Progress and Status of River Otter Reintroduction Projects in the United StatesAuthor(s): Elaine J. RaeslyReviewed work(s):Source: Wildlife Society Bulletin, Vol. 29, No. 3 (Autumn, 2001), pp. 856-862Published by: Allen PressStable URL: http://www.jstor.org/stable/3784412 .Accessed: 16/10/2012 12:05

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Translocations 856 RIVER OTTER REINTRODUCTIONS

Progress and status of river otter reintroduction projects in the

United States

Elaine J. Raeslty Abstract The river otter (Lontra canadensis) is an important North American furbearer species that

was eliminated from most of its range by the early 1900s. Many state agencies have undertaken restoration efforts, although no comprehensive study on the extent or type of management exists. I conducted telephone interviews with wildlife agency biologists in the 49 continental states (USA) to update status and management of river otters, with emphasis on reviewing the use of reintroduction as a management tool to restore extir- pated otter populations. As of 1998, river otters occupied at least portions of their his- toric range in every state except New Mexico. Between 1976 and 1998, 21 states and l national park implemented reintroduction projects, releasing 4,01 8 river otters. States conducting reintroduction projects obtained otters from a variety of sources, but 14 (64%) used at least some otters obtained from coastal Louisiana. All states implemented post- release evaluations, including radiotelemetry studies by 1 5 projects. Based on various forms of direct and circumstantial evidence, most biologists stated that reintroductions were successful in restoring extirpated otter populations.

Key words Lontra canadensis, reintroduction, river otter, survey, United States

Historical records indicated that river otters (Lon- tra canadensis) were well established throughout most major drainages in the continental United States and Canada prior to European settlement (Hall 1981). The continent's largest otter popula- tions occurred in areas with abundant aquatic habi- tats such as coastal marshes, the Great Lakes region, and glaciated areas of New England (Nilsson 1980, Toweill and Tabor 1982, Melquist and Dronkert 1987). Interior riverine habitats also supported viable otter populations (Nilsson 1980).

By the early 1900s, unregulated trapping, water pollution, and other degradations of aquatic and riparian habitat had caused otters to decline throughout most of their historic range (Nilsson 1980, Toweill and Tabor 1982, Melquist and Dronkert 1987). Nilsson (1980) reviewed the sta-

tus of otters in the United States and determined that populations were extirpated in 11 states and had experienced severe declines in 9 others. Although most extirpations occurred in interior riverine habitats, population declines were docu- mented in all states.

During the 1970s, improvements in furbearer man- agement techniques and water quality coincided with increased concern about otter declines in North America (Endangered Species Scientific Authority 1978). Consequently many wildlife man- agement agencies developed strategies to restore or enhance otter populations, including reintroduction (Ralls 1990), which were first initiated in Colorado in 1976 (Tischbein 1976). By 1990, 17 states and 1 Canadian province (Alberta) reported use of reintro- ductions (Melquist and Dronkert 1987, Ralls 1990).

Author's address: Department of Biology, Frostburg State University, Frostburg, MD 21532, USA; e-mail: eraesly~yahoo.com.

Wildlife Society Bulletin 2001, 29(3):856-862 Peer refereed

River otter reintroductions * Raesly 857

Several projects included radiotelemetry studies to document post-release movements and survival of reintroduced river otters. Results of these stud- ies were generally encouraging, suggesting that sur- vival and interactions among reintroduced otters were sufficient for restoration (Serfass and Rymon 1985, Erickson and McCullough 1987, Johnson and Berkley 1999). Serfass et al. (1993a) and Johnson and Berkley (1999) documented survival and reproduc- tion of river otters in Pennsylvania and Indiana, respectively. However, there have been no other pub- lished reports of long-term persistence of reintro- duced otter populations or a systematic effort to document status of otter reintroduction projects that have occurred in the United States.

My objectives were to review and update the status and progress of river otter reintroduction projects in the United States and to provide information and ref- erences for agencies implementing and considering reintroductions. I was particularly interested in determining number of states that have implemented otter reintroduction projects, reviewing various approaches used to facilitate reintroduction, and evaluating fates of reintroduced otter populations.

Methods I conducted telephone interviews from 11

August to 3 September 1998 with wildlife biolo- gists in each state within the continental United States to determine current status and management of river otter populations. To guide the interview, I developed a 4-page questionnaire consisting of par- tially close-ended questions for which choices were provided but the respondent could create an indi- vidualized response (Dillman 1978). Wildlife biolo- gists were first asked questions related to the fol- lowing otter management issues for their state: legal categorization, harvest, population status and trends, factors contributing to any historic declines, and whether otter reintroductions had occurred or were planned in the state. If the state had reintro- duced otters, I asked detailed questions about start- ing and ending dates of the project, number and source(s) of otters released, captive management protocols, release sites, post-release evaluations, sta- tus of reintroduced populations, and success of the project. Multiple releases in close spatial proximity in the same system were defined as a single release site at the discretion of the biologist.

Twelve biologists provided reports and other data to supplement information provided during the tele-

*~~~~~~~~~~~. ... ....

* : j 4 Adureoed

-41'

Figure 1. Occurrence of native river otter populations only, reintroduced populations only, or both population types in the United States. * indicates that river otters are extirpated.

phone survey. I used follow-up phone calls and elec- tronic mail to obtain information not available during the initial interview and to verify data. I was unable to obtain some data due to lack of state records. I cal- culated summary statistics for numeric data and per- centage of responses for categorical data.

Results Distribution, status, and management of river otters

River otters now occupy at least portions of their historic range in every state within the continental United States except New Mexico (Figure 1). Pop- ulations consisting solely of native otters were reported in 27 states. Trends of these native popu- lations range from stable to growing (Figure 2). Since 1976, efforts to restore extirpated otter pop- ulations through reintroduction projects have been initiated in 21 states (Table 1). Otters were extir- pated completely in 6 of the states that reintro- duced them (Figure 1), and 15 states that retained remnant otter populations implemented reintro- duction projects to restore regionally extirpated populations.

858 Wildlife Society Bulletin 2001, 29(3):856-862

-Increasing Stable to Increasing

E Stable

Figure 2. Population trends in 27 states of the United States whose populations consist solely of native river otters, 1998. *indicates that river otters are extirpated.

River otters were listed as endangered, threatened, or other similar designation in 15 states (Figure 3). Regulated trapping seasons for otters existed in 28 states, 21 of which have entirely remnant otter populations. Maryland, Minnesota, NewYork, North Carolina, Tennessee, and Virginia have trapping sea- sons in areas occupied by native populations but also have reintroduced otters. Massachusetts has an established season, but no otters are harvested because all leghold, conibear, and snare traps are illegal. In 1996, Missouri became the only state to allow legal trapping of otters that originated from reintroduced populations.

Status and management of reintroduction projects

Most states involved with otter reintroduction projects have completed release phases of their projects (Table 1). Thirteen states completed or plan to complete their otter reintroduction projects in ?5 years, but 5 states have continued otter releas- es for >10 years (Table 1). Indiana, NewYork, Penn- sylvania, and South Dakota were the only states that released otters in 1999. Michigan is considering a reintroduction project for the future. All but 3

H Harvested = Not harvested

A 3

: 3 _~~~~~~~~~~~~

Figure 3. Harvest and legal designations of river otters in the United States in 1998. A) harvest limited by region, B) season exists but all snare, leghold, and conibear traps are illegal. 1) extirpated, 2) experimental population, 3) protected species, 4) species of special concern, 5) species at risk, 6) state threat- ened, 7) state endangered.

reintroduction projects have been initiated or administered by state wildlife agencies. In addition to state-sponsored releases in North Carolina and Tennessee, the National Park Service reintroduced river otters in Great Smoky Mountains National Park (GSMNP), including drainages in both states. Also, Native Americans of the Santee Sioux tribe in Flan- dreau, South Dakota, initiated and implemented otter reintroduction efforts in that state, and all releases will occur on tribal lands. State wildlife officials and private conservation organizations in New York formed a corporation (NewYork River Otter Project, Inc.) to facilitate otter reintroduction efforts.

All projects indicated that the purpose of reintro- duction was reestablishment of a native species. Illinois and Iowa included the potential for harvest as another important reason to reintroduce otters. Pennsylvania and GSMNP indicated that aesthetics related to watchable wildlife was an important pur- pose. The Flandreau Santee Sioux Tribe cited the cultural significance of river otter as the primary reason for reintroduction, although reestablishment

River otter reintroductions * Raesly 859

Table 1. River otter reintroduction projects in the United States, including number and source of individuals released, number of sites, criteria for selecting source and sites, and type of post-release surveys conducted. Data were collected with a telephone sur- vey and follow-up interviews of state wildlife biologists, 1998.

Source Post-release State Dates indiv Sourcea criteriab # sites Site criteriac surveysd

Arizona 81-82 46 LA A, N 1 GH, HH, L, P A, R, S Colorado 76-91 107 LA, NF, WI A 5 F, GH, P, R, W A, R, S Illinois 94-97 346 KY, LA A, Q 15 GH, HH, L, S, W, O A, S Indiana 95-99 251 LA A, Q, S, U 10 F, GH, W A, R, S Iowa 85-91 262 LA A, E, Q, U 14 GH, P A, R, W Kansas 83-84 11 ID, MA A, U 1 GH, HH, P A, R Kentucky 91-94 355 LA A, Q, R, U 14 GH, L, S, W, 0 A Maryland 90-91 70 1 A, E, 0 2 GH, W A, W Minnesota 79-82 24 1 A, P 2 GH, L, P A, S Missouri 82-92 845 AR, LA, ONT A, S 43 F, GH, L, P, W, 0 A, R, S, 0 Nebraska 86-91 159 AK, BC, ID, LA, A, P, S 7 F, GH, W, P A, S, O

Ml, ONT, WI New York 95-ongoing 144 1 A, G, P 9 HH, W, 0 A, R, S North Carolina 90-95 267 1 A, G, 0 11 GH, P, W, S A, S Ohio 86-92 123 AR, LA A, U 4 GH, L, P, W, O A, R, S Oklahoma 82-83 17 LA A, P 2 HH, 0 A, R Pennsylvania 82-ongoing 105 I, LA, MD, Ml, A, G, S, U 6 L, P, W R, S, 0

NH, NJ, NY South Dakota 98-99 17 LA A, G, O, U 1 GH, L, P, R, W A, S Tennessee 84-94 412 1, LA, NC, SC A, E, S 49 GH, P A, R Utah 89-92 58 AK, NV A,Q,S 4 F,GH,HH, P,W R,S Virginia 88-89 17 I, LA A, N, R, U 2 GH, L, P, A, R, S

R, S, W, 0 West Virginia 84-97 245 MD, NC, SC, VA A 14 F, P, W A, R, S GSMNPe 86-92 137 I, LA, SC N, Q, U 15 GH, P R

a Source codes are (I) in-state source; (BC) British Columbia, Canada; (NF) Newfoundland, Canada, (ONT) Ontario, Canada; and other codes represent state postal codes. b Criteria used to select source were: (A) availability-ease in obtaining, (E) economic constraints, (G) genetic concerns, (N) only

source available, (P) geographic proximity, (Q) could obtain in quantity needed, (R) reputation of LA supplier, (S) same subspecies, (U) successful use of that source by another state, (0) other. c Criteria used to select release sites were: (F) Feasibility study; (GH) good habitat, including lack of channelization, distribu-

tion of tributaries, wetlands, water level fluctuations, stream flow, denning areas, and cover; (HH) historic habitat; (L) land use; (P) prey base; (R) research or published literature; (S) size of drainage; (W) water quality; (0) other, can include more than one response from one state. d Type of post-release surveys completed by reintroduction projects were: (A) anecdotal sightings by trappers and the public are

recorded, (R) radiotelemetry study, (S) survey for sign, (W) observations made by wildlife personnel are recorded. e Great Smoky Mountains National Park.

of the species for ecological reasons also was important.

Number of otters reintroduced in the United States between 1976 and 1998 was 4,018 (Table 1). Number of otters reintroduced per project ranged from 1 1 in Kansas to 845 in Missouri (x= 183,Table 1). A mean of 19.6 otters (SD = 9.3) were released/site and there was a mean of 11 distinct release sites (range 1-49,Table 1). Total and per-site sex ratio information was incomplete or unavail- able from most states. Seventeen states conducting reintroduction projects obtained otters from out-

side their state (Table 1). Projects in Maryland, Min- nesota, NewYork, and North Carolina reintroduced otters obtained exclusively from within their respective states. Pennsylvania,Tennessee, and Vir- ginia translocated otters from remnant populations within their states but also obtained otters from other states (Table 1). Most projects (14 projects, 64%o) purchased some or all of their otters from a private vendor in Louisiana (Lee Roy Sevin, Bayou Otter Farm, Theriot, LA 70397, USA). Twelve proj- ects (55%) used more than one source for otters. State agencies have applied various criteria to

860 Wildlife Society Bulletin 2001, 29(3):856-862

select sources of otters (Table 1). All projects con- sidered availability or ease in obtaining river otters as a major factor. Other criteria cited as important in selecting sources of otters included successful use of that source by another state (n = 8), genetic concerns (n = 5), and subspecies delineation (n =4).

Projects implemented various strategies for han- dling newly acquired otters. Colorado, New York, North Carolina, Oklahoma, and Pennsylvania were the only states to implement formal captive man- agement programs in which otters were routinely held in excess of 10 days. Utah, after experiencing high captive mortality with a 10-day holding peri- od, began releasing otters soon after they were obtained. Although other projects did not have extensive captive management programs, many purchased Louisiana otters that had been held cap- tive for at least 4 weeks while they were habituat- ed to captivity, treated for capture-related injuries, and vaccinated for canine and feline distemper (D. Sevin, Bayou Otter Farm, personal communication). All otters from Louisiana were examined by a vet- erinarian and issued a health certificate prior to transport. Most projects had veterinarians examine otters, and all radiotransmitter implant surgeries were performed by veterinarians.

Projects used a minimum of 2 criteria (x=3.9) to choose release-site locations (Table 1). Six projects (27'S,) based release-site selection on a formal fea- sibility study. The most common criteria used by projects to select release sites were good habitat (n = 17), prey base (n = 15), water quality (n = 15), and land use or presence of public lands (n=9,Table 1).

Project evaluations and outcomes All projects except Minnesota and South Dakota

marked otters with various combinations of ear- tags, web-tags, subcutaneous microchips, or implanted radiotransmitters to facilitate post- release location and identification of reintroduced otters. All projects conducted post-release evalua- tions (xS= 2.2 evaluations/project, Table 1) to assess status of reintroduced populations. Nineteen states (86%) recorded anecdotal sightings by trappers or the general public, 15 (68%) performed post-release radiotelemetry studies, 15 (68%) surveyed for scats or sign, and 5 (23%) recorded incidental observa- tions reported by wildlife agency personnel. Eigh- teen projects (82%) indicated evidence of repro- duction and 17 (77%) indicated range expansion of reintroduced populations. Trends among reintro- duced otter populations were described as growing

in 15 states, stable in 1 state (Nebraska), stable to growing in 3 states (Arizona, Colorado, and Min- nesota), and undetermined in 2 states (New York and South Dakota) and GSMNP. Based on these evaluations, all projects except NewYork and South Dakota concluded that their reintroduction proj- ects were successful in establishing otter popula- tions. Biologists in New York and South Dakota consider it too soon to comment on the success of their projects.

Discussion The pattern of current legal protection and har-

vested populations of otters reflects the historic declines (Figure 3). Nilsson (1980) documented river otter extirpation in 11 states, whereas I found past or present extirpation in 6 states. This dis- crepancy can be explained by differing interpreta- tion of sighting records or believed persistence of river otters in remote areas. Improvements in water quality and furbearer management tech- niques, including implementation of reintroduction projects, appear to have contributed to dramatic improvements in the status, distribution, and poten- tial for future, natural expansion of otter popula- tions in many areas of the United States. Based on my survey results, reintroduction appears to be an effective management tool to restore extirpated otter populations.

Various criteria have been established to select sources of individuals for reintroduction projects. Ideally, reintroduced animals should be obtained from areas that represent the same subspecies that occurred at the reintroduction site (Ralls 1990, IUCN 1998). Seven subspecies of river otters are currently recognized (Hall 1981, Wilson and Ruff 1999). The range of Lontra canadensis lataxina, which inhabits the common supply state of Louisiana, occupies large portions of the Mississip- pi River drainage, extending north through Iowa and east through southern New York (Hall 1981). Louisiana otters represent the appropriate sub- species for at least half of the states conducting reintroduction projects. Although recent elec- trophoretic data from 23 presumptive gene loci did not agree with current subspecies delineations, subspecies designation should not be used as the sole criterion to select sources of otters for reintro- duction (Serfass et al 1998). Geographic proximity is suggested as a criterion because of probable his- toric gene flow and climate and habitat similarities

River otter reintroductions * Raesly 861

(Meffe 1987, Serfass et al 1998). Although all proj- ects used availability or ease in obtaining otters as a criterion to choose a source, only 4 projects (18%) used geographic proximity and 8 projects (36%) used genetic or subspecies concerns (Table 1).

I was unable to determine whether including a captive management program enhanced the likeli- hood of successfully reintroducing otters. Prere- lease care and evaluation varied considerably among otter reintroduction projects. Projects in Colorado, New York, North Carolina, Oklahoma (Hoover 1984; Hoover et al. 1984,1985), and Penn- sylvania (Serfass et al. 1993b) consistently main- tained extensive captive management programs with veterinarian participation. The issue is further confounded because of differences in holding facil- ities and strategies among projects and frequent use of otters from Louisiana where captive care was provided. Serfass et al. (1993b) found that otter stress was reduced and prerelease condition was improved by using specially designed PVC trans- port tubes for both refuge in captivity and trans- portation and by housing otters in pairs or small groups. Several authors (Hoover et al. 1984, Dodd and Seigel 1991, IUCN 1998) recommended com- prehensive veterinary care and evaluation of translocated animals to enhance post-release sur- vival and minimize spread of disease. Post-surgical stress was reduced when otters were acclimated to captivity prior to surgery (Serfass et al. 1993b). More extensive post-release monitoring may deter- mine usefulness of captive management programs.

Monitoring initial fates of translocated wildlife and subsequent long-term studies to determine whether self-sustaining populations become estab- lished is an important aspect of reintroduction proj- ects (IUCN 1998). Ideally, costs to conduct post- release evaluations should be included in initial proposals for a reintroduction project (Berg 1981, Dodd and Seigel 1991, Reinert 1991). However, few projects have implemented formal, long-term sur- vey procedures to evaluate status and distribution of reintroduced otter populations. All projects using radiotelemetry followed each individual for a time period less than or equal to the life of the transmitter (approx. 2.5 yr). Five states (Indiana, Nebraska, New York, Pennsylvania, Utah) were con- ducting annual or ongoing surveys for otter sign, and Ohio performs necropsies on all accidental takes. Twenty projects recorded otter sightings by trappers and citizens. However, Beck (1993) warns that these types of sightings often have been unre-

liable for determining presence of otters in Col- orado. Eccles (1989) found scent station and sign surveys at bridge crossings to be effective in deter- mining relative abundance of river otters in Kansas. Swimley et al. (1998) developed models using 6 habitat characteristics to improve efficiency of locating otter latrine sites. Agencies should adopt rigorous data-recording procedures, and publica- tion of studies associated with reintroduction proj- ects should be an important component of the rein- troduction process (Griffith et al. 1989, Scott and Carpenter 1989, Dodd and Seigel 1991, Reinert 1991). Unfortunately, there have been very few for- mal studies, accompanied by published reports or other external documentation, evaluating short- or long-term status of reintroduced populations. Erickson and McCullough (1987), Serfass et al. (1993a), and Johnson and Berkley (1999) reported favorable survival rates and persistence of otters based on radiotelemetry studies conducted at rein- troduction sites in Missouri, Pennsylvania, and Indi- ana. I strongly encourage more rigorous data- recording procedures, further post-release surveys, and publication of results to document changes in river otter populations.

Acknowledgments. I am grateful to the numer- ous wildlife biologists who participated in the tele- phone survey. The Department of Biology, Frost- burg State University, provided costs for phone calls and other logistical support. I would like to thank T. L. Serfass for early involvement in this project and R. L. Raesly,J. P.Jennings, D.A. Miller, L.Andrews, and 2 anonymous reviewers for providing useful com- ments on drafts.

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Elaine IRaesly is currently a graduate student at the University of Maryland, College Park, in the sustainable development and conservation biology masters program. She received her B.S. (1999) in wildlife from Frostburg State University and was a past president of that student chapter of The Wildlife Society.

Associate editor: Miller