J.P. Ross 20 December 2005

Measurable Biological Goals (MBG) are the bench mark against which we will judge all of our regulatory and management efforts. FWC proposes basing the MBG for gophers on the criteria used to determine their State listing status. They propose that the goal for gopher management and conservation should be to achieve habitat and numbers of gophers that allows FWC to change their listing to the next less imperiled level. The goal is to improve the actual and listed status of gophers in Florida to ensure their long term survival.

To understand how this links gopher management to measurable goals, we have to understand the listing criteria. Florida uses a process based on quantitative measures and thresholds to determine whether species should be listed as Endangered, Threatened, Species of Special Concern or not at all. There are five criteria that determine listing status (see website for details). These are:

• Declines in the past or anticipated in the future, even if the species remains abundant.
• Found in, or restricted to, a very small or fragmented area.
• A small number and also declining, or found in a small or fragmented area.
• Extremely small numbers.
• A mathematical calculation predicting extinction.

The current (2005) biological assessment of gophers indicates that only one of these criteria that can be applied to gophers-- declines in the past. It is not possible to accurately count or estimate the numbers of gophers but we can assume that if there is less habitat there will be fewer gophers. Estimating the area of habitat thought to be occupied around 1900 and currently indicates gophers have lost 65-70% of their original habitat. The thresholds for this criterion are Species of Special Concern<30% decline , Threatened< 50% decline, Endangered < 80% decline. Therefore gophers will qualify at the level of Threatened.

Our immediate Biological Goal is therefore to reduce the rate of decline to below the 50% threshold that would allow us to reclassify them as Species of Special Concern. (See figure 1.) Because the threshold for decline is a measurable quantity, in this case the measured decline in available habitat, this gives us a very concrete measurable goal, to

reduce the loss of habitat. The MBG goes on to suggest two complementary strategies for achieving this: 1) to ensure that current and future protected land supports as many gophers as possible and 2) to reduce the loss of habitat (largely in private ownership) to the degree possible. The MBG therefore shares the responsibility for gopher management between the private sector and public land managers. The MBG also recognizes some very difficult truths:

• Land development and some loss of gopher habitat is likely to continue
• Management of gophers on public land is in many cases not adequate and should be improved.
• Some continued decline in gophers probably cannot be avoided, our goal is to minimize it.

The goal becomes more complex when we consider the nature of gophers biology. The time period over which the listing criteria are measured is “10 years or three generations, whichever is greater”. This formulation recognizes that animals with very long life spans take a long time to decline and a long time to recover. In the case of gophers, the best estimate of ‘generation time’ is 31 years and so the period of consideration for decline and recovery is nearly 100 years. This does not mean that we must wait 100 years to do anything or that we should wait 100 years before we can evaluate our progress toward the goal. What it does mean is that progress toward the goal is constrained by gophers long lives and slow reproduction and is likely to take a very long time before we achieve our full result. 

Florida’s species listing process requires that a management plan to conserve the species is developed as an integral part of listing. Therefore, the changed listing of gopher currently underway (from SSC to Threatened) requires that we develop suitable management and regulatory activities. Therefore the actual details and measurable goals for gophers will be incorporated into the management plan. These are currently in development and include topics such as:

• Increasing the area of gopher habitat protected in public ownership.
• Developing incentives for private owners to protect habitat.
• Increasing beneficial land management activities such as prescribed fire.
• Relocating gophers from developed lands to suitable protected areas where they are at low density.
• Removing impediments that prevent rescuing gophers from development.

Each of these will have a numerical target assigned that balances feasibility with the requirements of the MBG and can be evaluated at regular short term intervals (1-5 years) as a measure of our progress toward the long term goal.

 The Measurable Biological Goal for gophers is therefore a hierarchy or pyramid

• A fundamental commitment to preserve the species in perpetuity.
• An MBG of improving the actual and listed status of the species.
• A long term goal of reducing habitat loss.
• A strategy sharing this responsibility between private and public sectors.
• A management plan involving concrete targets of measurable activities such as area of habitat, numbers of gophers relocated.

Figure 1. Schematic view of declines in gopher tortoises estimated from habitat area loss and projections of likely future declines if effective management is implemented. 

Between 1900 and 2005 approximately 69% of habitat was lost and this was assumed to be more rapid in the period of Florida’s maximum development 1960-2000.

If proposed targets for reduced habitat loss and improved protected habitat area are achieved for the next 50 years, initially the rate of decline over 3 generations changes little, although the trend in decline will be greatly slowed.

Eventually, as we approach 2100, the rate of decline is projected to stabilize within the available protected (public and private) habitat.