Katherine J. Frisch- Katherine.Frisch@fwc.state.fl.us
Florida Fish and Wildlife Conservation Commission,
Florida Marine Research Institute,
100 8th Ave SE,
St. Petersburg, FL 33704
Popular version of paper 4aAB10
Presented Thursday morning, November 13, 2003
146th ASA Meeting, Austin, TX
Manatee researchers and wildlife managers continue to explore alternatives for optimally protecting manatees without unduly restricting human use of waterways. To date, manatee protection management in Florida has primarily consisted of speed restrictions for boaters in crucial waterways used by manatees and the establishment of refuges and sanctuaries that limit human use in critical manatee habitat. In an effort to provide additional management tools, the 2001 Florida legislature appropriated $200,000, annually recurring, to fund a program called the Florida Manatee Avoidance Technology Program in which technological solutions are explored to address the problem of collisions between manatees and boats.
The Florida Marine Research Institute (FMRI), a division of the Florida Fish and Wildlife Conservation Commission (FWC), was given the task of managing this program. The program began with a request for proposals that were evaluated by a selection committee appointed by FWC. The committee selected six proposals for funding. Four of the projects examine the potential for automatic manatee vocalization detectors to alert boaters to the presence of manatees in the vicinity. The other funded studies were investigations of how infrared or night vision cameras might be used to locate and count manatees and how sonar, much like that found in fish finders, might be used to show boaters when manatees are nearby. In addition to the six projects selected by the committee, FMRI funded work to develop a prototype manatee alerting device that works somewhat like a deer whistle.
Manatee vocalization detectors consist of a hydrophone (underwater microphone) attached to a microprocessor. The sounds picked up by the hydrophone are then analyzed by the microprocessor. Depending on how the device is programmed, the microprocessor will look at different parameters for determining if a sound is from a manatee. The microprocessor compares incoming sounds to what it has been programmed to recognize as manatee sounds. If a manatee sound is registered, the processor will send a message to a signaling device, such as a light or horn, which will alert boaters to be cautious because manatees are in the area.
The four research groups who worked separately on similar manatee vocalization detection projects were University of South Florida and Mote Marine Laboratory / Drs. David Mann and Douglas Nowacek; University of Florida and / Drs. Deke Beusse and Christopher Niezrecki; Lamp-Herbert Consultants / Dr. Thomas Herbert; and Mr. Randy Warner. Each research team developed its own device. FMRI coordinated lab and field-testing of the devices with the participants. Field tests were conducted using recordings of manatee vocalizations played in a natural environment (Listen to four example vocalizations, samples courtesy of Dr. Mann).
Results were mixed: correct identification of vocalizations ranged from 37% to 76% depending on the device. One factor that researchers had to consider was that detectors that were less sensitive than others might have fewer false detections but would also miss more vocalizations than would the more sensitive detectors. The main benefits of using such technology to detect manatees are that it warns boaters of manatees presence while not requiring manatees to change their behavior and that such a device could be placed on a buoy or post in a waterway making it easy to maintain. One drawback to this technology is that manatees may be present in an area but not vocalizing and therefore not detected, which could result in boaters having a false sense of security. Another problem is that because manatee sounds may not be very loud relative to the background noise, the detection devices would have to be very sensitive and placed fairly close together making this technology potentially expensive to implement.
Dr. Ed Keith of Nova Southeastern University explored the use of see-in-the-dark cameras and imaging for detecting manatees. Dr. Keith tested thermal infrared, night-vision, and night-shot video cameras and infrared imaging. The goal of the project was to use infra-red imaging cameras connected to a visual imaging system to determine how many manatees were in a given area and then display that number on a sign to alert boaters. He tested this technology with the theory that the system would be able to detect manatees exhaled breaths. Testing showed that manatee breaths did not show up as well as expected because the temperature of the air breathed out was close to the background air temperature (see picture below). He also found that most forms of infrared imaging did not penetrate water very well. Dr. Keiths results indicate that while there may be some applications for infrared technology there are also some drawbacks, including the expense of the equipment and imaging system and the inability of some infrared cameras to penetrate water.
Manatee exhaling at the surface.The nostrils are white in the image. The
animal is moving towards the lower right corner of the image (arrow). Photo
courtesy of Dr. Keith.
Dr. Ann Bowles of Hubbs-SeaWorld Research Institute proposed a project in which sonar is used to locate manatees in a way similar to that used by fish finders to locate fish. The sonar device would be attached to a buoy platform along with a signal that would be flashed to oncoming boaters when a manatee was detected alerting boaters that manatees are in the area. The success of this project will depend in part on how well manatees bodies reflect sound waves back to the detector as well as the range at which they can be detected. While testing has begun on captive manatees, the necessary permits for testing on wild manatees have not yet been approved. If sonar works in this context, it would be another method for alerting boaters to the presence of manatees without altering the behavior of the animals. In addition, use of a stationary buoy system would be low hassle for boaters who wouldnt have to maintain it. However, some people are concerned with the fact that sonar projects sound waves into the environment. Adding additional sound to the underwater environment may have unforeseen consequences, though the sonar frequencies used are well above the hearing range of manatees. There is also concern about the high cost of implementing such technology.
Dr. Edmund Gerstein (Florida Atlantic University) received funds to develop a prototype of a manatee alerting device (an acoustic alarm) attached to boat hulls that projects a beam of sound that could alert manatees to move out of the way of approaching boats. As with the sonar device, he also has not yet obtained a research permit that will allow him to test the device with manatees in the wild. This technology is controversial because it requires the manatee to avoid the boats, which is a change in the manatees behavior rather than that of the boaters. There is nothing inherent in the sound that will necessarily cause manatees to be afraid of it so avoiding the sound would be a learned behavior. Another concern is that this device, like the sonar device, adds sound to the underwater environment. This added sound may have unforeseen consequences, especially to other coastal animals in the area like dolphins who will be able to hear the device. Dr. Gerstein estimates that the devices will cost approximately $100 each, though in order to be effective, every boat in Florida would have to have one. This could pose problems for some boaters who might not be willing to purchase and maintain the devices.
The solution for the near future will likely be one that combines the use of technology with existing manatee protection efforts. Applying both science and new technology to manatee protection efforts could help manatees and boaters more effectively avoid each other, thus providing both with a safer environment. Though still in its infancy, projects like the Florida Manatee Avoidance Technology Program should be encouraged so that the latest advances in science and technology can be incorporated into wildlife management plans.
The final reports for the program studies that have been completed are available at http://www.floridamarine.org .