Survival and growth of European eels stocked as glass‐ and farm‐sourced eels in five lakes in the first years after stocking
-
Published source details
Simon J. & Dörner H. (2014) Survival and growth of European eels stocked as glass‐ and farm‐sourced eels in five lakes in the first years after stocking. Ecology of Freshwater Fish, 23, 40-48.
Published source details Simon J. & Dörner H. (2014) Survival and growth of European eels stocked as glass‐ and farm‐sourced eels in five lakes in the first years after stocking. Ecology of Freshwater Fish, 23, 40-48.
Actions
This study is summarised as evidence for the following.
Action | Category | |
---|---|---|
Release wild-caught captive-reared eels to re-establish or boost native populations ('head-starting') Action Link |
![]() |
|
Translocate wild eels to re-establish or boost native populations (‘stocking’ or ‘restocking’) Action Link |
![]() |
-
Release wild-caught captive-reared eels to re-establish or boost native populations ('head-starting')
A replicated study in 2005–2010 at five lakes in Brandenburg, Germany (Simon & Dörner 2014) found that 8–17% of released wild-caught captive-reared European eels Anguilla anguilla survived after 3–6 years and were a similar size to translocated wild glass eels after 5–6 years. After 3–6 years, the percentage of eels surviving in each lake was estimated to be 8–17% for wild-caught captive-reared eels and 5–45% for translocated wild eels (difference not statistically tested). Five and six years after release, wild-caught captive-reared eels had similar average lengths (179–347 mm) to translocated wild glass eels (186–311 mm) in four of five lakes, despite being released at significantly larger sizes (average length: captive-reared = 165 mm; wild = 72 mm). In the other lake, too few eels were recaptured for analysis. Between 2004 and 2007, wild-caught captive-reared eels (55 eels/ha, average 7 g/eel) and translocated wild glass eels (200 eels/ha, average 0.3 g/eel) were released into each of five lakes (<20 ha) on two occasions in April–June. Eels were tagged and marked before release. Captive-reared eels were wild-caught in France as glass eels and reared at commercial eel farms. Wild glass eels were obtained from commercial fisheries in England. The lakes were previously stocked with farmed eels until 1997–2004. In May 2005–2009, each lake was sampled three times by electrofishing from a boat along the shoreline. Captured eels were identified, measured and weighed before being released. Survival rates were estimated from a mark and recapture experiment in April–June 2010.
(Summarised by: Anna Berthinussen)
-
Translocate wild eels to re-establish or boost native populations (‘stocking’ or ‘restocking’)
A replicated study in 2005–2010 in five lakes in Brandenburg, Germany (Simon & Dörner 2014; same sites as Simon 2023) found that translocated wild European glass eels Anguilla anguilla reached a similar size to released wild-caught captive-reared eels after 5–6 years. Five and six years after release, translocated wild glass eels had similar average lengths (186–311 mm) to wild-caught captive-reared eels (179–347 mm) in four of five lakes, despite being released at significantly smaller sizes (average length: wild = 72 mm; wild, captive-reared = 165 mm). After 3–6 years, the percentage of eels surviving in each lake was estimated to be 5–45% for translocated wild eels and 8–17% for wild-caught captive-reared eels (difference not statistically tested). Between 2004 and 2007, translocated wild glass eels (200 eels/ha, average 0.3 g/eel) and wild-caught captive-reared eels (55 eels/ha, average 7 g/eel) were released into each of five lakes (<20 ha) on two occasions in April–June. Eels were tagged and marked before release. Wild glass eels were obtained from commercial fisheries in England. Captive-reared eels were wild-caught in France as glass eels and reared at commercial eel farms. The lakes were previously stocked with farmed eels until 1997–2004. In May 2005–2009, each lake was sampled three times by electrofishing from a boat along the shoreline. Captured eels were identified, measured and weighed before being released. Survival rates were estimated from a mark and recapture experiment in April–June 2010.
(Summarised by: Anna Berthinussen)
Output references
|