Entanglement in and ingestion of fishing gear and other marine debris by Florida manatees, 1993 to 2012
Entanglement in and ingestion of marine debris by marine life has become a recognized threat worldwide, and the endangered Florida manatee is no exception. Manatees are known to become entangled in various types of fishing gear and other marine debris, and foreign objects are often found in the gastrointestinal tract of dead manatees. We examined a 20 yr dataset (1993 to 2012) of manatee rescue and necropsy records for evidence of entanglement in or ingestion of marine debris. In over 6500 manatee necropsy reports, over 11% either had ingested or showed evidence of entanglement in marine debris (or both). Fifty manatees died as a direct result of either entanglement in or, most commonly, ingestion of marine debris; fishery-related gear was involved in over 70% of these cases. With respect to live manatee rescues (n = 1244), over 25% were related to entanglement in or ingestion of fishery gear or marine debris, making entanglement the top anthropogenic reason for rescue during this time. Fishing gear, primarily trap lines and monofilament fishing lines, was a factor in over 85% of these rescues. Female manatees in particular were disproportionally affected by marine debris. The Florida manatee represents an example of estuarine fauna that is subject to harm from marine debris, and continued efforts to reduce and remove marine debris from estuarine environments will benefit manatees and other estuarine species.