Acoustic monitoring using passive hydrophones is the primary tool for tracking the critically endangered vaquita porpoise, with fewer than 20 individuals believed to survive.
Individual vaquitas caught in gillnets drown in a traumatic death that takes minutes. This is both a severe individual welfare harm and a catastrophic conservation crisis at the population level. Remaining animals live in an environment of ongoing net entanglement threat, representing chronic stress. The 2017 capture attempt illustrates the tension between ex situ conservation and individual welfare. Current strategy prioritizes net removal and enforcement in the Upper Gulf Refuge to protect remaining individuals.