Manatee Captures for Health Assessment
By Michael Mock
On November 9th and 10th 2011, Dr. Tucker selected five students from the conservation biology class to participate in manatee captures for health assessment in Crystal River, Florida. Students from the College of Coastal Georgia, as well as, veterinary students attending the University of Florida and other Universities and agencies worked alongside scientists from the United States Geological Survey and the Florida Fish and Wildlife Conservation Commission.
The Florida manatee is a large aquatic mammal that migrates to the warmer waters of Florida in the winter months of the year to thermoregulate. Manatees live in a wide variety of environments and can be found in areas as diverse as large urban waterways to freshwater artesian spring habitats with little human interaction and even salt marsh habitats. Manatees face a number of factors that make them vulnerable to population decline, making their well-being of particular interest to conservation groups. One of these factors is the manatee’s low reproductive rate, only having one calf every three years and having an 11-13 month gestation period. Along with the reproductive rate, the calf is usually dependent on the mother for two years which requires significant parental investment. Florida manatees are also thought to have low genetic diversity which could be the result of the founder effect, suggesting the population was started by only a few individuals or was dropped to a low number at some point in the past.
The purpose of the captures was to gain knowledge of the health, sex ratio, genetic diversity, and migratory patterns (through telemetry) of the manatees that were present in this area of Crystal River. With regular assessments, the data that is gathered can be used to show patterns and assess the health of the manatees in the area. It can be treated as a baseline for future studies as well. Is the population declining? Staying the same? Or is it improving?
Manatees were initially spotted by a team using a bridge as a good vantage point. Once spotted, a team on an adjacent beach was alerted and prepared to encircle the passing manatee with a large net being trailed from the capture boat. Once confined in the net, a team standing on the beach pulled the net in and landed the manatee on the shore. Lone manatees were targeted as to not separate a cow and calf pair in most cases, yet some pairs with older calves were captured. Once on the shore, the manatee was moved in a stretcher apparatus carried by 10-12 individuals to a transport boat to taxi the animal around the bend to the data collection beach. This small beach was outfitted with several tents which held different stations to gather various kinds of data. Being removed from an aquatic habitat and surrounded by strange people in the terrestrial environment caused the manatees to struggle in some cases, but for the most part were calm and kept as comfortable as possible. Blood was drawn, all vitals were checked first thing and small tissue samples were taken for genetic and contaminant analyses. The animals were also weighed and morphometric data was collected by measuring the length and girth of the animal at several points. The sex was also recorded. The manatees were scanned to see if it had any pit tags indicating it as being an individual that had already been previously captured. These pit tags are similar to the microchips that they put in your household pets nowadays. If no pit tag was found, one was implanted in each shoulder area and recorded in a log so the individual could be documented. One of the more interesting aspects of the captures was the photo identification of each manatee to include in the database of manatees using external features such as scars from boat strikes or any other distinguishing features. These photos are compiled to have a list of members of a population so identification can be done to recognize manatees if observed or captured at a later point. The manatees were kept on land for an average of an hour with regular application of water to the body and oxygen supplied to ensure their comfort and their health status.
This experience allowed me to get an idea of the kind of work and man hours required for the conservation efforts that go into the preservation of one species. The amount of data recorded in just two days will take a great deal of time to evaluate and used to make management efforts more efficient. The attention paid to detail, as well as the requirement of consistency were paramount while working with animals that are so important and fragile in an area. The care for the animal was also of high importance, making sure that conservation efforts do not cause more harm than good. Respect for the animal while gathering data was balanced well, so I believe that this particular event was successful and will go far in the protection and promotion of this important species.