My daily travels inevitably include the routine passing of several road-side swamps, ponds, and river systems during service calls. The most-frequented twenty-mile +/- stretch of terrain allows the opportunity for the skilled trapper mindset to wander; as I can’t help but survey the landscape in the brief window of passing along these natural mile-markers. The yearning mental inquiry as to what’s changed from day to day undoubtedly tugs enough to notice otherwise seemingly minuscule cues.
While my observances vary over the years, there are some aspects that can always be counted upon as I pass by the regular wetland haunts around home. The beavers tend to pack more mud and chew sticks atop the prominent lodges, the great blue herons wade in statue-like stillness, and when winter sets in - the river otters display their acrobatic antics for the trained eye that knows where (and when) to look. Whether they’re chomping down on a freshly-caught perch, sun bathing in the limited January sun, or busting holes through the shallow ice to torpedo through dark waters, the otter’s appearance on this small stretch of New England landscape seems to increase year over year. Wintertime particularly allows for the otter’s characteristic silhouette to protrude against an otherwise white icy backdrop, accompanied only by the expected and never-changing outlines of water logged stumps, cattails and downed trees.
My work in beaver management also allows for additional observations of similar aquatic inhabitants; and otter sign is always in abundance year-round among the muddy banks and rocky shorelines of southern New Hampshire. It seems to this inquisitive critter-wrangler that otter populations are thriving “swimmingly”.
A new report published in the June 2020 Journal of Fish & Wildlife Management seems to solidify the hunch.
The study reveals that river otters (Lontra canadensis) now inhabit most of their historic range in the U.S. and, more importantly, that no states are reporting declining populations of the charismatic mustelids. In fact, the study reveals they may actually be approaching maximum geographic distribution in the United States.
A Historical Ebb and Flow
River otter populations have expanded noticeably in the last 50 years. The success is attributed to assistance from state and federal agencies, native tribes, and the implementation of effective management programs - which include restoration and reintroduction, habitat preservation, and sustainable trapping practices.
(Photo | Hean Prinsloo)
Otters historically inhabited every major watershed in the contiguous United States prior to being extirpated as a result of habitat degradation and destruction as well as unregulated harvest. By 1977, the river otter was included as an Appendix II species under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) - not necessarily for the river otter’s sake, but more so for that of similar species with endangered status, whom officials feared would be inadvertently targeted by the fur trade in a case of mistaken identity. The study notes that the river otter has never been considered a globally threatened or endangered species.
Despite the animal’s current abundant status, criticism over the regulated hunting of otters remains in many areas. Today, the river otter still stands as a pivotal staple of take by fur trappers, who value their silky fur pelts in areas where their populations thrive enough to allow for regulated harvest. With an increased abundance also comes societal conflict with humans - most notably in the form of fish depredation (both private ponds and commercial fish farms) and public health concerns when otters (who may travel in groups of 9+ individuals) routinely defecate and vomit in boat houses, on docks and around water-front properties.
A Multi-pronged Approach
For the study, researchers dove deep into past research, as well as soliciting information from state wildlife agencies on harvest and observational data pertaining to otters. Most states used multiple methods to monitor their otter populations - which includes harvest-based surveys from trapping reports - the most commonly used method. Some states also relied on otter sign observations - such as bridge surveys (presence vs. absence track surveys conducted at bridge crossings), bow-hunter surveys, winter track/print surveys, and agency field questionnaires. Trail camera surveys and empirically derived population predictions were also listed in the report.
River otters are listed as legally trapped/hunted in 40 states, while closed trapping seasons existed in 9 states (including Arizona, California, Colorado, Nebraska, New Mexico, Rhode Island, South Dakota, Utah, and Wyoming). Of the states that do not allow regulated trapping of otters, its worthy to note that four of those states (Nevada, Rhode Island, Utah, and Wyoming) did not report any monitoring efforts for otters at all.
The U.S. Fish and Wildlife Service maintains, through the Division of Scientific Authority, that the export of river otter pelts and products from the United States has not been detrimental to the animal’s viability. The study points out that the expansion of river otter populations in states where they are managed by regulated hunting/trapping is “likely enhanced by the frequency of these regulatory reviews”. In other words - regulated hunting adds integral value and motivation to keep otter population success in the forefront of state agency professionals’ purview.
Not just a matter of “take”
Throughout the late 20th century, with recognition that river otters were extirpated across much of their historic home range, licensed trappers began to work with state agencies and wildlife officials to reintroduce otters to areas in need of population rebounds. Otter reintroductions were common during this time.
By 2016, over 4,000 river otters had been translocated to 23 states. This increase in reintroduction effort would come to be known as one of the most ambitious and extensive carnivore restoration efforts in history. Even here in my home state of New Hampshire, trappers assisted other states with otter reintroduction throughout the 1980’s and early 1990’s.
Read More: Otter/Fisher Reintroductions Assisted by NH Trappers
According to the study, 50% of river otter reintroductions implemented in the United States were in areas where otters had been extirpated. Other restoration efforts were conducted to help bolster existing populations and expand otter distributions.
Now, with populations observed as healthy, otter reintroductions are far less frequent than decades past. Since 1998 only two states have implemented otter reintroduction efforts, and, as the study notes, Utah has been the only state to conduct a reintroduction project since 2010.
Of the twenty-three states that implemented reintroductions, twenty one reported that populations were increasing or had reached population goals, and 2 states (Minnesota and North Dakota) indicated that populations were either stagnant or “geographically restrained”.
The study estimates that by the early to mid-2000’s, river otters had expanded and inhabited approximately 90% of their formerly extirpated range.
Taking all inhabited and distribution areas into account, data suggests only portions of the mid-west and south-west United States appear to lack robust otter population insight. Holes in the national data come as little surprise since river otters are difficult to monitor; both due to their secretive nature and their aptitude to naturally occur at relatively low densities on the landscape.
The study also reinforces that while state wildlife management agencies use a variety of techniques to monitor changes in river otter population size and distribution, regulated harvest management programs provide the foundation for most population monitoring that occurs. Of the 40 states that incorporate harvest management programs, the study notes, the majority used data from regulated harvest seasons (such as trapper surveys, estimates of trapper effort (CPUE), or collection of biological samples to gather insight on demographic and health data) to both monitor river otter populations and ensure harvest levels are sustainable. The study points out that “for many furbearers, including river otter, harvest-based data are the only information available with sufficient sample sizes large enough for robust analyses”.
(Photo | Elisa Stone)
In other words, while some may be squeamish over the notion of trapping river otters for their hides, this activity, in a structured and regulated sense, helps to foster and reap the most robust data set for river otter population insight available. Furthermore, the expansion of river otter populations has continued to grow and be successful with hunting/trapping activities taking place on the landscape. Licensed otter trappers join a diverse grouping of stakeholders who both hope for, and contribute to, healthy wildlife populations across the country.
The study concludes that river otters have expanded their range significantly in the contiguous United States since the last assessment in 1998 (Melquist et al. 2003) - findings that demonstrate a true conservation success story.
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