Modelling daily catches of silver-phase European eel (Anguilla anguilla) in two hydropower-regulated rivers |
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| Authors: | Eamonn S Lenihan T Kieran McCarthy Colin Lawton |
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| Institution: | 1. Animal Ecology and Conservation Unit, Zoology, School of Natural Sciences, Ryan Institute, National University of Ireland, Galway, Ireland;2. Animal Ecology and Conservation Unit, Zoology, School of Natural Sciences, Ryan Institute, National University of Ireland, Galway, Ireland
Deceased |
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| Abstract: | Estimation of silver eel production, Anguilla anguilla L., is fundamental for the management of eel stocks. In the hydropower-regulated rivers Shannon and Erne, Ireland, production is calculated using catch data from a conservation trap and transport programme. However, in both rivers gaps in silver eel catch datasets tend to occur, which can lead to biases in production estimates. Generalised additive models (GAMs) were used to model daily catch in these rivers based on a variety of environmental variables. Final models for the Shannon and Erne explained 83.7% and 78.8% of deviance in daily catch, respectively. A second model on the Erne included catch from a nearby fishing site in an attempt to increase explanatory power and explained 91.7% of deviance. Although model accuracy was increased, reliance on catch from another site may limit the applicability of the model. Model predictions were combined with estimates of fishing efficiency to predict production for the Shannon (36,210 kg; 0.85 kg/ha) and Erne (66,899–67,047 kg; 2.55–2.56 kg/ha). These values represented a 9.3% and 2.8%–3.0% increase on production estimated from incomplete catch records alone for the Shannon and Erne, respectively. |
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| Keywords: | environmental factors generalised additive model hydropower migration production silver eel |
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