The vaquita, the world’s smallest and most endangered marine mammal, is a rare and elusive species found exclusively in the northern Gulf of California. With fewer than 20 individuals remaining, the vaquita’s rarity is a result of a combination of factors, including its limited geographical range, specialized habitat requirements, and, most significantly, human activities.

• Limited geographical range: Vaquitas inhabit a small area in the upper Gulf of California, making their population naturally restricted. This confinement leaves them vulnerable to localized threats and reduces their ability to recover from population declines.
• Specialized habitat requirements: Vaquitas prefer shallow waters with a depth of around 50 meters, where they can find their preferred prey, such as small fish and squid. This habitat specificity further narrows their range and makes them susceptible to environmental changes and disturbances.
• Human activities: The most significant factor contributing to the vaquita’s rarity is human activities, particularly fishing. Vaquitas often become entangled in gillnets set for fish and shrimp, as well as those set illegally for the endangered totoaba. This bycatch has led to a dramatic decline in the vaquita population, pushing them to the brink of extinction.
• Low reproductive rate: Vaquitas have a relatively low reproductive rate, with females giving birth to a single calf every two years. This slow rate of reproduction makes it difficult for the species to recover quickly from population declines. Curiously, some research suggests that vaquita might be responding to their low numbers by increasing their reproductive output; like other porpoises, they might adapt by having a calf every year.