With less than a hundred individuals in the wild, the vaquita is the world's rarest marine mammal. This compact porpoise was only discovered in 1958 - a little over half a century later, the vaquita is at risk of total extinction. Vaquita are often caught and drowned in gillnets used by illegal fishing operations in protected areas within Mexico's Gulf of California. As a result, more than half of the population has been lost within the last three years.