The migration of stocked, trapped and transported, and wild female American silver eels through the Gulf of St. Lawrence

Published source details Béguer-Pon M., Verreault G., Stanley D., Castonguay M. & Dodson J.J. (2018) The migration of stocked, trapped and transported, and wild female American silver eels through the Gulf of St. Lawrence. Canadian Journal of Fisheries and Aquatic Sciences, 75, 2024-2037.
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This study is summarised as evidence for the following.

	Action	Category
	Capture and transport eels around dams/barriers (‘trap and transport’) Action Link
	Translocate wild eels to re-establish or boost native populations (‘stocking’ or ‘restocking’) Action Link

Capture and transport eels around dams/barriers (‘trap and transport’)

A controlled study in 2011–2014 in a river system in Ontario, Canada (Béguer-Pon et al. 2018) found that American eels Anguilla rostrata that were captured and transported downstream of dams were detected migrating to the ocean in similar proportions to eels that were not transported around dams. Overall, the proportion of eels detected migrating from the river system to the ocean did not differ significantly between eels captured and transported around dams (9%, 10 of 106 tagged eels) and eels not captured and transported (4%, 6 of 138 tagged eels). Each year in 2008–2014, large (>800 mm long) female yellow American eels were captured in commercial hoop nets (1,000–1,800 eels/year), tagged (in 2009–2011), and transported and released downstream of two large hydroelectric dams. In September–November 2011–2014, silver eels (106 transported, 138 not transported) were captured migrating downstream, tagged with acoustic transmitters, and released.  In 2011–2014, tagged silver eels were detected by acoustic receivers (154–186 receivers/year) deployed across a channel connecting the river system to the ocean. 

(Summarised by: Anna Berthinussen)
Translocate wild eels to re-establish or boost native populations (‘stocking’ or ‘restocking’)

A study in 2011–2014 in a river system in Ontario, Canada (Béguer-Pon et al. 2018) found that a greater proportion of translocated wild American eels Anguilla rostrata were detected escaping to the ocean than naturally occurring eels, but migration speeds were similar. Overall, a greater proportion of translocated wild eels were detected escaping from the river system to the ocean (20%, 27 of 134 tagged eels) than naturally occurring eels (4%, 6 of 138 tagged eels). Average migration speeds did not differ significantly between translocated (22–39 km/day) and naturally occurring eels (22–42 km/day). In spring 2005–2010, approximately seven million glass eels and elvers were captured in coastal regions and translocated to two lakes connected to the river system. In September–November 2011–2014, silver eels (134 translocated, 138 naturally occurring) were captured migrating downstream, tagged with acoustic transmitters, and released. In 2011–2014, tagged eels were detected by acoustic receivers (154–186 receivers/year) deployed across a channel connecting the river system to the ocean. Migration speeds were calculated for 46 eels (27 translocated, 16 naturally occurring, three origin not reported).

(Summarised by: Anna Berthinussen)