Inbreeding and Lesser Fishing Best Choice to Revive Population of Rare, Critically Endangered Gray Porpoise

International conservation agencies also consider one of the world's critically endangered mammals, called the vaquita marina, as the planet's most rare mammal at sea.

Commonly known as the gray porpoise, these mammalian species come in smaller sizes than their swimming cousins. The animals are distinguished easily from other marine-based mammals due to the striking black marks around their eyes and mouth.

Vaquita Marina's Near Extinction

(Photo: ALFREDO ESTRELLA/AFP via Getty Images)
Picture of makeshift porpoises taken during a demonstration by the World Wildlife Fund (WWF) on the International Day of Protecction of the Vaquita Marina demanding protection for this rare species of porpoise, in front of the National Palace at Zocalo square in Mexico City on July 8, 2017. Mexico announced plans on July 7 to use trained dolphins to corral the last remaining vaquita marina porpoises into a protected breeding ground, a last-ditch bid to save the critically endangered species. Scientists estimate there are just 30 remaining vaquitas, the world's smallest porpoise, a species found only in the waters of the Gulf of California. The WWF, which has warned the vaquita risks going extinct by next year, praised the move.

The most common sightings of this rare animal are only exclusive to the northern water bodies of Mexico's Gulf of California. According to the historical records, the species were pushed to near extinction due to overfishing activities.

The vaquita marina, or little sea cows, could be saved from being wiped out from the planet in a new study.

University of California's Institute for Human Genetics specialist and lead author of the study Jacqueline Robinson explained that there is still hope to revert the current state of the gray porpoise's populations.

Inbreeding is among the best solutions to improve the current number of vaquita marinas in the sea. According to a report by NPR, this approach would inflict minimal negative impacts on the animals while effectively increasing their remaining population.

Today, only ten little sea cow individuals are confirmed living in the Gulf of California.

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Robinson's team discovered that the inbreeding procedures could level up the chances of their survival by stunning rates if the plan is successful. Outcomes would also be better for the gray porpoises when they are prevented from being trapped in the gillnets scattered across the sea, as these submerged materials cause uncontrolled capture and drowning of the species.

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In the study, the experts said that the recorded vaquita populations are normally small. This resulted in fewer genetic variations among the individuals of the species. The little sea cows have a maximum weight of 45 kilograms or about 100 pounds and grow to only 1.5 meters or four to 5 feet in length.

Inbreeding to Increase Porpoise Population Ineffective if Humans Fish Excessively

Robinson said that their minimal population size and low genetic diversities throughout their evolutionary history could protect them from other common problems during inbreeding and might prevent an exaggerated decline in their populations.

The authors estimated the rates of their survival chance through a set of 20 genomes extracted from an archival tissue sample.

The vaquita marinas did not exceed 5,000 individuals throughout millennia due to their restricted habitat requirements. The sum even decreased over time due to illegal poaching activities, specifically in the regional waters of Baja California.

The area is also known as a habitat for the extremely endangered fish species of Totoaba macdonaldi. They are treasured due to their expensive swim bladders sold in the black markets of Asia.

If appropriately preserved, the vaquita marinas would have a 6 percent chance of being extinct for the next 50 years. However, the authors emphasized that these simulation estimates would be useless if the gillnets increase in numbers and there is a surge in overfishing activities.

The study was published in the journal Science, titled "The critically endangered vaquita is not doomed to extinction by inbreeding depression."

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