The alligator snapping turtle (Macrochelys temmicnkii) is one of the giant freshwater turtles in Northern America. It is aquatic and some of its biological aspects remain unknown. The historical distribution of this turtle remains distributed in around 14 states. There are a single species that is recognized in its genus; however, it is genetically marked with structural differences among the known generations. There has been adequate information on the physical characteristics, diet and reproduction of M.temminckii, however, little information is known the survivorship, recruitment, habitat, lovengenicity and habitat use. Between 1960 and 1970, there were increased levels of commercial harvest of the turtles leading to the decimated levels of the turtles. As such, it leads to protection of the turtles from commercial harvest.
Key words: Allagator Snapping Turtles, habitat, Commercial Harvest
Introduction
The alligator snapping turtle (Macrochelys temmicnkii) is one of the giant freshwater turtles in Northern America. It is aquatic and some of its biological aspects remain unknown. The historical distribution of this turtle remains distributed in around 14 states. There are a single species that is recognized in its genus; however, it is genetically marked with structural differences among the known generations. There has been adequate information on the physical characteristics, diet and reproduction of M.temminckii, however, little information is known the survivorship, recruitment, habitat, lovengenicity and habitat use (Howey et al.). Between 1960 and 1970, there were increased levels of commercial harvest of the turtles leading to the decimated levels of the turtles. As such, it leads to protection of the turtles from commercial harvest. The aim of this paper is to describe the ecology and the effects of commercial harvesting on the alligator snapping turtles.
Life History
According to Riedle et al., the Alligator snapping turtles are believed to be the most abundant freshwater turtles in North America. They primarily have three broad, pronounced ridges that run from the front to the back of their carapace. Besides, they have powerful jaws, large heads, and eyes on their sides which make them unique. They are primitive in their appearance. They live in freshwater areas mostly in the southeastern United States. They live in the deepest waters within their habitats including the swamps, lakes, rivers and the canals (Howey et al.). The male alligator snapping turtles live from 11-45 years within an average of 26years while the females live for 15-17 years with an average of 23 years. These species spend most of their time in the water with only the female venturing on the land (Riedle et al.). The alligator snapping turtles are both scavengers and hunters. They are believed to feed on both plants and animals.They are mostly active at night while during the day; they lie quietly staying at the bottom of the murky water and then open their jaws and tongues which then attract the fish (Riedle et al.). The alligator snipping turtles use the chemosensory cues for the location of prey items. They use the gular (throat) pumping to draw water in and out to sample the surrounding water for any chemicals that may have been released by prey species.
The alligator snapping turtles are susceptible to severe decline in the numbers due to their life history characteristics such as long generation times, delayed sexual maturity, slow growth rate, low egg and hatchling survivorship. Research estimates that the harvest of the turtles can lead to the reduction in the population size, size distribution shifts as well as change in adult, juvenile ratios (Echelle et al.). With the commercial harvest, there has a drastic reduction in the rates of the alligator snapping turtles. Most of the larger individuals of the turtle populations are removed from the population at a very big rate leading to a biased adult sex ratio which favors the smaller sex as well as exacerbate a skewed overall size distribution. Research indicates that male often reach the much larger sizes than the females and the larger turtles are often preferred by the trappers thereby making changes in the adult distribution as well as adult sex ratio. There have been attempts to reintroduce the population species; however, it may be faced with tremendous impacts due to their life characteristics that have made them susceptible to the population decline. Previous researchers suggests that, following the commercial harvests of the turtles, the females dominates the males however their survivorship is high. Consequently, the high survivorship may ameliorate the effects of the historical commercial harvest, with the slow growth rates, low reproduction success as well as the long generation times.
In addition to harvesting, other environmental factors have led to the declining ranges of the alligators snapping turtles. In this case, there is the loss of the of the species native habitat in areas associated with freshwater streams as well as the modifications of the nesting sites of these species. Research studies have investigated on the impacts of the hurricanes on the turtles habitat and results have indicated that, the hurricanes leads to the drastic decrease in the overall abundance of the turtle species (Schriever et al). Besides, the hurricanes altered the community composition as well as increased species evenness within the habitats on investigation as well as potentially affecting the long term community dynamics as well as the species interactions.
Harvesting of the Alligator Snapping Turtles
Research indicates that the alligator snap turtles have for long been harvested by the human as a source of food in the southeastern United States. However, there was a dramatic increase in the size of the market between the 1960’s and 1970’s. During the same period, the majority of the restaurants and dealers purchased vast numbers of the macrochelys. As a result, there was an increase in the number of alligator snapping turtles harvested with the aim of meeting the growing demand. Consequently, there was a decrease in the population sizes which was below the viability. Among other states in the US, there was also a depletion of the commercial market. Due to the large-scale harvesting of the reproductive turtle adults, it leads to the swift decline in most of the macrochelys population (Boundy et al.). However, due to inadequate data on the historical population sizes of the turtles, interviews were conducted with the turtle trappers as well as other individuals who exploited the resource. Due to the increase in harvesting of the turtles, it led to the legal protection of the turtle species especially in the regions where it occurs.
Impacts and the Solutions
Reintroduction is one of the methods that have been used as a conservative management tool for the species that have experienced population, but there have suitable habitats (East et al.). As such, this method is used with the aim of repopulating the areas that the species have extirpated as well as supplement the depleted populations that lack sufficient numbers for recovery without intervention. Research indicates that the method of reintroduction is often associated with particular drawbacks including; aberrant behavior which results from the captive rearing, increased mortality rates which of the released animals often attribute to the inexperience finding of the local resources and identifying and evading predators and finally low genetic diversity for the among the issued stock (Schriever et al.).
Previous studies shows that the reintroduction of the alligator snapping turtles has been successful and the species can thrive in a novel environment (Anthony et al.). Survival rates have varied by the age, the release site, however some other factors such as the mortality rates have led significantly to the survival rates. According to Anthony et al., despite the success in the reintroduction of the turtles, there is the need for continued close monitoring for the purpose of ascertaining the ultimate success of the endeavor.
Conclusion
The alligator snapping turtle is one of the large freshwater turtle in the Northern America. These turtles often inhibit the freshwater systems which are associated with the fluvial habitats including the lakes, swamps, ponds and the oxbows. Besides, these species occurs in the rivers which are associated with the habitats of several drainages. In the previous decades, there was a drastic increase in the commercial harvest of the species which led to their reduction, however, with implementation of various policies where the turtles are found has led to the conservation of the species. Some of the regulatory programs that have been employed include the restrictions which ban only commercial harvests of the turtles, purchase and sale as well as export. Therefore, there has been a drastic change in the habitats of the alligator snapping turtles which has also seen a reduction in the number of the species.
Work cited
Anthony, Travis, et al. "Monitoring of a reintroduced population of juvenile alligator snapping turtles." Chelonian Conservation and Biology 14.1 (2015): 43-48.
Boundy, Jeff, and Curtis Kennedy. "Trapping survey results for the alligator snapping turtle (Macrochelys temminckii) in southeastern Louisiana, with comments on exploitation." Chelonian Conservation and Biology 5.1 (2006): 3-9.
East, Mitchell B., and Day B. Ligon. "Comparison of diet among reintroduced and wild juvenile Alligator Snapping Turtles (Macrochelys temminckii) and adult female Ouachita Map Turtles (Graptemys ouachitensis)." The Southwestern Naturalist 58.4 (2013): 450-458.
Echelle, A. A., et al. "Conservation genetics of the alligator snapping turtle: cytonuclear evidence of range-wide bottleneck effects and unusually pronounced geographic structure." Conservation Genetics 11.4 (2010): 1375-1387.
Howey, Christopher AF, and Stephen A. Dinkelacker. "Characteristics of a historically harvested alligator snapping turtle (Macrochelys temminckii) population." Copeia 2013.1 (2013): 58-63.
Riedle, J. Daren, et al. "Microhabitat use, home range, and movements of the alligator snapping turtle, Macrochelys temminckii, in Oklahoma." The Southwestern Naturalist 51.1 (2006): 35-40.
Schriever, Tiffany A., et al. "Effects of hurricanes Ivan, Katrina, and Rita on a southeastern Louisiana herpetofauna." Wetlands 29.1 (2009): 112-122.
