Abstract

By the early 1940s environmental pollution of aquatic ecosystems, persecution as a predator, and unregulated trapping collectively resulted in extirpation of the Nearctic otter (Lontra canadensis) from western New York state.⁷ Since abundant numbers of otters were present in the northeastern and southeastern parts of the state, and dispersal of these populations to the western parts of the state was projected to take up to 20 years, the New York State Department of Environmental Conservation (NYSDEC) elected to develop partnerships to re-establish the otters in western New York. Thus, a melding of private, public, and state organizations became the New York River Otter Project, Inc. (NYROP). Although many individuals and groups made significant contributions, the principals included the Division of Wildlife, NYSDEC, the Board of Directors of the NYROP, and the Section of Wildlife Health, College of Veterinary Medicine, and Cornell University.

In all 306 otters were captured, 279 of which were released at 16 sites deemed acceptable by NYSDEC Division of Wildlife Biologists. Health assessment, medical problems, captive management, and prerelease conditioning of the otters was intensive and has been previously reported.^1,3-6 Radio transmitters were surgically placed in 37 otters which were released at three different sites, with the most (28) being released at a single large, protected site.^2,4

Between 1996 and 2004 the methods used to assess post-release survival and reproductive success have included observational techniques (e.g., specific identification of adult otter and offspring, signs [tracks], slides, scats, dens, and toilets) and the recovery of otter carcasses for detailed postmortem evaluation. Reproduction has been documented at more than 90% (14 of the 16) of the sites via observation of females with young and by recovery and identification of immature and juvenile (based on cementum annuli tooth analysis) otters in and around these sites.

From 1996–2003, 77 otters were recovered and presented for necropsy. Of these, 36 were identified as released individuals, with 41 presumed to be offspring of released females. This was based on their age and lack of an implanted identification chip. Thirty (39%) of these were vehicular casualties, which occurred during the breeding season of March through April. The remaining 47 (61%) died as a result of non-target trapping accidents (open water beaver traps) occurring during the month of December. All ROP and non-ROP otters examined at necropsy were found to be in excellent body condition and exhibited minimal gastrointestinal and respiratory system parasitism. Some of these individuals had been released six years prior to recovery.

In summary the procedures and protocols used, and contributing to the success of this project, have direct relevance and application to other in situ Nearctic otter conservation efforts.

Literature Cited

1.  Hartup BK, Kollias GV, Jacobsen MC, Valentine BA, Kimber KR. Exertional myopathy in translocated river otters from New York. J Wild Dis. 1999;35:542–547.

2.  Hernandez-Divers SM, Kollias GV, Abou-Madi N, Hartup BK. Surgical technique for intra-abdominal radio transmitter placement in North American river otters (Lontra canadensis). J Zoo Wildl Med. 2001;32:202–205.

3.  Kimber KR, Kollias GV. Infectious and parasitic diseases and contaminant-related problems of North American river otters (Lontra canadensis): a review. J Zoo Wildl Med. 2000;31:452–472.

4.  Kimber KR, Kollias GV, Dubovi EJ. Serologic survey of selected viral agents in recently captured North American river otters (Lontra canadensis). J Zoo Wildl Med. 2000;31(2):168–175.

5.  Kollias GV. Health assessment, medical management, and prerelease conditioning of translocated North American river otters. In: Fowler ME, Miller RE, eds. Zoo and Wild Animal Medicine. Philadelphia, PA: WB Saunders; 1999:443–448.

6.  McEwen MM, Moon-Masset PF, Butler EC, Kollias GV. Polymerized bovine hemoglobin (Oxyglobin® solution) administration in two river otters (Lontra canadensis). Vet Anesth Anal. 2001;28:214–219.

7.  Raesly EJ. Progress and status of river otter reintroduction projects in the United States. Wild Soc bull. 2001;29:856–862.