Manatee Necropsied at CMAST
A regular but uncommon summer visitor to NC waters suffered a catastrophic boat propeller injury to the head sometime shortly before October 15th in Bogue Sound. A 10.7-foot-long adult male Florida manatee (Trichechus manatus) was reported dead at 0815 am Tuesday morning. NC Division of Marine Fisheries Marine Patrol Officer Bolton towed it to a landing site near Gales Creek where a team of investigators from the North Carolina Division of Marine Fisheries, NC State CMAST, NC Aquariums, and UNC Wilmington conducted a postmortem exam.
Estimated to weigh in at over 1000 pounds, it could not be dragged all the way to land, so it was examined in knee-deep water. The animal was belly-up and could not be rolled over to examine its top side until weight had been reduced by examining and removing the underside and insides. Until it was rolled over, it had the appearances of a robust healthy animal, in good body condition with abundant internal fat stores and with stomach and intestines full of sea grasses. As soon as it was turned over, three parallel slices across the top of the head were immediately apparent, with the central slice cutting deep into the skull. It also had an older, mostly healed set of boat skeg and propeller scars over the center of its back.
Although better known from Florida, manatees are routinely sighted in North Carolina from spring through fall. Winter temperatures in North Carolina are too cold for their survival, so they migrate back south to warmer waters or risk suffering cold stress syndrome, which can be fatal.
Manatees are listed as threatened and are protected under the Endangered Species Act and are listed as depleted under the Marine Mammal Protection Act. Threats include natural causes (cold stress, harmful algal bloom toxins), human causes (boat strikes, net entanglements) and mixed causes (collapse of foraging habitat with high nutrient run-off destroying sea grass beds). Of the relatively few dead manatee strandings in NC (17 over 32 years), most have been attributed to cold stress, but wherever there are both boats and manatees, there is a high risk of boat strikes. Lacking a dorsal fin, manatees can be difficult to detect for boaters, and most manatees bear propeller scars on their backs.
If you spot a live manatee in NC waters, please report the sighting at the UNCW Sighting Manatee Website : https://uncw.edu/research/major-programs/marine-mammal-stranding/manatee-sighting. If you see a dead manatee in NC, please call 252.241.5119.
