Angler catch data as a population monitoring tool for non-indigenous European barbel Barbus barbus in a lowland river.

Abstract

Alien freshwater fish are often introduced to diversify angling experiences and enhance catch rates. European barbel Barbus barbus have been introduced into many rivers outside of their natural range for angling diversification, including the River Severn in western England, where they established, dispersed and now support a catch-and-release recreational fishery. This includes in its River Teme tributary, which has been renown for the quality of its catch-and-release barbel angling since the 1980s. However, since 2007, angler dissatisfaction has increased substantially in this fishery due to alleged declines in barbel catch rates and population abundances. These alleged declines were investigated here through analysis of fisheries monitoring surveys and angler catch data. Monitoring surveys revealed the mean number of sampled barbel per year has declined since the early 1990s, but has been relatively unchanged since the early 2000s. However, the number of surveys was low and varied considerably between years. Four analysed angler catch data sets, covering 1995 to 2016 and involving 981 captured barbel of 0.5 to 5.3 kg, did reveal a general pattern of declining barbel catch rates in recent years. These decreased catch rates were strongly apparent since 2010 and were generally coincident with reduced angler effort, suggesting low catches were at least partially responsible for the angler dissatisfaction. These results suggest there has been a substantial decline in the non-indigenous barbel population abundance and fishery performance in this river and highlights the utility of using angler catch data for analysing temporal changes in exploited fish populations.