A caution for conservation stocking as an approach for recovering Atlantic eels

Published source details Stacey J.A., Pratt T.C., Verreault G. & Fox M.G. (2015) A caution for conservation stocking as an approach for recovering Atlantic eels. Aquatic Conservation: Marine and Freshwater Ecosystems, 25, 569-580.
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This study is summarised as evidence for the following.

	Action	Category
	Translocate wild eels to re-establish or boost native populations (‘stocking’ or ‘restocking’) Action Link

Translocate wild eels to re-establish or boost native populations (‘stocking’ or ‘restocking’)

A study in 2009–2011 in a river system in Ontario, Canada (Stacey et al. 2015) found that translocated wild American eels Anguilla rostrata had faster growing females, a higher percentage of males, and matured and migrated at smaller sizes compared to naturally occurring eels. On average, female translocated eels grew faster at ages 2–3 years (90–120 mm/year) than naturally occurring eels (53–56 mm/year). Growth rates did not differ significantly at ages one (101 vs 87 mm/year) and four years (53 vs 47 mm/year). A greater percentage of males were captured for translocated eels (40–52%) than naturally occurring eels (0%). Migrating translocated eels were reported to be shorter in length (average 651 mm) than naturally occurring eels (average 940 mm), although the difference was not tested for statistical significance. In 2005–2010, approximately 6.8 million glass eels captured in rivers by commercial fishers in Nova Scotia and New Brunswick were translocated to three sites in the river system. Eels were quarantined and marked before release. In May and September 2009–2011, translocated eels were captured during electrofishing surveys at two of the release areas. Naturally occurring eels were collected from an eel ladder at a power station. Captured eels (68 translocated, 96 naturally occurring) were weighed and measured, and a sample euthanized to determine age and sex. Migrating eels (191 translocated, 1,277 naturally occurring) were captured in the estuary of the river system by commercial fishers.

(Summarised by: Anna Berthinussen)