Status and Distribution of Manatees in Honduras and the Use of Side-Scan Sonar

<p>All manatee species are listed as endangered or vulnerable. Studying these animals is very challenging because of their reticent behavior and the remote and complex habitats in which they are found. This study dealt with three challenges in manatee conservation: identification of hotspots, manatee detection in turbid and tannin-stained waters, and regional collaboration between countries. Using the West Indian Manatee <em>(Trichechus manatus</em>) as the study subject, these three challenges were examined and possible solutions were presented.</p> <p>The distribution of manatees in Honduras is known from sporadic death reports and informal interviews. Like many other countries in Mesoamerica, Honduras had not been surveyed aerially for manatees for several decades, providing a substantial challenge to those wanting to develop a current recovery plan for the remaining population of manatees. Replicate aerial -surveys were flown over the northern coast of Honduras (Rio Aguan to Rio Tinto) to update manatee distribution and identify locations of importance along the coast. These surveys provided critical information about the distribution and relative abundance of manatees in northern Honduras. The results from these slirveys were compared to six replicate surveys conducted in 1979-80 to determine change in relative abundance. The average number of manatee sightings was significantly less than the prior study (p < 0.001). Finally, twenty-five manatee death records were compiled from interviews, museum specimens, and unpublished reports from 1970-2006 to determine the main threats to manatees. Most deaths resulted from entanglement in gillnets.</p> <p>Turbid and tannin-stained waterways are difficult habitats to study and manage aquatic wildlife, particularly when dealing with endangered and solitary animals. The use of side-scan sonar, which produces a picture-like image of the substrate and objects in the water column, was explored to acoustically detect West Indian Manatees in various environmental conditions and habitats. Blind transects (observer looked only at sonar image) were run in both Mexico and Florida to determine sonar detection rate. Good sonar images were produced during most environmental conditions experimented, as long as water movement was minimal, however, they could not be produced by rotating the transducer. Detection rates in Florida were 70% (95% with correction for hidden calves and animals beyond limit of sonar) and 93% in Mexico. This study concludes that sidescan sonar is sensitive enough to accurately detect manatees in the wild, and can be an effective and affordable tool to study and manage them throughout their range.</p> <p>The First Symposium for the Biology and Conservation of the Antillean manatee <em>(Trichechus manatus manatus)</em> in Mesoamerica, was held in Antigua Guatemala, Guatemala, November 1-2, 2006. The primary purpose of this symposium was to update the current knowledge about the status and distribution of Antillean manatee in Mesoamerica. The result of this symposium was the development of a Mesoamerican Manatee Research Workgroup, which aims to unite manatee research and conservation efforts within Mesoamerica.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year

2007

Author dc:creator

• Gonzalez-Socoloske, Daniel

Contributors dc:contributor

• Robert E. Ford
• William K. Hayes
• Leonard R. Brand
• Catherine A. Langtimm

• Biology
• Manatee; West Indian manatee -- Honduras; Animal behavior; Endangered species; Conservation biology.

Statement dc:rights

• This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Language dc:language

English

Repository record dc:identifier

https://scholarsrepository.llu.edu/etd/578

OAI identifier oai:identifier

oai:scholarsrepository.llu.edu:etd-1735