Utilizing eDNA and Plankton Sampling to Monitor American Eel Recruitment in Texas

Purpose/Objectives

The objective of this research was to collect juvenile American eels utilizing plankton nets in coastal waters along the central to upper Texas Coast, as well as collect eDNA samples in conjunction with an established eel ramp network to document the presence of the species in this region. The purpose of the ongoing research was to better understand the recruitment of American eel in Texas, providing critical data required by resource management agencies to determine the conservation and management needs of American eel populations in Texas.

Study Area

Central to upper Texas coast (Matagorda, Galveston, and Sabine Bay systems and adjacent coastal areas)

Project Period

2022 - 2023

Description

The American eel (Anguilla rostrata) is a catadromous panmictic species of greatest conservation need in Texas. In-water diversions and water control structures pose a potential threat to American eel because of their highly migratory, catadromous life history. An important area of study is the recruitment of juvenile (glass eel and elver) stages to the coastal waters of the state. This recruitment or ingress of glass eels and elvers is likely to regulate the long-term local population success of the species. Recently, extensive field efforts to document recruiting American eels along the Texas coast have not been successful at detecting any individuals. As a result, recommendations to explore other novel methods, such as eDNA, to document recruitment along the Texas coast have been made.

This study included a pilot-scale effort to utilize plankton nets at Gulf of Mexico passes and near coastal river mouths in an effort to detect ingressing juvenile eels. Additionally, we utilized eDNA sampling to detect the presence of American eels. These data helped to provide baseline information for detecting the spatial and temporal recruitment of American eel to the Texas Gulf Coast. This critical information will assist natural resource agencies in determining the conservation and management needs of American eel populations in Texas.

Publications and Presentations

Oakley, J.W., Kean, P., Sak, A., Underwood, E., Swinford, J., Anderson, J., Curtis, S., Davis, S., and Guillen, G. 2023. Utilizing eDNA and plankton sampling to monitor American eel recruitment in Texas. Final report. Prepared for the Texas Parks and Wildlife Department, Contract 0002501. EIH 23-014, 24 pp.

Oakley, J.W., Curtis, S., Hansen, J., Sak, A., Underwood, E., Swinford, J., Anderson, J., and Guillen, G. 2022. Determination to detect recruitment of American eel (Anguilla rostrata) in Texas. Texas Bays and Estuaries Meeting, Port Aransas, TX. Poster.

Oakley, J.W., Curtis, S., Swinford, J., Sak, A., Underwood, E., Kean, P., Anderson, J., Davis, S., Fredrickson, A., and Guillen, G. 2023. Eel ramps and eDNA to detect recruitment of American eel (Anguilla rostrata) in Texas. Annual Meeting of the Texas Chapter of the American Fisheries Society, Corpus Christi, TX. Poster.

Project Sponsors and Partners

• Texas Parks and Wildlife Department, River Studies Program
• Texas Parks and Wildlife Department, Coastal Fisheries
• Texas Parks and Wildlife Department, Perry R. Bass Marine Fisheries Research Center
• Lower Colorado River Authority

Related links

Distribution, Abundance, and Habitat Use of the American Eel

From sea to stream: tracking the elusive American eel as it slithers from Texas’ estuaries into its rivers, Texas Saltwater Fishing Magazine

Glass eels found in Texas for the first time, Texas Parks & Wildlife Magazine