Health Assessment, Medical Management and Pre-Release Conditioning of Translocated North American River Otters (Lontra canadensis)
Division of Wildlife Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
North American river otter population numbers are improving following marked decreases resulting from the additive effects of wetland destruction, aquatic pollutants, and unregulated trapping for the fur industry in the late 19th and early 20th centuries. Although a variety of conservation efforts throughout North America have been instrumental in enhancing population numbers, the IUCN Otter Specialist Group still considers population status determinations of high priority in states and provinces where trapping for fur is currently permitted. Two of the many conservation strategies implemented in a number of states are reintroduction and translocation. The first strategy includes reintroduction of river otters from areas with dense populations to historic habitats with sparse or small populations and where introduction has previously been attempted. A second strategy involves translocation of river otters from densely populated locales to areas, within or outside the same state, from which otters have been extirpated or are found in very small numbers. There are logistical, fiscal, and biological advantages and disadvantages to each strategy. Reintroduction may ultimately be more financially costly, presents the challenge of screening for and eliminating certain infectious diseases that may be of importance to other resident mustelids, and may result in higher mortality following release.
The monetary costs of translocation, even within a state, may be relatively high also (approximately $1,000/otter) depending on the trapping methods used, the individuals responsible for trapping (state wildlife biologists vs. private trappers), the methods of transport (vehicle vs. airplane), and which health screening, treatment and preconditioning protocols are implemented to maximize survival, and ultimately reproductive success, following release. Translocation of river otters within a state does have distinct biological and logistical advantages over introduction or reintroduction. First, the probability of "foreign" diseases being introduced is low or minimal. Secondly, the stress of holding prior to transport is minimized, as well as the total transport time for individual otters.
We have developed health assessment, treatment, husbandry and preconditioning procedures over a 2-yr period as part of an ongoing collaborative river otter translocation project in the State of New York. The principals involved include the New York State Department of Environmental Conservation, the New York River Otter Project, Inc., and the College of Veterinary Medicine at Cornell University. This ongoing project has resulted in the successful release of 72 otters (92% of the individuals trapped) into three geographically separated sites in the western part of the state. Although there have been similar projects undertaken in other states, few have implemented the in-depth health assessment, medical management, and infectious disease screening protocols that are now standard operating procedure for the New York River Otter Project.