The Eel’s Amazing Migration: A Focus on the Adult Spawning Run Sarah Mount sarah.mount@dec.ny.gov

American eel Anguilla rostrata “Freshwater eels” Catadromous

1. American eels (Anguilla rostrata) hatch here Catadromous, spawn once, one breeding population. Define terms: Yellow and Silver. Note male and female differences. Transition from yellow to silver eel is focus of this study. 1. American eels (Anguilla rostrata) hatch here

Eel numbers are going down  Catadromous, spawn once, one breeding population. Define terms: Yellow and Silver. Note male and female differences. Transition from yellow to silver eel is focus of this study. 1. American eels (Anguilla rostrata) hatch here

Possible Factors Causing Recent Eel Declines Historic order of impact: Habitat loss Dams and barriers Water pollution Overfishing Hydroelectric turbines Climate change Food web changes Parasites (adapted from John Casselman, Queens College)

Hudson River Eel Project: Glass Eel Monitoring Each spring, nets are placed in the mouths of streams Teams of trained volunteers catch, count, and release eels You can get involved too!

1. American eels (Anguilla rostrata) hatch here Catadromous, spawn once, one breeding population. Define terms: Yellow and Silver. Note male and female differences. Transition from yellow to silver eel is focus of this study. 1. American eels (Anguilla rostrata) hatch here

Tagging adult eels Béguer-Pon et al. 2015 Many groups have tried to tag eels and track their migration to the Sargasso, but tags are large and either pop off too early or the eel is eaten Béguer-Pon et al. 2015

Until just a few months ago, when a study came out in which they could track ONE female eel to the northern edge of the spawning grounds. Still mysterious, lots to study and learn. Béguer-Pon et al. 2015

Daily vertical migrations Data from tagged eel on its way to the Sargasso. Vertical migrations early on are used to test salinity gradients. Later they help in predator avoidance and metabolic requirements of migration. Impairments to the swim bladder may impact ability to successfully reach spawning grounds Béguer-Pon et al. 2015

Study of eels in the Enderkill Albany NYC Study of eels in the Enderkill Summer and fall electrofishing surveys

Study of eels in the Enderkill Albany NYC Study of eels in the Enderkill Fall fyke netting for silver eels

PIT tags Eels ≥25 cm were tagged with unique IDs Measurements chosen to get at morphological changes from yellow to silver, preparing for ocean migration

Maturity indicator measurements Total length Weight Horizontal and vertical eye diameter Pectoral fin length Coloration change noted Measurements chosen to get at morphological changes from yellow to silver, preparing for ocean migration

Some Results! Since 2013 we’ve: Tagged 421 eels Recaptured 127 eels at least once, many multiple times Methods allow us to investigate: Growth (~1 cm/year) Movement (62% don’t move) Maturity

A stationary eel Some eels have been recaptured many times, always at the same site. This eel was caught at Site B six times! July 2014 August 2014 August 2016 September 2016 July 2017 August 2017

Data Story of Eel Maturity Albany NYC Data Story of Eel Maturity July, 2014 4x4 mm eye diameter 14 mm fin length Marsh

Data Story of Eel Maturity Albany NYC Data Story of Eel Maturity July, 2014 4x4 mm eye diameter 14 mm fin length October, 2014 6x6 mm eye diameter 17 mm fin length Marsh

Data Story of Eel Maturity Albany NYC Data Story of Eel Maturity July, 2014 4x4 mm eye diameter 14 mm fin length October, 2014 6x6 mm eye diameter 17 mm fin length Marsh Heading to the Sargasso!

Comic by Bella Dalton-Fenkl

Thank you! Questions? Sarah Mount sarah.mount@dec.ny.gov