Can Management Intervention Achieve
Sustainable Exploitation of Turtles?


1Canadian Botanical Conservation Network, Royal Botanical Gardens,
P.O. Box 399, Hamilton, Ontario L8N 3H8, Canada / e-mail:
2Department of Zoology, University of Guelph, Guelph, Ontario N1G 2W1, Canada / e-mail:
3Current address: Department of Biology, Carleton University, Ottawa K1S 5B6, Ontario, Canada

        ABSTRACT:  We examined the feasibility of sustainable exploitation of adult snapping turtles, Chelydra serpentina, using data from a northern population. Three criteria were used to assess sustainable harvest:  juvenile survivorship from life tables, density-dependent responses, and economic cost of hatchling supplementation to replace adults.  Life table analyses suggest that turtle populations respond weakly to variation in survival or number of offspring relative to survival of adults.  Furthermore, observed depletion of adult turtles within a population by natural predation events, which served as a natural removal experiment, indicated no density-dependent responses in size or number of eggs, rate of growth, age at maturity, or frequency of reproduction.  Natural populations of these turtles do not therefore display a Maximum Sustainable Yield (MSY) inflection in growth rate.  We analysed the economic sustainability of our study population under various modelled regimens, including harvesting of adults, supplementation by incubation of eggs, and protection of hatchlings.  Our analysis indicated that removal of adults from supplemented populations can not be sustained economically, even assuming that survival and growth of the offspring compared favourably with that of incubated eggs.  Mature turtles cannot therefore be harvested sustainably from northern populations.  Without supplementation by artificially reared hatchlings or juveniles, produced at costs far exceeding any economic return, such populations will inevitably decline, even with low levels of exploitation.  Northern populations must be afforded complete protection, and the public and wildlife biologists must be educated that even widespread and “common” turtle species have life histories that preclude sustainable exploitation under most circumstances.

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