Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 May 2007

Comparison of Diet, Reproductive Biology, and Growth of the Pig Frog (Rana Grylio) from Harvested and Protected Areas of The Florida Everglades

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Page Range: 436 – 448
DOI: 10.1643/0045-8511(2007)7[436:CODRBA]2.0.CO;2
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Abstract

Distinct differences in body size exist among three Rana grylio populations in areas of the Florida Everglades that differ in frog harvest pressure and hydroperiod. Frogs from two populations are harvested regularly throughout the year, while those in the third are protected from harvest. We compared seasonal and sex differences in diet, reproduction, and growth across these populations to examine life-history patterns. By volume, crayfish and anurans were the most abundant prey items for all adults across sites. Frogs from drier sites consumed more crayfish than frogs from the wettest site. Anurans were abundant in the diet during the wet season, while crayfish and fish were abundant during the dry season. More frogs with empty stomachs were captured during the wet season than the dry season. Feeding, growth, and fat deposition were greatest during the dry season across all sites. Although females were found in all reproductive stages throughout the year, the highest percentage of females had mature ova during the late dry season and spent ovaries during the early wet season. Individual patterns of growth were similar across all sites and matched historical growth data from the 1950s. Differences in body size among sites were most likely attributable to differential mortality (i.e., harvest pressure, predation) rather than to differences in food access or growth.

Copyright: 2007 by the American Society of Ichthyologists and Herpetologists
Figure 1
Figure 1

Map of south Florida showing collection sites. Lines represent canals, stippled area refers to Everglades National Park (ENP), and black dots represent collection sites.


Figure 2
Figure 2

Body size distributions of harvested (Site A SVL and Site B SVL, solid and triple lines, respectively) and protected Pig Frog populations (Site ENP SVL).


Figure 3
Figure 3

Selective size distributions of harvested (GSVL) and randomly collected capture–recapture (MSVL) Pig Frogs from Site A (Kolmogorov-Smirnov D = 0.6228, P < 0.001) and Site B (Kolmogorov-Smirnov D = 0.80, P < 0.001).


Figure 4
Figure 4

Percent of Rana grylio prey item numbers found at sites A, B, and ENP.


Figure 5
Figure 5

Percent of each Rana grylio sex–size class with empty stomachs throughout the year. Respective sample sizes for each season: males (n = 25, 24, 75, 38), females (n = 47, 26, 132, 48), and juveniles (n = 82, 73, 64, 26).


Figure 6
Figure 6

Relationship between body size (SVL) and mass for female Rana grylio across sites relative to historical data (Ligas, 1960).


Figure 7
Figure 7

Reproductive stages of female Rana grylio throughout the year from Sites A, B, and ENP.


Contributor Notes

Section editor: T. W. Reeder.

Received: 10 Feb 2005
Accepted: 29 Nov 2006
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