Escaped farmed fish interact with wild populations in ways that have welfare implications for both groups. Understanding these interactions informs advocacy for better containment and escape prevention.
Fish escape welfare involves multiple groups of animals with different welfare interests. Escaped farmed fish face immediate welfare challenges: predator avoidance skills are lower than wild fish, behavioral repertoires adapted to farm conditions are maladaptive in the wild, and energy expenditure from escaping and surviving may be significant. Wild fish affected by competition with escapees experience resource competition and genetic changes over generations that affect population fitness. The welfare and conservation case for preventing escapes through better containment technology is strong. The welfare case for land-based recirculating systems that eliminate escape risk entirely is even stronger.