kokomo Tribune here.
Information on river otter from the Indiana Department of Natural Resources is here. It includes links to several data sets, including a mortality study.

Photo: courtesy Indiana Department of Natural Resources

River Otters Exposed to Banned Chemicals

otter teamRiver otters have made a remarkable comeback in the last few decades, particularly in Illinois, as we reported recently. However, those Illinois river otters have significant amounts of long-banned chemicals — such as PCBs and DDE (a chemical that results from the breakdown of DDT) — in their tissues, a recent study from the Illinois Natural History Survey has found.

A press release from the University of Illinois reveals that for one chemical, the concentrations were higher in the otters now than they were when the chemical was in legal use:

The researchers were surprised to find that average concentrations of one of the compounds they analyzed, dieldrin — an insecticide (and byproduct of the pesticide aldrin) that was used across the Midwest before it was banned in 1987 — exceeded those measured in eight river otters collected in Illinois from 1984 to 1989. Liver concentrations of PCBs and DDE (the latter a breakdown product of the banned pesticide DDT) were similar to those in the earlier study, the release says.

Scientifically, this is a mystery still to be solved. Were the chemicals used long after they were banned? Did it take decades for the chemicals to climb the food chain from algae to top predator? Are female otters passing the contaminants to their offspring in their milk?

But for wildlife managers, it has a lesson useful right now. When trying to find causes for unknown population declines, don’t dismiss the effects of toxic chemicals just because those toxic chemicals were banned from use decades ago.

The University of Illinois press release.
The paper, in the journal Ecotoxicology and Environmental Safety. It is a free access journal.

Photo: Samantha Carpenter (left), a wildlife technical assistant with the Illinois Natural History Survey (INHS); Kuldeep Singh, pathobiology professor at the U. of I. Veterinary Diagnostic Laboratory; Nohra Mateus-Pinilla, an INHS wildlife veterinary epidemiologist; and U. of I. animal sciences professor Jan Novakofski found that Illinois river otters are contaminated with banned pesticides and PCBs.  Credit: L. Brian Stauffer