Modelling the impact of the regulation of estuarine drift‐netting on the declared rod catch of Atlantic salmon Salmo salar L. in the River Usk

• Published in: Freshwater Biology
• Main Authors: Bowker, Ferns, Phillips, Mawle
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1998
• Subjects: Usk; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1046/j.1365-2427.1998.00294.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-2427.1998.00294.x; https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2427.1998.00294.x

1. A novel method was used to determine if the statutory regulation of drift‐netting at the mouth of the River Usk in Wales was associated with a significant improvement in the stock and rod catch of salmon in the river upstream. 2. A linear regression model was constructed, in which the annual rod catch of salmon declared from the Usk between 1977 and 1988 was the dependent variable and the simultaneous annual catch declared from the nearby River Wye was the independent variable. The model was extrapolated to project the annual rod catches of salmon on the Usk, relative to the Wye, between 1989 and 1995. 3. The model accurately projected the actual rod catches declared from the Usk in 1989, 1990 and 1991. However, between 1992 and 1995 the declared catches deviated significantly ( P ≤ 0.05) from those projected by the model. The upsurge in rod catches declared after 1992 from the Usk, relative to the Wye was concomitant with the regulation of estuarine drift‐netting. 4. It was concluded that diminished estuarine exploitation had a beneficial impact on salmon angling success on the Usk. However, the utility of the model was restricted by inconsistencies in the methods used to generate the data, by changes in fishery management policies and by a lack of essential information on the interrelationships between catch, effort, stock and environmental conditions.