American Eel (Anguilla rostrata) Monitoring in Florida

FWC is mandated by the Atlantic States Marine Fisheries Commission to monitor young-of-year and adult yellow eels in Florida. Since 2001, data have been collected for eels that inhabit northeast Florida waterways.

Recent reports have raised concerns over the status of the American eel stock and have urged increased protection. Observed declines in the abundance and recruitment of this stock may be due to overfishing, habitat degradation, chemical contamination, and/or oceanographic changes. An exotic swim bladder nematode, Anguillicola crassus, has infected some U.S. populations; this parasite may affect eel behavior and even cause death. Other factors in the decline may include mortality due to turbine operations of hydroelectric dams and the harvest of sargassum weed from its breeding habitat. Due to its complex life history, it is extremely difficult to determine cause and effect between these factors and the observed declines. Furthermore, because it is a panmictic spawner (meaning all individuals are considered one interbreeding stock), populations throughout its entire range must be monitored simultaneously using similar methods to determine what factors are most important and how best to protect the species.

In 1999, the ASMFC developed a Fishery Management Plan for American eel, which is an interstate cooperative effort to protect and enhance the Atlantic stock of American eel in the United States while providing for a sustainable harvest of the species. A total of 15 Atlantic coast states are involved in this effort. Each of these state agencies is mandated to collect both specific fishery-independent and -dependent data. As part of this requirement, FWC and University of Florida personnel conduct routine monitoring of young-of-year (also known as glass) eels at Guana River Dam (St. Johns County) and juvenile eels at Rodman Reservoir or Kirkpatrick Dam (Putnam County), from January to March. Over an eight-week period in January and February, dip-net sweeps are made twice every half-hour during flood tide at the Guana River Dam site on four randomly selected nights each week. During February and March, lift nets are used to sample juvenile eels twice per week at Rodman Reservoir Dam during randomly selected periods at night. In addition to obtaining catch data, the eels' length, weight, and pigmentation stage are recorded. These data have been collected since 2001 and, along with data from the other participating states, were used in the 2005 coast-wide stock assessment. Environmental parameters, such as conductivity, flow, and moon phase, are also recorded to determine what factors may be driving the inland migration and movement of this species.