Rapid response achieves eradication - Chub in Ireland

Abstract

Rapid reaction to the initial discovery of invasive alien species (IAS) is key to eradication, but this is often frustrated by lack of resources and coordinated actions. However, examples of successful eradications may encourage and empower others to follow. Chub (Squalius cephalus) were illegally introduced into the River Inny in Ireland in the late 1990s or early 2000s, reputedly by anglers. The habitat in this river is favourable for chub and, should this species establish, it would likely compete with the indigenous fish communities and impact on other flora and fauna. Central Fisheries Board (now Inland Fisheries Ireland) coordinated chub removal operations and provided the necessary resources (manpower and equipment) to effectively remove chub from this large river. Three electric fishing crews supported by two tank boats and land-based personnel were required in each operation to effectively remove the chub. These crews worked on this task each year between 2006 and 2013. Between 2006 and 2008, 24 adult and two juvenile chub were removed and euthanised. In 2008, two chub were radio-tagged, released back to the river and tracked monthly for 12 months. Over the next two years these “Judas” chub, and two untagged male chub that were located in proximity to the tagged fish, were removed from the river. Intensive electric fishing of the river and regular contact with the local angling community between 2010 and 2017 revealed no further chub specimens. Monitoring of the fish populations in the river will continue but it is suspected that chub may have been eradicated from this river system and, hence, from the island of Ireland. This provides a rare case study of the potential to eradicate aquatic IAS when rapid reaction is resourced and coordinated.