Research Activities: Siren and Amphiuma Population Demography

Background

       Apex-level studies are critical components of the ARMI program which include research on population estimates, demographic rates, and other long-term research on focal species.  In 2005 SEARMI began an apex mark-recapture study on the large aquatic salamanders Siren lacertina and Amphiuma means.  These large aquatic salamanders are often abundant in aquatic ecosystems in the southeastern U. S., but their life history is poorly known.

       This study is being conducted at Lake Suggs on the Katharine Ordway Preserve-Swisher Memorial Sanctuary, a property jointly owned by the Nature Conservancy and the University of Florida and managed by the UF Department of Wildlife Ecology and Conservation. This research project is a continuation of a project conducted from Aug 2001 – Jul 2002 by then ARMI biologist Kristina Sorensen (Sorensen, 2004).  In the initial study 58 A. means and 66 S. lacertina were marked using Passive Integrated Transponder (PIT) tags.  Due to the low recapture rate, calculation of growth rates in the initial study was difficult. 

       The objectives of the current study are to: (1) evaluate the population size and demographic structure for A. means and S. lacertina at Lake Suggs, (2) obtain growth rate and survival estimates for each species, and (3) understand activity and movement patterns of these species. 

Methods

       Sirens and amphiumas are collected at Lake Suggs using 20 mesh-lined crayfish traps which are set 5 m apart on permanent trap poles for four nights each month.  Data collected for all captured sirens and amphiumas includes snout vent length (SVL), total length (TL), and weight. Animals larger than approximately 150 mm TL are marked by injecting a PIT tag into the lateral tail muscle. Data are also collected on the number of other animals captured in each trap, including fish and invertebrates.

Results 

       ARMI began this project in Jun 2005, for a total of 380 trap nights through Nov 2005. Thus far we have 45 captures of sirens and amphiumas. Most of the animals we have caught thus far are relatively large in size, although we have caught more small sirens than amphiumas.  Our recapture rate of amphiumas appears to be higher than that of sirens.  Preliminary data are as follows:

Amphiuma means Siren lacertina Number of captures 21 24 Number marked 10 16 Number recaptured from 2001-2002 study 2 1 Total number recaptured 6 2  Snout vent length (mm) 496 274  Total length (mm) 665 409  Weight (g) 360 313

Future Plans

       This mark-recapture study will continue through 2006 and beyond as time and funds are available. We are encouraged by our recaptures from the initial study in 2001-2002, which provides new data on longevity of these species in nature.

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