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Declared Turtle Trade From the United States

 

Issues - Results of the Turtle Trade  - Wild Caught Issues

 

In the course of preparing this work some very large numbers have been mentioned,  millions of sliders in total, turtles in shipments of a hundred thousand or more Pseudemys and Trachemys going to countries all over the world,  more than a million Trachemys scripta scripta going to Europe and over thirteen million turtles going to Hong Kong alone.  Lost in this plethora of data are numbers that are nowhere near as large but numbers that none-the-less may be the most important ones in this work.  The possibly overlooked data are the numbers of wild caught turtles exported.

 

In the time period covered by these data 173, 243 Chelydra serpentina,    11,081 Chrysemys picta, 223 Clemmys gutatta, 4694 various Kinosternon, 1450  Malaclemys terrapin and 21,797 various Sternotherus,  all wild caught , were exported.

 

Turtles are very long lived animals who, under normal conditions, have a combination of high adult survival and very low hatchling and juvenile survival. Low recruitment into a population is offset by the long breeding life of the adults under normal circumstances.  These chelonian traits are what makes them so resilient to external pressures with the exception of removal of the adults from the population.  When an adult turtle is removed from the wild  it is not just that turtle that is being removed ,  but also the reproductive potential of that animal over a breeding life that may exceed 50 years. Research has shown that there is no compensation of increased hatchling survival in response to a reduced adult population. (Brooks, Brown, Galbraith. 1991)  As a result removal of even a few adults from a population can result in the decline and eventual loss of the entire population.     (Congdon et al, both references)

 

An example of this can be seen in the extirpation of a healthy and protected Glyptemys insculpta population in just a decade after the area was opened to recreational usage.  It is assumed that the sole difference in conditions was the removal of occasional adults by recreational users. (Garber and Burger. 1995).

 

Similar results were noted by Brad Compton with Glyptemys insculpta in Maine. Compton found that  reproductive recruitment declines as adults are continually removed.  Compton built a demographic model to estimate the effect of the annual removal of a small number of adults from a hypothetical population of wood turtles.  The model indicated that removal of a single adult annually from a stable population of 100 adult turtles would cause a 60% decline in over 100 years, and that removal of two animals annually would extirpate the population in less than 80 years. (Compton)

 

There have been numerous studies on the effect of roads and associated road kill during nesting migrations on turtle populations (Burke and Gibbons, 1995), . (Wood and Herlands. 1997) as well as incidental take of Malaclemys terrapin in crab pots.  (Seigel and Gibbons. 1995)

 

As collection for the trade takes the adults out of a population much like the above situations,   the effects of the collection of  turtles directly for the market can be  hypothesized. It is this situation,  removal of the adults from wild populations,  that perhaps should prompt the most discussion of this overall work.   While the raw numbers in comparison look small,  they may have the farthest reaching consequences. 

 

 

 

Resources:

 

Brooks, R. J., G. P. Brown, and D. A. Galbraith. 1991. Effects of a sudden increase in natural mortality of adults on a population of the common snapping turtle (CHELYDRA SERPENTINA). Can. J. Zool. 1314-1320

 

Burke, V. J. and J. W. Gibbons, 1995. Terrestrial buffer zones and wetland conservation: A case study of freshwater turtles in a Carolina bay. Conserv. Biol. 9(6): 1365—1369.

 

Compton, Brad,  MS Thesis University of Maine,  Ecology and Conservation of the Wood Turtle (Clemmys insculpta) in Maine

 

Congdon, J.D., A.E. Dunham and R.C. van Loben Sels. Delayed sexual maturity and demographics of Blanding's turtles: implications for conservation and management of long-lived organisms. Journal of Conservation Biology  7:826-833.

 

Congdon, J.D., A.E. Dunham and R.C. van Loben Sels. Demographics of common snapping turtles: Implications for conservation and management of long-lived organisms. American Zoologist  34:397-408.

 

Garber, S. D. and J. Burger. 1995. A 20-yr study documenting the relationship between turtle decline and human recreation. Ecological Applications 5: 1151-1162. 

 

Iverson, J. B. 1991. Patterns of survivorship in turtles (order Testudines). Can. J. Zool. 69:385-391.

 

Seigel, R. A., and J. W. Gibbons. 1995. Workshop on the ecology, status, and management of the diamondback terrapin (Malaclemys terrapin), Savannah River Ecology Laboratory, 2 August 1994: Final results and recommendations. Chelonian Conservation Biology 1:240-243.

 

Wood, R. C. and R. Herlands. 1997. Turtles and tires: The impact of road-kills on northern diamondback terrapin, Malaclemys terrapin terrapin, populations on the Cape May Peninsula, southern New Jersey, USA. In: J. Van Abbema (ed.), Proceedings: Conservation, Restoration, and Management of Tortoises and Turtles- An International Conference, pp. 46-53.

 

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