Risks to eastern Pacific marine ecosystems from sea-cage mariculture of alien Cobia

Mariculture of Cobia (Rachycentron canadum) has become popular in various regions of the world due to the species' hardiness, fast growth and high market value. Despite not being native to the Eastern Pacific, Cobia was introduced for offshore sea-cage aquaculture in Ecuador in 2015, with the first Cobia escape occurring there several months after that culture effort began. Here, we report on new sightings of mature Cobia in the Colombian Pacific coast in 2017 with evidence that this alien fish is able to integrate into food webs and reproduce in the region. Using a decision-support tool developed for aquatic species (Aquatic Species Invasiveness Screening Kit, AS-ISK), we screened Cobia to identify its potential of becoming invasive in the tropical eastern Pacific (TEP). Based on the present state of knowledge, AS-ISK results indicated that Cobia has a medium to high risk of becoming invasive in this region. These results indicate that Cobia sea-cage mariculture in the TEP is not advisable. Carangid fishes native to the TEP that are already used in sea-cage aquaculture elsewhere provide an alternative to Cobia mariculture.