Gopher Tortoise Council

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Minimum Viable Population

See reports below.
Gopher Tortoise Minimum Viable Population and Minimum Reserve Size Working Group Report 

Prepared by: 
The Gopher Tortoise Council 
24 July 2013 

A workshop was held on 13-14 March 2013, to define the minimum viable population (MVP) for the gopher tortoise (Gopherus polyphemus) using the best available scientific information. In this case, the purpose of establishing MVP parameters is to provide acceptable benchmarks for conservation and recovery efforts and is not to determine absolute minimum thresholds that if not met will result in certain population demise. Invited attendees included gopher tortoise biologists, land managers, and experts in demographic modeling (Table 1).

Background:
The U.S. Fish and Wildlife Service’s 12-month finding for listing the gopher tortoise as Threatened under the Endangered Species Act (ESA) has stimulated additional interest in conservation of the species. A Candidate Conservation Agreement and a comprehensive conservation strategy have been developed for the gopher tortoise. It will be necessary to define a minimum viable population size, the number of viable populations needed, and the ideal geographic distribution of these populations in order to successfully conserve this species.

The scientific literature provides mixed guidance about what constitutes a minimum viable gopher tortoise population. Results from existing population viability models vary from 25 to 250 individuals under ideal habitat conditions (Table 2). In addition, there is no consistency in the scientific literature regarding how large a parcel of habitat must be to support a viable population. Therefore, there was a clear need to convene experts in gopher tortoise biology, ecology, management, and demographic modeling to reach consensus regarding the following  objectives: 

(1) Define a minimum viable gopher tortoise population size based on the best scientific information available. 
(2) Identify the minimum reserve size needed to support a viable gopher tortoise population. 
(3) Identify the number and distribution of viable gopher tortoise populations necessary to ensure  the long-term viability of the species.

Please download the complete report file titled "MVP_Report_Final.pdf".  You will need Adobe Reader to open this file. Adobe Reader can be downloaded for free at http://get.adobe.com/reader/

Papers and related discussion can be found at https://sites.google.com/site/gophertortoisepva/home

Please feel free to comment below. 
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Jess Gonynor McGuire,
Oct 10, 2013, 6:12 AM
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