Application of the Manatee Photo-identification
Database for Population Research

Cathy A. Beck and Catherine A. Langtimm

U.S. Geological Survey, Florida Integrated Science Center, Gainesville, Florida

 Poster presented at the Manatee Population Ecology and Management
Workshop, 1-4 April 2002, Gainesville, FL
 

ABSTRACT – Many Florida manatees can be identified by the scars they bear from non-fatal encounters with boats.  Photographic identification records of these features have been collected for over two decades and have been used for research on adult survival, and to elucidated various life history traits.  In recent years new statistical techniques and the development of new models have enabled researchers to utilize the photo-identification data for more sophisticated research investigations.  Statistical estimation of adult survival has improved and now includes the ability to test for populations trends, to test hypotheses concerning environmental effects on survival, to determine reproduction success, and to model the success of proposed and existing management actions.

MIPS – Manatee Individual Photo-identification System:  The MIPS is a computerized database of manatee observational histories, created to provide an automated system to catalog, search and maintain data and images of individual manatees.  Image and sighting data collection began in earnest in 1978, although records for some individuals date to the late 1960's. The MIPS now totals nearly 2,000 individual manatees, recognizable by unique features, consisting almost exclusively of scars and mutilations from propeller strikes and entanglement injuries, as seen in the images below.

Photographs and data are collected primarily while the manatees are aggregated at warm water sites during winter.  These sites include natural springs and warm water industrial effluents.

Images are compared to those of known individuals in the MIPS. Matches enable additions to the sighting history of known manatees, and may add information on reproduction and other life history parameters.  Photographs of manatees that are not matched to known individuals eventually may be added to the database, once the individual meets the criteria for accession:  (1) complete photographic documentation of the back, sides, and tail and (2) the manatee has healed features that are unique enough to be recognized upon resighting. MIPS users can access the information by geographic region or by using queries that describe the features, identification number, or nickname of each manatee.

Manatee population research has evolved into a collaborative effort with experts from other USGS Science Centers. The research team includes manatee biologists from the FCSC, as well as Drs. James D. Nichols, Michael Runge, and William Kendall from Patuxent Wildlife Research Center (PWRC), and Ron Osborn from the Midcontinent Ecological Science Center (MESC). The PWRC team brings expertise on the development of new mark-resighting statistical models, population demographic models, and adaptive resource management models.  They are developing new mark-resighting statistical applications to address specific manatee issues, advising FCSC biologists on analyses with mark-resighting statistical models, and leading the population modeling efforts. Ron Osborn of MESC developed the MIPS program and provides invaluable system support.  He was responsible for the redesign of MIPS to an Access-based system utilizing available commercial software packages (Asymetrix Toolbook II©, MS Access 2000©, Corel Draw 8©).

Current and planned research using the MIPS database is broad, but focuses on many aspects of manatee population dynamics:

Reproduction success, estimation of reproduction rates, and cost of reproduction: Population models can assess the impact of reproductive effects on population growth rate. Many of the observational histories for females in MIPS includes reproduction information. Employment of multi-state models will be utilized to model reproduction probabilities.

Survival in relation to major environmental events (e.g. hurricanes, red tide, severe cold): In a retrospective analysis of 19 years of sightings of known individuals from the NW coast manatee population, we estimated adult survival rates with mark-resighting statistical models and found lower survival during three years with major hurricanes or extra-tropical storms.  With this same data set, we are estimating past storm effects on reproduction rate.

Assessment, rate of acquisition, and healing dynamics of nonfatal boat strikes: Since the documentation of manatees by distinct features is a continual effort and most individuals continue to acquire new scars, there is substantial information in the MIPS database to assess the frequency and impact of sub-lethal boat strikes on individuals and the population.  Multi-state mark-recapture statistical models now provide a valid means to estimate annual rates of acquiring new scars and to test for correlation with factors that could affect acquisition rates, such as the implementation of boating regulations for manatee protection.

Development of adaptive management models for evaluating management actions and use of a stage-based approach to model manatee population dynamics: For example, movement probabilities between industrial aggregation sites can be analyzed to determine if movements are correlated with availability of warm water.  Processes affecting annual estimates of survival, reproduction, or resighting can be modeled using recently developed techniques.

The MIPS is a valuable tool for manatee population research. Data from longitudinal studies are rare, especially for long-lived species, making this 20+year database essential for addressing short- and long-term research and management questions. Continued collection of photo-identification data can address questions concerning changes in population dynamics over time. Resightings of individual manatees has enabled the estimation of annual adult survival rates in each of the designated regions in Florida and is now the backbone of a USGS study to quantify, elucidate and understand processes in the population dynamics of this endangered species.  Retrospective analysis of the historical photo-id data will provide important information for management, which in turn can be used to design targeted photo-id studies to assess the success of new or proposed management actions.