Alligator Snapping Turtle Biological Status 

Review Report

March 31, 2011

FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION 

620 South Meridian Street 

Tallahassee, Florida 32399-1600
Alligator Snapping Turtle Biological Status Review Report 2

Biological Status Review

for the

Alligator Snapping Turtle

(Macrochelys temminckii)

March 31, 2011

EXECUTIVE SUMMARY

The Florida Fish and Wildlife Conservation Commission (FWC) directed staff to 

evaluate species listed as Threatened or Species of Special Concern as of November 8, 2010 that 

had not undergone a status review in the past decade. Public information on the status of the 

alligator snapping turtle was sought from September 17 through November 1, 2010. The 5-

member biological review group (BRG) met on November 9-10, 2010. Group members were 

Bill Turner (FWC lead), Chris Lechowicz (Sanibel-Captiva Conservation Foundation), Peter 

Meylan (Eckerd College), Paul Moler (independent consultant) and Travis Thomas (FWC) 

(Appendix 1). In accordance with rule 68A-27.0012, Florida Administrative Code (F.A.C.), the 

BRG was charged with evaluating the biological status of the alligator snapping turtle using 

criteria included in definitions in 68A-27.001, F.A.C., and following protocols in the Guidelines 

for Application of the IUCN Red List Criteria at Regional Levels (Version 3.0) and Guidelines 

for Using the IUCN Red List Categories and Criteria (Version 8.1). Please visit 

http://myfwc.com/wildlifehabitats/imperiled/listing-action-petitions/ to view the listing process 

rule and the criteria found in the definitions. 

In late 2010, staff developed the initial draft of this report which included BRG findings 

and a preliminary listing recommendation from staff. The draft was sent out for peer review and 

the reviewers’ input has been incorporated to create this final report. The draft report, peer 

reviews, and information received from the public are available as supplemental materials at 

http://myfwc.com/wildlifehabitats/imperiled/biological-status/.

The BRG concluded from the biological assessment that the alligator snapping turtle met 

criterion B2ab(iii); citing severe fragmentation of the population as part of the criterion. This is

described in the guidelines for listing as “a taxon can be considered to be severely fragmented if 

most (>50%) of its total area of occupancy is in habitat patches that are (1) smaller than would 

be required to support a viable population, and (2) separated from other habitat patches by a 

large distance.” After the review was conducted, staff further evaluated the concept of “severely 

fragmented” and believes that it does not apply to the alligator snapping turtle. When conducting 

the Regional Assessment, the BRG discussed that should there be a catastrophic event in Florida 

that eliminated populations of alligator snapping turtles, there could be a rescue effect from 

turtles outside Florida. In these situations, the listing guidelines consider downgrading the initial 

listing finding to a less imperiled status. Taking into consideration both of these factors, staff 

recommends not listing the alligator snapping turtle as Threatened and to remove it from the 

Species of Special Concern list. 

This work was supported by a Conserve Wildlife Tag grant from the Wildlife Foundation 

of Florida. FWC staff gratefully acknowledges the assistance of the biological review group 
Alligator Snapping Turtle Biological Status Review Report 3

members and peer reviewers. Staff thanks Dr. Dale Jackson for serving as a data compiler on the 

species and drafting the Biological Information section of this report.

BIOLOGICAL INFORMATION

Taxonomic Classification – The alligator snapping turtle (Macrochelys temminckii)

(Harlan 1835) is universally recognized as a full species with no close living relatives (Ewert et 

al. 2006).

Life History and Habitat Requirements – Life history and habitat of the alligator 

snapping turtle have been summarized by Ewert et al. (2006), Pritchard (2006), and Ernst and 

Lovich (2009). In Florida, the species is restricted to rivers and associated permanent freshwater 

habitats. The latter include floodplain swamp forests characterized by tannic or turbid waters, 

bald cypress and tupelo, and numerous channels and deep holes (Ewert and Jackson 1994). The 

only lakes supporting the species are either impounded sections of large rivers (Lake Seminole: 

Apalachicola, Lake Talquin: Ochlockonee) or natural lakes with at least occasional connection to 

a river (e.g., Lake Iamonia, Leon County). Alligator snapping turtles also make use of 

surprisingly small streams, such as the seepage streams on Eglin Air Force Base. A few adults 

have been taken from brackish water habitats (e.g., Ochlockonee Bay, Franklin County), with 

some individuals even supporting barnacles, but movements into salt water are extremely rare 

(Ewert et al. 2006, Pritchard 2006). The alligator snapping turtle is by far the largest North 

American freshwater turtle. Although both sexes achieve large body size, the oft-pictured 

behemoths (up to 250 lbs, 29 inch carapace length [CL]) are all males, which grow considerably 

larger than females (maximum ca. 62 lbs, 22 inches CL) (Ewert et al. 2006, Pritchard 2006). 

Both sexes require at least 15, and probably 20 years to mature (Sloan et al. 1996, Tucker and 

Sloan 1997, Reed et al. 2002). Lifespan in the wild is unknown, but captives have lived in 

excess of 75 years (Snider and Bowler, 1992). Based on these data, a conservative estimate of 

average age of parents (generation time) is 30-40 years. Reed et al. (2002) estimated generation 

time at 49 years. All studies (e.g., Allen and Neill 1950, Dobie 1971, Ewert and Jackson 1994) 

indicate that females produce but one clutch per year, and some may occasionally skip years 

(Dobie 1971). The nesting season is correspondingly short, extending from late April to midMay in Panhandle Florida (Ewert 1976, Ewert and Jackson 1994). Nests are constructed in 

sandy soils when available, normally within 20 m of water but sometimes as far as 200 m. 

Natural berms 2-3 m high are favored along the lower Apalachicola River, but these have been 

supplemented and in part replaced by man-made deposits of sandy dredged spoil, which tend to 

produce more female hatchlings as a consequence of temperature-dependent sex determination 

(Ewert and Jackson 1994, Ewert et al. 1994). Clutch sizes along the lower Apalachicola River, 

the best studied site, average ca. 36 eggs (range 17-52). Most eggs there hatch in the second half 

of August after 100-110 days of incubation, followed within a few weeks by hatchling 

emergence (Ewert and Jackson 1994). Although little studied in Florida, the diet of the alligator 

snapping turtle across its range is rather broad and chiefly carnivorous, although plant matter 

seems also to be important (Ewert et al. 2006). Juveniles feed predominantly upon small fish, 

but the diet broadens with age and growth. While fish remain important, crustaceans, mollusks 

(both bivalve and gastropod: Allen and Neill 1950), aquatic salamanders, water birds, mammals, 

and other turtles all become significant components.
Alligator Snapping Turtle Biological Status Review Report 4

Population Status and Trend – Based on past extent of harvest (Ewert et al. 2006, 

Pritchard 2006), there is little doubt that the alligator snapping turtle once was extremely 

numerous and accounted for substantial biomass throughout many Southeastern riverine systems, 

including those in Florida. Although rigorous data documenting the century or more of human 

take do not exist, there is equally little doubt that extensive harvest, both commercial and 

personal, depleted populations in many rivers. Typically, after periods of heavy effort, declining 

yields forced harvesters to move on to other sites (Pritchard 2006). This is not unexpected given 

the long generation time of alligator snapping turtles and the normally low rates of recruitment of 

virtually all turtles. Beginning in 1973, enactment of a series of protective rules by FWC (then 

the Florida Game and Fresh Water Fish Commission [GFC]) reduced the species’ rate of decline 

in Florida, although harvest (legal and illegal) still occurred. FWC rule changes in 2009 

prohibited take of all snapping turtles and ended legal harvest. Whether the statewide population 

has stabilized or begun to increase is undetermined, although some Florida rivers support healthy 

populations (Ewert et al. 2006). 

Geographic Range and Distribution – The alligator snapping turtle occupies Gulf 

Coast drainages from Florida to Texas and northward to Illinois; in Florida, the species inhabits 

most, if not all, of the larger drainages in the Panhandle and Big Bend regions, from the 

Escambia River to the Suwannee River (Ewert et al. 2006, Pritchard 2006).

Quantitative Analyses – The principal attempt at modeling population demography of 

the alligator snapping turtle and evaluating population effects of changes in life history 

parameters is that of Reed et al. (2002). They concluded that an annual survival rate of 98% for 

adult females was necessary for population stability, that any lesser rate would lead to long-term 

population decline and eventual extirpation, and that even successful efforts to increase egg and 

juvenile survival would be unlikely to compensate for continued loss of adult females. While the 

model may have underestimated the rates of nest and/or juvenile survival in the wild, which 

might lead to an overestimate of necessary female survival rate (Ewert et al. 2006), the 

conclusion that long-term population viability requires very high rates of female survival is 

sound.

BIOLOGICAL STATUS ASSESSMENT

Threats – Not surprisingly given its size and catchability, the alligator snapping turtle

has a long history of both commercial and personal harvest for meat throughout its range, 

including in Florida (Dobie 1971, Sloan and Lovich 1995, Reed et al. 2002, Ewert et al. 2006, 

Pritchard 2006). There is little doubt that this suppressed populations locally and regionally. 

Beginning in the 1970s, rules enacted by the GFC to limit take likely slowed the rate of mortality 

in Florida, though both legal and illegal harvest still occurred. Legal take of alligator snapping 

turtles was prohibited by rule changes enacted by FWC in 2009. However, it may be years or 

decades before the negative impacts of long-term harvest are fully reversed. Even in the absence 

of legal harvest, there remains a problem of bycatch mortality on lines set for fish, especially 

catfish. These include both trot lines (long lines of submerged baited hooks) and bush lines 

(single hooks suspended from tree branches) (Ewert et al. 2006, Pritchard 2006). The latter may 

be more widely used in rivers and hence likely present a greater problem for the alligator 

snapping turtle. Because rivers tend to be relatively stable and persistent systems compared to 
Alligator Snapping Turtle Biological Status Review Report 5

most Florida habitats, outright habitat destruction is not a major threat to this turtle. Nonetheless, 

various human-generated insults to the integrity of lotic systems, including their floodplains, can 

and do affect Florida’s riverine turtles (Jackson 2005). Chemical pollution (from industries such 

as pulp mills, and waste products from cities and agricultural activities, including those in 

Alabama and Georgia) always poses a potential threat to all riverine fauna, though even a major 

spill along one Panhandle river would not endanger the species’ statewide population (Ewert et 

al. 2006). Other than the industrially degraded Fenholloway River in Taylor County, which once 

may have supported the alligator snapping turtle but presumably no longer does (Jackson 1999), 

the Escambia River in western Florida is probably the most polluted (from pulp mill effluent) yet 

still retains the species (Moler 1996, Jackson 2005). Siltation from road crossings, borrow pits, 

or other situations probably can reduce the suitability of smaller streams, such as the clear 

seepage streams on Eglin Air Force Base, that the species utilizes. Although both major 

impoundments (by dams designed to provide electricity, flood protection, and recreation) within 

the alligator snapping turtle’s Florida range (Lake Talquin: Ochlockonee River, Lake Seminole: 

Apalachicola River) still support the species, long-term impacts of microhabitat changes and 

shoreline development are unstudied but potentially negative (Ewert et al. 2006). A third 

impoundment has been proposed for the Yellow River but would require substantial review by 

regulatory agencies to be considered further. As for all turtles, predation, particularly by 

raccoons, accounts for the loss of a majority of alligator snapping turtle eggs (about 2/3 along the 

lower Apalachicola River). Additional potential predators include wild hogs and imported fire 

ants. Nest flooding following very heavy regional rains also destroys entire clutches in some 

years (Ewert and Jackson 1994).

Population Assessment – Findings from the BRG are included in the Biological Status 

Review Information Findings tables. The BRG concluded from the biological assessment that 

the alligator snapping turtle met criterion B2ab(iii); citing severe fragmentation of the population 

(B2a) as part of the criterion. When conducting the Regional Assessment, the BRG discussed 

that, should there be a catastrophic event in Florida that eliminated populations of alligator 

snapping turtles, there could be a rescue effect from turtles outside Florida. In these situations, 

the listing guidelines consider downgrading the initial listing finding to a less imperiled status.

After a careful review of the information with regards to sub-criterion B2ab, staff 

believes that the BRG misinterpreted guidance on fragmentation which led to a misapplication of 

the B2a sub-criterion. Staff believes the alligator snapping turtle is not severely fragmented 

under the definition used in the biological status review process. 

The BRG and staff both referred to the Version 8.1 of the IUCN Guidelines for Using the 

IUCN Red List Categories and Criteria for guidance on fragmentation. Under the section 

entitled “4.8 Severely fragmented (Criterion B),” fragmentation is defined as “a situation in 

which increased extinction risks to the taxon result from the fact that most of its individuals are 

found in small relatively isolated subpopulations.” Further guidance is given that, “a taxon can 

be considered to be severely fragmented if most (>50%) of its total area of occupancy is in 

habitat patches that are (1) smaller than would be required to support a viable population, and (2) 

separated from other habitat patches by a large distance.” It is implied that the distance is large 

relative to the species’ ability to cover the distance. The BRG considered alligator snapping 

turtles “severely fragmented” because alligator snapping turtles are not known to frequently 
Alligator Snapping Turtle Biological Status Review Report 6

move between the rivers where their populations occur, which considers the second part of the 

guidance. While this may be valid, the first part of the fragmentation guidance is not supported 

by current data. There is no indication that more than 50% of the alligator snapping turtles are in 

habitat patches smaller than would be required to support viable populations. If non-viable 

alligator snapping turtle populations were in habitat patches so far apart that the snappers could 

not move from one to another, then alligator snapping turtles would indeed be at risk of 

extinction. This is not the case. Within most rivers there seem to be viable populations of 

alligator snapping turtles. For this reason, staff does not consider alligator snapping turtle 

populations severely fragmented and believe the B2a sub-criterion is not met. 

LISTING RECOMMENDATION

Staff recommends not listing the alligator snapping turtle as a Threatened species and to 

remove it from the Species of Special Concern list.

SUMMARY OF THE INDEPENDENT REVIEW

John Jensen (Georgia Department of Natural Resources), Kenneth P. Way (Florida State 

University) and Joseph Apodaca (Florida State University) reviewed this document. Although 

all three peer reviewers supported the findings of the BRG, one did not support the staff 

recommendation to not list the alligator snapping turtle as threatened. This reviewer expressed 

that the alligator snapping turtle populations in Florida were fragmented and doubted that 

alligator snapping turtles from outside of Florida could repopulate some Florida river systems. 

One reviewer also pointed out that the Suwannee River clade of alligator snapping turtles 

is genetically distinctive from the other alligator snapping turtles in Florida and as such may 

warrant protection. This issue was discussed in the BRG. Although the Suwannee River clade is 

morphologically and genetically distinctive from other populations of alligator snapping turtles, 

the taxonomic status of this clade is uncertain. Until the taxonomy of the Suwannee River clade 

is determined, the turtles in this clade will be given the same considerations as other alligator 

snapping turtles in Florida. The reviewer recommended that the population receive further 

study. 

A reviewer stated that there has been heavy harvest pressure on alligator snapping turtles, 

although the species has been protected by FWC rules since the 1970s. He also stated the 

species is easily harvested at high rates. This does not seem to be the case. Although alligator 

snapping turtles are caught on trot lines, they are not caught at a high rate compared to other 

turtles probably due to their low density in the habitat. Because of FWC rules, alligator snapping 

turtle harvest has not been commercialized in Florida.

Full text of the peer reviews is available at myFWC.com.
Alligator Snapping Turtle Biological Status Review Report 7

LITERATURE CITED

Allen, E. R., and W. T. Neill. 1950. The alligator snapping turtle Macrochelys

temminckii in Florida. Ross Allen's Reptile Institute Special Publication 4:1-15.

Dobie, J. L. 1971. Reproduction and growth in the alligator snapping turtle Macroclemys 

temminckii (Troost). Copeia 1971:645-658.

Ernst, C. H., and J. E. Lovich. 2009. Turtles of the United States and Canada. Second edition. 

The Johns Hopkins University Press, Baltimore, Maryland, USA. 827pp.

Ewert, M. A., and D. R. Jackson. 1994. Nesting ecology of the alligator snapping turtle

(Macroclemys temminckii) along the lower Apalachicola River, Florida. Florida Game 

and Freshwater Fish Commission, Nongame Wildlife Program Report NC89-020, 

Tallahassee, Florida, 45pp.

Ewert, M. A., D. R. Jackson, and P. E. Moler. 2006. Macrochelys temminckii – alligator 

snapping turtle. Pages 58–71 in P. A. Meylan, editor. Biology and conservation of 

Florida turtles. Chelonian Research Monographs No. 3.

Ewert, M. A., D. R. Jackson, and C. E. Nelson. 1994. Patterns of temperature-dependent sex 

determination in turtles. Journal of Experimental Zoology 270-3-15.

Florida Natural Areas Inventory. Tallahassee, Florida, USA. [contacts: via the Internet at 

www.fnai.org, or telephone 850-224-8207]

Harlan, R. 1835. Genera of North American Reptilia and a synopsis of the species. Pages 84–

160 in Medical and Physical Researches. Lydia R. Bailey, Philadelphia, Pennsylvania, 

USA.

Jackson, D. R. 1999. Survey of an important distributional "gap" in the Florida range of the 

river cooter and other freshwater turtles. Final Report to Nongame Wildlife Program, 

Florida Game and Fresh Water Fish Commission.

Jackson, D. R. 2005. Florida rivers and turtles: an interdependence. Pages 163–168 in W. E. 

Meshaka, Jr., and K. J. Babbitt, editors. Amphibians and reptiles: status and conservation 

in Florida. Krieger Publishing Company, Malabar, Florida, USA. 318pp.

Moler, P. E. 1996. Alligator snapping turtle distribution and relative abundance. Florida Game 

and Freshwater Fish Commission, Final Report 7544. 13pp.

Pritchard, P. C. H. 2006. The alligator snapping turtle: biology and conservation. Second 

edition. Krieger Publishing Company, Malabar, Florida, USA. 140pp.

Reed, R. N., J. D. Congdon, and J. W. Gibbons. 2002. The alligator snapping turtle

[Macroclemys (Macrochelys) temminckii]: a review of ecology, life history, and 
Alligator Snapping Turtle Biological Status Review Report 8

conservation, with demographic analyses of the sustainability of take from wild 

populations. Report to: Division of Scientific Authority, United States Fish and Wildlife 

Service. [available on the Internet at http://www.uga.edu/srelherp]

Sloan, K. N., K. A. Buhlmann, and J. E. Lovich. 1996. Stomach contents of commercially 

harvested adult alligator snapping turtles, Macroclemys temminckii. Chelonian 

Conservation and Biology 2:96-99.

Sloan, K.N., and J. E. Lovich. 1995. Exploitation of the alligator snapping turtle, Macroclemys 

temminckii, in Louisiana: a case study. Chelonian Conservation and Biology 1:221-222.

Snider, A. T., and J. K. Bowler. 1992. Longevity of reptiles and amphibians in North American 

collections. Second edition. Society for the Study of Amphibians and Reptiles 

Herpetological Circular 21:1-40.

Tucker, A. D., and K. N. Sloan. 1997. Growth and reproductive estimates from alligator 

snapping turtles, Macroclemys temminckii, taken by commercial harvest in Louisiana. 

Chelonian Conservation and Biology 2: 587-592.
Alligator Snapping Turtle Biological Status Review Report 9 

Biological Status Review Information

Findings

Species/taxon: Alligator Snapping Turtle

Date: 11/10/10 

Assessors: Chris Lechowicz, Peter Meylan, Paul Moler,

Bill Turner and Travis Thomas

 Generation length: 30-40 years (ca. 35 years)

 

Criterion/Listing Measure Data/Information Data Type* Sub-Criterion 

Met? References

*Data Types - observed (O), estimated (E), inferred (I), suspected (S), or projected (P). Sub-Criterion met - yes (Y) or no (N). 

(A) Population Size Reduction, ANY of

(a)1. An observed, estimated, inferred or suspected 

population size reduction of at least 50% over the last 10 

years or 3 generations, whichever is longer, where the 

causes of the reduction are clearly reversible and understood 

and ceased1

Has been harvest throughout the past 90 years however 

due to historic harvest pressures and existing sampling 

data it is unlikely that there has been a 50% decline. I N 

Ewert et al. 2006, Pritchard 

2006

(a)2. An observed, estimated, inferred or suspected 

population size reduction of at least 30% over the last 10 

years or 3 generations, whichever is longer, where the 

reduction or its causes may not have ceased or may not be 

understood or may not be reversible1

We suspect that there has not been a 30% decline 

although there was historic and continuing harvest. 

S N 

Ewert et al. 2006, Pritchard 

2006

(a)3. A population size reduction of at least 30% projected 

or suspected to be met within the next 10 years or 3 

generations, whichever is longer (up to a maximum of 100 

years) 1 

Projections for sea level rise during the next 90 years 

may increase the salinity of the waterways which could 

result in habitat loss and reduction of the population, 

but group is uncertain that the reduction would be at 

least 30%. 

S N 

(a)4. An observed, estimated, inferred, projected or 

suspected population size reduction of at least 30% over any 

10 year or 3 generation period, whichever is longer (up to a 

maximum of 100 years in the future), where the time period 

must include both the past and the future, and where the 

reduction or its causes may not have ceased or may not be 

understood or may not be reversible.1

We suspect that there has not been a 30% decline 

although there was historic and continuing harvest and 

potential for additional decline due to projected sea

level rise. S N 

Ewert et al. 2006, Pritchard 

2006

1 based on (and specifying) any of the following: (a) direct observation; (b) an index of abundance appropriate to the taxon; (c) a decline in area of occupancy, extent of occurrence 

and/or quality of habitat; (d) actual or potential levels of exploitation; (e) the effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites. 

(B) Geographic Range, EITHER

(b)1. Extent of occurrence < 20,000 km2 (7,722 mi2 ) OR 46,000 km2 E N D. Jackson GIS polygon

(b)2. Area of occupancy < 2,000 km2 (772 mi2 ) 440 km2 E Y D. Jackson GIS polygons

AND at least 2 of the following: 
Alligator Snapping Turtle Biological Status Review Report 10

a. Severely fragmented or exist in ≤ 10 locations Occupies 12 river drainages in FL - the group thought 

that the population is severely fragmented because the 

rivers isolated by drainage basin and reduced terrestrial 

mobility across drainage basins, but individual river 

basin populations are viable

I Y

Ewert et al. 2006, FL Natural 

Areas Inventory (FNAI)

b. Continuing decline, observed, inferred or projected 

in any of the following: (i) extent of occurrence; (ii) area 

of occupancy; (iii) area, extent, and/or quality of habitat; 

(iv) number of locations or subpopulations; (v) number 

of mature individuals

Projections for sea level rise during the next 90 years 

may increase the salinity of the waterways which could 

result in habitat loss and a corresponding decline. 

Future water quality decline and increased human 

demand for the water could also result in decline of the 

population.

I/S Y

c. Extreme fluctuations in any of the following: (i) 

extent of occurrence; (ii) area of occupancy; (iii) number 

of locations or subpopulations; (iv) number of mature 

individuals

No; extreme fluctuations unlikely in long-lived species; 

rivers relatively stable. S N

(C) Population Size and Trend

Population size estimate to number fewer than 10,000 

mature individuals AND EITHER

The alligator snapping turtle has a very restricted area 

of occupancy, 12 drainages. Travis Thomas (BSR group 

member) estimates 6 turtles per km from his research. 

Using this values multiplied by length of the rivers 

gives an estimate of 3000 turtles for the Suwannee and 

Santa Fe Rivers (where Thomas is conducting research). 

Group suspects there are over 10,000 alligator snapping 

turtles in Florida

S N

Moler 1996, Ewert et al. 

2006 offer catch-per-uniteffort data, but no population 

numbers.

(c)1. An estimated continuing decline of at least 10% in 10 

years or 3 generations, whichever is longer (up to a 

maximum of 100 years in the future) OR

Defer to Cc2.

(c)2. A continuing decline, observed, projected, or inferred 

in numbers of mature individuals AND at least one of the 

following: 

With strong enforcement of 2009 FWC rules 

prohibiting take, population likely to grow. P N

a. Population structure in the form of EITHER No suitable quantitative population size data but likely 

>1000 in Apalachicola and Suwannee drainages. S N

Ewert et al. 2006

(i) No subpopulation estimated to contain more 

than 1000 mature individuals; OR

(ii) All mature individuals are in one 

subpopulation

No; occurs in at least 11 independent drainages. I N Ewert et al. 2006, FL Natural 

Areas Inventory (FNAI)

b. Extreme fluctuations in number of mature 

individuals

No; extreme fluctuations unlikely in long-lived species; 

rivers provide relatively stable habitat. S N Jackson 2005, Ewert et al. 2006

(D) Population Very Small or Restricted, EITHER 

(d)1. Population estimated to number fewer than 1,000 

mature individuals; OR

Few quantitative data available, but Moler's trapping 

survey and Ewert/Jackson nesting study on 

Apalachicola River suggest >1000.

S N

Moler 1996, Ewert et al. 

2006, FL Natural Areas 

Inventory (FNAI)
Alligator Snapping Turtle Biological Status Review Report 11

(d)2. Population with a very restricted area of occupancy 

(typically less than 20 km2 [8 mi2]) or number of locations 

(typically 5 or fewer) such that it is prone to the effects of 

human activities or stochastic events within a short time 

period in an uncertain future 

Both estimated area of occupancy (440 km2) and 

number of inhabited rivers (1@; each river is at least 

one location) exceed this. S N

Ewert et al. 2006, FL Natural 

Areas Inventory (FNAI), D. 

Jackson GIS polygons

(E) Quantitative Analyses

e1. Showing the probability of extinction in the wild is at 

least 10% within 100 years

Uncertain; Reed et al. (2002) model assumptions 

questionable, but suggests possible with even moderate 

take. P N Reed et al. 2002

Initial Finding (Meets at least one of the criteria /sub-criteria OR Does 

not meet any of the criteria/sub-criteria)

Reason (which criteria/sub-criteria are met)

meets one criterion B2ab(iii)

Is species/taxon endemic to Florida? (Y/N) N

If Yes, your initial finding is your final finding. Copy the initial finding and reason to the final finding space below. If No, 

complete the regional assessment sheet and copy the final finding from that sheet to the space below.

Final Finding (Meets at least one of the criteria/sub-criteria OR Does 

not meet any of the criteria/sub-criteria)

Reason (which criteria/sub-criteria are met)

meets one criterion B2ab(iii)
Alligator Snapping Turtle Biological Status Review Report 12 

Regional Assessment

1 

Biological Status Review Information

Regional Assessment

Species/taxon: Alligator Snapping Turtle

2 Date: 11/10/10 

3 Assessors: Chris Lechowicz, Peter Meylan, Paul Moler,

4 Bill Turner and Travis Thomas

5 

6 

7 

8 Initial finding 

9 

10

2a. Is the species/taxon a non-breeding visitor? (Y/N/DK). If 2a is YES, go to line 18. If 2a is NO or DO NOT KNOW, 

go to line 11. N 

11

2b. Does the Florida population experience any significant immigration of propagules capable of reproducing in 

Florida? (Y/N/DK). If 2b is YES, go to line 12. If 2b is NO or DO NOT KNOW, go to line 17. Y 

12

2c. Is the immigration expected to decrease? (Y/N/DK). If 2c is YES or DO NOT KNOW, go to line 13. If 2c 

is NO go to line 16. N 

13

2d. Is the regional population a sink? (Y/N/DK). If 2d is YES, go to line 14. If 2d is NO or DO NOT 

KNOW, go to line 15. 

14 If 2d is YES - Upgrade from initial finding (more imperiled) 

15 If 2d is NO or DO NOT KNOW - No change from initial finding 

16 If 2c is NO or DO NOT KNOW- Downgrade from initial finding (less imperiled) Downgrade

17 If 2b is NO or DO NOT KNOW - No change from initial finding 

18

2e. Are the conditions outside Florida deteriorating? (Y/N/DK). If 2e is YES or DO NOT KNOW, go 

to line 24. If 2e is NO go to line 19. 

19

2f. Are the conditions within Florida deteriorating? (Y/N/DK). If 2f is YES or DO NOT 

KNOW, go to line 23. If 2f is NO, go to line 20. 

20

2g. Can the breeding population rescue the Florida population should it decline? (Y/N/DK). 

If 2g is YES, go to line 21. If 2g is NO or DO NOT KNOW, go to line 22. 

21 If 2g is YES - Downgrade from initial finding (less imperiled) 

22 If 2g is NO or DO NOT KNOW - No change from initial finding 

23 If 2f is YES or DO NOT KNOW - No change from initial finding 

24 If 2e is YES or DO NOT KNOW - No change from initial finding 

25

26 Final finding 
Alligator Snapping Turtle Biological Status Review Report 13

Additional notes. Calculation of generation time presented at the BSR group meeting

Generation length is defined as the average age of parents of the current cohort, which is greater 

than the age at first breeding and less than the age of the oldest breeding individual. We estimate 

generation length for the alligator snapping turtle as follows. Dobie (1971) estimated both sexes 

mature in LA in 11-13 years (no data for FL) but noted a two-thirds decline in growth rate by 

ages 16-35; this suggests slightly later maturation, probably closer to 15-20. Lifespan in the wild 

is unknown (Ewert et al. 2006), but individuals may live >75 years in captivity (Snider and 

Bowler, 1992). We therefore conservatively estimate average age of parents at 30-40 years and 

recognize that this is more likely to be an underestimate than overestimate. Reed et al. (2002) 

estimated a generation length of 49 years.
Alligator Snapping Turtle Biological Status Review Report 14

APPENDIX 1. Brief biographies of the Alligator snapping turtle Biological Review Group 

members.

Chris Lechowicz is the Interim Director of the Wildlife Habitat Management Program and staff 

herpetologist at the Sanibel-Captiva Conservation Foundation where he has worked since 2002. 

He has a B.S. in Zoology and Computer Science from Southern Illinois University at Carbondale 

and will complete his M.S. in Environmental Science from Florida Gulf Coast University in 

2010. Chris’s focus is on riverine turtles with a specialty on the Genus Graptemys. Chris is a 

member of the IUCN/SCC Tortoise and Freshwater Turtle Specialists Group as well as a board 

member of the Florida Turtle Conservation Trust.

Dr. Peter A. Meylan received his Ph.D. from the University of Florida. He is a Professor of 

Biology at Eckerd College in Saint Petersburg, FL. His research interests include the 

evolutionary history, ecology, and conservation biology of amphibians and reptiles, especially 

turtles. Current research includes 2 sea turtle projects: an investigation of the ecology and 

migrations of sea turtles of Bocas del Toro Province, Panama (funded by the Wildlife 

Conservation Society) and the Bermuda Turtle Project, which is a cooperative project with the 

Bermuda Aquarium and the Caribbean Conservation Corporation (as well as continuing to work 

with Florida freshwater turtles with the Eckerd Herpetology Club on the Rainbow River). He 

has many scientific articles on turtles and is the editor of a book on the biology and conservation

of Florida turtles.

Paul E. Moler received his M.S. in Zoology from the University of Florida in 1970 and his B.A.

in Biology from Emory University in 1967. He retired in 2006 after working for 29 years as a 

herpetologist with FWC, including serving as administrator of the Reptile and Amphibian 

Subsection of the Wildlife Research Section. He has conducted research on the systematics, 

ecology, reproduction, genetics, and conservation biology of a variety of herpetofaunal species in

Florida, with primary emphasis on the biology and management of endangered and threatened 

species. He served as Chair for the Florida Committee on Rare and Endangered Plants and 

Animals in 1992–94, Chair of the Committee on Amphibians and Reptiles since 1986, and editor 

of the 1992 volume on amphibians and reptiles. Paul has more than 90 publications on 

amphibians and reptiles.

Travis Thomas received a Bachelor’s Degree in 2008 from the University of Florida in Natural 

Resources Conservation. He is currently pursuing a Masters Degree in Wildlife Ecology and 

Conversation under the supervision of Dr. Perran Ross. His primary research focuses on the 

ecology and management of fauna in riparian systems. He was hired by FWC in 2008, and he 

has worked on numerous projects concerning reptile and amphibian ecology. He worked for 3 

years in the Herpetology Dept. under Dr. Kenneth Krysko at the Florida Museum of Natural 

History. He has spent time as a volunteer on numerous projects in Kenya, Africa, under the 

supervision of Leigh Ecclestone and the Kenyan Wildlife Service. He has published several 

notes on the ecology and distribution of reptiles and is currently a co-author on a study of the 

ecology of M. temminckii in O’Leno State Park as well as the primary author on a study of the 

morphology of M. temminckii.
Alligator Snapping Turtle Biological Status Review Report 15

William M. Turner received his B.S. from Erskine College and M.S. in Biology from the 

University of South Alabama. From 2003 to 2007, he was the Herpetological Coordinator for 

the Wyoming Game and Fish Department. In Wyoming, he conducted statewide surveys for 

amphibians and reptiles, focusing on emerging amphibian diseases and the impacts of resource

development native reptiles. Since 2007, he has been the Herp Taxa Coordinator for FWC in the 

Division of Habitat and Species Conservation. He has conducted research on native amphibians 

and reptiles in Florida, Alabama and Wyoming that has resulted in several published papers and 

reports.
Alligator Snapping Turtle Biological Status Review Report 16

APPENDIX 2. Summary of letters and emails received during the solicitation of 

information from the public period of September 17, 2010 through November 1, 2010.

A comment was received via email from Jeff Preacher, who is a recreational catfish 

fisherman in the Milton, FL area. He has captured alligator snapping turtles while fishing on the 

Blackwater, Yellow and Escambia Rivers using trot lines and bush hooks. He stated that alligator 

snapping turtles seemed as abundant now as 30 years ago. He claimed from observation of 

captive and wild turtles that alligator snapping turtles grow more quickly than most suppose. He 

felt that large ones 90+ lbs in weight were only in their 20s. His data are based on aging turtles 

with the annular rings on their scutes (scales on their dorsal shells). He felt that alligator 

snapping turtles were able to endure “man’s encroachment” into their habitat because they often 

remained unseen. He stated that the main threat to alligator snapping turtles is commercialization 

and that the current turtle rules (no take of alligator snapping turtles) are too restrictive. He felt 

that the alligator snapping turtles could be harvested with a permit and stated that he would 

gladly participate in such a permitting system.