1. The Eel’s Amazing Migration: A Focus on the Adult Spawning Run
Sarah Mount

2. American eel
Anguilla rostrata
“Freshwater eels”
Catadromous

3. 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

4. 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

5. 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)

7. 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!

8. 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

9. 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

10. 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

11. 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

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

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

14. 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

15. 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

16. 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

17. 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

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

19. 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

20. 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!

21. Comic by Bella Dalton-Fenkl

22. Thank you! Questions?
Sarah Mount