Turtle Populations in Louisiana

The role of turtle populations in fresh water biology has been generally ignored although these animals may, in some areas, be the dominant vertebrates. Available information is inadequate to define precisely the relation of any turtle population to that of another animal. Analysis of the significance of aquatic turtle populations in fresh water requires information on the abundance and habitat preferences of each species. Trapping provides the best basis for estimating this information. Traps are unsatisfactory in that they are selective for certain size groups of each species and catches vary with the type of bait, method of set, water temperature, and water depth. Too, the first individual to enter a trap may determine the nature of the total catch. Thus a large Chelydra or Macrochelys in a trap will often prevent others from entering, and a female will attract males during the periods of sexual activity. Such factors must be considered when utilizing trap returns in population studies. Hand collecting tends to produce an abundance of Pseudemys, Chrysemys, and Graptemys but few A myda, Macrochelys, or Chelydra. Regardless of these factors in trapping, which cannot be evaluated at present, trap results are the best basis for determining relative abundance. Turtle traps were operated in 14 water bodies in Louisiana during the summer of 1947 (Fig. 1). The traps were made of 1" square mesh netting suspended on three 36" diameter steel hoops. An adjustable net throat was attached at one end and a draw string outlet at the other. Bamboo poles were used to spread the three hoops and to hold the traps in place. Bait (fresh gar, bowfin, catfish) was suspended in a can just in front of the open throat.