The effect of a large-scale angling restriction in minimum angling size on harvest rates, recapture rates, and average body weight of harvested common carps Cyprinus carpio

Abstract

The Common carp, Cyprinus carpio, is a fish species of high value in commercial and recreational fisheries. Large-scale angling restrictions are often used to prevent the exploitation of fish populations by anglers. Since January 2016, the minimum legal angling size of common carp was increased from 35 cm to 40 cm TL in Czechia. This study aimed to estimate the effect of the restriction in minimum legal angling size on harvest, recapture rates, and the size of harvested common carps. Data from mandatory individual angling logbooks were used to assess the differences in harvesting common carp. This data was collected on 241 fishing sites by the Czech Fishing Union over years 2006–2017 in Prague and Central Bohemia. The goal was to compare harvest and recapture rates of common carp before and after the minimum angling size was increased. The resulted showed anglers performed 6.2 million fishing trips and harvested 2 000 tons of common carp over 12 years. Recapture rates of stocked common carps were an overall high at 107 % of biomass. The angling restriction had a significant effect on common carp harvest and recapture rates. Both harvest rates and recapture rates of stocked common carps decreased, and anglers also started harvesting larger common carps after the restriction was introduced. Harvest per effort was negatively affected by fishing effort and positively affected by fish stocking. The recapture rate was positively affected by fishing effort. A higher intensity of fish stocking led to a lower percentage of recaptured stocked common carps. The introduction of the minimum angling size did not lead to a lower interest in fishing by anglers. In conclusion, the decreased minimum legal angling size led to a decreased harvest and recapture rates of common carp even through increased fishing effort.