You can’t always get what you want: fish, sensors and fishermen

Fishing is an important recreational activity in Trentino with an estimated economic impact of approximately €1.5 million per year in seasonal and daily fishing licenses, without considering revenue generated by equipment, participation in fishing tournaments, hospitality, etc. In this region, anglers’ expectations are geared towards trout (Salmo truta L) and fishing associations regularly stock brown trout to meet this demand. For higher altitude lakes however, stocking with brown trout is no longer permitted and provincial fish management plans require replacing non-native species such as brown trout and rainbow trout (Oncorhynchus mykiss) with native Arctic char (Salvelinus alpinus). This has led to complaints from stakeholders (resident and visiting anglers, wardens, associations) about lower catches with loss of revenue for anglers’ associations. While lower altitude lakes are often repeatedly stocked with brown trout, they do not always provide suitable habitats for salmonids. This is often the case where upstream water abstraction changes the hydrological regime of a lake that historically supported a trout population. Temperature sensors, such as iButtons and HOBOs, are an economical educational tool useful to illustrate the compatibility of seasonal water temperature with salmonid survival. Examples from Lakes Campo and Roncone are given.